Victim: 1986 E-250 van w/302 V8 fuel injected 150k miles Recently had the TFI battle whereupon I changed the TFI module, Ignition coil, rotor, cap, pcv valve and breather filter. Vehicle now starts where it was dead before. HOWEVER, after running my diagnostic tester I get a #34. Removed the electronic EGR/EVP assembly and found it plugged with carbon. Cleaned to the point where I can apply a vacuum and the plunger/popett will move smoothly up and down. While there I cleaned (as best I could the matching inlet hole in the manifold with carb cleaner, round wire brush and paper towels). Reinstalled. Ran the diagnostics (did a clr before to be sure NOT reading the same/leftover code again). Still get a #34. Following the vacuum routing diagram vacuum comes from the vacuum canister to the EGR vacuum control selenoids assembly(2 small selenoids side by side). It appears only one controls the vacuum to the EGR valve. I started the vehicle and measured the voltage on the two electrical leads 12 volts +/-. Ran a 'run' test and the voltage never disappeared (remained 12 volts - normal??) Upon completion still get a #34. Manually energized the egr selenoid valve and could hear a hissing noise and felt small amount of vacuum at the egr fitting. Started vehicle again, at idle attached a manual vacuum pump and when it got to about 10in vacuum the engine dropped rpm and started to stumble. This tells me the valve is working and while there may still be some residual carbon in the intake there is still enough open area to allow the EGR system to work. My questions then are: is it normal for 12 to be constantly ON at the controling egr vacuum control selenoid? if not what is keeping it on? While the egr selenoid valve was letting some vacuum through can/could the valve be blocking the vacuum needed to move the valve? Would a defective EVP valve cause these problems (selenoid energized, no stem movement)? AS you can see I am stumped by contradictions to evidence. I don't like NOT being able to solve a problem therefore ANY and ALL help and suggestions will be greatly appreciated....... Look forward to your knowledgeable advice.....Thanks...
- posted
18 years ago