I failed smog on my 89 formula 5.7l today and was wondering if anyone could give me a direction on how to find the gremlin.I also have tunerpro for datalogging

 

The usual culprits. Carbon build up, clogged or old cats, bad oxygen sensor, EGR valve, fuel filter, needs a tune up (new plugs and oil). Is this a daily driver?

 

o2 sensor peaked above .8v and below .2v when reviewed from a datalog. plugs and fuel filter were done last september. Oil just changed last week. Its a daily city driver. only put between 2-4k miles a year. so that leaves me with possible carbon build up, cats, and egr valve. cats would be the last thing i would want to try. Thank you for your input.

Oh, also it feels like I'm getting really bad mpg its probably around 6-8 mpg.

 

The egr valve reduces NOx. You may want to clean the egr passages.

 

Turns out EGR valve was not holding vacuum(probably has a tear in the diaphram). any tips/pointers for cleaning out the passageway with it on the car? Ordered the parts to tackle on my next day off. Thanks for the help!

 

Bad MPG sounds like clogged Cats as well, or something else choking the engine.

 

ur in so cal? plenty of smog spots that will pass u no problem. might be cheaper than finding and fixing the issue. normally 200-350 for the smog.

 

Why pass illegally and have a car not working properly and getting bad milage when he can fix it correctly and pass smog legally and get his fuel mileage corrected as well. Stick to the good advice.

 

Well you have to remove the TPI plenum and runners. I used to take a hanger wire and run it into the egr passages. Then attach a small vinyl hose to my shop vac and vacuum the junk out. Then spray carb cleaner into the passages. Use the hanger wire again, vacuum and repeat. When I have had the intake manifold removed, I would use rifle brushes (I think that is what they are called).

 

Thank you everyone for the input. I like to fix things right. Illegal pass would be a last resort type of thing.

 

Any update on your car?

 

any updates?

 

Sorry about the late reply. In the process of putting injectors and egr valve in. My dumbass messed up one of the runners(missed one of the bolts and bent one attempting to hammer it off , but you live and you learn) so I had to wait for that to come in. I'll post results after everything is together again and smogged.

 

Yeah - Well, I'm a gross polluter.... Everything else was in line... but I'm apparently pumping gasoline out of the tailpipe. I won't hijack your post with the saga...