Powerlogger IDC & RPM Spike

[STF420@comcast.]

Hi,

Made some runs at Atco Sun 11/10/13. The RPM & IDC show a Spike in my Powerlogger logs. The IDC Spike is in all screens The RPM shows in Graph mode only. The Car felt fine ran great. On Run5 The check engine may have briefly flickered when it happened. Would this be a sign of a going bad Ignition Module or Computer? The Rpms did not flare Some kind of glitch?
86 Gn Stock Turbo, Stock longblock TT5.7 LC-1 WB

Thanks, Mike

 

[TurboDave]

Not likely a sign of any ignition module problems. Could be a noise spike, could be a dirty connection on the powerlogger connection point. Keep an eye on it. If it gets any worse might be time to pull the PL and re clean that connection point.

 

[STF420@comcast.]

Hi Dave,

I will check the PL connection.
I think the False RPM spike is causing the Injector spike. In run5 the WB A/F goes rich for an instant after the spike. So the injectors did increase flow.
The Crank sensor is about a month or 2 old, The ECM is about 3 weeks.

Thanks, Mike

 

[TurboBob]

I only see a tiny afr rich spot in one log, the others didn't look like a rich spot.

Ignore the injector dutycycle, its not real data. Its calculated from Injector Pulsewidth and RPM.

I don't see any spikes in injector pulsewidth.

In any case, you may have a noisy ignition module or something like that. The crank and cam signals are buffered by the ignition module, so a bad module (or loose connector terminal) or a bad ground could cause this sort of thing.

Bob

 

[STF420@comcast.]

UPDATE

Fixed, Swapped out Ignition Module. This fixed the Rpm spike, But am leaning towards bad connection at Module.
I tested the old module with a Caspers tester It worked perfect, Better than 1/2 the replacements I tried. The best one I found was from Autozone DR143. It took 2 tries to get a good one. BWD was best coil. same took 2 tries.

Thanks, Mike

 

[TurboDave]

Interesting.