Need diagnosing help on 99 M3 E36, Rough Idle, Cold Start Issues

[kazamali]

Hi Everyone,

I'm posting to a number of forum sites in hopes of getting some good advice on my issues(I apologize if you've seen this already):


First, the data:

-99 M3 E36 Coupe
-99k miles
-Active Autowerke Stage 2 Twinscrew Supercharger (AA intake, stock exhaust)
-All maint/SC work is DIY
-Inspections done on time
-No negative history on the car at all
-No major sensor/equipment replacement (except for MAF)

History:

-Bought the car in '02 (36k miles)
-Supercharged it in '06 (80k miles)
-Ran perfect before SC
-Ran perfect WITH SC for 2+ years
(except the occasional <every few weeks> 1188/1189 CODE with no visible performance effects. just reset it, no biggie)
-Dec '08, Car refused to start/hold idle one nite after a short trip and was dumping mass amounts of fuel, blk smoke/soot out of the exhaust(had to disconnect MAF to limp home)
-tried starting it a few times after that before confirming a MAF issue
-replaced MAF(AA uses an e39 MAF for the higher flow), no change
-replaced Active's calibrator unit (connects between MAF and DME to cap E39 MAF voltage to DME), car finally started

Problems(since above steps):

-On cold start, the engine shudders violently for the first 20-30 seconds, like it can barely hold idle (basically you can hear the clanging of the exhaust because the engine is so out of balance
-if I try to back the car out of the garage in the first minute or two, the idle dives as soon as I hit the gas (like the fuel or air is literally cut when hitting the pedal)
-once car warms for a couple of minutes, idle smooths out, but it feels like the engine "skips" a beat (hard to explain, but it's like a minute hiccup at idle every 10-15 seconds
-if I take a short trip (say a mile or two), stop the engine for a few minutes, then start it again, the idle starts to "hunt" or bounce up and down and then drives rough (like choking for a few minutes)
-on longer trips at freeway speeds, I can feel the engine "skip a beat"
-Hard acceleration can "hiccup" as I hit the higher RPM's (but this problem is not always consistent)
-Engine codes thrown CONSTANTLY: 1188/1189 (fuel control bank1/2 sensor 1), 0170/0173 (fuel trim malf. bank1/2)


Before I nosedive into buying the wrong items (ICV, ECT, O2 sensors-which probably need to be replaced anyway), I wanted to see if all of these issues together point to a smoking gun and can possibly help someone else. Yes, my car is at almost 100k miles and yes some component degradation might have been accelerated due to the supercharger, but I'm hoping someone out there has seen this and thru their own troubleshooting have found the solution. I've walked thru the whole vacuum/intake system with carb cleaner to find a leak, but no joy.

I'm not a beginner mechanic(I put in the SC without any issue), but I'm also not heavily exposed to many varied situations like a pro or forum folks. I've scoured many forums and have tried some non-intrusive stuff thus far. I know this can be the "holy grail" of troubleshooting, so any help would be much appreciated.

Thanks!

-Kazam

[kazamali]

It's a manual tranny, btw

[talisman318is]

And hope the source of your issues is at least in part a vacuum leak that can be inexpensively remedied.

[saltshaker185]

can you swap the software back and put it to a regular intake to see if its the supercharger or its software?

[jmo69]

Cleaning the ICV isn't hard but IDK if that would cause all your problems. I cleaned mine at 114K because of bouncing idle but it wasn't as dirty as some I've heard of. At least I know it's loose and free. Just my $.02

[kazamali]

Thanks for the replies, guys. I'm going to check the fuel regulator first and then do a smoke test (suggestions from the other forums since I'm using an SC and carb cleaner checks don't work). Once that's done, I'll move on to the ICV and the O2 sensors since, as someone put it, the DME ignores the O2's at warm up since it works in a closed loop mode.

Swapping the software isn't an option as I had to send it to FL to have that done (i'm in San Jose, CA). I highly doubt that's the problem, but I'll keep it on my last resort list.

I'll keep you guys posted on the results.

[kazamali]

First of all, thanks to all of those who responded and jarred my brain a bit. I tried the following(and most were due for a change anyway) to no avail:

- Smoke test: All good
- Inspected vacuum lines for kinks: All good
- Fuel Regulator: All good
- Spark plugs: All good
- Inspected/Stetho'd' Injectors: All good
- Cleaned MAF: All good
- Cleaned ICV: All good
- O2 sensors: All good (BTW, use NTK only..other brands are crap)
- Fuel Filter: All good

So I got desperate and just ordered *another* frigging MAF to replace the 3 month old one and guess what? All fixed. I mean ALL fixed. None of the symptoms I described above are present. I'm extremely happy and ticked at the same time, but lessons learned. I'm taking my old(well, the old/new) MAF to the nearest shop and having it tested to see what is wrong.

Again, thanks for the help guys and if you want really good priced parts, go to Auto Parts Warehouse (no, I don't work there) via Microsoft Cashback. You literally get %10 cashback for any purchases there. No joke.

[witeshark]

Glad to see you got it sorted!

[AlpineSixAndSeven]

Originally Posted by kazamali

Again, thanks for the help guys and if you want really good priced parts, go to Auto Parts Warehouse (no, I don't work there) via Microsoft Cashback. You literally get %10 cashback for any purchases there. No joke.

lol yeah i ordered stuff through them... but they sent me the wrong A/c Comp. and wouldn't take it back...