QX4 VQ35 issues MAFS? TPS? anyone?

[chicoson]

ok so i decided to order a bigger air filter for my intake on my 01 QX4 and while i was at it i used MAFS cleaner to hose down the MAFS. ok so all done and complete i start her up and go down the road. full throttle seems to be ok but when acceling slower under normal driving the throttle response is rather wierd. it feels like im driving a CVT trans vehicle lol. shift points seem funky and it feels like it doesnt have any power. trans fluid is nice and pink no burnt smell. just feels like there isnt the proper fuel delivery under slower acceleration.

any ideas? think i screwed up the MAFS using the cleaner? its driveable but just not enjoyable anymore.

so far i plan on changing out my regular maitenence items like plugs,fuel filter and get the trans fluid and filter changed with lube guard additive. FYI lube guard is the sheet! just kinda wondering if i should buy a $70 new aftermarket MAFS from ebay and try it out.

anyone have similar issues with drivability after a air intake install. FYI i have been running this intake for months no isses until now when i cleaned the MAFS and installed a bigger diameter filter for more airflow.

[CanuckQx4]

Where do you live? I have 2 Maxima mafs that are direct replacement with the 01 Qx4's. Nissan part number 22680-2Y001. One of them is brand new in oem box unopened, the 2nd was mounted and run for less than a few hours. The problem ended up not being the MAF. Where are you located? pm me if youre interested

This is ofcourse is assuming it is your MAF at fault since after you sprayed it.

[chicoson]

im in flint michigan. ill have to check my part number but i may get one from you. i cant seem to figure it out. im not throwing any codes either. no engine light, nothing. ive been looking on ebay and they have new aftermarket MAFS for 65.00 shipped. i will let you know if it ends up being that.

[ARKQX33V6]

After install of your new larger air filter, and MAF cleaning:
Idle warm up RPM?
Fuel filter clogged?
Fuel rail pressure?
What are your shift points in RPM ?
Are there any air leaks in the conduits feeding the throttle body?
Any vacuum leaks?
Verify the TPS is connected with all junction points.
Can you run at all RPM ranges even with the weird shift points or are you running higher now than when you started.
Check to see if you have any first stored codes especially transmission codes.

[chicoson]

well what i have done is fuel filter,trans fluid and filter change (nothing found wrong) there is no engine light or codes. i unplugged the TPS sensor clip and cleaned it. all vaccum lines are free and not pinched. shift points seem to be good. basicly under partial throttle or normal driving it seems to surge but does not feel like the trans. the trans shop that just did the fluid change seen no signs of wear or anything in the filter. they also said it did feel funny but not trans related. im stumped. when i mat the gas its fine. swirl valve is fine too. IDK maybe i shoud just buy a new MAFS offline and take my chances. wish i had someone close by me with the same SUV so i could test it before i buy one.

[ARKQX33V6]

Try cleaning the throttle body and throttle plate. Look inside the entrance to the TB, see if you have a black sooty deposit. Your EGR valve is probably partially plugged. Your coolant temperature sensor may be hanging up, can you feel or hear a definite change as the engine warm up and idle comes down...it should happen all within the same period of time during the warm up period. The idle air could also be hanging up, you might hear a buzzing sound in the engine bay drivers side at about the final warm up period.

I do not understand exactly what your weird feeling is, like a CVT, are you saying you can not feel shift points. Nissan Q's and Pathy's will shift without feeling the shift points if the oil is new and clean and the oil is fully warmed especially under light throttle.

But if you feel no difference with the throttle lever until you are on the floor, check your actuation between the gas pedal and the throttle plate and see that the cruise control cabling is free and no binding. This will take 2 people and good communication skills. With a minor push on the gas pedal are you getting a minor change in the throttle plate, then does the sensor TPS, relate this movement.

Check the TPS physical connection between the plate and the sensor, do the swings match or is the connection between then breaking apart?

[chicoson]

i guess the only way to really descibe it is while cruising or low/normal driving and acceleration it kind of surges. the shift points are correst. i guess saying it feels like a CVT is kinda misleading. it seems like a vaccum issue or MAFS issue. ive never had a MAFS go bad except for on my 240 when it just went a out to the point i couldnt drive. the only thing i did different was clean the MAFS. i have been told our MAFSs are very touchy and they should not be messed with. i did not move or disturb any vac lines other than the 2 on the intake and all i did was un hook them then hook them back up. nothing is pinched or anything. i wish i had someone close by who had a same year pathy or QX so i could try out thier MAFS before buying one. im almost dead set on that being the issue. the inside of the TB is a tad black but nothing abnormal for a 138k vehicle. i guess i can clean that and the TPS when i remove the TB to do my plugs later today. ive checked almost everything i could and so far everything is looking new. my 1st thought was a pinched off vac line to the swirl valve or a bad swirl valve. nothing found there but i also cant test the swirl valve either. all i can do is make sure the vac line running out of it is clean and free of debris. does anyone know if another MAFS from another vehicle would work? i have access to 300ZXTT MAFSs and a few others. is there any one i may be able to cross reference to maybe try out before i make the dive and buy one?

oh i almost forgot. the warm up and idle are fine and so is the trans. everything works correctly except for when im under low throttle or cruising.

[chicoson]

fixed her up. it was the MAFS. i noticed alot of unburnt fuel on my plugs when i changed them. im guessing it was dumping too much fuel due to the sensor being bad. i installed new plugs and the old sensor then it still acted up. my new sensor came in yesterday so i installed it. it acted up for about 10-15 minutes and now its fine. my guess is the plugs were fuel soaked again and needed to burn it all off?

[Buzzman]

fixed her up. it was the MAF. it acted up for about 10-15 minutes and now its fine. my guess is the plugs were fuel soaked again and needed to burn it all off?

Sounds like it just had to relearn the new MAF? (Anyone?)
Either way, glad it works again for you.

[chicoson]

yeah well that and the un burned fuel that was fouling out the new plugs from the old sensor has now burnt off too.

[chicoson]

figured i would update this.

seafoamed it and cleaned out the TB and IAC valve and slightly adjusted the butterfly stop now its awesome. was pretty gunky in the IAC valve. thanks for the insights guys.

[CanuckQx4]

How was the IACV gunky?

I didnt think much of any of it went inside the engine??

[chicoson]

Well the IAC is below the TB and the blowby from the valve cover goes up the intake pipe and gummed up my TB and I'm assuming some of the gummy oily junk fell down thru the opening in front of the throttle plate that leads to the IAC. Unless I'm mistaking that valve and calling it something its not. The blowby is a common issue on some VQ35s from what I've read.

[CanuckQx4]

Ya I was confused I thought you meant your IACV valve itself was gummed up and fouled.

You can always pull that first fat black hose that vents from the valvecovers into your intake and vent to atmosphere.. or a catch can, instead of recirculating it.

I pulled my IACV before, looks like this.




I forget if I cleaned the air hole though, might have to go in there with a Q-tip and carb cleaner tomorrow