I Recently bought a 1990 IROC w/ 5.7L TPI and i just got the safety certificate for it and the mechanics still cant get it to pass the emmisions test and i was wondering if anyone had any ideas what is wrong. they put it on the five gas annilizer this morning and it was running about 250 HC at curb idle and when they put it up to 2500 rpm it went up to over 1000 hc.

its running really rich right now and its burning a bit of oil.


any ideas? thx

 

That high HC count indicates to me that the catalytic converter may be shot (or removed by previous owners). The fact that it burns oil can also increase the HC count. I would look at doing a full tune up (plugs, wires, cap, rotor, 02 sensor, all filters). Make sure the TPS is set correctly and check for any vacuum leaks. Check the timing, fuel pressure and possibly have the injectors cleaned out b/c one or more might be leaking/overflowing. If the car is burning oil I'd run Lucas Oil Stabalizer. That stuff is miraculous and might stop the burning of oil. Also, make sure all the A.I.R. stuff is working properly.Good luck.

--Chris

 

the mechanics put new cats on it, adjused the timing, new plugs, the oil stabilizer and other stuff but i can t remember.

its still burning oil and running really rich

as for the oil problem could it be valve seals?
and the fuel problem i dont know, its running 18-1 fuel air ratio

 

Does the car burn oil constantly or mainly on start-up and when revving? My Camaro burned oil like crazy but it was only on start-up and when it was cold. I got a valve job done and that fixed everything. I would suspect that your valve stem seals are shot but if it burns oil constantly it could also be your rings that are shot.

An 18-1 fuel ratio is very lean. I'm a little confused because you said the car was running rich. A rich-running car would have an A/F ratio of 12-1 or something less than 14-1. Running lean can be very bad for the engine as you are at risk for detonation. The cause of the car running lean could be a lot of things. As I said before, I would check fuel pressure. A bad pump that isn't giving the car all the fuel it needs could be the cause. Another problem could be the FPR, although usually when it fails the car will be rich. The oxygen sensor is very important in controlling the A/F mixture once the car is warmed up and in closed-loop operation. They are cheap (~$20) and worth replacing if it hasn't been done. Another potential problem is the MAP sensor. It could potentially cause the car to run lean, but in most cases that I've seen a rich and crappy running condition are usually the result. Also, I would have the timing verified. Timing that is off could be screwing things up too. And make sure that any and all vacuum lines are OK.

--Chris