I posted this at G35driver a couple of weeks ago but didn't get any responses so I'm hoping one of you guys can't help me out.

So here's my history. 2003 G35 Coupe with TN kit on reflash. I hit limp mode a couple of times I believe due to an overboost issue. I have the new pipes but I haven't installed them yet. Ever since I had the issue I have not taken my car above 4k since the MAF has a problem at 4500rpm. Now between 3 and 4k when I'm under boost my AFR will start at 11.x and slowly creep up to 13.x until I shift at 4k. Before I had the limp mode/overboost problem my AFRs were solid 11s all the way to redline.

I think I'm going to get a new MAF sensor and see if that fixes it. Any other ideas?

Thanks.

 

Perhaps one of the seals or rubber couplers came loose on your fuel pump. Whats you fuel pressure reading?

 

Fuel pressure has been solid since the kit was installed last December.

 

Hmm perhaps a vacuum leak of some sort?

 

your walbro might be getting older and not flowing the same as it originally did.

 

The reason you are leaning out would be because of the overboosting.....

 

Check your plumbing for a slight leak. If not.. it's probably because of the MAF freaking out.

 

I'm still reading 65-67psi solid on fuel pressure. I'm getting the lean condition while around 3-4psi so it's not from the overboosting. That's why I'm leaning towards the last reply that my MAF is done.

 

Not true.

Unless he's hitting 10+psi at higher rpms and completely maxing out those injectors then the ECU should be able to control fuel.

How much boost are you hitting anyway?

 

Usually 3-4 because I don't go WOT because of the problem and I have been shifting at 4k. Occasionally I hit 6 but I'm not coming anywhere near 10.

 

So do most of you agree that my MAF is probably done?

I'm going to get a new one, install the new pipes, and get a 4 psi spring and boost controller. I wanted to wait for Stage 1.5 but because of the limited tuning facilities and the delays I'm leaning more towards a UTEC.

 

Utec + MAP sensor

 

With no WOT and not going above 4k you might see 12 or 13 afr. Cruising at 3400 i see 13.7 sometimes. Take it somewhere strap it in and see whats going on.

 

I understand cruising I should see 13s and 14s. When I hit boost, under load of course, my AFRs start at 11.2 for a few hundred and then go up to 13s as I reach 4k.

 

I am quoting myself here.

Just tested my walbro 255 and it looks like it is only flowing like a 130-150lph. I checked it at idle, and it is only a couple of months old!!!

 

really? How did you do the test?

 

you need to have a fuel return system to do this.

basically, you would just disconnect the ruturn line and divert the return fuel into some sort of measurement device (I used a gas can.) essentially, a 255 lph pump should pump 4.25 liters per minute (about 1.1 gallons per minute)

I started my car and let it idle for 1 minute while collecting fuel in the gas can. At the 1 miute mark, I shut it down. The result was about 6/10 of a gallon.

I'm gonna put a new pump in. If that doesn't fix it, I must have a problem elsewhere.......that won't be fun tracking down. I sure hope it's the just the pump.