89 740 gl 137000 Im failing emmissions on high hydrocarbons...everything else looks great. All other readings are very low. HC as I understand it is unburnt fuel The possible causes include ignition components, lean fuel mixture from vacuum leaks or improper cpu signals(Mass air meter, o2 sensor)....Before the first test Id replced the plugs, wires and air filter also drove for about a 1000 miles since the car had set for a year. It failed with almost double the readings...I then replaced the cap and rotor, fuel filter and ran a tank of injector cleaner. The second test was worse...much worse, but the other readings CO, NOX were even lower.
I recently did a clutch job and had to replace the flywheel. As far as I understand I indexed the flywheel correctly. If I was a bolt hole off it would of ran poorly or not started at all if Im right then this is not the issue, but Im begining to suspect that the timing is way retarded...The car runs well and starts fine. Its not peppy or fast by any means, but I didnt think it should be.
I found top dead center as follows..removed #1 plug and rotated crank until pressure built against my thumb..then inserted a pencil and slowly rotated until it quit rising. The mark on the crank pulley was not in the right place as the local volvo shop warned me they are often wrong. Can the crank pully be installed incorectly? This is why I found top dead center on my own. I then installed the flywheel as described in the manual and the car fired right up. It was right? I installed the transmission and have drove almost 2000 miles now.
Im stumped and ready to sale the car to someone who dosnt need a smog test. The car gets 27mpg so It cant be running that bad. I tried to check the timing...something Im doing is wrong. I made a white mark on the pulley at TDC and tried to test it..The mark would appear then slowly work its way to the left and not reappear. Does that make sense. The mark would not stay steady. I tried a white mark on the notch in the crank pulley and tested again. Same result. Instead of being stationary it would drift to the left and vanish...Im very confused. It seems to be retarding.
Ive got 1500 in the car and can sale it for that much. It runs fine, Ive done a alot of work ..it just wont pass emmisions yet. Im hesitant to put a few hundred more and not succeed. Ive thought of mysellf as a decent mechanic I try to do things right, but this car is not liking me.Thanks for your help.