Static ignition timing retarding by its self
 

ok this is a strange one, had the car back on the dyno and all was going well it was making good hp until the tuner did another power run and as soon as it came onto boost it was obvious something major was going on as it lost 100whp at 5-5500rpm. Very strange as it was still making the same boost as previous runs, so after a bit if troubleshooting we checked the static ignition timing and it had retarded 12 degrees seemingly by its self. We think we've checked everything mechanical that could cause this, the cam gears havnt slipped, the cas is locked in the same position, remember the early evo motors cas run off the intake camshaft. Everything from the crankshaft to the cas looks fine, so it looks like its something electric causing it.

This isnt the first time it has moved on its own accord, after a previous tuning session i came back and the tuner rechecked the timing before we put it on the dyno and it had retarded 4 degrees, very odd so he reset it back to where it should be but now it has done it again as mentioned above. The car runs a MSD DIS 2, Haltech E6K, something must be going on with one of these but theres no real reason or way it can, got us scratching our heads. So what we've decided to do is im going to drive the car around easy (no boost) for the weekend and recheck the timing next week and see if it has changed again. Really need to find the cause of this before any tuning can be done, imagine if it advanced the timing 12 degrees in a power run, goodbye engine :nuke:

what are you using to log the timing?

the haltech logs ignition timing but its the static timing thats changing. My tuner set the cas with the timing light, locked the timing in the ECU, does a few pulls and it has retarded 12 degrees.

ok, I'm following you now. I don't see how that would be changing either, maybe something is wrong with the CAS.

also, do you have to ground something to set the CAS and base timing? You do with a 3000/Stealth.

http://www.stealth316.com/2-ignition-timing.htm

I know how. THe trigger disk in the cas gets worn and can move back and forth. Check it, take the cas apart and you will see the movement of the disk. Used to have that problem in the 1g with high RPM applications.

Hope that helps.

Sean

ok guys ive still got this same problem, we changed the cas on the dyno and were able to tune with no dramas, so i thought it was fixed. Recently the cars been feeling slugish so i rechecked the timing and sure enough its retarded again. So its not the MSD, CAS, or any wiring issue, can this be an ecu problem?

any ideas before i rip the ecu out? : /

bump