Hello, I ran into a little problem and would like your expert advices.

I have the 03 G35C 5AT. I've had MREV2 + MD 5/16" Spacer + Injen CAI for a while now (almost 2 yrs). Had the UTEC and Tuned by FP. Car ran great.

I took off the MREV2 and Spacer yesterday and put back stock plenums + a Injen SRI (instead of a CAI). Reset the ECU (Overnight).

Car starts up and idles fine. However, after a while, the idle starts to sputter lower and lower and eventually turns itself off. Car doesn't throw any code.

I thought it's because of the "tuned" map on UTEC (car ran really rich), so I switched to Map 0 (supposed to be bypass). However, it's still the same.

I took off the Utec today to run on Stock ECU, Reset the Throttle Body (all 3 resets as they were suggested by Motordyne). The problem's still there.

What could be causing the problems?

The only thing different is the gasket (between the lower and upper plenums). The Original OEM Gasket has the middle skeleton. The new gasket (Nissan OEM) that's on there now is has only the outer ring and not the middle skeleton part.

Can that cause the problem, or the problem is somewhere else? The car ran fine, accelerated and cruised fine without any problems. Only after a while (after idle for couple mins or driving then come to a red light stop) then it starts to sputter. I have to keep revving to keep the RPM up then it drives fine.

Please advise.

Thanks.

 

Did you make sure your MAF was connected when you put the different intake on?

 

yup. It would shut off right away or throw some CEL if the MAF isn't connected.

It looks like there's a Vac leak.

I talked to a friend today, who's a ASE Master Tech, today and he suggested it's may be the Vac leak of the Gasket. It needs the middle skeleton gasket section to seal the Vac from those 6 holes of the upper plenum (or some sort).

However, a few other G owners said that their OEM gaskets doesn't have the Middle Skeleton part which kinda intrigued me.

Look here for 2 example:

Original OEM Gasket:




The one I'm using now, supposed to be Nissam OEM Gasket as well, but it has only the outer ring (please disregard the spacer, just look at the gasket below it):




Anyone got some other insight?

 

Like this:

http://cpwstore.carpartswholesale.co...+w0133-1627438

 

^yup, we're thinking may be the one that's on their now doesn't have the middle part, it'd cause the leak. I wonder if I should go back and use the old one?

 

I would. I'm thinking, "Original parts, original gaskets".
GL getting it working right.

 

You NEED a metal-to-metal surface sealed where vacuum is encountered. I have no idea why the 'new' gasket is like that, but I would bet a month's salary you have a vacuum leak, in addition to whatever else may be wrong. When I went back to stock I reused the old OEM gasket and had no problems at all, great idle vacuum.

 

take it from me (i used to work at aam and sell the spacers) YES the spacers use an OEM gasket WITH the middle section cut out. The NEW (supplied) gasket just needs to seal the upper plenum and the spacer so we use the mighty sisscor to remove the ceter gasket. YOU NEED THIS PART. GO BUY and OEM gasket at nissan for $25 and try that. Upon reinstalling teh middle plenum bolts u need to make sure you do not tighten past "hand tight" as the plenum will easily crack (i have replaced a few on my car before i learned this teh hard way). YOu definately have a vacuum leak...no ifs ands or buts...i just hope it's only the gasket and not a cracked upper plenum.

 

thanks guys. I just confirmed with Tony from MD as well and I DO need the middle skeleton part. I'll get the new one ASAP. Will report back when I change it out. Car's in the bodyshop so I won't get it it until it's done.