Is this kind of idle normal for a boosted z, or is it another problem bad tune, vacuum leak, maybe plugs etc.Any input would be helpful. Sorry if they may seem like noob question. I included a short vid towards the end.

The afr bounces around from 13 to 17 at times for idle then sometimes stays steady in around 14.7. I have dw 600cc injectors with uprev. my tuner said it is caused by the larger injectors the small lope in idle? The idle has been like this since day 1 after tune.

Another problem I have had was random misfires which i have read are normal for z's with forced induction so I would always just delete the code and not really think much about it. Though in october i was at a local drag strip test and tune and received at two different times a cel for a misfire on cylinder 6 at both times a was at full boost in 4th towards the end of the track. So would a bad injector or maybe running 1 step colder plugs cause this? I checked the plugs and they looked fine afterwards.

Here is a vid of the idle. first part i try to show the afr bounce around and then towards the end I zoom into the tach to try and show how the idle bounces.

 

You have to run 1 step colder plugs anyway. Spark blowout? Bad coilpack?

 

I've read somewhere that colder plugs were not really required until higher hp/built blocks though i still have colder plugs installed. One of the reasons i brought up the plugs I thought it may be from how much they were gapped, there ngk iridiums they are gapped more than stock ones believe .40 or .45 . I thought about making the gap smaller but always thought iridium plugs were not to have the gap altered.

 

As far as I know 1 step colder were always required in boost, as you know the regular plug would heat up and could preignite which would not be good at all, the gap is usually adjusted to be smaller on the plugs because of possible blow out at the higher rpms. In the 3.0 our gaps are around .35.

 

My plugs dint start to glaze until 600 rwhp with stock heat range, I was running a lot of meth but I would say not needed till 500, just a safety thing. Gap should be closer to .035, you have to be careful though.

Op find a new tuner people have run larger then that on uprev with a perfect idle so that's a bs excuse.

 

ok so tonight i put new plugs in and gapped them to .035 and idle still is the same. vacuum stays at -19 steady so i don't think i have a vacuum leak or anything.

 

looks decent to me. a little bit of misfire. could be improved on in the tune but as long as it's firing up every time i wouldn't worry. as for the misfire in boost you should probably get the tune checked out on a dyno, could be leaning out on one bank.

 

[I]I've been rockin the MTM kit on my built block for about a year now .

The idle issue you are having are largely due to tuning of the MAF tables at the low end of the tables. My shop spent quite a bit of road tuning time sorting most of that out for me.

However; mine still burps once in a while ( randomly spikes lean once in a while) at idle . I have been speculating that there maybe a minor issue with where MTM has placed the driver side O2 sensor. It is placed almost in the center of a the merge between left and right banks in the up pipe. This could be polluting the driver side O2 with passenger side corrections ( the ECU expects the two O2 sensor to largely be isolated. So given the slight bias , once in a while the ECU has to burp A/F to re-balance. Just a theory.

I have delayed moving that O2 bung , since it's pretty cramped down there and it's a pretty small issue.. Only place to move it would be to the center of the U-bend (driver side).

 

Well who tuned it? What are you using?

 

Two things that I have experienced alot with my car in the past:

Clean your maf! get a can of CRT MAF cleaner, with car cold ignition off ofcourse, spray the sensor of the MAF. Wait a while so it can dry before starting it. Little by little the turbo lets out very little oil and over time the maf starts getting a film of oil/dirt on it. Try this before doing anything else, its easy.

How old are your o2's, perhaps they are starting to go out, or one of them, so when in closed loop they dont read properly and throws off the AFR.... just an idea. I would bet on the MAF though.

 

Yes , try the MAF cleaning, but in my case , cleaning the MAF has never improved my idle from randomly popping out of A/F lock. Mostly the tuning data point in the low end of the MAF table (i use a GT_MAF and Uprev).

You can use Cipher to watch bank0 vs. 1 A/F corrections. If both sensors deviate about the same on average , likely not your "front sensors".

 

Ugggg

https://my350z.com/forum/forced-indu...-problems.html

I had same problem, plus a few more..
Still isnt fixed.

But I am buying a Fully Built and sleeved engine, plus a Haltech, and RFS, so I hope the problem is fixed in the process haha

 

Might want to sell your momentum kit and replace it with a Boosted Performance kit. Your kit won't flow big hp, and a sleeved block will go to waste.