multiple random cyl misfires. all 6 cyl misfire codes

[volks88]

always all 6 cylinder misfires. never limited to a certain cyl. no other codes, nothing else. WTF! could a boost leak be causing this? could a cracked intercooler endtank cause this? im pulling the intercoolers tomorrow. everything else is new!!!

[AudiSportB5S4]

a cracked endtank might just do it. you should yank yours off tonight see what they look like. after that man, idk i would send a sample of oil to blackstone see what comes up maybe theres something internal that you wont find

[AudiSportB5S4]

and you've tried another EPL tuned stage 3 ECU ?

[volks88]

and you've tried another EPL tuned stage 3 ECU ?

not yet. i'll get the intercoolers swapped maybe tonight, definitely tomorrow. then if that isnt it its up to cincy to swap ecu's and some logs.

[The_Jerbel]

Have you done a leak down test on the engine?

[AudiSportB5S4]

i think he said he did a compression test on the cylinders.. im not sure about a leak down. you should (OP) get a thread going with EVERYTHING you've done to fight the misfiring bitch and post it here so people can keep track of it and try to help out. and i thought MY problem was annoying! i would probably of sold it by this point lol

[RolledMySTi]

always all 6 cylinder misfires. never limited to a certain cyl. no other codes, nothing else. WTF! could a boost leak be causing this? could a cracked intercooler endtank cause this? im pulling the intercoolers tomorrow. everything else is new!!!

A boost leak could most definitely cause misfires like that. I know it did in my car. Pressure test asap before you spend any money trying to fix the problem.

[IamEzraM]

are random multiple cylinder misfires ok ? as in I clear them and they don't come back for a few months ?

[volks88]

ok so after talking with a mercedes tech tonight he says to me... did you change your motor mounts when you did your swap? yes i did. he then asked if i had replaced my crankshaft position sensor and i said i didnt. we took the car for a spin and he said he'd bet the cost of the sensor that it was it. i didnt have vag with me but he had a little handheld scanner and said that when i go WOT the car is showing 10300 rpm's. he also said that it would trip misfire codes like that.

[AudiSportB5S4]

so get that sensor! eventually when its sorted out you will be a resource to all misfiring victims. you can probably say you've done EVERYTHING.

[volks88]

so get that sensor! eventually when its sorted out you will be a resource to all misfiring victims. you can probably say you've done EVERYTHING.

yeah im sitting here since 6a.m. waiting for the parts dept to open lol

[wackoo]

what plugs u using and what gap. I had the same problem for a year!!

[THICK S4]

sorry to hear man

[RogueStatus]

your car just doesnt stop huh! you work on it more than you drive it...although it seems to be most of us do haha

[volks88]

ok so i installed the ER sidemounts and the crankshaft position sensor tonight. now the car still has more of a sputter than a hesitation but its still doing it. although now i can keep it pinned and it works its way thru it, pulls strong and doesnt go into limp mode like before. you think i could have fouled plugs from previously before? also i logged block 115 and the boost requested/actual is very close and doesnt drop off like before.

[AudiSportB5S4]

and you said you've already tried another ECU right? i mean idk man, seems like you've covered the list.... what about that place you were going to bring it to ??

[Daft]

While a bad cam position sensor would throw off the ignition, I don't think that you'd just simply get some misfires. You'd be more likely to have a car that barely runs properly or not at all.

So just to confirm, the misifres are the only codes thrown?

[volks88]

just went and drove it. the car threw 2 codes. random cyl misfire and cyl 5 misfire. CEL blinks when car starts to stutter. although now like i said it doesnt hit limp mode. it will stutter but continue to pull. fouled plugs from before when the crank sensor was cutting out? i have no fucking idea and neither does anyone else . i really think its part out time

[GetAwayFromMe]

look into replacing your plugs with proper gap. Also if you can find a coil tester to test your coils and make sure that they all are good as new.

[Daft]

just went and drove it. the car threw 2 codes. random cyl misfire and cyl 5 misfire. CEL blinks when car starts to stutter. although now like i said it doesnt hit limp mode. it will stutter but continue to pull. fouled plugs from before when the crank sensor was cutting out? i have no fucking idea and neither does anyone else . i really think its part out time

So did you ever replace/test any coils?

What about the ICMs?

This sure sounds like an ignition problem.

The key to isolating the issue is to see if cylinder #5 is a repeat offender. If it is, move that coil to another location and watch to see if the problem moves.

Another thing to check is to use the misfire recognition blocks in VAG-COM and watch to see which cylinders misfire and how often. This will give you a better picture of what is happening at what times.

[volks88]

So did you ever replace/test any coils?

What about the ICMs?

This sure sounds like an ignition problem.

The key to isolating the issue is to see if cylinder #5 is a repeat offender. If it is, move that coil to another location and watch to see if the problem moves.

Another thing to check is to use the misfire recognition blocks in VAG-COM and watch to see which cylinders misfire and how often. This will give you a better picture of what is happening at what times.

all new coils. new icm's. before the crank position sensor all 6 were misfires. now its just 5 but that was with the same plugs as before. i just changed all the plugs and the car is running great! wooo fucking hooooo! now ive had new plugs help before for a little bit only to have it fall flat a few days later so i'll see what happens.

[obijohn22]

NICE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!it's about time. Crank position sensor. file that in memory everyone!

[The_Jerbel]

You mean to say that we should file "spark plugs" in our memory

[volks88]

well everyone you cant file shit! those plugs were good for 2 pulls. now car is back doing it. ok so with vag-com my boost requested is 2550 and my actual is around 24xx. my boost gauge is a 25psi and it pegs itself. i think im overboosting like a mofo and if this is a software issue im gonna be pissed off

[Dr. Jekyll]

For the amount of money you've spent blindly replacing things, you could have bought ECUx and figured out what your problem is from the logs.

I've said it before and I'll say it again, you need to log your car with ECUx. Otherwise you're just guessing at what's wrong and wasting money on parts that don't need to be replaced.

[Daft]

well everyone you cant file shit! those plugs were good for 2 pulls. now car is back doing it. ok so with vag-com my boost requested is 2550 and my actual is around 24xx. my boost gauge is a 25psi and it pegs itself. i think im overboosting like a mofo and if this is a software issue im gonna be pissed off

Ah so you're running more boost that the plugs can handle. The misfires are the plugs getting blown out by the turbulence at this point.

How is the car under 3/4 throttle? I'm guessing that it's fine that way.

[volks88]

Ah so you're running more boost that the plugs can handle. The misfires are the plugs getting blown out by the turbulence at this point.

How is the car under 3/4 throttle? I'm guessing that it's fine that way.

yes under light throttle pressure and rolling the throttle on its fine. once it gets floored it will stutter around 22 or sometimes it will pass 25psi and look like its bouncing like a rev limiter.

[AudiSportB5S4]

see not only is brett (daft) the moderator he also knows ALL. what plugs are you running?? have you asked EPL about which ones they recommend?

[Daft]

see not only is brett (daft) the moderator he also knows ALL. what plugs are you running?? have you asked EPL about which ones they recommend?

I just happen to remember when my A4 (98.5 AEB motor) used to do that same thing years ago. It was a balance between boost and plug gap.

I had to run a 0.028" gap to prevent the boost from blowing the plugs out under WOT.

Volks: What gap are you running? Are these the stock NGK plugs (PFR6Q)?

[TRU_PSI]

How do the plugs look after you pull them out?

[volks88]

the plugs look great. daft: im running the bkr7e. those are the ones tony from epl recommends. i have tried gaps from .024 and .028. there at .026 now as epl says. i just picked up my MBC tonight so i'll put that on in the morning and check it out. funny thing happened. i installed the crank sensor and when i drove it after it still hesitated but not as bad. well i assumed it was the same thing. so i clear the codes and drive around. watching my boost gauge close i try and get the CEL to flash and get some codes. i get random cyl and cyl 5. clear them again and drive. same 2 codes. turns out the crank sensor WAS bad. so im sitting here and i think... well if its cyl 5 twice try swapping out the no.5 coil with a good one i had laying around. all misfires are gone! now its just my boost gauge going waaay beyond 25psi.

[Dr. Jekyll]

If you're overboosting that much you could have a busted N75 or a leak in a wastegate line (which will not show up on a pressure test). Don't bandaid it with an MBC until you make sure it's not a hardware issue.

[volks88]

If you're overboosting that much you could have a busted N75 or a leak in a wastegate line (which will not show up on a pressure test). Don't bandaid it with an MBC until you make sure it's not a hardware issue.

well ive tried swapping out the n75 with my buddy's n75r or whatever they call the race valve and it was no different. i put a MBC on not to mask a problem but to find out if its boost related. well after a few pulls today anything before 19psi its fine. occasionally a small misfire but it will work right thru it. now if i turn it up over that it hesitates and hits limp mode. i may have to bite it and buy ECUx. im going to a dyno on friday where they are a APR dealer so maybe i'll just wait since they have access to it anyway.

[Dr. Jekyll]

Well the car wasn't tuned for an N75r so it's just going to create more problems. And using an MBC only when the car is suppose to be using an N75 will most certainly cause limp mode.

Again, pressure test the wastegate lines and try a known good N75. And yes, you really need ECUx logs to figure out your misfire issues.

[volks88]

Again, pressure test the wastegate lines

whats the best way to do this?

[Dr. Jekyll]

Unplug the N75 and blow into hose that goes to the wastegates. Not the most accurate method, but it will let you know if there is a big leak. You can also cut off the valve stem from a bike tub and clamp it into the WG hose that connects to the N75. Then get a bike pump with a pressure gauge and connect it to the bike valve stem. Pump up the WG lines to ~10 psi. At around 7 psi you should be able to hear the WG's crack, and the pressure should remain constant (you should not lose any air pressure).

[AudiSportB5S4]

you said that you already did ALL 6 coilpacks right? because just a bit ago you said you replaced 5 which was on the bad cylinder and it got better... just wondering if all were new or not

[volks88]

the line going to the bottom of my n75, well i can blow thru that with my mouth. the other line i cannot.

[Dr. Jekyll]

I'm not sure which is the line that goes to the WG's. You'll have to search for that one... it's been a while since I checked mine.

[volks88]

I'm not sure which is the line that goes to the WG's. You'll have to search for that one... it's been a while since I checked mine.

yeah im looking for a diagram right now.