Why do I have high negative fuel trims?
#51
Driving my unreliable rx8
Thread Starter
Wow man, it drove me crazy as hell for a couple of months. I pulled my UIM about 5 times and was ready to roll it out of the garage and set it on fire. I can't imagine a year
#52
US Navy Rotary Enthusiast
iTrader: (3)
Yeah replaced my engine in January of 2012. Took of uim at least once a month and would recheck for cracks and seals and everything. Started to think I had a leak in the lim. I even posted YouTube videos and no one knew anything. After it got to 180 and the cat was nice and hot it would run fine.
#53
Glad y'all figured it out. I hunted this problem down in Fall 2012 after I had it rebuilt. I too was spraying highly flammable stuff through the bay hoping for a vacuum leak, but only managed to dry out some plastic.
Happy Tuning
Happy Tuning
#54
Flame On!
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High Negative LTFT after Hard 1rst gear pull
Didn't want to make a new thread... so I'm adding to this one...
2004 6spd GT, 122k ODO, aprox 70k miles on engine (LOW COMPRESSION, no starting/running issues).
MODS that might matter--
BHR Coils
Gutted cat w/catback
vFAD - disabled/blocked
TB by-passed
COBBAP - (Minor changes to OEM map) (No recent changes)
Oil catch can (intake capped, can vented)
I'll try to make this short and sweet... About a month ago I finally found my vacuum leak and got my LTFT back to near ZERO (use to be +7). Car has been running PERFECT since then till 2 days ago. (No other work done to car)
I was on my way home from work and decided to do a 1/2 pull before I got to my place... She pulled good thru both gears but out of nowhere, Blue/Black smoke started pouring out of the exhaust, and mean bad, like I couldn't see behind me anymore... So instead of pulling in to my street I kept going and about 2 miles down the road everything went back to normal.. (no smoke). Today I was checking it out and everything seems fine under the hood.
I went go drive it, I did a pull thru 3rd/4th nothing. Drove around some more and did a 1/2 pull right by my house and the same thing happened, tons of smoke right after letting off, followed by about 2 miles worth of "can't even see if someone is behind me" smoke. I skimmed thru the gauges on the GOODBox, LTFT -22, AFR 14.2 (4th gear @30mphish). After about 2 miles everything settled back to how it should be, no smoke, LTFT 0, AFR 14.7. All other gauges read normal.
The ONLY thing I am aware of that needs to be changed is the Air filter. When hunting down the vacuum leak I had removed the filter and accidentally stepped on the corner of it making a small 1inch tear the side of it. (A new one is ordered).
----Oh, and while it was pouring out smoke the engine ran fine, other than the smoke... Felt smooth, idled good. Restarting engine had no effect, still took 2 miles to clear up.
Anyone?
2004 6spd GT, 122k ODO, aprox 70k miles on engine (LOW COMPRESSION, no starting/running issues).
MODS that might matter--
BHR Coils
Gutted cat w/catback
vFAD - disabled/blocked
TB by-passed
COBBAP - (Minor changes to OEM map) (No recent changes)
Oil catch can (intake capped, can vented)
I'll try to make this short and sweet... About a month ago I finally found my vacuum leak and got my LTFT back to near ZERO (use to be +7). Car has been running PERFECT since then till 2 days ago. (No other work done to car)
I was on my way home from work and decided to do a 1/2 pull before I got to my place... She pulled good thru both gears but out of nowhere, Blue/Black smoke started pouring out of the exhaust, and mean bad, like I couldn't see behind me anymore... So instead of pulling in to my street I kept going and about 2 miles down the road everything went back to normal.. (no smoke). Today I was checking it out and everything seems fine under the hood.
I went go drive it, I did a pull thru 3rd/4th nothing. Drove around some more and did a 1/2 pull right by my house and the same thing happened, tons of smoke right after letting off, followed by about 2 miles worth of "can't even see if someone is behind me" smoke. I skimmed thru the gauges on the GOODBox, LTFT -22, AFR 14.2 (4th gear @30mphish). After about 2 miles everything settled back to how it should be, no smoke, LTFT 0, AFR 14.7. All other gauges read normal.
The ONLY thing I am aware of that needs to be changed is the Air filter. When hunting down the vacuum leak I had removed the filter and accidentally stepped on the corner of it making a small 1inch tear the side of it. (A new one is ordered).
----Oh, and while it was pouring out smoke the engine ran fine, other than the smoke... Felt smooth, idled good. Restarting engine had no effect, still took 2 miles to clear up.
Anyone?
#55
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Sounds like oil getting ingested into the intake, being ingested, generating a lot of smoke, and the O2 sensor getting coated in oil, which would give it a very hard time reading any oxygen at all.
#60
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Well I got a "more mechanically inclined than me" friend heading over to have a drive/look in/at it. And I'll grab a data log too while I'm at it.
If it is a oil control ring failing, I'll assume there is no fix other than rebuild, like the Rx-7? My first FC had a similar issue, tho it was never solved and argued to death on 7club, between the mechanical mop and oil control rings failing. That POS made it another 70k miles before I sold it for another one.
If it is a oil control ring failing, I'll assume there is no fix other than rebuild, like the Rx-7? My first FC had a similar issue, tho it was never solved and argued to death on 7club, between the mechanical mop and oil control rings failing. That POS made it another 70k miles before I sold it for another one.
#65
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Unless perhaps it's only recording 60, but is actually higher or "full open" (figuratively speaking), letting engine vacuum suck as much oil through the lines as possible?
(Similar to how the AFR won't record above or below a certain point, but can still be higher or lower)
(Similar to how the AFR won't record above or below a certain point, but can still be higher or lower)
#67
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Oh, but it would... lol. I generally run a stock map, except for a few minor adjustments. But I have experimented in the past... At idle it will blow tons of blue smoke...
Unless perhaps it's only recording 60, but is actually higher or "full open" (figuratively speaking), letting engine vacuum suck as much oil through the lines as possible?
(Similar to how the AFR won't record above or below a certain point, but can still be higher or lower)
(Similar to how the AFR won't record above or below a certain point, but can still be higher or lower)
I want to also add here when I initially started the car it ran extremely ruff for about 2 mins (no smoke). AFRs were +16, STFT -13... Cleared up on it's own, but was idle hunting a little, I assume the new spark plugs are toast, again....
#69
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would it make too much sense to open up the intake and verify whether or not oil ingestion has occurred? It might help to keep the discussion intelligent.
60 on the MOP map is not enough oil injection to cause what you described.
oil ring failure is more of an issue on the Renesis than the 13B due to the side seals overlapping onto the side exhaust port, just pointing that out, not saying it is related to what is happening
the MOP rate increased because that is also where the PCM transitioned to open loop control
60 on the MOP map is not enough oil injection to cause what you described.
oil ring failure is more of an issue on the Renesis than the 13B due to the side seals overlapping onto the side exhaust port, just pointing that out, not saying it is related to what is happening
the MOP rate increased because that is also where the PCM transitioned to open loop control
#70
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I'll open it up first thing in the morning just for you sir. Although, I would be clueless on to how it got there... Oil neck line goes to catch can which is vented. But hey, I've seen stranger things, and It will only take a sec.
Also, I checked the oil level again just now after a drive on the stock mop map (+1) It was at the half way mark... sure did burn that oil fast, but I did put a good beating on her too several times today...
Did some more logging, I went out to I-10 and pulled over by the on-ramp to let her finish warming up and she was blowing a little smoke.. Cleared up by the time it finished warming up. Tried to repeat the same scenario, over and over again, nothing, she performed flawlessly minus the ruff idle from the rest.
Also, I checked the oil level again just now after a drive on the stock mop map (+1) It was at the half way mark... sure did burn that oil fast, but I did put a good beating on her too several times today...
Did some more logging, I went out to I-10 and pulled over by the on-ramp to let her finish warming up and she was blowing a little smoke.. Cleared up by the time it finished warming up. Tried to repeat the same scenario, over and over again, nothing, she performed flawlessly minus the ruff idle from the rest.
#71
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Opened the intake, bone dry.
Went go drive it again.. Did a hard 1/2 pull on the on-ramp, nothing. About 2 miles later did a 3rd gear pull, smoked like crazy, STFT shot to -25, cleared up quickly. Did 2 more 3rd gear pulls, almost exactly the same as the first, no smoke, no high negative fuel trims...
Just seems like if it was oil control rings it would happen all the time.....
Went go drive it again.. Did a hard 1/2 pull on the on-ramp, nothing. About 2 miles later did a 3rd gear pull, smoked like crazy, STFT shot to -25, cleared up quickly. Did 2 more 3rd gear pulls, almost exactly the same as the first, no smoke, no high negative fuel trims...
Just seems like if it was oil control rings it would happen all the time.....
#75
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No, but the map I was using was probably close to a year old for the most part, changed the MOP values and fan temps about 4-5 months ago. Nothing else.
I'll load up the stock map and see what happens...
---
Just watched some youtube videos of flooded rx8's starting, matches the color of my smoke and the miss.... interesting... I've actually only flooded a rotary once... when I was 17, never again lol.
I'll load up the stock map and see what happens...
---
Just watched some youtube videos of flooded rx8's starting, matches the color of my smoke and the miss.... interesting... I've actually only flooded a rotary once... when I was 17, never again lol.
Last edited by 1.3_LittersOfFurry; 04-23-2014 at 10:58 AM.