Help with rough idle and deciphering AP datalogs
#1
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Help with rough idle and deciphering AP datalogs
Hi guys,
I need help resolving a mysterious issue with the idle stumbling at a stop sometimes and other weird car behavior. Can anyone look at the attached datalogs and tell me if anything pops out at you?
Some background on the car and symptoms: original 6-port engine with 74K miles. Compression was tested by Mazda last year and was good. Running OEM coils and plugs and Magnecor wires with 5K miles on them. No starting issues, hot or cold. Only relevant mods are an RB airbox, 3" midpipe with HJC cat and MM tune.
After an auto-x event a few months ago I threw a misfire CEL, accompanied by an idle stumble almost everytime I came to a stop and LTFT at idle in the neighborhood of -15%. Because of the misfire, I decided to replace the 2 trailing coils with old ones I had lying around. LTFT returned to normal and the car ran fine for ~400 miles.
Soon afterwards, LTFT at idle dropped again to -8% or so and the idle issues started again. The idle dips and then comes back up when stopped, either just once or repeatedly, but without stalling. Even when the idle is stable, you can feel the engine 'missing' every few seconds. No misfire codes. At some point, LTFT went from -8% to +6/+8% without me making any changes to the car. At this point I took some datalogs at WOT as someone suggested to me and noticed my AFR was in the 13.5-14 range past 7500 RPMs. It had never run so lean on this tune, so I immediately switched back to the MM base map because I was afraid of leaning out the car. Now it's not running lean anymore with the base map, but the idle problem persists and trims are still in the +5/+8% range (see attached datalogs).
I took the car to Mazda for diagnostics and they couldn't find an issue. They didn't see any misfires or vacuum leaks and they said the trims are 'normal' and the idle may be due to the 'old age' of the car. :p That still doesn't explain why it's happening, or why the car decided to run lean at WOT with the MM tune, or why the fuel trims at idle have been all over the place. I'm honestly stumped... Any help and suggestions would be highly appreciated!
I need help resolving a mysterious issue with the idle stumbling at a stop sometimes and other weird car behavior. Can anyone look at the attached datalogs and tell me if anything pops out at you?
Some background on the car and symptoms: original 6-port engine with 74K miles. Compression was tested by Mazda last year and was good. Running OEM coils and plugs and Magnecor wires with 5K miles on them. No starting issues, hot or cold. Only relevant mods are an RB airbox, 3" midpipe with HJC cat and MM tune.
After an auto-x event a few months ago I threw a misfire CEL, accompanied by an idle stumble almost everytime I came to a stop and LTFT at idle in the neighborhood of -15%. Because of the misfire, I decided to replace the 2 trailing coils with old ones I had lying around. LTFT returned to normal and the car ran fine for ~400 miles.
Soon afterwards, LTFT at idle dropped again to -8% or so and the idle issues started again. The idle dips and then comes back up when stopped, either just once or repeatedly, but without stalling. Even when the idle is stable, you can feel the engine 'missing' every few seconds. No misfire codes. At some point, LTFT went from -8% to +6/+8% without me making any changes to the car. At this point I took some datalogs at WOT as someone suggested to me and noticed my AFR was in the 13.5-14 range past 7500 RPMs. It had never run so lean on this tune, so I immediately switched back to the MM base map because I was afraid of leaning out the car. Now it's not running lean anymore with the base map, but the idle problem persists and trims are still in the +5/+8% range (see attached datalogs).
I took the car to Mazda for diagnostics and they couldn't find an issue. They didn't see any misfires or vacuum leaks and they said the trims are 'normal' and the idle may be due to the 'old age' of the car. :p That still doesn't explain why it's happening, or why the car decided to run lean at WOT with the MM tune, or why the fuel trims at idle have been all over the place. I'm honestly stumped... Any help and suggestions would be highly appreciated!
![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
#2
did you ask them to do another compression test? I would replace the plugs with a completely fresh set(all 4)
do you have a way to check fuel pressure? maybe the pump is failing? I'm just brain storming here. I can see the hiccup in the logs but its tough to say what exactly is causing it.
do you have a way to check fuel pressure? maybe the pump is failing? I'm just brain storming here. I can see the hiccup in the logs but its tough to say what exactly is causing it.
#3
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Hi guys,
I need help resolving a mysterious issue with the idle stumbling at a stop sometimes and other weird car behavior. Can anyone look at the attached datalogs and tell me if anything pops out at you?
Some background on the car and symptoms: original 6-port engine with 74K miles. Compression was tested by Mazda last year and was good. Running OEM coils and plugs and Magnecor wires with 5K miles on them. No starting issues, hot or cold. Only relevant mods are an RB airbox, 3" midpipe with HJC cat and MM tune.
After an auto-x event a few months ago I threw a misfire CEL, accompanied by an idle stumble almost everytime I came to a stop and LTFT at idle in the neighborhood of -15%. Because of the misfire, I decided to replace the 2 trailing coils with old ones I had lying around. LTFT returned to normal and the car ran fine for ~400 miles.
Soon afterwards, LTFT at idle dropped again to -8% or so and the idle issues started again. The idle dips and then comes back up when stopped, either just once or repeatedly, but without stalling. Even when the idle is stable, you can feel the engine 'missing' every few seconds. No misfire codes. At some point, LTFT went from -8% to +6/+8% without me making any changes to the car. At this point I took some datalogs at WOT as someone suggested to me and noticed my AFR was in the 13.5-14 range past 7500 RPMs. It had never run so lean on this tune, so I immediately switched back to the MM base map because I was afraid of leaning out the car. Now it's not running lean anymore with the base map, but the idle problem persists and trims are still in the +5/+8% range (see attached datalogs).
I took the car to Mazda for diagnostics and they couldn't find an issue. They didn't see any misfires or vacuum leaks and they said the trims are 'normal' and the idle may be due to the 'old age' of the car. :p That still doesn't explain why it's happening, or why the car decided to run lean at WOT with the MM tune, or why the fuel trims at idle have been all over the place. I'm honestly stumped... Any help and suggestions would be highly appreciated!![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
I need help resolving a mysterious issue with the idle stumbling at a stop sometimes and other weird car behavior. Can anyone look at the attached datalogs and tell me if anything pops out at you?
Some background on the car and symptoms: original 6-port engine with 74K miles. Compression was tested by Mazda last year and was good. Running OEM coils and plugs and Magnecor wires with 5K miles on them. No starting issues, hot or cold. Only relevant mods are an RB airbox, 3" midpipe with HJC cat and MM tune.
After an auto-x event a few months ago I threw a misfire CEL, accompanied by an idle stumble almost everytime I came to a stop and LTFT at idle in the neighborhood of -15%. Because of the misfire, I decided to replace the 2 trailing coils with old ones I had lying around. LTFT returned to normal and the car ran fine for ~400 miles.
Soon afterwards, LTFT at idle dropped again to -8% or so and the idle issues started again. The idle dips and then comes back up when stopped, either just once or repeatedly, but without stalling. Even when the idle is stable, you can feel the engine 'missing' every few seconds. No misfire codes. At some point, LTFT went from -8% to +6/+8% without me making any changes to the car. At this point I took some datalogs at WOT as someone suggested to me and noticed my AFR was in the 13.5-14 range past 7500 RPMs. It had never run so lean on this tune, so I immediately switched back to the MM base map because I was afraid of leaning out the car. Now it's not running lean anymore with the base map, but the idle problem persists and trims are still in the +5/+8% range (see attached datalogs).
I took the car to Mazda for diagnostics and they couldn't find an issue. They didn't see any misfires or vacuum leaks and they said the trims are 'normal' and the idle may be due to the 'old age' of the car. :p That still doesn't explain why it's happening, or why the car decided to run lean at WOT with the MM tune, or why the fuel trims at idle have been all over the place. I'm honestly stumped... Any help and suggestions would be highly appreciated!
![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
Ok sorry I'm better know.
I had a whole list of simple easy free things to check.
AutoX car is going to have more wear and tear.
Do all the easy stuff
- clean and reset maf
- check motor mounts
- check air filter
- clean maf
- check/replace all spark plugs
- check coils and leads using HEI Coil tester
- Check battery and terminals
Idle logs:
Positive LTFT not aways but can indicate a vacuum leak.
Actually the LTFT on the stumble log is better than the Normal log.
However the Normal idle log has a higher G/S and a better AFR, with the stumble log is leaner and a lower g/s value ... vacuum leak showing its presence? maybe
How far apart in time where these logs taken?
Where they both from the MM tune?
Same question with the WOT logs, both MM tunes?
Why did you ever switch from the MM tune in the first place?
What was this other tune you were using?
Did you and MM discuss that the car would be AutoX'd as I think he does run a bit more fuel up top with cars that are going to be run hard but I'm not sure what that AFR would be?
The WOT Logs you're running pretty rich for a NA "street car" (see above question)
Your reporting 12 and 11 AFR (LTFT is adding 3.74%) fuel at about 5700 rpm and up on both 2nd and 3rd WOT's
That could be causing your misfire.
I also noticed a weird blimp with the Throttle position in the WOT log at row 239 .. did you let off the throttle?
Something must have changed to cause all this ... I would be checking for vac leaks.
![Name: Wot2nd3rd_zpsb70b7eec.jpg
Views: 141
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Last edited by wcs; 01-03-2013 at 08:25 AM.
#4
I would check your MAF (clean it). I recently had the same issue after taking my 8 in for an oil change at the dealership.
They over filled my oil and I ended up getting some oil in my AEM intake tubing... I had the same symptoms (higher LTFT and slight shudder at idle; never stalling but it was noticable).
After cleaning my MAF and the intake tubing everything went back to normal.
They over filled my oil and I ended up getting some oil in my AEM intake tubing... I had the same symptoms (higher LTFT and slight shudder at idle; never stalling but it was noticable).
After cleaning my MAF and the intake tubing everything went back to normal.
#8
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![Big Grin](https://www.rx8club.com/images/smilies/biggrin.gif)
Do all the easy stuff
- clean and reset maf
- check motor mounts
- check air filter
- clean maf
- check/replace all spark plugs
- check coils and leads using HEI Coil tester
- Check battery and terminals
- clean and reset maf
- check motor mounts
- check air filter
- clean maf
- check/replace all spark plugs
- check coils and leads using HEI Coil tester
- Check battery and terminals
Idle logs:
Positive LTFT not aways but can indicate a vacuum leak.
Actually the LTFT on the stumble log is better than the Normal log.
However the Normal idle log has a higher G/S and a better AFR, with the stumble log is leaner and a lower g/s value ... vacuum leak showing its presence? maybe
How far apart in time where these logs taken?
Where they both from the MM tune?
Positive LTFT not aways but can indicate a vacuum leak.
Actually the LTFT on the stumble log is better than the Normal log.
However the Normal idle log has a higher G/S and a better AFR, with the stumble log is leaner and a lower g/s value ... vacuum leak showing its presence? maybe
How far apart in time where these logs taken?
Where they both from the MM tune?
Same question with the WOT logs, both MM tunes?
Why did you ever switch from the MM tune in the first place?
What was this other tune you were using?
What was this other tune you were using?
Did you and MM discuss that the car would be AutoX'd as I think he does run a bit more fuel up top with cars that are going to be run hard but I'm not sure what that AFR would be?
The WOT Logs you're running pretty rich for a NA "street car" (see above question)
Your reporting 12 and 11 AFR (LTFT is adding 3.74%) fuel at about 5700 rpm and up on both 2nd and 3rd WOT's
That could be causing your misfire.
Your reporting 12 and 11 AFR (LTFT is adding 3.74%) fuel at about 5700 rpm and up on both 2nd and 3rd WOT's
That could be causing your misfire.
I also noticed a weird blimp with the Throttle position in the WOT log at row 239 .. did you let off the throttle?
![Angel](https://www.rx8club.com/images/smilies/angel.gif)
![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
Something must have changed to cause all this ... I would be checking for vac leaks.
Same, the clutch has no effect.
Going to do that, even though I did it not too long ago. Glad it worked for you!
#11
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Yup, he's aware. He's not overly concerned about the idle 'stumble', but he doesn't know what caused the AFR/LTFT to change either. He thought it could be the weather, but it's been warm all along here.
Since that WOT log was taken with the Base map (not with a custom one), MM said that my car seemed leaner than typical for the Base map. And to clarify, the misfire CEL happened with the custom tune. I think I truly had a bad coil because at the time my car picked up a ton of negative trim (-14%) and after I swapped out the trailing coils, it was fine for a long while.
Since that WOT log was taken with the Base map (not with a custom one), MM said that my car seemed leaner than typical for the Base map. And to clarify, the misfire CEL happened with the custom tune. I think I truly had a bad coil because at the time my car picked up a ton of negative trim (-14%) and after I swapped out the trailing coils, it was fine for a long while.
It`s not just the temperature that can effect the trims but the Barometric pressure as well.
Generally +-3% LTFT is acceptable.
I don`t want to work against what you and Jeff have talked about.
Does he know you`ve switched back to the base map?
I`ve seen some of the Base Maps and they run super rich and are not intended to be used long term.
Because you are now back to a base map the LTFT is no longer relative, well relative in the sense that we can`t tell if we have corrected the initial problem.
You see when Jeff scales the Maf table, that's what removes the LTFT (all things being equal and mechanically sound) that is why on his custom tune you saw no trim for a long time.
Something happened and you started getting some trim, for example the failed coils. After fixing the coils, I would have just reset the ecu with the same custom tune and waited to see if I gained some trim again.
The base map you are running likely does not have a corrected or scaled maf table suited to your unique car.
So any trim values gained here could be because of the Maf table or something else.
Have you tried going back to the custom tune and putting a few drive cycles on it?
The trim values in the latest log are way better than the first post (which came from the custom tune so this makes sense).
Again I don`t have to mix up what you Jeff have decided on but I would go back to the Custom Tune. Drive around for a day or two and see what the trim looks like.
And just so we are on the same playing field ... what AFR range are you looking for at WOT?
edit:
Just reviewing that log in your latest post again. On row 21 I see the spike to 14.11 at 7395 rpm which is right after the VDI opens. Yeah that does seem lean but look at the Calc Load is only at 89% that must be the first gear pull. Things happen so fast in first gear.
The rest of the log looks fine at low to mid 13's
Also try turning off some of the logging parameters in the Cobb AP this will give us a higher logging resolution.
For example we don't need the knock or ignition timing stuff, Throttle Position and MOP
Last edited by wcs; 01-06-2013 at 10:16 AM.
#12
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Well today 6mtgirl and I met up not for another car shoot, but to help figure this issue out.
Used the starter fluid method for vac leaks as well as checked all the hoses and fittings; nothing
Motor mounts good
Air filter good
Battery and terminals good
Cleaned the throttle body even though it was already clean
Cleaned the crank sensor even though it was already clean
Intake tube has some residue in the bottom, possibly "cough up" from the oil pan. Advised for catch can as I have and will be looking into if a catch can is legal for STX class Auto-X..
Cleaned MAF (cant really tell if it was dirty or not, cleaned anyways especially with accordion residue..)
Checked for spark from coils; All seemed to spark very well with the exception of the front trailing coil. Front trailing seemed a little on the weak side, will get that addressed as soon as possible. If finances permit will get BHR setup, if not OEM for now..
Pulled plugs to check them, took pictures of my findings. Basically from looking at the photos it appears that the front trailing plug isnt firing very well. We believe this to be due to that coil not firing very strong.
Our current perspective on the situation is her front trailing coil is on its way out and her MAF is getting slightly dirty (especially after hard running autox events) from oil pan gunk coming up into the intake since she doesn't have a catch can. Couldn't find anything else that could be to blame. The ONLY other thing I believe it could be that we didn't discuss is the possibility of also there being an issue with the front O2 sensor not reading consistently.
Used the starter fluid method for vac leaks as well as checked all the hoses and fittings; nothing
Motor mounts good
Air filter good
Battery and terminals good
Cleaned the throttle body even though it was already clean
Cleaned the crank sensor even though it was already clean
Intake tube has some residue in the bottom, possibly "cough up" from the oil pan. Advised for catch can as I have and will be looking into if a catch can is legal for STX class Auto-X..
Cleaned MAF (cant really tell if it was dirty or not, cleaned anyways especially with accordion residue..)
Checked for spark from coils; All seemed to spark very well with the exception of the front trailing coil. Front trailing seemed a little on the weak side, will get that addressed as soon as possible. If finances permit will get BHR setup, if not OEM for now..
Pulled plugs to check them, took pictures of my findings. Basically from looking at the photos it appears that the front trailing plug isnt firing very well. We believe this to be due to that coil not firing very strong.
Our current perspective on the situation is her front trailing coil is on its way out and her MAF is getting slightly dirty (especially after hard running autox events) from oil pan gunk coming up into the intake since she doesn't have a catch can. Couldn't find anything else that could be to blame. The ONLY other thing I believe it could be that we didn't discuss is the possibility of also there being an issue with the front O2 sensor not reading consistently.
#13
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Great pics! Thanks
Yes, I hadn't thought about the front O2 sensor ... what year is the car?
The log data doesn't show a crazy afr reading, when my front O2 sensor died it bottomed out and wouldn't move.
I've also had a Maf sensor go as well.
Let's not get ahead of our selves here, those first two pictures of the spark plugs don't look normal. Well the first leading plug isn't bad but that trailing plug is fouled.
Do you have a timing light available?
Hook that up to the front trailing plug wire and rev the engine a bit. If the timing light stops flashing you've found at least one problem.
edit:
Hate to say it, any chance you can get a compression check on that front rotor?
We know the trailing plug is bad, why? Coil, Lead or Plug .. replace all dunno what your budget or time is like
What are your thoughts on the ECU Map? Have you switched back to the custom tune?
Did you remember to do the 20 brake stomp after cleaning the ESS?
There are different break points across the Maf table for the LTFT ... what are we getting at idle right now? Don't need a log file for this
Yes, I hadn't thought about the front O2 sensor ... what year is the car?
The log data doesn't show a crazy afr reading, when my front O2 sensor died it bottomed out and wouldn't move.
I've also had a Maf sensor go as well.
Let's not get ahead of our selves here, those first two pictures of the spark plugs don't look normal. Well the first leading plug isn't bad but that trailing plug is fouled.
Do you have a timing light available?
Hook that up to the front trailing plug wire and rev the engine a bit. If the timing light stops flashing you've found at least one problem.
edit:
Hate to say it, any chance you can get a compression check on that front rotor?
We know the trailing plug is bad, why? Coil, Lead or Plug .. replace all dunno what your budget or time is like
What are your thoughts on the ECU Map? Have you switched back to the custom tune?
Did you remember to do the 20 brake stomp after cleaning the ESS?
There are different break points across the Maf table for the LTFT ... what are we getting at idle right now? Don't need a log file for this
Last edited by wcs; 01-07-2013 at 06:28 AM.
#15
Project Seca
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We did test them using that tool, which is also why I said front leading coil seems to be firing on the weak side.
Great pics! Thanks
Yes, I hadn't thought about the front O2 sensor ... what year is the car?
The log data doesn't show a crazy afr reading, when my front O2 sensor died it bottomed out and wouldn't move.
I've also had a Maf sensor go as well.
Let's not get ahead of our selves here, those first two pictures of the spark plugs don't look normal. Well the first leading plug isn't bad but that trailing plug is fouled.
Do you have a timing light available?
Hook that up to the front trailing plug wire and rev the engine a bit. If the timing light stops flashing you've found at least one problem.
edit:
Hate to say it, any chance you can get a compression check on that front rotor?
We know the trailing plug is bad, why? Coil, Lead or Plug .. replace all dunno what your budget or time is like
What are your thoughts on the ECU Map? Have you switched back to the custom tune?
Did you remember to do the 20 brake stomp after cleaning the ESS?
There are different break points across the Maf table for the LTFT ... what are we getting at idle right now? Don't need a log file for this
Yes, I hadn't thought about the front O2 sensor ... what year is the car?
The log data doesn't show a crazy afr reading, when my front O2 sensor died it bottomed out and wouldn't move.
I've also had a Maf sensor go as well.
Let's not get ahead of our selves here, those first two pictures of the spark plugs don't look normal. Well the first leading plug isn't bad but that trailing plug is fouled.
Do you have a timing light available?
Hook that up to the front trailing plug wire and rev the engine a bit. If the timing light stops flashing you've found at least one problem.
edit:
Hate to say it, any chance you can get a compression check on that front rotor?
We know the trailing plug is bad, why? Coil, Lead or Plug .. replace all dunno what your budget or time is like
What are your thoughts on the ECU Map? Have you switched back to the custom tune?
Did you remember to do the 20 brake stomp after cleaning the ESS?
There are different break points across the Maf table for the LTFT ... what are we getting at idle right now? Don't need a log file for this
Trailing plug definitely fouled and likely not firing..
Didn't have one available, no.. but if need be we can get our hands on one.
She plans to test compression right before warranty is up, but should be okay..
Could be her coil and from using tester I believe it is at least part of the problem. wires are also rather difficult to get on plugs which also leads me to believe at one point possibly someone put the boots on the plugs but it wasn't properly connected to them, just something to look out for after changing coil and plug.
I have a rather open schedule and I'm sure 6mtgirl would be fine letting me work on her 8 to get it back on its feet again running strong. However budget is rather tight for her due to recent events...
It is reset, and after doing all the work on the car we let it idle and the LTFT started off at -3% and slowly worked up to 0%. That however was before going on the drives to go eat and stuff so the current LTFT is unknown to me.
#16
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![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
You see when Jeff scales the Maf table, that's what removes the LTFT (all things being equal and mechanically sound) that is why on his custom tune you saw no trim for a long time.
Something happened and you started getting some trim, for example the failed coils. After fixing the coils, I would have just reset the ecu with the same custom tune and waited to see if I gained some trim again.
Something happened and you started getting some trim, for example the failed coils. After fixing the coils, I would have just reset the ecu with the same custom tune and waited to see if I gained some trim again.
![Wallbash](https://www.rx8club.com/images/smilies/wallbash.gif)
Have you tried going back to the custom tune and putting a few drive cycles on it?
And just so we are on the same playing field ... what AFR range are you looking for at WOT?
edit:
Just reviewing that log in your latest post again. On row 21 I see the spike to 14.11 at 7395 rpm which is right after the VDI opens. Yeah that does seem lean but look at the Calc Load is only at 89% that must be the first gear pull. Things happen so fast in first gear.
The rest of the log looks fine at low to mid 13's
Just reviewing that log in your latest post again. On row 21 I see the spike to 14.11 at 7395 rpm which is right after the VDI opens. Yeah that does seem lean but look at the Calc Load is only at 89% that must be the first gear pull. Things happen so fast in first gear.
The rest of the log looks fine at low to mid 13's
Also try turning off some of the logging parameters in the Cobb AP this will give us a higher logging resolution.
For example we don't need the knock or ignition timing stuff, Throttle Position and MOP
For example we don't need the knock or ignition timing stuff, Throttle Position and MOP
2005.
Let's not get ahead of our selves here, those first two pictures of the spark plugs don't look normal. Well the first leading plug isn't bad but that trailing plug is fouled.
Do you have a timing light available?
Hook that up to the front trailing plug wire and rev the engine a bit. If the timing light stops flashing you've found at least one problem.
Hook that up to the front trailing plug wire and rev the engine a bit. If the timing light stops flashing you've found at least one problem.
![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
edit:
Hate to say it, any chance you can get a compression check on that front rotor?
We know the trailing plug is bad, why? Coil, Lead or Plug .. replace all dunno what your budget or time is like
Hate to say it, any chance you can get a compression check on that front rotor?
We know the trailing plug is bad, why? Coil, Lead or Plug .. replace all dunno what your budget or time is like
There are different break points across the Maf table for the LTFT ... what are we getting at idle right now? Don't need a log file for this
What concerns me now is the oil, vapor residue or whatever it is on on the intake tube - and enough of it to cause idle issues within a month of cleaning it. I haven't overfilled the oil and I always use a long neck funnel.
Last edited by 6MTGirl; 01-07-2013 at 10:53 AM.
#18
Registered
iTrader: (25)
Overfilling the oil sump is likely not the issue because it has to be 2+ qt.s over. All you can do is clean it and see if it comes back.
A timing light is a poor way to check coils. Even if it catches a weak spark (and theres a good chance you won't since its not load-based) how do you figure out if its the coil, wire, etc.? The tester is $15 at most parts stores.
Idle is heavily dependent on the trailing coils. If you think one is weak that would be a good place to start.
A timing light is a poor way to check coils. Even if it catches a weak spark (and theres a good chance you won't since its not load-based) how do you figure out if its the coil, wire, etc.? The tester is $15 at most parts stores.
Idle is heavily dependent on the trailing coils. If you think one is weak that would be a good place to start.
#19
Throttle body
For 3 years I had the rough idle problem My 04 has 104,000 miles on it now. the original motor. Finally 2 weeks ago the Idle got to the point where it would stall in traffic. I have been working a lot and have not been the DIY guy I use to be but I did some quick work. I changed the RB in take replaced the warped air filter and air flow control pipe. The car ran better but still was stalling. I broke down and brought it to the dealer. They found 2 motor mounts were bad and replaced them. The cars idle was smooth but it still was dipping and stalling in traffic. I brought it back to the dealer. They found that the throttle body was bad. Once they changed that the car runs as smooth as glass. I did do the coils and changed the plugs a year ago. I might check the coils again since I still feel a little lose of power. My cat is bad so that's next item on my list. My advice is check the throttle body. I believe this was the cause of my rough idle all along.
#20
Surf Hard, Drive Hard
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^...................wonder if the TB was truly bad, or just needed a good cleaning?
As stated in some other thread, I have put that one on my general maintenance list.
My car will act as you describe.........starts to act up in neutral coming to a stop and idle. Once I feel the RPM's start to move much below 750ish, it's time to clean it.
As stated in some other thread, I have put that one on my general maintenance list.
My car will act as you describe.........starts to act up in neutral coming to a stop and idle. Once I feel the RPM's start to move much below 750ish, it's time to clean it.
#21
Project Seca
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TB is fine, i checked it... Just spent a weekend with 6mtgirl in Sebring for some AutoX.. Even rode in the car with her to watch for changes. Everything was fine up until post AutoX when LTFT starting going positive again. Checked the intake accordion and there was oil residue. I'm very confident that its blow-by and other gunk coming up from the oil pan. Advising a catch can, however unsure if that is STX legal...
Waiting for 6mtgirl to chime in..
Waiting for 6mtgirl to chime in..
#22
Drive like a girl
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I took my car in for another compression test and to have the oil blowback checked out, since my engine warranty expires in a few days. The shop foreman told my SA that the oil in the intake tube could be caused by engine braking (supposedly a lot more vacuum is created when you get off the gas and the rpms drop than when you're actually on the gas). 'Splain that?
Also the shop foreman told my SA after driving the car that "this car doesn't need a new engine, it's got plenty of power, we replace engines on a weekly basis and I'd be afraid to put a new engine in it because it may end up with less power than it already has". And "we can do a compression test, but it would be a waste of money".
I had them do a test last year (3,500 miles ago) and the results were: front 8.24/8.67/8.67 and rear 7.46/7.46/7.46 normalized for 250rpm. That's more than a 1 kgf/cm2 difference between rotors, but the baro test was within spec and Mazda said no way are we replacing this engine.
The question is, with those numbers should I insist on another compression test and possibly a new engine?
Also the shop foreman told my SA after driving the car that "this car doesn't need a new engine, it's got plenty of power, we replace engines on a weekly basis and I'd be afraid to put a new engine in it because it may end up with less power than it already has". And "we can do a compression test, but it would be a waste of money".
I had them do a test last year (3,500 miles ago) and the results were: front 8.24/8.67/8.67 and rear 7.46/7.46/7.46 normalized for 250rpm. That's more than a 1 kgf/cm2 difference between rotors, but the baro test was within spec and Mazda said no way are we replacing this engine.
The question is, with those numbers should I insist on another compression test and possibly a new engine?
#23
Registered
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since the tube connects both before and after the throttle body my assumption is that a catch can on it would not technically be legal for STX. That particular hose is also shown as part of the emission system rather than the intake system so it seems to fail the test all around.
however, the avg competitor probably care less though it would be a possible way to lose money or points
and tell the genius mechanic that the tube bleed point is ahead of the throttle body and won't see vacuum there regardless. It simply gives combustion gases seeping into the oil sump an emissions-compliant place to flow to rather than accumulate in the sump and build up pressure or dumped out into the air as pollution.
.
however, the avg competitor probably care less though it would be a possible way to lose money or points
and tell the genius mechanic that the tube bleed point is ahead of the throttle body and won't see vacuum there regardless. It simply gives combustion gases seeping into the oil sump an emissions-compliant place to flow to rather than accumulate in the sump and build up pressure or dumped out into the air as pollution.
.
Last edited by TeamRX8; 01-16-2013 at 05:21 PM.
#24
Drive like a girl
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I will tell him tomorrow when I go to pick up my car. ![Big Grin](https://www.rx8club.com/images/smilies/biggrin.gif)
Dixie is looking like the only big event I'll be able to take the car to this year. But I can always remove the catch can for national events and keep an eye on the intake tube. Of course, I'll make sure my local competition is okay with me having it. Ruggles especially.
![Big Grin](https://www.rx8club.com/images/smilies/biggrin.gif)
Dixie is looking like the only big event I'll be able to take the car to this year. But I can always remove the catch can for national events and keep an eye on the intake tube. Of course, I'll make sure my local competition is okay with me having it. Ruggles especially.
![Wink](https://www.rx8club.com/images/smilies/wink.gif)