Rough idle with forced induction

Originally Posted by Mitco39

I have the exact same issue. I have been spending a bunch of time as of late tuning and playing with Uprev. Take a look in the Edmonton group (I believe your a member in there) under the mod discussion thread.

Anyways I believe its being caused by 2 things. The fact that the BP kit removes the PVC on the boost tubes, which is needed. But I also think its trying to activate some sort of emission operation that is causing the lean issue. There is something going on in the backend and the fact that your having the same issues as I mean that its not just something I inadvertently did. How is your idle when it is meeting or close to 14.7? Mine hunts, again I think its a byproduct of removing the emission systems but I dont see anyone else having these issues, or they are just living with the bit of a lopy idle.

This kind of relates to my rich lean bank thing that I got figured out. It is not a leak causing this issue, the ECU is directly causing this issue. It might also be related to the VVEL on the car. I will be spending some more time logging and playing with it this weekend I hope.

Also if you have the ability unplug your Post cat O2s if you notice the engine richening up at idle for no reason. This fixed that issue for me, but after tuning mine a few days ago I now have the lean out on idle.

If you figure it out before I get time to play with it let me know. haha

Originally Posted by Mitco39

I have money on the post cat O2s. Sasha put both of them in one bank as your aware and they do have an effect on the engine and the tuning. Unplugging them and turning off the associated CELs and now mine idles around 14.5-14.9 give or take. If you check your long term trims that will give you a bit of a look at what the engine is doing. IIRC if your LTFTs get to 75% or 125% it will throw a rich or lean bank code respectfully.

As far as that right lean condition goes I am still trying to work through that one.

Originally Posted by jwick

I guess I'll chime in here too. If I follow your descriptions I'm having the same issue. It was much worse on my base map than it is on my tune but I specifically pointed it out to my tuner.

Best I can describe it is this. When I'm coming off closed loop conditions (i.e. just cruising) and pull up to a stop sign/light. The car will behave just fine and then I get a hiccup in the idle. Rpms drop a couple hundred and i lean out a bit (low 16s). It immediately catches itself and idles 'fine' after that. I quoted fine because the idle is decent but not rock solid like it was NA. It held steady N.A. and now it bounces within a 50 rpm range.

I'll give more details in a follow-up post but Is this similar to what are talking about?

Edit: idle Afr on my innovate is between 15.2-14.4

Originally Posted by 09 Nismo#400

Just thought I would add my two cents to this. I have been going a bit crazy due to this. Like others have stated it is a bit better now after getting a tune then what it was on the base map. It hunts at idle all the time, idle Afr on mine is between 15.2-14.2 so if someone finds a solution please let me know. I am glad now that I am not the only one.

Originally Posted by Mitco39

A lean or rich bank code is either a bad 02 or incorrect tuning. If your compensation table is not setup correctly you can easily get those trim codes. A bad 02 will also cause the engine to trim outside its limits and cause the code. I would log the car, easy way to tell if its a bad O2 is just compare the trims on each bank, if they are reading roughly the same then its a tuning issue, if one is consistently reading wacky then its an O2. Like I said earlier disconnecting the O2s is almost needed because mine one bank would constantly run rich even tho the target was 14.7.

I would love for a pro tuner to chime in just to see what tables they have access to that none of us do. I know Megan has it on here.

Originally Posted by Cell

Eli @ Project X Customs tuned my car.

Before getting it tuned, I had the exact same symptoms everyone else is having here. My idle would drop between 50-150 and it feels like the car is trying to fight to bring it back up. The AFR would also bounce up and down between lean and rich. I do not remember how big of a bounce it was but it was enough for me to see that it is not normal.

Now, after the tune, the AFR still bounces but not as drastic as on the base map. The idle is far more consistent and feels normal now.

I will need to jump back in my car and really pay attention this time around to see how it is as I haven't really paid much attention to it. Mostly because it hasn't been an issue.

Here is a video I made when I was running the base map. It doesn't show it dipping much because I didn't rev it but it does show that it is bouncing about 50 rpm.

Originally Posted by jwick

To continue the discussion...Sorry Gale for stealing your build thread but since we all happen to be having similar issues and would love a solution, figure you won't mind much. I thought about this more last night and watched it pretty closely the entire way into the office this morning.

- My AFR idle is no where close to as bad as the one in Cell's video. I bounce around from 14.6-15.2 but not as erratically as that. I'm also convinced my Innovate is a couple tenths high on readout. It's always read that way and everything checked out on the dyno as good, so I just live with it. All My idle rpms seem to be pretty close to inline with his.
- One thing to note on my tune. The problem in question was much worse on the base map from Vince. I even sent some log files thru Sasha to him, received an updated base map and it didn't make it any better. I mentioned it to my tuner when I got my custom tune. I don't know what else he might have done behind the scenes but I know for a fact that one of the things he did to compensate was adjust off throttle idle timing. If I remember correctly when coming off throttle and dropping rpms, he added additional timing starting about 1200 rpms until my idle set point at 850. He told me he did that to specifically fight the hiccup we are all experiencing. It didn't fix it but it's way better than the original base map.
- To throw another monkey wrench in the discussion. I performed the throttle body relearn procedure a few weeks back. The first couple of times I ran the car after that it almost completely fixed the issue. Within a day or two it was back.

All in all no real solution from me but figured I throw the items above out as additional data points. I would love nothing more than to get this figured out because it really pisses me off to have a car that I worked this hard on and spent this much money on and it just doesn't idle right. Makes power all day, runs great in open loop but has random hiccups under no throttle.

Originally Posted by theDreamer

Check fuel & MAF readings like I mentioned in the other thread, another idea to help is if all of those with the problem could data log via Uprev the same paramters and post them. This will allow for some comparison and narrow what potential problems are causing it.

Originally Posted by jwick

I'll do this when I get home. Since it's so hot here I have to let the car cool down in the garage for several minutes before I'm comfortable killing it. I'll plug UpRev in and get a log going.

Originally Posted by Cell

Hey guys, just reporting back from Gale's thread.

Today I drove my car to the gym and paid extra attention to the AFR and idle.

So, my idle is perfectly normal and stable. No bounce.

My AFR at idle is reading between 13.7-14.7. That is at both extremes. For the most part at idle it is usually bouncing around 14.0-14.4.

Seems like, from face value without data logging, my tuner made it run a bit rich at idle.

Originally Posted by Mitco39

Maybe the richness is the trick to keep it from doing what we describe. You would have to just log it to see what the target afr is set at. I suspect you might just have the same issue I had where one bank is at 14.7 and the other is at ~13.7 or so.

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.