Misfires without any Vag Codes, help troubleshooting please

[ENDEE666]

Looking for a more specific way to troubleshoot this other than just trial and error of buying parts and throwing them on for no reason. Is there ways to test coil packs or ICM's with a multi meter or something? For all I know it may even be an injector as well. This is an issue I have had very often for a while now, off and on. And a lot of things have been replaced, and it keeps coming back way too soon, before parts should be anywhere near worn.

Running a basic 93 tune right now. Plugs are only a few months old (NGK BKR7E or whatever the # is), coil packs about 9-12 months old, injectors are 60# Siemens, under 2 years old. Vag Com shows no error codes at all. Unfortunately I have never been able to get ECUX to work on my new laptop with Windows 7, so I have not been able to log since like September.

It breaks up under boost. Starts off intermittent then over time it gets worse to the point its shaking & shuddering hard every time I boost. Its back again, in its early stages, just like it always starts. Boost gauge shows normal stability when it happens. No part changes have taken place.

So what can I do to troubleshoot aside from just buying everything involved with the ignition system for nothing. Since it keeps coming back even after replacing things, the problem must have deeper roots, causing these failures. Can a multi meter be used to test the coil packs or ICM's? I feel like I should start there..

[A62TURBO]

How much boost are you running and who did the tune?

Edit: I would also check for FPR and fuel pump, you might need more fuel at WOT

[ENDEE666]

How much boost are you running and who did the tune?

Thought everyone in the A6 forum kinda knew my car. SSP Tuned, as my sig states, and 23 psi

Oh, and I usually use Bosch side-fires and still get the issue after a couple months with those as well. This is the first time in a while I used NGK's. They were good for a couple months, now the issue is happening in the same way it did with the side-fires...

[A62TURBO]

ECM, coil pack, plug problems usually result in a cel or code stored in the ecu, I would def look into FPR and fuel pump.

[ENDEE666]

Fuel pump is brand new Bosch 040 cause pump was a suspect as well, but still happening again.. FPR not old either.

[redneck truck]

Do you have any vacuum leaks? Is(are) your suction pump(s) clean? If it gets progressively worse the harder/longer you drive, maybe you're not storing enough vacuum or you're losing it faster than you're building it. I could see that causing symptoms like the ones you're experiencing.

Since you've experienced this symptom before, what did you do to fix it last time, and how long did that fix last?

Also, silly question, but I ask everyone. How are your battery and your grounds? I've seen stranger things result from a bad battery and/or loose grounds.

[redneck truck]

Also, are your primary o2 sensors good? In three of my vehicles, replacing those remedied pinging, excessive emissions, poor gas mileage, and poor fuel economy. Maybe you're running too rich or lean, but your o2 sensors aren't catching it because they're fouled. Is that possible?

[ENDEE666]

Do you have any vacuum leaks? Is(are) your suction pump(s) clean? If it gets progressively worse the harder/longer you drive, maybe you're not storing enough vacuum or you're losing it faster than you're building it. I could see that causing symptoms like the ones you're experiencing.

Since you've experienced this symptom before, what did you do to fix it last time, and how long did that fix last?

Also, silly question, but I ask everyone. How are your battery and your grounds? I've seen stranger things result from a bad battery and/or loose grounds.

O2's are pretty new. Battery is new, also added ground wires a while back in an effort to fix it. Usually the fix is either plugs or coil packs. But my point in all this is that something is killing plugs & coils way too quickly. Thats what I want to find diagnose and since they are all electrical things, there has to be a way to test them with a multi meter. I found a bunch of articles online of how to test coil packs for various other cars, but nothing for 2.7's.

What are these suction pumps? Not familiar with those. Boost holds ok and vac is around 22-25 on the gauge at idle..

[skiroad'r]

Any chance this is transmission related?

This may sound completely absurd, but my Tiptronic was low on fluid as a result of my failed top attempt after a timing belt job. Under hard acceleration, it would infrequently hesitate on shifts and the car would not boost. It also felt down on power when it was hesistiating. I did the drain and fill service and it's al better now. Completely different car.

If you have a 6MT, is it original clutch, etc? A friend just put a HFC and stage 2 flash into his car and the extra power highlighted that the PO could not drive a manual for shit.

Given you have no codes, I think you are looking in the wrong place.

[ENDEE666]

Car is a 6 spd, so not trans related. This morning on the way to work it was mostly traffic but the few times I mildly boosted it didn't seem to break up until I had been at normal temps for a while, like 20 min or more. Before that it seemed ok and gradually came back. Yesterday when it did it I had been driving a while. I guess this now brings temps into the mix but not sure how it plays into it all.

[skiroad'r]

stumpted ** will check with my b5 S4 brain trust.

[Deep6ed]

OP, are you recieveing engine power loss, or is the power there & the car just shaking? Are you positive it is engine sputter/misfire? What suspension do you have?

[ENDEE666]

Yes, there is power loss, its engine related.

[awtst3.a6]

Yes, there is power loss, its engine related.

I was about to say it sounds piston or a seal where you're losing compression. Local honda had the same issues with pinging issues and ended up being that. GL

[ENDEE666]

Motor was just swapped with a very fresh one (all new head gaskets, seals, etc) and the exact same thing was happening with old motor. So I'm thinking the block and all inside it is non variable. Has to be in the components that were common from then til now. Which is injectors (not pump), coil packs, icm's, harness, etc. EGTs are new. O2's not very old.

[awtst3.a6]

Have you checked the fuel filter? I know you said the fuel pump was new didn't see about the filter. Also have you tried to just reset your spark plugs?

[SPRX]

It coulbe something as simple as temperature sensor... Have a look at the plugs after it will just happen... Black? Then it's too rich, colud be sencor cuz it sends signal that engine is cold all the time and it runs in that mode (richer when cold), causing your problems. Just a thought yaknow? ;)

[A62TURBO]

it has to be sensor related if you're saying it happens when you reach normal temps, how about coolant temp sensor? That could be making your car run rich/lean causing your plugs to foul.

[ManyAudis]

In the UrS6 a misfire under boost was almost always due to one or more week coils. If it occurs at idle then it is one of the ICM channels. ICM channel failures are easy to find. Just unplug one injector controller at a time. One of them will not result in a rougher idle and that is the one that is bad. The coils are more difficult because they typically only start to fail when hot and under boost. You either have to replace them all or get one new one and move it around until the problem goes away. The UrS6 guys would use the second option because the coils were > $100 each. High boost makes the engine even more sensitive.

Having said this, the second most common cause of boost under load in high boost UrS6 engines was spark plugs. People tried a lot of different plugs in that engine because the Audi recommended Bosch plugs were $15 each. Even with one less cylinder than you have, that made for an expensive plug change, and they are almost impossible to find locally. Almost everyone who deviated from the OEM recommended plugs ended up switching back due to misfire problems.

The fact that you do not have the problem when cold rules out fuel pump problems. It could be a sensor like O2 failing at high temperature but they typically will throw a code if they are bad.

Good luck. These things can be hard to find.

[ENDEE666]

See thats the thing, it has happened now with 3 styles of plugs, side fires included. Coil packs has been the culprit as well at which time they were changed. But I feel like the problem must be further up stream thats causing the plugs and coils to fail so frequently...

Picked up new NGK BKR7E's today, gonna throw them in tonight for now and also check condition of current plugs and report back results. Otherwise, I might try the idea of replacing one coil pack at a time to see if that can at least pin point which cylinder, if the plugs doesn't make it better. But even if they do, I still want to find the root of it all that causes this to reoccur..

Thanks for the help thus far all...

[bryzf1]

Check out post #20 in this thread and see if it helps you get EcuX running on Windows 7.

http://www.audizine.com/forum/showth...=1#post4768189

[ENDEE666]

Somebody had mentioned possibly the FPR. The part # on mine says 078 133 681 AR. Is the the right one to go with my Bosch 040 & Siemens 60#?

[ENDEE666]

Promised to report back to all. Found a few things when changing my spark plugs. For starters, there was a wire harness not plugged in at the back of the passenger side head by the top corner of the valve cover, it plugged in to a black cylinder thing. Not sure what it was but I plugged it in.. Aside from that, the plugs were A LOT worse than expected!! And only like 2500 miles on them. Very black, but some other discoloring as well. 4 of them were gapped to .025 but one was .028 & one was .029. I figured some pics would tell the story best. Gap is labeled on the ones not .025, but all the ones on the driver side were proper gap..

Pass side. Left in pic is front, right in pic is rear-



Driver side. Right in pic is front, left in pic is rear-



Maybe all this can shed some light? I sure as shit hope so..... Tired now, but I have a decent drive in the morning that will show if it still does it after warming up. But again, I need to know what is causing this.

[ENDEE666]

Ok, so today it still breaks up. Only this time it feels a little less harsh, but still does it. The really weird thing, is now it even does it when cold. Before heating up for a while.. Now I am REALLY stumped!

[A62TURBO]

Are those plugs a range colder than the stockers?

Edit: it looks like you're running stock plugs, I would try one heat range cooler, http://http://www.ngk.com/charglossa...?kw=Heat+range

Were these the plugs you ran, they are a heat range cooler and specify high boost applications. http://www.jhmotorsports.com/shop/ca..._66_68_192_200

[Siricospeed]

It appears that you should be running a plug 1 colder than stock so as not to pre-ignite the fuel mixture during high boost. But that most likely is not the issue. Secondly, close the plug gap to lower the resistance in the cylinder under boost. (this keeps the coils firing under high boost/heavy load caused by full cylinder charging) More boost = more fuel in the same space= more resistance (electrically) to firing, hence the smaller gap. Lastly, coil packs that are weak usually start out misfiring hot, and then progress to misfire colder and colder (and under less boost) until failure is complete.

Also, take a magnifying glass to the plugs you took out. If you see little shiny specks on the porcelain, it is pre-ignition - Too hot a plug, or too lean.

I hope this helps you diagnose which issue you are experiencing. It can be a frustrating process.

[ENDEE666]

BKR7E is the temp range everyone recommends. Stock is temp range 6 for NGK, these are 1 notch colder. And yes, I have also run Bosch side-fir F5DPOR as well, and get the same issues after a while.

[A62TURBO]

Honestly according to all your info I would check the tune if I were you, there's nothing else that you can really point to.

[audirs]

try testing your o2's and related items. here is the link ive used

http://forums.vwvortex.com/zerothread?id=1265064



use the link on how to test the blocks. blocks to test are below in my post for the 2.7



Block 030 - Oxygen Sensor Regulation
Shows four fields instead of two... all 4 sensors shown.

Block 032 - Oxygen Sensor Control Learned Values
both pre-cat sensors shown.

Block 033 - Pre-Cat Oxygen Sensor Control
both pre-cat sensors

Block 036 - Post-Cat Oxygen Sensor Control
both post-cat sensors shown

Block 034 - Aging of Pre-Cat Oxygen Sensor
shows one pre-cat sensor b1s1 (other one in Block 035)

Block 035 - Aging of Pre-Cat Oxygen Sensor
shows one pre-cat sensor b2s1 (other one in Block 034)

Block 046 - Catalytic Converter
shows one cat bank1 (other one in Block 047)

Block 047 - Catalytic Converter
shows one cat bank2 (other one in Block 046)

[KTG]

Endee666, I am having what seems very similar to you. I just changed the plugs today with no help. My power has gotten weaker on my Revo tune. Does your car sputter at idle? Mine has a nice hummmm, then all the sudden putt putt hummmm putt hummmm etc etc. I have no codes, but know somethings not right. I had a code a couple weeks ago, but it was for the SAI. I replaced the fuel filter a year or so ago, o2's a year or so ago and tbb a year ago. Could a fowled injector not throw codes?

[ENDEE666]

Audirs- I will check that out tonight or tomorrow. Thanks for that! I have no cats and the secondary O2's are deleted at the ecu, but the rest should still be checked for the main O2's..

KTG- My idle is fine. Cruising is fine. Below 3500 rpm or so seems fine too. And in the same boat as you as far as not throwing codes. Thats the most frustrating part!

[KTG]

Yeah, usually you hate to see the check engine light, but in situations when you know somethings not right...It sucks its not on!

[Mantis]

It appears that you should be running a plug 1 colder than stock so as not to pre-ignite the fuel mixture during high boost. But that most likely is not the issue. Secondly, close the plug gap to lower the resistance in the cylinder under boost. (this keeps the coils firing under high boost/heavy load caused by full cylinder charging) More boost = more fuel in the same space= more resistance (electrically) to firing, hence the smaller gap. Lastly, coil packs that are weak usually start out misfiring hot, and then progress to misfire colder and colder (and under less boost) until failure is complete.

Also, take a magnifying glass to the plugs you took out. If you see little shiny specks on the porcelain, it is pre-ignition - Too hot a plug, or too lean.

I hope this helps you diagnose which issue you are experiencing. It can be a frustrating process.

This is good info, but he is already using the 1 range cooler plug, and the gap is also very tight 0.025 vs stock 0.032, I hope you find a cause for this, I have a friend who was suffering the same fate.

[Siricospeed]

You know, the last plug on the driver's side looks lean. I would also recommend some injector cleaner. The rest look ok for a boosted car. They appear rich because they run a richer mixture under boost than a n/a car. Perhaps you are not experiencing a misfire, but a lack of fuel in one cylinder. That would not necessarily trigger a cel.

[Mantis]

You know, the last plug on the driver's side looks lean. I would also recommend some injector cleaner. The rest look ok for a boosted car. They appear rich because they run a richer mixture under boost than a n/a car. Perhaps you are not experiencing a misfire, but a lack of fuel in one cylinder. That would not necessarily trigger a cel.

Good catch, a lack of fuel would definitely give a rough ride, but not trigger the CEL

[ENDEE666]

Good catch indeed. And since its just that specific plug that looks different, it may also help pin point the cylinder with the issue. Should I inspect the injector on that cylinder? What kind of things can I test or look for to indicate a faulty injector?

[djez016]

good info my car is having some what the same problem

[Siricospeed]

Well, if it were mine, I would try fuel injector cleaner in the gas. Then change the injector position and re check the plugs. (swap it with a different injector, from the same motor or a different one.)

Sometimes there is an Injector balance test in the snap-on scantools which shuts off one injector at a time at idle and measures the rpm drop. I can't remember if there is one for this car, but you could do it manually by unplugging the injector at each cylinder and checking rpm and o2 readings.

Good luck!

[G Men 08]

i hate these stupid problems! my automatic trans, v8 does something similar im not sure what it is. seems like the car bogs down and stutters a bit, when i watch the rpms the drop during this issue 1-300 rpms. ive changed the air filter, fuel filter and spark plugs. idk what else to do with it. i get no CEL

[KTG]

I was having this similar problem..Plugs are 1 colder then stock. Took them out and I never gapped them. They were all at the stock .032...Dropped them to .026 and its much better now! Still get a shutter every so often, maybe an injector cleaning will solve it all.

And to the above...These cars are bastard machines