Rough idle with forced induction

Mitco39 · 07-13-2014, 02:05 AM

I think I may have found the fix today. I believe the car switches to the "cold" fuelling tables. I copied my main table into the cold (or what uprev calls cold) and it seems like its just fine now. I will have to get more seat time on it to make sure that was indeed the issue and its not just some fluke it has not came back.

Jason, unplug your 2 downstream O2s and see what happens, you will have a CEL but the car will run just fine (or you can delete it with the tuner cable if your tune is unlocked).

On a side kinda related note, I went to the track and ran 12.7 (not the best), but trapped at 120mph which I thought was awesome. Last year IIRC my trap speed was 110mph.

jwick · 07-13-2014, 02:20 AM

Quote:

Originally Posted by Mitco39

I think I may have found the fix today. I believe the car switches to the "cold" fuelling tables. I copied my main table into the cold (or what uprev calls cold) and it seems like its just fine now. I will have to get more seat time on it to make sure that was indeed the issue and its not just some fluke it has not came back.

Jason, unplug your 2 downstream O2s and see what happens, you will have a CEL but the car will run just fine (or you can delete it with the tuner cable if your tune is unlocked).

On a side kinda related note, I went to the track and ran 12.7 (not the best), but trapped at 120mph which I thought was awesome. Last year IIRC my trap speed was 110mph.

do you have to remove the post cat O2 sensors to do this fix or can you just copy the cold start settings?

Mitco39 · 07-13-2014, 12:12 PM

Quote:

Originally Posted by jwick

do you have to remove the post cat O2 sensors to do this fix or can you just copy the cold start settings?

You could try just the cold timing tables. The O2s were to just get it to idle and drive with both banks at the target afr. I found that if you keep the O2 plugged in one bank will always run richer than the other under closed loop.

jwick · 07-13-2014, 12:53 PM

Quote:

Originally Posted by Mitco39

You could try just the cold timing tables. The O2s were to just get it to idle and drive with both banks at the target afr. I found that if you keep the O2 plugged in one bank will always run richer than the other under closed loop.

soon as I get my new ft O2 sensor I'll have to do some more closed loop logging. I don't recall one being richer than the other.

are we sure the ECU doesn't use the post cat O2s for anything?

GaleForce · 07-13-2014, 08:27 AM

Quote:

Originally Posted by Mitco39

I think I may have found the fix today. I believe the car switches to the "cold" fuelling tables. I copied my main table into the cold (or what uprev calls cold) and it seems like its just fine now. I will have to get more seat time on it to make sure that was indeed the issue and its not just some fluke it has not came back.

Jason, unplug your 2 downstream O2s and see what happens, you will have a CEL but the car will run just fine (or you can delete it with the tuner cable if your tune is unlocked).

On a side kinda related note, I went to the track and ran 12.7 (not the best), but trapped at 120mph which I thought was awesome. Last year IIRC my trap speed was 110mph.

Nice work Mitch. Keep us posted with the results after more seat time. Also nice trap speed.

I'm sure my tune is locked. I may just have to deal with it until I get a retune, or put up with the CEL.

jwick · 07-13-2014, 09:49 AM

Quote:

Originally Posted by GaleForce

Nice work Mitch. Keep us posted with the results after more seat time. Also nice trap speed.

I'm sure my tune is locked. I may just have to deal with it until I get a retune, or put up with the CEL.

who tuned your car? if you have a good relationship with him he could probably just email you the updated map with O2 sensors removed

GaleForce · 07-13-2014, 06:10 PM

Quote:

Originally Posted by jwick

who tuned your car? if you have a good relationship with him he could probably just email you the updated map with O2 sensors removed

Vince at R/T Tuning.

I'll let Mitch do some more testing to be sure this is the fix before I call R/T Tuning to see if they can patch my tune.

Z4fun · 01-19-2019, 10:10 AM

I have idle surge between 13.5 and 15.5. this only happened after mechanic installed A2A kit I got second hand in Tampa, I doubled checked everything and it was in good condition. He said its normal to have idle surge since it has a bov but doesn't make sense since its before the maf lol

car 370z - has stillen sc , test pipes & catback exhaust, 9psi upgrade pulley, a2a kit , tial bov.

I placed the csv log in a zip file on here , I have a vid but its pretty much the same as the other one on the thread its just hunting and idle bounces as well. I sprayed the maf's just to make sure they were clean, as well as carb cleaner around the engine to check for leaks but no joy.. can it be the o2 sensors are black after the tune since it was kicking out black soot in the beginning ?... any ideas ?

jwick · 01-19-2019, 10:57 AM

Quote:

Originally Posted by Z4fun

I have idle surge between 13.5 and 15.5. this only happened after mechanic installed A2A kit I got second hand in Tampa, I doubled checked everything and it was in good condition. He said its normal to have idle surge since it has a bov but doesn't make sense since its before the maf lol

car 370z - has stillen sc , test pipes & catback exhaust, 9psi upgrade pulley, a2a kit , tial bov.

I placed the csv log in a zip file on here , I have a vid but its pretty much the same as the other one on the thread its just hunting and idle bounces as well. I sprayed the maf's just to make sure they were clean, as well as carb cleaner around the engine to check for leaks but no joy.. can it be the o2 sensors are black after the tune since it was kicking out black soot in the beginning ?... any ideas ?

You might want to start a new thread titled for your specific issue. Everyone discussing their issues, me included, on the thread has the BP turbo kit.

Z4fun · 01-19-2019, 01:17 PM

Quote:

Originally Posted by jwick

You might want to start a new thread titled for your specific issue. Everyone discussing their issues, me included, on the thread has the BP turbo kit.

Ok, thanks. Didn't think the thread was only turbo, since it says Rough idle with FI.

Cell · 07-14-2014, 07:58 PM

Quote:

Originally Posted by Mitco39

I think I may have found the fix today. I believe the car switches to the "cold" fuelling tables. I copied my main table into the cold (or what uprev calls cold) and it seems like its just fine now. I will have to get more seat time on it to make sure that was indeed the issue and its not just some fluke it has not came back.

Jason, unplug your 2 downstream O2s and see what happens, you will have a CEL but the car will run just fine (or you can delete it with the tuner cable if your tune is unlocked).

On a side kinda related note, I went to the track and ran 12.7 (not the best), but trapped at 120mph which I thought was awesome. Last year IIRC my trap speed was 110mph.

Not that it really matters but when I had my car tuned, it was a whole new tune and not from the modifying the base map. Maybe that is why I do not have any problems with idle.

jwick · 07-14-2014, 08:02 PM

Quote:

Originally Posted by Cell

Not that it really matters but when I had my car tuned, it was a whole new tune and not from the modifying the base map. Maybe that is why I do not have any problems with idle.

all the base maps are locked. all of us have custom tunes from scratch

Cell · 07-14-2014, 08:05 PM

Quote:

Originally Posted by jwick

all the base maps are locked. all of us have custom tunes from scratch

Then I have no idea. Maybe the cold fuel table was missed by other tuners.

jwick · 07-14-2014, 08:07 PM

Quote:

Originally Posted by Cell

Then I have no idea. Maybe the cold fuel table was missed by other tuners.

I'm definitely clueless. just hoping somebody finds a fix. mine is starting to idle worse. I think it might be that O2 sensor going out. replacement should be here Wednesday

MyKindaGuise · 07-15-2014, 10:34 AM

Quote:

Originally Posted by jwick

I'm definitely clueless. just hoping somebody finds a fix. mine is starting to idle worse. I think it might be that O2 sensor going out. replacement should be here Wednesday

I had that happen and my idle went to ****.

Also fwiw I have my rear O2s deleted since I went to boost. Im on ecutek so I cant modify maps on the fly like you guys can on uprev but I haven't seen any negative side effects to it yet?

07-13-2014, 02:05 AM	#1 (permalink)
Mitco39 A True Z Fanatic Join Date: Aug 2012 Location: Edmonton Alberta Canada Posts: 2,089 Drives: 40th 370z Rep Power: 133	I think I may have found the fix today. I believe the car switches to the "cold" fuelling tables. I copied my main table into the cold (or what uprev calls cold) and it seems like its just fine now. I will have to get more seat time on it to make sure that was indeed the issue and its not just some fluke it has not came back. Jason, unplug your 2 downstream O2s and see what happens, you will have a CEL but the car will run just fine (or you can delete it with the tuner cable if your tune is unlocked). On a side kinda related note, I went to the track and ran 12.7 (not the best), but trapped at 120mph which I thought was awesome. Last year IIRC my trap speed was 110mph. GaleForce likes this. __________________ 2007 Chevy Duramax - EFILive Tuned By Me 2010 40th W/ Nav - Boosted Performance - UpRev Tuned By Me The Mrs. Ride -2012 335XI N55 BMW - Cobb Tuned By Me, Built by her My Build --> http://www.the370z.com/members-370z-...39s-build.html

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