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>


</P>

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...