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View Full Version : Constant misfire cylinder 1 AWM motor 2001 1.8tqm Check Engine Mil flashing at idle



gq331
04-21-2012, 06:23 AM
Aight, I've searched high and low and have seen people post this with no resolve.

I've replaced all coilpacks, swapped plugs, swapped injectors, etc, and still have the same issue.

Cut open shrink housing all the way to the back of block to inspect coilpack wires. None were cracked.

Replaced broken harness clip to coilpack.

Did compression check on cylinder 1. 90 in 2cyles 115 on the third.

fault codes come up p0300 and p0301 for random misfire and cylinder 1

VAG-Com measuring block 015 comes up with constant crazy misfire on cylinder 1 and log number goes up into the 100's

Flashing MIL at idle only, no rough idle.

Any idea of what the heck is going on?? Fix?

Just hit 200k miles today. Go me!

EDIT: Replaced ECM. Still Same Issue

EDIT: Here are some vag pics I took last night so you guys know what the heck I'm talking about

Pictures while car is under load doing approx 70-80mph
http://img59.imageshack.us/img59/3504/img20120425235003resize.jpg
http://img84.imageshack.us/img84/5647/img20120425235010resize.jpg
http://img254.imageshack.us/img254/2734/img20120425235236resize.jpg

Pictures while car is at idle....this will blow your mind. Also, car is not shaking, car is running fine. notice misfires in cylinder 1.
http://img715.imageshack.us/img715/383/img20120426001253resize.jpg
http://img440.imageshack.us/img440/5272/img20120426001301resize.jpg
http://img696.imageshack.us/img696/3411/img20120426001344resize.jpg

Any other ideas??

EDIT: Car failed leak down test. =( Cylinder 1 had 70% loss. Time for a new car. =( Anybody want to buy this 2001.5 a4 1.8tq Avant? Still drivable.

a4_1.8t_01
04-21-2012, 06:38 AM
Probably the wiring to the coils, the insulation comes of leaving bear wires exposed. if its not that it could be coolant leaking into the cylinder.

gq331
04-21-2012, 06:52 AM
Probably the wiring to the coils, the insulation comes of leaving bear wires exposed. if its not that it could be coolant leaking into the cylinder.

I chased the wires already and none were cracked. cut open the shrink housing all the way to the back of the block. coolant in only cylinder 1?

thenj3
04-21-2012, 07:51 AM
compression test time

gq331
04-21-2012, 07:53 AM
compression test time

Already did that, cycle 2x, gets to 90, then 115 on the third.

thenj3
04-21-2012, 11:35 AM
what about the other 3 cylinders? also check to see if the injector is squirting fuel

gq331
04-21-2012, 11:51 AM
what about the other 3 cylinders? also check to see if the injector is squirting fuel

They are. I'm thinking I have a ecm issue. Shop wants to do a leak down test too. I swapped out the injectors. no rough idle, still pulls. took the car up to 130mph today, nothing. get off the highway and let it idle, check engine starts flashing. no shake. my mind is blown.

thenj3
04-21-2012, 02:02 PM
whats the compression on the other three cykinders?

gq331
04-21-2012, 03:22 PM
whats the compression on the other three cykinders?

all over 100.

any way to test just the ecm??.....really not in the mood to run wires all the way to the coils if I don't have to. I really hate shooting in the dark like this. trial and error crap. fuuuuuuuuuuuuuuuuuuuu

R.G
04-22-2012, 11:39 AM
so it runs fine on full throttal? no misfire when you hit 130mph?

bmarshall
04-24-2012, 02:05 AM
You could fault find with a CRO on the signal wire from the ecu. That will show you everything.
You said there was coolant on one plug? Dis you fix that?
You could be getting pre ignition from carbon build up.

gq331
04-24-2012, 05:29 AM
so it runs fine on full throttal? no misfire when you hit 130mph?

Yep, nothing. Driving this sob daily. Car is bone stock.

guy022077
04-24-2012, 05:34 AM
did you do a vac leak test yet?

what is your maf reading at idle?
Just hit 200k miles today. Go me! nice work

gq331
04-24-2012, 05:38 AM
You could fault find with a CRO on the signal wire from the ecu. That will show you everything.
You said there was coolant on one plug? Dis you fix that?
You could be getting pre ignition from carbon build up.

No coolant. one of the posts in here said I may have coolant leaking into cylinder 1. But the reservoir tank is still level. So doubt it's coolant.

CRO....you mean using one of those wire testers? Good point. But car drives normally. That's why I keep thinking it's the ecm. Ugh. I'll try it. Got an ecm coming tho so I'll keep updating.

gq331
04-24-2012, 05:44 AM
did you do a vac leak test yet?

what is your maf reading at idle?
Just hit 200k miles today. Go me! nice work

No idea what the maf is reading. Kinda ruled that out since it's only cylinder 1. What measuring block do you want to know? Same with vac leak. Ruled that out since only on cylinder 1.

guy022077
04-24-2012, 06:39 AM
No idea what the maf is reading. Kinda ruled that out since it's only cylinder 1. What measuring block do you want to know? Same with vac leak. Ruled that out since only on cylinder 1.

i agree because of only cly 1 it is not likely but to actually check it to make sure would be better.


maf is 002 give us some readings idle, acceleration

gq331
04-25-2012, 04:07 PM
i agree because of only cly 1 it is not likely but to actually check it to make sure would be better.


maf is 002 give us some readings idle, acceleration

2.6 g/s at idle 10+ under accel. So no problem with the maf. Just received a used ECM so i'll keep everyone posted. Also, as i was watching block 15 @ 2k rpm, car did not miss. The misfiring only happens at idle and only in cylinder 1. Going to drive the car home, plugged into vag and see what happens.

gq331
04-26-2012, 10:06 AM
ECM was not the problem. AGBalahgsadkruewqpiojgksdfla;!!!!! SOB, see updates on first post.

walky_talky20
04-26-2012, 10:48 AM
So basically we are dealing with false misfires. The ECU is identifying misfires that aren't actually happening. The ECU uses the engine speed sensor (rpm signal) to detect misfires. This thread has some discussion on that:
http://www.audizine.com/forum/showthread.php/368836-Boost-issue-wastegate-flutter-%28have-logs!%29

I'm thinking it could be a signal issue. One of the impulse teeth that excites the engine speed sensor is damaged, creating funky rpm signal during cylinder 1 combustion every time. Being just 1 tooth, it smooths over at high rpm, so you only get errors at idle. That's just one idea, though. Throwing a scope on the crank sensor signal at idle would be a good first step in this case.

gq331
04-26-2012, 12:45 PM
So basically we are dealing with false misfires. The ECU is identifying misfires that aren't actually happening. The ECU uses the engine speed sensor (rpm signal) to detect misfires. This thread has some discussion on that:
http://www.audizine.com/forum/showthread.php/368836-Boost-issue-wastegate-flutter-%28have-logs!%29

I'm thinking it could be a signal issue. One of the impulse teeth that excites the engine speed sensor is damaged, creating funky rpm signal during cylinder 1 combustion every time. Being just 1 tooth, it smooths over at high rpm, so you only get errors at idle. That's just one idea, though. Throwing a scope on the crank sensor signal at idle would be a good first step in this case.

Well, I already replaced the engine speed sensor when I had an issue with firing up the car and the epc light coming on. As for one of the teeth being damaged, how would i even replace something like that? Any step by step help would be greatly appreciated. I'm entering a realm that I've never had to deal with. TIA.

Could it possibly be the ECM relay?

walky_talky20
04-26-2012, 01:39 PM
Is the replacement sensor genuine or aftermarket?

First you'd have verify that you even have a signaling issue. You'd do that with a scope on the sensor.

catbed
04-26-2012, 01:53 PM
Well, I already replaced the engine speed sensor when I had an issue with firing up the car and the epc light coming on. As for one of the teeth being damaged, how would i even replace something like that? Any step by step help would be greatly appreciated. I'm entering a realm that I've never had to deal with. TIA.

trigger wheel is on the crank, held on by 3 screws. crank needs to come out to change it. to look at it, you may be able to remove the oil level sender on the bottom of the pan and look in, or remove the pan entirely.

walky_talky20
04-26-2012, 06:04 PM
You could just remove the crank sensor to look for damage on the trigger wheel.

Again, this is just a wild guess. I'm just grasping at straws here to try and explain your issue. My other guess would something to do with a knock sensor. There is some debate as to whether ME7 uses the crank sensor or knock sensor for misfire detection (see previously linked thread). But whatever the method, something is triggering it only for one particular cylinder.

Come to think of it, if it was a tooth on the crank wheel that was causing it - it ought to cause misfire detection on cylinder 1 AND 4. Because the first turn would be the power stroke for cylinder 1, and the next rotation would be for cylinder 4. So perhaps that wouldn't even explain it. This is a mystery indeed. Coil pack wiring would make more sense because cylinder 1 definitely has the most length of wire over the valve cover. A minor wiring fault causing the softest misfire in history could be another explanation.

B5RiceEater
04-27-2012, 01:58 PM
U need a new valve or a new head i've been thru the same thing i took my head off and the exhaust valve seat was cracked i had low compression in cyl 1 90psi cyl 2 160 cyl 3 180 cyl 4 180
I changed injectors coils and rewired harness yep its a 8itch :-(

gq331
04-27-2012, 04:05 PM
Is the replacement sensor genuine or aftermarket?

First you'd have verify that you even have a signaling issue. You'd do that with a scope on the sensor.

of course it's genuine. i will never ever again put aftermarket stuff like that on the car. way to many issues with aftermarket stuff.

gq331
04-27-2012, 04:10 PM
U need a new valve or a new head i've been thru the same thing i took my head off and the exhaust valve seat was cracked i had low compression in cyl 1 90psi cyl 2 160 cyl 3 180 cyl 4 180
I changed injectors coils and rewired harness yep its a 8itch :-(

did cylinder 1 max out at 90psi?

yeah, i'm trying to eliminate every option possible before having to take the head off. thanks for responding to my PM from earlier. because of the crazy amount of misfires in a really short period of time, i'm thinking it's electrical. but, a new head means i might as well buy a new car since a head job is probably half of the price of what the car is worth. I'm thinking the ecm relay because that sends signal/power to the crank sensor and it might be it and it's a cheap solution. And so the hunt continues. will keep updating. this is just nutz. and i'm still daily driving this sucker.

gq331
04-27-2012, 04:14 PM
You could just remove the crank sensor to look for damage on the trigger wheel.

Again, this is just a wild guess. I'm just grasping at straws here to try and explain your issue. My other guess would something to do with a knock sensor. There is some debate as to whether ME7 uses the crank sensor or knock sensor for misfire detection (see previously linked thread). But whatever the method, something is triggering it only for one particular cylinder.

Come to think of it, if it was a tooth on the crank wheel that was causing it - it ought to cause misfire detection on cylinder 1 AND 4. Because the first turn would be the power stroke for cylinder 1, and the next rotation would be for cylinder 4. So perhaps that wouldn't even explain it. This is a mystery indeed. Coil pack wiring would make more sense because cylinder 1 definitely has the most length of wire over the valve cover. A minor wiring fault causing the softest misfire in history could be another explanation.

yeah, but the wiring would have to be bad from the ecm to the back of the block. already check wires running over the engine. i'm going to try the ecm relay. if that doesn't do it, i'm going to give in and take it to a shop. =(

walky_talky20
04-27-2012, 04:46 PM
How about a leak down test? That would confirm your valve sealing problem. I highly doubt it's the ECM relay. The wires for the Engine speed sensor go directly to the ECU. The power doesn't come from the ECM relay. That relay powers the coil packs.

gq331
05-01-2012, 09:45 AM
I finally took the car in for a full test, leak down, compression, etc.

Car failed miserably. 70% loss in cylinder 1. Time for a new car. =( Anybody want to buy this off of me? 2001.5 a4 1.8tqm Avant

Militant-Grunt
05-01-2012, 05:43 PM
How much are you looking to get? Pics? Mileage? Details.