engine sputters at higher rpms or fast acceleration

[kehoe603]

97 a4 quattro 1.8t


this problem is driving me nuts, i havent started trouble shooting it quite yet, have a few ideas but didnt know if anyone has had this problem before. figured id throw a line out and see if anyone knows. the issue seems to be getting gradually worse, at first i thought it was related to me doing the cone filter mod and thinking it was just sucking in some hot air, but now sometimes it sounds pretty bad. almost like i have a fully automatic rifle under my car...so then i was thinking (and kinda hoping) that maybe my cat was getting a clog so that way i could swap with a high flow cat to give more spool...but, i dont have an engine light or anything on, also a while back an o2 sensor threw a light but hasnt been back on is months. it seems like there could be so many different things it could be as far as air, fuel, or whatever...so i hope you guys can give me some insight, thanks for taking the time to read this and i thank u in advance if u have any ideas for me.

[Seerlah]

Sounds like a misfiring issue to me. The reason you aren't getting any CEL/MIL is because the misfire needs to be harsh enough to trigger one. But if you log your ECU (VAG Com) to check for misfires, you should be able to find out what cylinder(s) is misfiring and can hep you diagnose it easier.

Your cone filter may actually not be of a greater quality and making your MAF dirtier faster than the OEM intake filter is doing. Try unplugging your MAF conector from the housing and se if your misfires continue. Don't expect to boost, though. This is just one possibility, but come back and post up results after doing this. Also, what mods do you have on your vehicle? Last time plugs were changed?

[coolgraymemo]

it could be your plugs or the coil packs.

[kehoe603]

im gonna check the plugs now and is there anything i can use to clean the MAF?

[coolgraymemo]

^
go to an autoparts store and they have MAF cleaner.

[Seerlah]

If your MAF is faulty and not just dirty, there is no return for it. The CRC MAF cleaner will clean it only if it's dirty. That's why I suggested unplgging it first to see if the misfires persist.

[kehoe603]

Replaced the plugs, cleaned the maf with the cleaner and cleaned, checked and recharged the filter, havent tried it yet but if it still happens i should unplug the maf and try running it like that to see if it persists? Just wanna make sure i understand u right...that will tell if it is the maf if it doesnt continue right?

[Seerlah]

If misfires persist after this, unplug the MAf to see if misfires still continue. If it does, then you have a MAF issue. But the possibilities in this thread are just a few reasons. There could be your ICM craping on you, ignition coil (rare on the AEB, but it happens), lowered compression (this is bad), 02 sensor, etc.

[coolgraymemo]

also, dont oil your filter too much. it will get your MAF dirty quickly and can lead to it malfunctioning.

[kehoe603]

i did i as explained in the above...it is a ton better but if i take off quick and continue to accellerate quickly it happen just like it was...under normal driving conditions it does seem better, just when i really get on it, it happens...the MAF was practically spotless when i tried cleaning it with c?? cleaner, whatever its called, and a q-tip. the q-tip had almost nothing on it...now, the icm is the module screwed to the heatsink that was in the air box right?...i was getting similar, but not as bad, responses when i left the heat sink off of it

[kehoe603]

now this might be a stupid question but i gotta ask, i keep seeing people running different MAF's from different vehicles,and a4's r real scarce around here in bone yards...so my question is can i use one from another vehicle just to atleast test it and possibly replace it if necessary? if so, what should i be looking for, just another 1.8t? or can my selection be a bit more broader?

[Seerlah]

^To answer your last question about switching MAFs, no. You "need" to use the correct MAF for your application. You can not even use the same MAF I have in my vehicle (stock MAF).

Also, how did you clean your MAF. If you look inside of the MAF housing, there is the element that sits right under where the connector is (in the middle iof the housing). That's what you are supposed to spray. But cleaning the outside of the housing will def help in removing any dirt that had the possibility of making he element dirty. If I were you (just saying if I were in your position) I would try spraying it again, seeing how you stated you still get misfires up top. The only real way to tell if your MAF is 100% is to log it with a VAG Com. Seems like your MAF may go out on you within the next year and half or so (from what I am reading).

[onemoremile]

MAF, vac lines, plugs, coil packs, coil pack wiring. It could also be the PCV system. I had a similar issue and that was the cause. It would rev clean at 0 or 5 psi to red line but anything over 7 psi would shudder and feel like a misfire.

[kehoe603]

i took the MAF out and cleaned the element inside, first by spraying it and wiping with a q tip and then by spraying a q tip and trying to scrub it clean, it seems to be back where it was, i thought it had been a bit better when i 1st changed the plugs but it might have just been wishful thinking...there is an audi specialist down the road from me but im trying to avoid bringing it to someone else so i can become as familiar with the car as possible but im gonna assume they have a vag-com and can tell me where the misfire is or if the MAF is crapping out...i recently read an DIY post on switching coil packs to the newer kind that doesnt need the ICM and bypassing it completely, it was saying that my setup (with the ICM) needs a smaller gap in the plugs to be as efficient sometimes and can create a misfire if the gaps r too big, or at least thats what i believe they were saying, does this sound like something that i should look into further or could the ICM be a factor? thanks again for helping me try to figure this out everyone too...i appreciate u taking the time

[frameshift18]

Spark blowing out? Are you on a stock tune? Correct plug gap?

[Seerlah]

You shouldn't have touched the element. I said to just spray it. You may have just damaged it ultimately. Same thing applies to the 02 sensor. NEVER touch the tip. Once again, unplug the MAF and report back if the misfires stop or not.

[kehoe603]

it stopped, i was unclear what u meant at 1st but i unplugged it and ran it down the road a bit and no skips...no boost either but...so how do i go about getting a new MAF if i cant replace it with even a stock one? ive never ran in to this issue before...do i gotta go new from dealer or is there anyway to get these reman?

[Racerx220]

i got my maf from discountauto for 48 bucks it works fine for me

[Seerlah]

You use a stock one..............designed for your vehicle and application. What I was saying is you can't just throw any MAF in your vehicle and expect it to run correctly. For example, I have an AWM (01-01.5). I use a different MAF than the AEB (97-99.5) and the ATW (00) engine. These are in relation to the B5 A4 chasis alone with stock MAF units. You "need" to use the correct MAF for whatever application you have. That is why you see people with bigger turbos running different MAFs (mostly from the VR6 motor), because the stock MAF can no longer be used on that application.

Where ever you decide to get your MAF from, be sure it is an OEM Bosch unit. And don't get it from the dealership, unless you want to pay dealership prices. MJM Autohaus is where I pick up things like this, due to their prices. Or AutohausAZ.

Edit: Wow, I had no idea the cost of the AEB MAF. I just tried to do a quick search to find a reasonable price on the Bosch units and those suckers are in the $200+ range. I bought mine for like $80 and it was a brand new OEM Bosch unit.

[kehoe603]

i see what u mean now...thats what confused me i kept seeing people using the vr6 MAF's and was unsure of the reasoning...so as long as i stay with the AEB application ill be golden...i got wicked nervous yesterday morning before i unplugged the MAF and tried...i took off and saw smoke from either me or the truck next to me and assumed the worst...figured maybe i was losing compression from a head gasket and now it was buning oil, so needless to say i was STOKED to see it correct itself when i unplugged it...never seen smoke and hope i dont ever!!!! thanks again man, ur a life saver!!!

[Seerlah]

You will need to replace your MAF. It isn't good to drive your car with the MAF unplugged. What happens is your ECU will have your fuel trims run rich, because it does not know the proper air being drawn into the intake. So, it will add fuel to compensate for it. Better to run rich than lean, but both have their consequences on the engine. Since you are now running rich, you have the possibility of clogging your cat converter (the stock cat is incredibly restrictive). Unplugging the MAF is just a quick fix so you can still get from point A to B (ie work), while you order the replacement part.

Does your exhaust now emit smoke? If so, could be from the running rich condition. Replace your MAF as soon as you can. And you order the MAF for the AEB engine code. You will learn proper ways of going about situations with this vehicle as time progresses. After a while, you will learn you will have no other choice unless you want to spend countless amounts of money at the mechanic's shop or stealership.

[kehoe603]

i only ran it for a day...its back on now, threw a light this morning and reminded me to plug it back in...the light reset itself. im fairly familiar with cars, my dad is a GM mechanic...but there lies the problem, always loved german cars and owned countless vdubs...1st turbo ive owned and i love it, just need to learn a bit more about her! lol...i gotta do a ps pump in her too...not too excited about pulling off the bumper and stuff to do it but thats what its telling me i gotta do, just a bit more different from what im used to thats all, i cant wait to finsh getting her up to par, so then i can start doing a bit more mods and learning that side of these beautiful cars...and as far as the smoke goes, that was the only time it did it, if in fact it was even me...i can be a hypochondriac some times....but that was before i unplugged it....as long as i dont really get on it i dont really notice a lot, but when im getting on the highway and accelerating a bit more than normal, i feel the skip...i can deal for a few more days, just trying to place one now...trying to find a new one at a decent price but most i do dont say they're bosch... just "OE replacemnt" which to me, doesnt say bosch

[Seerlah]

The CEL was more than likely because you had the MAF unplugged. If I were you, I would run it with the MAF unplugged till I got a replacement. Just don't run it like that for too long nor push the car. You can actually find someone parting their vehicle and purchase a used one from them. Might be the cheaper route.

[kehoe603]

thats what im looking at now...cheapest i found was like 180 without shipping, found a few on craigslist but seem to be from 00 and 01's...ill eventually find it, or just drop the coin for a new one

[Yoshisfather]

So I have been having the exact issue , when I unplug the sensor it runs good just rich with fuel . So I replaced the MAF and it still has the same issue , but whenever I plug it back in it's roughy on idle and even cuts off then I unplug it and it's good so new MAF and still having this issue . I scanned the car with a computer and it told me I have a misfire in cyl 4 but belive that's a result from a bad MAF not sure what to do I've changed spark plugs as well I'm thinking it might be a wire problem from the MAF plug itself