audibranquinho

hey guys, i have a 97 a4 1.8t quattro, manual trans. just two weeks ago my timing belt tensioner broke and the timing belt skipped and well, 12 valves got bent and i had to rebuild the cylinder head. okay put everything back together, now the check engine light came on with the codes 16684,16685 . the mechanic said these two codes have to do with misfire detected in cyc.1 and 4,and said it could be the air flow meter( above the air box).first question would be did the breaking of the timing belt tensioner do this or did id just happen and the second question is part covered by Audi as an emissions part. The last code that came up was 18089- control module programming not finished. the mechanic said he's not sure but thinks it might be the ecu, i have a MTM chip and he said maybe it's the chip or a loose wire in the ecu.. can anyone help me with these codes and what to do

Bert

<center><img src="http://pictureposter.audiworld.com/272/16684.jpg"></center><p>This maybe a problem with the reassembly. I don't know what 18089 is though.

HTH,
Bert

dudleydorighta4

I have a Bentley manual and I was looking for these.

Bert

Look for the DTC codes under the fuel injection &amp; ignition section.

audibranquinho

hey bert, thanks for the info on the codes, by the last code has to do with ecu and maybe the chip/ loose wire according to the dealership. i forgot to mention, that after all was reassembled the check engine lights came on. we checked for the codes( as mentioned before) but i forgot to say that i also checked the compretion of all four cylinders and came up with cyl. 1- 100psi, cyl.2- 150 psi, cyl.3- 150psi, and cyl.4 - 90psi. now did the timing belt skip wack the pistons so hard that it caused these two cyl. to loose comp. or is it the ICM, causing the misfire and the low comp. OR is it the air low meter causing a misfire and the low comp.OR just the low comp. causing the cyl. to misfire altogther. please can anyone help before i start taking the engine apart and rebuild the bottom end to restore my comp. back to normal...thanks

Bert

I'm not a professional mechanic but... bad compression can either point to bad rings or bad valve seating. Compression tests are done without spark to the cylinders, so a misfire should not result in low compression during a test. If your ECU was working fine before the the timing belt incident, I would think that it's not the problem.

Did your mechanic do a leak down test to isolate if the low compression is from the rings? The method that I use to do this is after the initial readings, squirt a little oil thru the spark plug holes and then retest. The idea being, if the rings are bad, the extra oil will seal the gaps and therefore your retest will show a higher compression reading. The compression reading will not change if the problem is with the valve seating properly.


Good luck with your engine,

Bert