82_Camaro

i rebuilt my 82 Z28 with cfi. it was running fine. then all of a sudden its not. i start it up and a couple times the rpms just started rising. recently hasnt done that. others it just dies. and some it back fires out of a throttle body and dies. i pulled apart the est connection and set up a timing light and it dies and i cant even set the timing. i just absolutley lost as to what to do now. not a clue. if anyone has any input even if its something out there id appreciate it. also my fuel pressure between throttle bodies is 12-13 psi.

zraffz

Any backfire is a fuel/spark issue, if you can rule out fuel pressure and are 100% certain the plug wires are in the right spots with a strong spark it is a timing issue.

82_Camaro

Well I know that the firing order is right and I have the Plugs gapped enough and fuel pressure is good. So if your certain that the timing is the problem, what would you suggest I should do about the fact that I can't even keep it running long enough to set the timing?
Thanks

Coprice 9C1

By "firing order is right" do you mean that you verified that the wires are on the distributor in the correct spots? They may be in the correct order, but not in the right spots. its an easy mistake to make.

Did you replace all the vacuum hoses? Crossfires hate vacuum leaks. you might replace the vacuum caps on the back of the throttle bodies just to make sure they don't leak too. The top plate on the intake is another likely culprit for leaks.

n1ffer

When you did the rebuild did you remove the throttle bodies? If so, they need to be balanced.

Vacuum lines are definitely an issue with crossfire. If any where brittle and cracked during removal or install it could be problematic.

Also need to make sure the TPS is set correctly. I have heard of the air system diverter valve causing problems, but mine came with the air pump belt removed and it runs ok. Is your air pump installed and working?

EGR vacuum lines should be checked. Is your MAP sensor line ok? The crossfire system is an entire system. These are some of the things you should be thinking to check. One sensor, valve, out of balance throttle body system or cracked and leaking vacuum line and it can get hairy.

In addition to the normal SBC stuff to check, timing, spark, ignition module, cap, rotor, plugs, wires, etc., you will have to look at all the sensors and settings for air and electrical.

8t2 z-chev

does sound like the problem is something with the MAP
or timing off...Getting a CEL?,any major sensor problem
should light the CEL and set a code.

sofakingdom

iTrader: (1)

Timing set

82_Camaro

got no code. I'm going to try to just advance the timing before i start it and see if it stays running. if so then I'm going to attempt to set the timing. 8 degrees is correct for crossfires right? or should i advance it a bit more for having a bigger cam

Coprice 9C1

I just re-timed my car at 8 degrees and it runs great. It's a stock cam though. Only exhaust mods.

82_Camaro

I just timed mine to 12 degrees and it's running good. I think I may advance it a couple more degrees. I till have yet to set te idle cause I'm looking around for te j tool but when I do I have a feeling I may need to set the timing again