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2K views 17 replies 9 participants last post by  DutchNY 
#1 ·
Hey all, I have found a good condition 2003 m5 with Dinan 1 on it. Owner is a genuine guy. Car is perfect for me except, the owner states it needs the heads ported and polished due to carbon build up.

Any thoughts on the heads and advice?

Thanks.
 
#2 ·
Welcome to the board! Carbon Build Up (CBU) is typical for these cars and not a major concern so if the rest of the car checks out then don't let that alone stop you. The error code to confirm CBU is "AA". It will throw a nuisance "service engine soon" light but it can be programmed out if that bothers you. Taking the engine apart just to clean out CBU would be overkill.
 
#5 ·
Congratulations, it looks like it has some great parts on it!
You might want to find out if it already had software installed. With the brake kit and Dinan wheels it may have a Diana flash? If it is any stage, I am pretty sure the ecu is modded.
Mine did and I had to take it to the dealership, have it flashed back to stock, and then I installed the shark. At the time it was annoying but now everything works great and the tune feels really responsive.
 
#7 ·
Thank you. It was a great deal.
Yes, I am not quite sure why it requires "Porting and Polishing" for carbon build up.

I will be sticking a scope in there soon to take a look. Probably run a carbon clean up before and after to see whats really going on.
 
#8 ·
Does the car have a check engine light on for the SAI fault code?
Here is a good write-up about what might be going on
 
#10 ·
Car did not pass CA smog.

Car is showing the an Air Pump code. Ordered a replacement. Should have it tomorrow.

I cleaned the throttle bodies, and sprayed some valve cleaner in since I was in there. Huge puffs of smoke.
I put everything back together and drove it. Also added cleaner to crankcase and in the fuel tank.

Once I install a new air pump and drive it for 100-200 miles, I will do an oil change and re test it for CA smog. Hopefully it works.
 
#9 ·
Congrats, shes a beauty.
 
#11 ·
If it is indeed the carbon build up, a scope isn't going to tell you much. There are small ports that run lengthwise in the head from the front, with "T's" off to each cylinder. they clog with carbon build up. I've actually had good luck with driving the car hard (after warm up) on repeated sessions after clearing the code and have it not come back for a long time after. All emissions monitors set and it passed inspection (New York). It did eventually come back, so I bought a tune and had them code out the AA code. Secondary airflow too low.

Great looking car with a lot of goodies! Dinan BBK front and rear, look like Dinan mufflers, if it's an S1 it should have Dinan suspension, could have tune, cold air intakes? Strut bar? and other M5 enthusiasts would kill for those wheels. They are very rare and desirable to some. I have a love/hate relationship with them... I get jealous when I see them but I don't actually think I would like them on my color car! haha How many miles on her? Do you mind us asking how much you paid for it?
 
#12 ·
If it is indeed the carbon build up, a scope isn't going to tell you much. There are small ports that run lengthwise in the head from the front, with "T's" off to each cylinder. they clog with carbon build up. I've actually had good luck with driving the car hard (after warm up) on repeated sessions after clearing the code and have it not come back for a long time after. All emissions monitors set and it passed inspection (New York). It did eventually come back, so I bought a tune and had them code out the AA code. Secondary airflow too low.

Great looking car with a lot of goodies! Dinan BBK front and rear, look like Dinan mufflers, if it's an S1 it should have Dinan suspension, could have tune, cold air intakes? Strut bar? and other M5 enthusiasts would kill for those wheels. They are very rare and desirable to some. I have a love/hate relationship with them... I get jealous when I see them but I don't actually think I would like them on my color car! haha How many miles on her? Do you mind us asking how much you paid for it?
Thanks for the info.

I am going to clear all codes, cold start a few days, and then drive the car hard for 40miles, while its hot and no code showing, take it straight to smog and test it. I have read this worked for others. Smog Passed
Once I get pass this smog issue Ill look into a permanent fix.

Dinan wheels, strut braces (F/R), intake, exhaust and tune. Suspension is KW v3 Coilovers.
I like the wheels but would have prefered the BBS Chr's wheels. Car has 94k miles, pretty much one local owner, picked it up for $16k
 
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