Engine misfiring at cruise with pegged 11.2 AFR-- Stalled at traffic light
#1
Engine misfiring at cruise with pegged 11.2 AFR-- Stalled at traffic light
Specs: 2005 GT - NA, Cobb AP, MM Tuned, BHR Coils, new plugs, Seafoamed last month.
As luck would have it these things happen on the way to an RX8 meet at MOSPORT International Speedway <sigh>
Situation:
- Cruise control set to 103 km, RPM's around 3100
- Engine starts running rough, holds speed. This continues for a few minutes, never gets a lot better but doesn't get worse.
- Approaching traffic light, I put car in neutral and it stalls, I re-engage clutch to start engine again.
- Pull over and car seems to idle fine
- Now I plug in the AP to monitor the situation
- Cruising down the highway AFR's are around 14.7 (good)
- After a minute or so the AFR pegs at 11.2, I can add some throttle and the AFR's respond and settle back to 14.7 at cruise. Rinse repeat.
- I get tired of this game and pull over at a coffee shop with a well light parking lot (it's 6am in morning)
- Engine idles for a minute and stalls.
- Starts back up <phew> Idles but is hunting/surging for a smooth level rpm. It almost stalls several times.
- During this I get out to try and inspect hoses and look/listen for whatever else. Check fittings etc. I find nothing.
- After a few minutes (maybe 5) the car finally settles down and idles fine.
- I say to myself "Self I still have a 2 hour drive ahead of me or a 40 minute drive home. Right home it is." Besides no use bringing a broken car to the track.
- On the way home the car runs perfect, better than perfect even. I thought that this was it, the last hooraw the engine is going to blow.
- No AFR pegging on the way back.
Impacting variables and items worth noting:
- Car has been running great lately, no issues
- Filled up with fuel yesterday, not at one of my regular gasoline stations (mmmmm misfire)
- Updated Cobb AP Software (maybe bug in software???? Pegging issue)
- No Cels generated
- Checked plugs yesterday to make sure they were in tight enough.
Ummmm yes, once in all my years of replacing plugs the last set I guess I didn't put in tight enough. So I'm a bit paranoid. I did get 1/8 - 1/4 turn out of all the plugs without really using a lot of muscle.
What could it be?
- I've been running this same tune for quite sometime and I've not lost power to the vechicle so I don't think ECU learning is an issue.
- Bad gas or vacuum leak?
- Cobb AP bug that happen to show at the same time as bad gasoline?
You guys got anything else please?
As luck would have it these things happen on the way to an RX8 meet at MOSPORT International Speedway <sigh>
Situation:
- Cruise control set to 103 km, RPM's around 3100
- Engine starts running rough, holds speed. This continues for a few minutes, never gets a lot better but doesn't get worse.
- Approaching traffic light, I put car in neutral and it stalls, I re-engage clutch to start engine again.
- Pull over and car seems to idle fine
- Now I plug in the AP to monitor the situation
- Cruising down the highway AFR's are around 14.7 (good)
- After a minute or so the AFR pegs at 11.2, I can add some throttle and the AFR's respond and settle back to 14.7 at cruise. Rinse repeat.
- I get tired of this game and pull over at a coffee shop with a well light parking lot (it's 6am in morning)
- Engine idles for a minute and stalls.
- Starts back up <phew> Idles but is hunting/surging for a smooth level rpm. It almost stalls several times.
- During this I get out to try and inspect hoses and look/listen for whatever else. Check fittings etc. I find nothing.
- After a few minutes (maybe 5) the car finally settles down and idles fine.
- I say to myself "Self I still have a 2 hour drive ahead of me or a 40 minute drive home. Right home it is." Besides no use bringing a broken car to the track.
- On the way home the car runs perfect, better than perfect even. I thought that this was it, the last hooraw the engine is going to blow.
- No AFR pegging on the way back.
Impacting variables and items worth noting:
- Car has been running great lately, no issues
- Filled up with fuel yesterday, not at one of my regular gasoline stations (mmmmm misfire)
- Updated Cobb AP Software (maybe bug in software???? Pegging issue)
- No Cels generated
- Checked plugs yesterday to make sure they were in tight enough.
Ummmm yes, once in all my years of replacing plugs the last set I guess I didn't put in tight enough. So I'm a bit paranoid. I did get 1/8 - 1/4 turn out of all the plugs without really using a lot of muscle.
What could it be?
- I've been running this same tune for quite sometime and I've not lost power to the vechicle so I don't think ECU learning is an issue.
- Bad gas or vacuum leak?
- Cobb AP bug that happen to show at the same time as bad gasoline?
You guys got anything else please?
Last edited by wcs; 09-18-2010 at 08:01 AM.
#6
Premix .... funny I wasn't running premix in this fill up.
I'm heading out shortly to the garage to do all the checks.
Why don't you get your *** up here and help me out and pick up or RB Gauge Pod kit.
Last edited by wcs; 09-18-2010 at 08:10 AM.
#7
Extraordinary Engineering
I hate saying bad gasoline, I can't ever recall having bad gasoline before. I guess there is always a first.
Premix .... funny I wasn't running premix in this fill up.
I'm heading out shortly to the garage to do all the checks.
Why don't you get your *** up here and help me out and pick up or RB Gauge Pod kit.
Premix .... funny I wasn't running premix in this fill up.
I'm heading out shortly to the garage to do all the checks.
Why don't you get your *** up here and help me out and pick up or RB Gauge Pod kit.
I'm going to try to stop by today...
#11
Extraordinary Engineering
I could tell you but then I'd have to kill you
I created a chart in Open Office (free )
Alt+PrtScn
Paste in Paint
Save as jpg
Post as attachment
So, what threw the fuel trims so far out of whack?
I created a chart in Open Office (free )
Alt+PrtScn
Paste in Paint
Save as jpg
Post as attachment
So, what threw the fuel trims so far out of whack?
Last edited by DarkBrew; 09-18-2010 at 09:15 AM.
#13
Update:
Can't find anything wrong.
I'm going to go with bad gasoline or a failing front O2 sensor.
I've not been able to reproduce the problem yet.
So I'll go out in a bit and refuel from one of my usual fueling stations, and/or wait for the O2 sensor to catastrophically fail.
Can't find anything wrong.
I'm going to go with bad gasoline or a failing front O2 sensor.
I've not been able to reproduce the problem yet.
So I'll go out in a bit and refuel from one of my usual fueling stations, and/or wait for the O2 sensor to catastrophically fail.
#14
Modulated Moderator
iTrader: (3)
There are a few other things that could make it go into spaz mode like that.....sensors...MAF, ECT, IAT...they should throw cel's..but stranger things have happenned
Bad gas is definitely one...I would throw some methanol into the tank to suck up the water and drive it.....was it raining a lot the few days before you left?
ECU glitch is another...sometimes they get a mind of there own....reset it and see what happens
Bad gas is definitely one...I would throw some methanol into the tank to suck up the water and drive it.....was it raining a lot the few days before you left?
ECU glitch is another...sometimes they get a mind of there own....reset it and see what happens
#16
There are a few other things that could make it go into spaz mode like that.....sensors...MAF, ECT, IAT...they should throw cel's..but stranger things have happenned
Bad gas is definitely one...I would throw some methanol into the tank to suck up the water and drive it.....was it raining a lot the few days before you left?
ECU glitch is another...sometimes they get a mind of there own....reset it and see what happens
Bad gas is definitely one...I would throw some methanol into the tank to suck up the water and drive it.....was it raining a lot the few days before you left?
ECU glitch is another...sometimes they get a mind of there own....reset it and see what happens
First thing MAF.
BTW I just came back from a nice cruise (haven't refueled yet) and I could not reproduce the problem and I hate to say it .... but the car seems to the butt dyno .... stronger.
Some logs for your perusal
Last edited by wcs; 12-12-2011 at 08:06 AM.
#20
rotary ninja
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you didn't disconnect the power or anything yesterday did you? What you describe is the kinda symptoms I normally get when power's been cut and the ECU tries to re-figure itself out... runs like **** for 30 minutes and threatens to stall all the time... then it finds it's way and everything's fine.
#21
Extraordinary Engineering
Just got back from visiting my daughter in Barrie
I was going to drop in @ your place to see how things are going...
Got no answer so I'm sitting home drinking instead!
I was going to drop in @ your place to see how things are going...
Got no answer so I'm sitting home drinking instead!
#22
Yaaa ... ummm I've not done a compression test ... some things you don't wanna know ... if you know what I mean ...
That being said I pulled a 196 HP on the dyno 2 month ago, I hope things haven't degraded that much since then.
17 hg vacuum on a heat soaked motor at idle.
Absolutely positive I've not lost power .... well in the sense that I didn't disconnect the batter and the car started no issue ....
But I hear you .....
I'm going with the water in the gasoline theory which has never happened EVER before to me .... with any car.
I'll report tomorrow and Monday on my progress....
Thanks everyone!
That being said I pulled a 196 HP on the dyno 2 month ago, I hope things haven't degraded that much since then.
17 hg vacuum on a heat soaked motor at idle.
you didn't disconnect the power or anything yesterday did you? What you describe is the kinda symptoms I normally get when power's been cut and the ECU tries to re-figure itself out... runs like **** for 30 minutes and threatens to stall all the time... then it finds it's way and everything's fine.
But I hear you .....
I'm going with the water in the gasoline theory which has never happened EVER before to me .... with any car.
I'll report tomorrow and Monday on my progress....
Thanks everyone!