i have no spark advance in a 88 c1500 pickup,, advice?
we already checked or replaced everything we could think of , distributor, timing chain, timing pickup. does this model yr truck have a crank or cam position sensor? we are at our wits end on this one p.s. no trouble code either.
5.7 litre v8 runs good until under load. then falls on its face. already tried most of the items already responded to this question
- Anonymous1 decade agoFavorite Answer
First of all, "IF" you have a distributor, then you won't have a crank/cam position sensor. You can try these things to see if you hit on anything. Plugged up fuel filter, bad spark plugs, or vacuum leak at the intake or the hoses. NO TROUBLE CODE is your key here, and tells you that the computer see's all systems as a go, and you need to start looking at the mechanical side of the picture. A lot of miles on the vehicle could indicate a worn out cam, but I would think you have already done a compression test on the cylinders. A stopped up fuel line on the pressure side or the return side would do just what the truck is doing since it wouldn't have enough fuel pressure to meet the demand of a load. Partially plugged injectors would also cause a starvation of fuel thing. A bad fuel pressure regulator, or a leak in the vaccum hoses could make the pressure regulator not supply the engine with enough fuel. Did you put a gauge on the fuel rail to eliminate the possiability of low fuel pressure as the culprit? Too wide of a gap on the spark plugs may do this, as in a burned up set of plugs that are just way out there on the gap setting. This is NOT some mystery, and you can check the advance on the distributor by hooking up a timing light and taking the RPM's to 1,500, and to 2,000, and to 2,500, and finally 3,000 RPM's, and you should be able to physically see the change on the scale as you change the RPM's. This will then tell you right away if the distributor, and computer are doing their thing as expected. As a last resort, you might consider the computer is shot, but I have my doubts about that, since they either work or don't work, and would have all kinds of wierd codes coming from it. Do a test with a vacuum gauge to see what's going on. A vacuum gauge can tell you a lot about the engine, and is a very useful tool in diagnostics of engine problems. A severly stopped up air filter could do this too, but I'm sure you been there already. Go back and make sure the distributor is in the correct notch. My race car did the same exact thing, but it was a lack of fuel doing it, and when I stepped up to a high volume pump the power came back. I have even saw a fuel hose collapse and cause this, and it only collapsed under a hard load. I hope I have pointed you in the right direction, as I just don't know what else to suggest, but if I think of anything I will add it to this.
Glad I could help you, Good Luck!!!Source(s): Certified Master Mechanic, Shop Owner, 40 years experience.
- 1 decade ago
It's been a while since I worked on one of those. If I remember correctly. U should have a four wire connector near the distributor .Or a single wire with a black or brown connector. Located on the right side of the kick panel. Either one of this perform the same duty. Your advance is controlled by the ecm. Receiving data from your map, tps o2, baro and cts. U need to make sure all sensors are working properly.By disconnecting the four or single wire connector u but the ecm in open loop. Set your timing accordingly. Check your under hood sticker for proper specs. It is normal for your check engine lite to flash while timing is being set. Don't forget to reconnect connectors U may have to clear the memory after u are done. Code 12 is normal. If u are still having problems with timing. And all sensors are ok. Expecially your cts. Check that the ecm is going into closed loop at the proper temp. Check your thermostate for being stuck open. That will cause the advance not to work. Let me know how it works out.
- hoaglinLv 44 years ago
maximum people who dont paintings a a dealership have not have been given any clue what this C-ok element skill.that's the 1st question i asked the provider supervisor as quickly as I have been given my activity at a chevy dealership.I instructed him on television the C-ok vans have been on sale.He instructed me that's the code the generating unit makes use of on vans.The C is a 2 wheelcontinual truck and the ok is a four wheelcontinual truck.This has helped me the final 19 years working interior the chevy dealership.desire this enables.