Generic OBDII scanner. Yes those were all the codes that come up every time I get this misfire.
I get it after accelerating hard at high speeds. Like if I need to get around a semi to get in the exit lane, or passing someone on a two-way, etc. Occasionally it will happen after a hard acceleration on the on-ramp. And yes, for whatever reason it's not WHILE accelerating, it's only a few moments after.

I should specify though that I don't have cruise control on my car (not working - don't care really) so it has nothing to do with that, just when dropping down to normal driving speed.

I get absolutely no other issues with this. No loss in power, no shake nor shudder.

 

That indeed is a weird one. If you have somewhere safe to stay wide-open a little longer, it would be interesting to see what would or would not happen. I'm wondering if the fuel pressure is dropping during/just after full throttle, due to the pump or regulator. I know it's a hastle to install a gauge, but perhaps you could T one in at the tank access cover, with the right side passenger seat folded down, and a helper sitting on the left to read the gauge. However, why that would affect only those particular cylinders is odd.

By the way, I'm a big believer in periodically disconnecting and spraying connector pins and sockets with WD-40, or a contact cleaner that leaves a residue to keep air out. I recently disconnected the battery, then removed the ECU box cover, to disconnect and treat all those connectors. Same with ignition, injector, sensors including O2s, etc. Same with any engine compartment grounds; loosen, spray, move around some to improve metal to metal contact, then retighten.

 

Well I'm part way through this next round of fixing/replacing parts. The one question I hope somebody (turbo510) can answer is about the fuel rail...

I took the 4 bolts off and it definitely feels free, and certainly loose, but it doesn't easily lift out. I get the impression it's because I'm lifting all 6 injectors and their o-rings out at the same time so it'll be a little stuck. I gave a generous pull but I was too nervous I was going to break something (not being terribly familiar with the injector/fuel rail setup).

It is just the 4 bolts yes? Then lift everything out evenly?

 

If you can't see anything hanging on, then it's just O-ring friction. Spray some WD-40 (I use it for all kinds of things) and the rubber should loosen up. If you have not relieved fuel pressure by pulling the FP fuse and running until it quits, there will be residual pressure when the first injector is removed, so I'd have goggles on and a catch pan underneath, along with some rags. Even with the fuse pulled and trying to start, there will be some pressure remaining, so expect it. Are you going to swap those injectors around? Record it somehow to you know where each one ended up. If the misfire problem follows the injectors, that's a good sign, because your fix will now be simple. My '96 developed a single-cylinder misfire, and rather than trying to replace that one only, I bought a refurbed/matched set from a place called South Bay fuel injectors, about 4 years ago, for only around $125 for all six. The engine still idles very smooth, especially for one with 260,000 miles, and I think the matched flows help.

 

Okay, another day along. Last part gets here thursday so I won't have much to report until then... I do have a question though.

I stupidly didn't pay attention when I lifted the fuel rail and disconnected two things. (FYI it was just the 4 bolts and a little elbow grease btw, thanks turbo).

Two lines came off two possible areas:

In the first pic you can see all 4 male and female connections:
(One is indeed the fuel pressure regulator)



One of the female ends goes back to where my finger points:

5grAvrG.jpg?1


One of the male ends (the other being the FPR) goes in front of the right cylinder head:
(at the top of the pic you can also see where the end comes out, as well as both missing female hoses)



If somebody knows ONE of the matches, obviously the other match will be correct as well.
Sorry I'm so dumb.
I have seen diagrams for the hoses/lines on top of the engine but I can't find them now (of course).

Thanks for the help!

 

Got it all taken care of.

For anybody else with this ultra random issue who, like me, wasn't in the mood to search "vacuum hose diagram"


(from: | Repair Guides | Vacuum Diagrams | Vacuum Diagrams | AutoZone.com)

(Also keep in mind with this ^^ one, #8 is NOT the one that curves back up into the FPR, #8 is the one that goes down into the reservoir. #5 is the one that hits a 'T' underneath all the vacuum hoses then goes into the FPR. This next image makes it clearer).



(from: http://www.justanswer.com/audi/3yd6j...buleprint.html)

Last part comes tomorrow so I hope to have it out this weekend as a test.

 

She's back together! And around the block a few times and revved up to 3k or so... All with no CEL's. Not that that little type of drive would have caused them before, I just feel a day when I work on my car and don't actually make it worse is a good day.

Here's my coolant temp sensor:



and I redid some of the vacuum hoses:



I hope to report back, good or bad, by the end of this weekend. Thanks for everybodys help

 

sadly I'm back with this issue.

I switched the left bank injectors with the right bank and am still getting the same 2, 4, 5, 6 misfire so at least I know it's not those.

Now I also have a new one: p0118 Engine coolant temperature circuit high input. A quick search on that shows it could just be a bad sensor. Does anybody else have input? I don't mind re-buying a sensor and switching it out, but this is the second time it's happened (first was an o2 sensor), so I'm curious if it's a common issue to get bad sensors.


Again though, if anybody has any advice on the misfire, I'll happily listen.

Thanks!

 

A couple of questions regarding this:

If I could beg/borrow/steal a vag-com setup, what exactly would I test? I have never used one but all I read about are these "blocks" you test to help diagnose. Would having one be any better than what I'm doing now with the guess-n-check method?

I beginning to think it's the cats... The guy I bought the car from put an aftermarket exhaust on and I think the two cats are cheapo Eastern Catalytic and Magnaflow (yes two different). Is it possible that one or both is clogging up and backing up my exhaust manifold causing this? If so, I could just replace them both with cheapo versions again and be on my way. I may need to do this yet again somewhere down the line because of the economy versions I put on, but I figure they'll last a few years minimum and given the fact I drive maybe 2-3k miles a year, I don't need anything amazing. Two new magnaflows + shop time I figure will be $300 or so which isn't terrible. Especially considering I've spent at least that trying to figure this out anyway.

I don't go to a mechanic because I like working on my car myself so I dont know... but is it appropriate to go to them solely for a diagnostic/troubleshoot to tell me whats wrong then drive away and do it myself? (Of course after paying them the $50-$150 for the diagnosis.) Should I tell them I just want a diagnosis before-hand?

 

Well I finally took it to a shop and they ran a bunch of diagnostics and took it test drives. They replaced/checked all the stuff I did and finally decided to replace the ECU... and it turns out that was it.

Unless it is hibernation and decides to rear it's ugly head again down the line, we'll know it was the damn computer. I'm annoyed two-fold, one in that I could never replace or test this myself. And two, in that from what I understand it's almost NEVER the ECU (unless you have an aftermarket chip with the 1.8). Logic says it's about 15 other things before the ECU and I did them all before giving up, and wouldn't you know it...

Anyway, what I've been chasing for a year and spent hundreds on turned out to be a $100 fix... but I would have never tried it before the others. And now I'm out what I spend trying to fix it myself + $450 at the mechanic. Oh well.