A4 Misfire
 

Hey all, I've visited and read this forum quite a bit but never have I posted. I have a '98 A4 1.8T and looking for some advice. Took a couple short trips today and car ran fine. This evening I hop in it to make another short trip. I fire it up and it's missing bad. Check engine light comes on. I use my other vehicle and come back to it about an hour later. Still does it. Disconnect battery, check plugs-good, swap ECM's to stock, check fuses. Still does it. No plugs were wet but exhaust stinks like it's got no spark to certain cylinders. Plugs have about 15-18K on them. No recent gas fill ups or anything. This is not a gradual thing either. It just started doing it, fine to bad.</P>


I'm thinking a coil problem/heat soak or something. It's certainly not hot here, east coast (50 deg) but the engine still had some warmth from the initial trips of the day. I know the later year A4's had coil problems so that has me thinking. The car has 56K miles.</P>


Any ideas or similar situations? I going to make calls tomorrow but any help would be appreciated.</P>


Scott</P>


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A4 Misfire
 

I'm pretty sure thats a dead coil pack or spark wires. Even the good ones die sometimes (not just the defective ones).

<edited><editID>brrman</editID><editDate>37956.3620138889</editDate></edited>

A4 Misfire
 

Thanks for the response Brrman. Would you question a coil/plug wire more than the power transistor / coil amp? Do you think if it is the coil amp and I reduce plug gap, I'd get a correlation? </P>


Even if I find the fault, since the check engine light came on, will I have to get it hooked to a scan tool to clear codes?</P>

A4 Misfire
 

If you fix it yourself the light will stay on for a while but most codes reset after a certain amout of trips without the problem reacuring but it depends on the code certain codes stay on longer than others some might stay on indefinately but you could disconect your battery and do a thottle body adaptation after. that might work<IMG src=smileys/smiley2.gif border="0">

A4 Misfire
 

Thanks Slim. I just got back from doing some tests on it. For the heck of itI regapped the plugs (they were a little wide from use) and I checked the plug wires, whichcame out good (2K ohms each). I'm starting to grind (which may be a good or bad thing). I'll try to make this short...A few weeks back the cowl drain plugged up and flooded the TCM. I got aused TCM from a recycler (didn't want to pay the dealer $1400). I noticed that the new TCM would shift real hard going into gearwhen it was cold (30ish deg). Once it warmed up it was fine. Did it only a couple times but then again, it hasn't gotten too cold here on the east coast. Today I'm playing with it and I could barely get it to start. It's cold today. It's got me thinking. When the old TCM got flooded, it caused all kinds of craziness besides trans function probs....instrument cluster went crazy, idle got erratic, etc.

A4 Misfire
 

Wait wait wait...

You had your TCM flooded!!??? Your tiptronic control module down in the sidewall of the passenger footwell? Man you could have shorted out all kinds of electronics in your car. The TCM is likely linked to a number of sensors... ignition, cluster, idle - all the things you mentioned. All these sensors could have gotten fried.

Its possible the junker TCM you got is also not for the correct car model/year - did you make sure?

A4 Misfire
 

Yes,the TCMgot flooded about a month ago. From what I hear this is a common prob. Check your cowl drain under the battery!</P>


The replacement was correct but as I mentioned, 3-5 times now it banged into reverse/drive only when cold. Once the replacement TCM was installed I had the codes cleared by a local Audi specialist and all was copecetic except for this occassional banging into gear. Here a month later and probably 500 miles, the misfire shows up. </P>


I don't think anything got fried or it would have showed up immediately. At least that's what my internal CW tells me...<IMG src=smileys/smiley6.gif border="0"></P>


I question the power transistor/coil amp but at $300I'm going to wait and send back the TCM (still under warranty at salvage yard) and find another one. Thinking I'll try that first to see if it clears things up.</P>


The feedback and any additional thoughts are much appreciated. </P>


</P><edited><editID>skonka</editID><editDate>37957.4035416667</editDate></edited>

A4 Misfire
 

Could be your ignition amplifier or a coilpack. I'd still bet on the coilpack and that the TCM problem is unrelated. Coilpacks do not cost $300 though.

ECSTuning<edited><editID>brrman</editID><editDate>37957.5227314815</editDate></edited>

A4 Misfire
 

Hey that is pretty cheap<IMG src=smileys/smiley4.gif border="0">

A4 Misfire
 

Yes, that is a good price on coils. I've got another TCM coming. I'll try that and if it's not it, I'll go with the coils. After that I guess it's the $300 power transistor/coil amp deal...

A4 Misfire
 

'$300 power transistor/coil amp'

You mean the piece under the plastic cover just above your turbo? That is the ignition amplifier. ECS tuning has that also for less than $300.

A4 Misfire
 

Brrman,</P>


Cool I see that. I ordered the coils today. We'll try them first. </P>

A4 Misfire
 

cool - let us know how it goes.

A4 Misfire
 

Wow they have the best prices and selection ive seen so far. hey Brrman is that timing kit they have the new style?

A4 Misfire
 

yes it is - its the one I used. I ordered from them. They also have an upgraded kit too where it includes a new snub mount, etc...

ECS really does have some of the best prices and selection for regular maintenance problem items...

I have a pic of the old vs new tensioner in the Photo Album.

A4 Misfire
 

Brrman, I've just got to say, your AVATAR rocks. Every time I see it I get to laughing....</P>


Rock on!</P>



Scott</P>

A4 Misfire
 

Well, bravo to ECS tuning. Despite ordering the coils, after talking to ECS again and hearing my symptoms, they felt it was the power transistor/coil amp. Got it yesterday. Also got the second used TCM. Installed today and all is well. BTW, the coils for my '98 were $49 each due to the engine code...</P>


Only issue is the lingering CHECK ENGINE light but I'll be expecting that to go out after a few starts/runs.</P>


Thanks for your input guys. </P>


Scott</P>

A4 Misfire
 

glad everything worked out man!<edited><editID>brrman</editID><editDate>37964.5893981481</editDate></edited>

A4 Misfire
 

<IMG src=smileys/smiley6.gif border="0">sounds like a bad ignition coil - I have a 2002 A4 1.8T and have gone thru five ignition coils - 4 were supposedly defective, and all replaced, but just had a replacement coil fail today. Good luck ...coil thing seems to be a big problem!!

A4 Misfire
 

From what I hear only the 2001/2002 model years were plaqued by the coil failures. My problem was the coil amp/power transistor mounted on the intake duct work. Check out Brrman's link to ECS Tuning listed above in the thread. They have good prices. You problably have the engine code where you can get a complete set of aftermarket coils for $90.</P>


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