Kit was runnign good for about 2 weeks. Yesterday i noticed it was running really lean (also felt like taking a while to spool, but im really not sure). about 2 weeks ago i the pipe from my compressor outlet to intercooler came off. If this connection is lose again now, and i have a minor boost leak, would this make me run more lean ( i would think yes)? Also got a check engine light today, gonna read it in a few.

 

Its possible yes..

 

How would it make his car run leaner? Air isn't metered until after it passes the MAF sensor. Which ECU are you running?

JET

 

I have seen two cars run lean with a boost leak at the plenum. I'm still not sure why but the cars were in the 12:1 AFR range. Fixing the plenum brought them back to 11:1. G352NV had this happen with his Crawford plenum. Car had a definite boost leak verified on the dyno and was at 12:1 AFR. Replaced with a stock plenum boost leak was gone and car was at 11:1 AFR. Also happened on another car I witnessed with a leak but with an AAM plenum spacer.

 

running greddy EU.

 

I thought he was talking about a boost leak at the compressor outlet specifically. A boost leak at that point would not cause a lean AFR.

I would think a boost leak at the plenum would cause a rich condition since X amount of air is being metered and the appropriate amount of fule is injected, but less air is actually reaching the cylinder for X amount of fuel. That would be an overly rich AFR? Wouldn't it?

JET

 

My car had a post wastegate exhaust leak and ran lean at idle and rich under WoT when I was on the reflash.

 

codes p-300 and p-175 . One is a misfire which sometimes i get at idle, and the other i am trying to figure out

 

Aside from strange cases where it only leaks at idle or boost, the only way a boost leak would cause a lean condition is if it was a leak after the MAF. On a boosted car it will cause it to run rich because the air will be forced out per the amount of fuel already called for by the MAF reading. On a N/A car it will cause a lean condition because the air will be sucked in the plenum after the MAF and the fuel will not be added to compensate. This is not true for all cars on the older Z32 300zx, if there is a boost leak before the compressor side of the turbo after the MAF it will cause a lean condition. On the 350z its different because the MAF is right before the plenum. In your theory of the inlet side of the innercooler leaking it would only cause lag because the MAF is still reading the air right before the throttle body. I believe this is correct if not im sorry feel free to correct me, every car is different.

 

I 100% agree but for some reason boost leaks at the plenum at least in the two cars I have seen caused a lean condition.

 

If it's a random cylinder mis-fire that is normal.

JET

 

The car running lean on a different plenum and rich on a stock might have something to do with air distribution to the cyls. I am not really sure because ive only tuned twin turbo cars and a few supercharged cars. All of which have had fully adjustable engine management so if it was running lean it was easy enough to go add more fuel.

 

random cyl misfire can be caused by hitting the rev-limiter too much.

 

That is probably it, but yesterday it was runnning lean and i really have no idea why. It did this a couple of weeks ago and a day later it was running great. I will check it tonight on my way to work.

It seems like if i slowly push up the rpms and the boost i will hit the 11.5 or so range (A/F), but if i just jump on it, it will not get down that low

 

you may want to check for leaks in your exaust before your wide band, and your maf may be out of range when you jump on it.