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, Manual tranny
-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

[Big Evil]

Crash Course. Your car is a 99 so you should have an OBD II connection. Plug into it with a scanner that will show you the data stream from your vehicles sensors (this is what the pcm is seeing) Since it's an idle issue you'll want to do this when the car is cold and having the issue. Your ambient air temp sensor needs to be correct, your maf needs to be correct, you ect needs to be correct. You'll have various load and baro sensors, MUST be correct. If ANY of them aren't you need to find out why (bad sensor, bad wire/connection). O2 dosen't mean a thing until the car is up to operating temp and the vehicle enters "closed loop" operation, chances are the O2 is good if the problem somewhat clears up when the car is warm as the pcm will start adjusting fuel trims. You may have a bad fuel regulator, pump, or injector. You can check injectors by using a mechanics stethoscope and listing for the injector action, if one doesn't click its stuck open most likely. Otherwise do a fuel pressure and volume test (basing this on the codes you're describing). Also from what you're describing once you do nail it down, replace your plugs as there most certainly fouled by now.

[kazamali]

Thanks for the reply

I have the Carsoft App that plugs directly into the engine bay DME port, so I'll check that again (I used it to reset the adaptation values). I guess the problem is knowing what all the expected sensor readings are supposed to be at cold temps. But I'll focus a little more and try this again.

I'm going to check the regulator first and then do a smoke test (a suggestion from the other forums since I'm using an SC and carb cleaner checks don't work well in a pressurized system vs. vacuum). You're right about the O2's. Even tho they're old, it doesn't sound like they'd be causing a "cold idle" issue. I have yet to stetho the fuel injectors and pull the plugs, so I'll be doing that too since it's about time (2 years)

I'll keep you 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.

[tree36]

hows the twinscrew supercharger? im pretty intrested in one. how much hp dose your car push? post some pics

[kazamali]

The TS definitely makes this a completely different car and since it's not centrifugal based, it doesn't suffer from heatsoak. 2.5 years and 20k later it still hums right along. I think it'll accelerate the deterioration of certain parts (MAF-haha, guibo, tires), but getting 370 rwhp at the dyno is well worth it(and the TS sound is to die for). I bought mine from Active Auotwerke for $$$$, but they don't sell it anymore. I think they have a centrifugal-based one now that produces the same hp.

Either way, I like it and it was easy to install, believe it or not AND my engine bay doesn't look all modded out. (It actually passed smog in CA, too. woot!)

Wasting those retarded STI's are always fun. I'll post some pics for ya in day or two.

[kazamali]

The TS definitely makes this a completely different car and since it's not centrifugal based, it doesn't suffer from heatsoak. 2.5 years and 20k later it still hums right along. I think it'll accelerate the deterioration of certain parts (MAF-haha, guibo, tires), but getting 370 rwhp at the dyno is well worth it(and the TS sound is to die for). I bought mine from Active Auotwerke for $$$$, but they don't sell it anymore. I think they have a centrifugal-based one now that produces the same hp.

Either way, I like it and it was easy to install, believe it or not AND my engine bay doesn't look all modded out. (It actually passed smog in CA, too. woot!)

Wasting those retarded STI's are always fun. I'll post some pics for ya in day or two.

[tree36]

thats awesome. yeah do it post pics of your engine too. how much did it cost you in total? i wanna know if i should even consider.