I think I need a new MAF, key word is 'think'. Your thoughts...

[Riverhawk44]

I own a 1995 Infiniti Q45t. I removed my air box, and fabricated an adapter to fit onto my MAF, then threw a K&N OILED air filter on there. I had no idea that the oil was bad bad bad. My car ran awesome for 3 weeks. Then I started experiencing acceleration problems at highway speeds (over 60mph) from 3000 rpms and up. If I keep my RPM's below 3000 I experience zero problems. And by 'problems' I mean bucking and zero acceleration. A perfect example being when I stomp the gas to pass a vehicle traveling 60 mph the car doesn't accelerate hardly at all even though the RPM's jump up, and while the RPM's are up it can start to buck. I even heard and felt a sort of backfire (pop) from under the hood and just about pooped my pants.

After reading many threads on here I am confident my oiled air filter ruined my MAF and I need a new one. I just wanted to confirm with everyone here on the forums because you are all much wiser than I. PS I've cleaned my MAF 3 times using the detailed instructions from q45.org. I cleaned the throttle body as well just to do it. I want all of you to know that this site inspired me to learn my FSM as well.

I also wanted people's opinions on purchasing a new MAF. I'm not doing the ebay/junkyard thing. So I narrowed it down to either buying a brand new factory MAF, or a Bosch MAF. I was leaning more towards the bosch because of the price and the fact that I've heard of that brand before. Obviously I know the factory option is a safer bet but I wanted to see if anyone here has heard anything about the bosch.

Also, feel free to tell me if I'm a retard for thinking its the MAF. I have not taken my car to anyone to get any kind of tests done. I live in a town of 5000 people and the closest REAL city is Seattle WA (3 hour drive). As always your opinions are encouraged and I look forward to drinking in your knowledge. -Ryan

[goody90q45]

How many miles on your Q? Possibly around 120K? Is the check engine light (CEL) on? If no CEL the problem could easily be a bad fuel pump, fuel pump control unit (FPCU) or both.

Welcome to NICO.

[maxnix]

Hope you kept the original CAI. Try cleaning, then order new from Joe if that doesn't work.

And never rely on advertising for relevant information again!

But also check fuel pressure, preferably while operating the car for WOT pressure.

[Riverhawk44]

I have 170K. I get regular oil changes. All the miles are highway miles. Last summer had every hose, belt and fluid replaced. The car runs like a dream. I put the K&N on there because I needed a small welding project to work on my welding skills (MAF adapter) and I thought my V8 would sound much better if it were allowed to breath.... The car with ZERO problems, and even then the problems came about 3 weeks after the air filter change - I LIKE WERE YOUR HEADS AT with the fuel pump etc and strongly considered the idea that because I was driving my car a littler harder than normal after the air filter cahnge that it could've brought about the problem. BUT I was thinking it can't be coincidence that I would experience acceleration problems after the air filter change. I noticed someone already suggested I put the original CAI back on, but if anything I was going to put a dry flow oiless filter on instead - after I determine what the acceleration problem is. I greatly appreciate your suggestion and I will keep that in mind and I look forward to more posts. I apologize for typing so much I worry people will reply to my thread hastily without reading all the pertinent info I have put in it. -Ryan

[Riverhawk44]

whoops I forgot to reply that there aren't any warning lights on.

also, is there a realistic way for me to check the fuel pump myself or do I need to enlist a mechanic. Please keep in mind I trust about 0 mechanics in the small s***ty town in which I live. If I had a huge 1984 ford truck lifted up then I would be safe and sound, but the look on a mechanics face around here isn't pleasant when he sees my car, and when I get the oil changed I always get the "oh you got one uh dem fancy cars. Not sure we got an oil filter fer dat." Bitter sweet moment rally because he referred to my 14 yr old car as "fancy" hahahha

[maxnix]

Just install a T after the fuel filter (hopefully replaced within the last year), record FP at idle after warm, then at WOT on the highway. Tape gauge to windshield. Should be about 34 psi and 43.4 psi.

[Riverhawk44]

Found a mechanic I trust, he tested the MAF and fuel pressure.... FP at WOT was 15psi. Ouch.

Goody so far you are looking like gold. I'll reply one last time after everything is installed to let you know if you successfully diagnosed the problem just from reading a thread.

To be on the safe side I'm going to go ahead and get a new fuel pump and PFCU. My car has 170K on it and from what I understand reading forums fuel pump can damage the FPCU, and I can afford to fix both, so it seemed like a logical decision.

Also giving in and putting original CAI back in.

Going forward this experiment has taught me to not do any cool mods unless I actually know what I'm doing. I suppose I'll stick with regular stuff like customs wheels and other basic garbage like that

-Ryan

[goody90q45]

Sometimes even a blind squirrel can find nuts.