Was told to post my MZ3 issue here.

[cawb352]

Alright, first for the obvious, I really stuck my foot in it. I aquired a 1998 MZ3 with the S52 and a whole bunch of performance goodies already installed. It had receipts for over $10K in a professional rebuilt engine, but it would barely run. I figured it had to be something stupid but the previous owner was fed up. I bought it for way too much money and found out this guy was robbed severely by this so called shop. Now I need some help before I too have had enough.

I tore into the car checking plugs, coils, compression, fuel, air leaks and found no faults. So I decided to check the valve train. What I found amazed me. Several broken bolts, broken flange on the exhaust camshaft and cam timing was way off. I re-timed the cams, and replaced lots of bolts, installed a few helicoils, and changed the oil. It starts and runs smoothly at idle, from off idle to about 2K-2500 rpms, it is an absolute dog. It's missing and bucking and just generally running like crap. After 2500 it runs like a scalded dog. It's actually very impressive. then when you get back out of it, it has trouble catching itself and returning to idle and sometimes just straight dies. I've tried everything I can think of besides throwing massive amounts of parts at it and I just want to bounce it off some other people before I do.

Here's a list of the goodies:
Schrick cams
Lightweight internals
lightweight F1 Flywheel
M50 intake
Dinan cold air
Long tube headers with cats deleted
Full mandrel bent 3" exhaust
Larger MAF
Dinan Tune

NEW PARTS
VANOS UNIT
VANOS SOLENOID
SPARK PLUGS
FUEL FILTER
PLUS ALL THE STUFF THAT'S REQUIRED IN A STANDARD REBUILD

So if anyone has any insight into what is driving me crazy i would truly appreciate it.

[meanEG]

I would guess a tune issue. Have another computer to try out that is stock?

[cawb352]

It was tuned over ten years ago and it only started running bad after this other shop attempted a rebuild and let it sit for two years

[328ijunkie]

Tuned for the 3.5" MAF? I dont recall dinan ever using those MAFs... Try unplugging MAF and see how it runs (be gentile somewhat as it will be pig rich).

ANy codes? Its OBD2. That should give you somefeedback...

[cawb352]

I appreciate all the help. I was reading the plugs again today and found a cracked coil boot. After I've put miles on it again 'Ill recheck the codes Thursday and see what happens cause I'll be out of town tomorrow.

[e30austin]

My money would be on knock sensors. Perhaps a different tune would help.

[cawb352]

Well after changing the coils and boots, it made no change. I feel much better knowing tho because some of them were originals and they were all different brands and year. I replaced the Crank position sensor after scanning it and finding a code. its better bu it still has its moments of stupidity. I performed a visual inspection on it and it appears the there is oil coming out of the bottom hose on the IAV. after it cools down I'm gonna do some digging and see what the cause of that is. I have a theory tthat it might be from the cyclonic, because I can find no evidence in any of the paperwork that it was replaced.