Still having issues-take two
Thread Starter
Melting Slicks
Joined: Jan 2007
Posts: 3,333
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From: Athens OH
Still having issues-take two
Some of you may remember my earlier thread about my mods. Earlier this year I did a number of mods. P1SC, Ported LS6 heads, LS6 intake, blower cam, Kooks headers with X-pipe and cats, LG fuel pump, 60lb inj, KB BAP, SPA boost and FP gauges, AEM wideband O2. I also installed a Spec stage 3+ clutch.
Had it tuned and it ran decent. WOT was great. it was 520HP/466TQ on 6lbs of boost. When cold, it cranked for a while before it would start. The wideband seemed a little erratic. It also had an occasional jerking or bucking like a dead miss or surge or something. Very similar to the bucking when driving in a gear too low. I took it back to the tuner to get it smoothed out.
I got it back and it put down 545HP/491TQ and gets slightly better mileage. I'm guessing they leaned it out a bit more. It runs incredibly well at WOT.
I am still getting the bucking movement and it seems to be more prevalent. and the wideband is still erratic and goes lean when cruising at a steady speed. I wonder if it is leaning out and misfiring or something.
Here are a couple of videos of the WB in action. It's a cell phone vid taken while driving so it isn't the best quality but you should get the idea.
At Idle(~900RPM)
Cruise control set at about 65 MPH at ~1500 RPM in 6th gear
Had it tuned and it ran decent. WOT was great. it was 520HP/466TQ on 6lbs of boost. When cold, it cranked for a while before it would start. The wideband seemed a little erratic. It also had an occasional jerking or bucking like a dead miss or surge or something. Very similar to the bucking when driving in a gear too low. I took it back to the tuner to get it smoothed out.
I got it back and it put down 545HP/491TQ and gets slightly better mileage. I'm guessing they leaned it out a bit more. It runs incredibly well at WOT.
I am still getting the bucking movement and it seems to be more prevalent. and the wideband is still erratic and goes lean when cruising at a steady speed. I wonder if it is leaning out and misfiring or something.
Here are a couple of videos of the WB in action. It's a cell phone vid taken while driving so it isn't the best quality but you should get the idea.
At Idle(~900RPM)
Cruise control set at about 65 MPH at ~1500 RPM in 6th gear
Burning Brakes
Joined: Jul 2004
Posts: 1,172
Likes: 71
From: MA
Possible air leak?
I am no expert at this, but could you possibly have an air leak somewhere?
My Innovate fluctuates by about .5, much less than yours does. As I understand the way the BCM works, it cycles between lean and rich when in closed loop to keep the cats functioning properly. But yours seems to be cycling much more leaner than mine. Perhaps your tune is off when in closed loop.
My Innovate fluctuates by about .5, much less than yours does. As I understand the way the BCM works, it cycles between lean and rich when in closed loop to keep the cats functioning properly. But yours seems to be cycling much more leaner than mine. Perhaps your tune is off when in closed loop.
Thread Starter
Melting Slicks
Joined: Jan 2007
Posts: 3,333
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From: Athens OH
It does fluctuate quite a bit, but I don't know how much is normal. What bothers me the most, though is that lean spike. Sometimes it just shows dashes where the numbers are. I know they replaced the 02 sensor, thinking that it was bad and causing the fluctuations, so it should be in there tight. I am pretty sure everything is tight, but if I get a chance to get it in the air, I'll doublecheck things.
Last edited by AMRAAM; Oct 19, 2008 at 10:31 PM.
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
I was just tuning a friends car yesterday. It likes to buck when trying to take off and cruise at low rpm's. Adding fuel helped a little until the adaptives took over and adding timing helped completely. Down low, I added 6°
Thread Starter
Melting Slicks
Joined: Jan 2007
Posts: 3,333
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From: Athens OH
Sounds very similar to my issue. Wanna come to Ohio for a dayor two? If that is the issue, why did the tuner not see that?
Thread Starter
Melting Slicks
Joined: Jan 2007
Posts: 3,333
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From: Athens OH
Also, would the timing affect the readings that the wideband is getting?
Race Director
Joined: Jan 2003
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From: San Antonio Texas
St. Jude Donor '05-'06-'08
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Melting Slicks
Joined: Jul 2005
Posts: 2,586
Likes: 2
From: Bardstown Kentucky
I wouldnt say lazy.. I have seen a car do this before. It sounds like the RAF table is not adjusted right at idle, causing the engine to kind of float in RPM. I am guessing this because of the blower whistle I hear jumping around. That kind of RPM change will hit the 02's with weird airflow, causing them to do their job just in a weird fashion. I would get a good idle tuner to fix that problem. I have also seen a lean creep like you explain driving at a constant speed. Its a little harder to explain in text... 
Melting Slicks
Joined: Jul 2005
Posts: 2,586
Likes: 2
From: Bardstown Kentucky
Edit: just watched the second video... Its not a "creep" at all, it fluctuates a lot. I would check the 02 bung to make sure its tight first but a lot of that is probably in the tune. If you can get a copy of some logs sent to me I will tell you if the 02's are going bad. How long did the tuner take to do the driveability tune for your car?
Burning Brakes
Joined: Oct 2003
Posts: 816
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From: peabody ma
mine was doing that exactly (seeing it on my aem a/f readout) I put the stock tune back in and even though i see the lean spike (not as bad but still there so it must be normal operation) i didnt get the bucking at steady throttle......
it also bucks a lot worse if i just ease up on the gas (not completely off the gas but just easing up)
i thought it was because i might have had my long term trims way off but now im not sure.......I might try to add a little timing at low rpms to see if that takes care of it with the tune..
I also replaced both my o2 sensors and it still did the same thing.....very interested in others opinions on this....i have a predator custom tune
it also bucks a lot worse if i just ease up on the gas (not completely off the gas but just easing up)
i thought it was because i might have had my long term trims way off but now im not sure.......I might try to add a little timing at low rpms to see if that takes care of it with the tune..
I also replaced both my o2 sensors and it still did the same thing.....very interested in others opinions on this....i have a predator custom tune
Thread Starter
Melting Slicks
Joined: Jan 2007
Posts: 3,333
Likes: 0
From: Athens OH
Edit: just watched the second video... Its not a "creep" at all, it fluctuates a lot. I would check the 02 bung to make sure its tight first but a lot of that is probably in the tune. If you can get a copy of some logs sent to me I will tell you if the 02's are going bad. How long did the tuner take to do the driveability tune for your car?
I couldn't tell you how long they spent tuning. I have had a number of issues since I started this project so they have spent a lot of time on a number of things.
I don't have the ability to log at the moment. What do I need to do that?
Thread Starter
Melting Slicks
Joined: Jan 2007
Posts: 3,333
Likes: 0
From: Athens OH
mine was doing that exactly (seeing it on my aem a/f readout) I put the stock tune back in and even though i see the lean spike (not as bad but still there so it must be normal operation) i didnt get the bucking at steady throttle......
it also bucks a lot worse if i just ease up on the gas (not completely off the gas but just easing up)
i thought it was because i might have had my long term trims way off but now im not sure.......I might try to add a little timing at low rpms to see if that takes care of it with the tune..
I also replaced both my o2 sensors and it still did the same thing.....very interested in others opinions on this....i have a predator custom tune
it also bucks a lot worse if i just ease up on the gas (not completely off the gas but just easing up)
i thought it was because i might have had my long term trims way off but now im not sure.......I might try to add a little timing at low rpms to see if that takes care of it with the tune..
I also replaced both my o2 sensors and it still did the same thing.....very interested in others opinions on this....i have a predator custom tune
Burning Brakes
Joined: Oct 2003
Posts: 816
Likes: 0
From: peabody ma
it also seems to get worse as the car warms up after 10-15 minutes or so, it doesnt buck/stumble at all before that...if that makes sense to anyone..
crappy part is the car is running great at wide open throttle and any time i accelerate, its just at steady or just a bit off the gas that it runs like crap/weird...
again ive changed plugs, wires, o2 sensors (i was getting a lazy warning on one of them)
Thread Starter
Melting Slicks
Joined: Jan 2007
Posts: 3,333
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From: Athens OH
Mine seems to be worse after warming up as well, however it still does it to some degree when cold. That kind of leads me to the o2 sensors. If I am not mistaken, the PCM ignores o2 sensors when in open loop(cold). Then after it goes into closed loop, the o2s come into play
Le Mans Master
Joined: Aug 2005
Posts: 5,375
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From: CA.
St. Jude Donor '13-'14-'15
A misfire would leave unburnt fuel in the exhaust and your 02's would show rich not lean-I would check for exhaust leaks--Also see what the 02 voltages are from side to side--just with the stock narrowband 02's see if there is a huge variation from left to right at WOT--- Make sure all your LTFT's are in line--"0" or slightly negative--At WOT the ECM will show a "0" with a psitive # just before going to WOT--so this would not create a lean condition--BUT with a postive # just before going to WOT the ECM would add that % to your fuel making it richer-not leaner
If you are having knock retard--taking timing out would again make it richer not leaner--
I would suspect the fuel trims are way off and also check to see if your MAF table hasn't been changed so much that it needs blending at certain points--(may have some WOT lean spots)
If you are having knock retard--taking timing out would again make it richer not leaner--
I would suspect the fuel trims are way off and also check to see if your MAF table hasn't been changed so much that it needs blending at certain points--(may have some WOT lean spots)
Thread Starter
Melting Slicks
Joined: Jan 2007
Posts: 3,333
Likes: 0
From: Athens OH
I know what you are saying about the misfire causing a rich mixture. I had the tune done by a shop and I don't have any type of data logger for this car. i have been considering it though.
I was finally able to get under the car this afternoon. I replaced the O2 sensors and kind of checked for any obvious leaks, but I had the front end up so I didn't want to start the car. Then I found the vacuum line from the EVAP switch to the EVAP solenoid?????. I put it back together and none of the above helped.
I was finally able to get under the car this afternoon. I replaced the O2 sensors and kind of checked for any obvious leaks, but I had the front end up so I didn't want to start the car. Then I found the vacuum line from the EVAP switch to the EVAP solenoid?????. I put it back together and none of the above helped.