Well i bought the car from a guy with this motor in it and The car was running on the stock 305 tune. I added 30lb injectors and a pcmforless tune (yea i know, but i needed this car driveable fast) Long story short, the motor is suggested to have a base timing of 10 degress advance. Well when i set it to that, i took it around the block and it knocked real bad up top. So i came home and put it down to 6 like factory...still pings bad. So i looked at the timing with the computer plugged in and noticed its running 30 degress advance at idle..which is wayyy to much no? I have a feeling its the tune, that he f'd up somewhere...but thats what im coming to you guys for. Suggestions?

 

My bet is that the tune sucks. Those aftermarket tuning companies just jack up the timing which is not the right way to go about it. You can have 2 identical engine that require different timing. For now, just retard the timing more.

 

yea he did a good job on my other car...since its speed density and would barely run with the cam change. and this car was almost the same way since it was a completely different motor running on the a 305 computer. I did manage to get the timing back down to 25 at idle...but i have to run 2 degrees advanced. I also yanked the plugs and regapped em from .035 to .045 because thats what the manufacturer of the engine wanted ( i didnt realize this at the time) i then went over the intake and found some loose intake bolts...tightened those up. The detonation SEEMS to be gone...but i really havnet driven it enough to know for sure..

 

possably an issue with te distributer. the distributer could be advancing the timing because of a malfunction.

 

I doubt it. The computer looks for a crank reference signal from the "crankshaft position sensor" (pickup coil)inside the distributer. Before this signal leaves the distributer, it gets amplified. This is an AC voltage with should look like a saw-tooth patern going to the ecm via a ppl/wht wire into pin D8. The computer then looks at the ac voltage that is generated out of the knock sensor and adjusts timing accordingly. At what range are you getting knock? ...WOT, idle, or midrange, low or high load, etc... Maybe your engine wants that much timing at idle but the SA may be too much in the high load range.

 

What is your compression and cam?

You need to log some data and send it to whoever burned the chip.

 

Yea i couldnt get the car to datalog for some reason..somethings up with my laptop

Anyway, it was detonating mid to high...high being real bad. I think i gotta fixed though, combo of the vac leaks, too much timing and the gap being wrong.

Compression is i believe 10:1 and the cam is a comp cam part # 08-502-8

.495 intake/.503 exhaust

218/224 duration at .50

112 lsa

 

just pulled two codes off the car...36 and 42

both revolving around spark control...

Having wierd issues with the car, sometimes she starts up and runs, other times she wont run...she just cuts off..no studder or stumble..just dies.

 

42 is est disconnect i think...

 

yea it wasnt going away for some reason so i thought it was something else

i replaced the maf burn off and cleared the codes...no more codes

so at least that is fixed, i got alittle more info for you guys, total advance is around 35-36 degrees and i yanked a plug, had black around the edges and (forgive my terms) the electrode looked ok, but the "hook" above it had a bright yellowish tint to it, like somehow had dabbed it in powdered sulfer or something..

fuel pressure is 41 @ idle, fuel filter has been changed..etc

 

i had the same type of problem and it was my distributer

PS it was on my 383 that i had this problem with

 

i took the chip the guy made me...stopped detonating

so i guess it was the tune heh, looks like i either gotta send it back or try tuning it myself...