high load exhaust pop

[300kGN]

After 4 years of storage, finally ran down the 1/4 again. First 2 pass went fine, 21# boost, no knock, a/f around 10-11, 13.24's @102. Not great but not bad considering. 3rd pass, got some popping just before the 1-2 shift, still ran 13.24. 4th pass, more severe popping. Checked direct scan log, when the popping started the PCM RPM jumped from 5000 to 6375 for a few frames-which really f'd the timing, etc. 6375 RPM was always the same during the popping. So I figured, the Ignition Module translates the cam reference into the tach signal, the IM must be failing. Ordered and installed an alledged GM IM and coil pack (which came in a plain white box and 1 coil spade was bent over backwards!). Problem is still there, may be worse, seems heat related, the tach signal is not smooth but doesn't peg 6375. I remember running into intermittent heat related failures on crank sensors on K motors, but I can't afford any more shells for the shotgun and I left my diagnostic dice at work Think I'll call the parts retailer on Monday.

 

[Quick6'n'-K.C.]

I wonder if the directscan cable is interfering with the ecm causing it to pop and sputter, ive heard of this and the cable should be pulled away from the ECM as far as possible.

If its really heat related, then yes, coil pack and module.

BW

 

[83ttypecooled]

Hi ,
Why are you rapping the engine so high?Most of our cars don't need such high rpms.5500 is usually shutoff for me;the motor gets buzzy after that. So, if you don't wind it out, you won't have the problem.

 

[300kGN]

Hi ,
Why are you rapping the engine so high?Most of our cars don't need such high rpms.5500 is usually shutoff for me;the motor gets buzzy after that. So, if you don't wind it out, you won't have the problem.

You misunderstood/I was not clear. This IS happening at 5k. The reading of 6375 is due to a failure somewhere, I believe in the primary ignition/crank sensor. The engine isn't actually making those revs. MPH, MAF go down, not up. The PCM is "seeing" 6375 on an actual 5000.

 

[Quick6'n'-K.C.]

So did you read my post?
BW

 

[300kGN]

So did you read my post?
BW

yes. The DS cable is ok. Might try disconnecting it just in case. Also going to look around for another IM I have burried somewhere. Thanks for the input.

 

[2QUICK2B6]

spark plugs fresh ? How old are the wires

 

[300kGN]

plugs(AC) and wires(Kenne Bell) are far from "new", but probably only have 5k on them. Car has been driven 100 miles in the last 5 years. On the last run the car shut down in 3rd at 4650RPM and lost data 19 sec. into the record for .2 seconds, lost battery at 19.38 sec. The very next frame everything went "normal". Lost data briefly, then battery, then normal. Through out the run tach signal on DScan is rough.