Waskly1977

Well...

I'm at my wit's end trying to figure out this issue. This is all on a '93 S4

I recently had a bunch of mods done on the car:
GT3071 turbo
Wagner EM
Stromung turbo back exhaust
42# injectors
1.9 WG spring
034 HO coils
044 fuel pump (relayed)
034 stage 1 GT3071 chipset

With all that installed, the car didn't quite run right (engine wouldn't rev very quickly) and had a miss / cutout under cruising conditions (2500rpm, little to no throttle input. Just keeping the car at a constant speed around 2500rpm)

I had a custom tune done on it and now it runs great! However, the miss / cutout is still present so I don't think the tuning is the culprit for that. It hasn't happened under heavy load or WOT. Only under light throttle or no throttle conditions.
Other parts that have been replaced in an attempt to remedy the issue:
RS2 MAF
Crank speed sensor (G28) (I had a code 00513 - Implausible Signal before. That's why it was changed)
CPS (G40)
Spark Plugs

I was thinking there was a dead spot in the TPS but logging the throttle angle shows no issues.

On top of all that, I put in a wideband AFR setup and a boost gauge. At first I couldn't glance over quick enough to see the AFR gauge when the miss / cutout happened. Lately I've been able to keep it in my peripheral view better and noticed that it goes about 1.0 lean when the cutout happens. Cruising sits around 14.5. Miss / cutout hits and it jumps to 15.5 or close to it and then immediately goes back to 14.5. Basically, it feels like the engine shuts down momentarily then comes back (rolling start basically).

I had the IA Stage 3+ (3kpa vmap) setup and an FMIC on a basically stock setup before all these upgrades and never experienced this miss / cutout condition.

I STFA'd and found 2 posts with pretty much the exact same condition. One pointed to the velocity stack in the air box and the other was due to coil on plug not completely seating on the plug. I'm not running coil on plug but I've checked all my coil / plug connections and they are good. I haven't gotten around to checking the airbox yet.

I've checked all grounds in the engine bay and haven't found anything loose or corroded. No boost / vacuum leaks (the car will pull ~23psi with no issues and loves it)

So, now I'm posing the problem to the people who've poured way more blood sweat and tears into these cars than I have. Suggestions on what to try next?

Thanks for the help.

- SO

speedtek

I know you're running 034 coils, but check the resistance on the coil packs. I had a similar issue when my D585 setup had a couple coils that had way higher resistance than the others. Strange part throttle miss, plus I had serious oil heating issues when driving it hard on the highway.

Waskly1977

I guess it would be fairly clear once I get all the readings on the coils if one is high / low that it's the faulty one.

Thanks for tip. I'll check them tonight.

Waskly1977

I'll be checking them out tonight.

speedtek

The main thing is they should all be within 10% of one another otherwise you can get some weird dwell issues. You want to measure across the primaries, if you get an open with the leads oriented one way, just reverse them and it should work. I'd guess they should be around 10M ohms.

Edit: NM, just noticed they are advertised as 4.8 M ohm

EB_1920

you should post this on the 'other' forum too

Waskly1977

Done...

Waskly1977

I'm looking at the 034 site and I can't figure out what pins I should be measuring across to get the readings. Since these coils have the ttl built in, is there a way they can be measured?

the pinout on the coil is on 034's site. Any ideas which of those pins I should measure resistance through to the coil output?

UrSobsessed

--

speedtek

You'll want one meter lead on the 12V, Pin "E" and the other on one of the grounds. I'd try pin "B" first. If you get nothing, reverse the leads....if you still get nothing, try moving on to either pin "C" or pin "D" (always reference with pin "E", that's your sure thing). You may have to try reversing the leads a couple times, but you should get a reading through the primary on one of those combos. Don't worry, you can't break it doing this. Once you find a reading, that's your primary, make a note of the resistance and make sure the other 4 are all within 10% of each other. Too much of a difference is going to cause problems in the ignition timing cct and all kinds of strange things can happen. It may or may not be your problem, but at least it's (should be) fairly easy to check.

Edit: I'm 80% certain it will be between pins "E" and "B" after having a look at the D585 pinouts and descriptions. The 585's use the transistor ground side to complete the cct through the primary, so these will probably be similar.