Ignition Timing Advance in tuner and in reality

Discuss General Motors (GMC, Chevy, Pontiac, Hummer, Cadillac, etc) tuning topics here. Request definitions, discuss parameters, etc.

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Joined: Sat Jan 09, 2021 7:10 pm

Ignition Timing Advance in tuner and in reality

Post by braggcreekdean »

Hello All. I am new to the TunerPro world and the forum. Looking forward to learning a lot. I have a 1989 5.7l C4 Corvette (large body distributor) that appears to have pretty serious ignition problems. I set the static timing with the bypass wire disconnected to 6 deg BTDC. Disconnected the battery to reset the ECU. Reconnected everything, started the car and interrogated with TunerPro. The ignition advance relative to reference pulse is 25 - 35 deg depending on throttle load, but my timing light shows no advance at all beyond static!

The engine runs like crap. Sometimes it breaks up badly and the timing light starts to fire intermittently. At one point the hot engine would not restart and the timing light would not trigger. I checked the Hall Effect coil and got 913 ohms which I believe is normal. Once it cooled off, it restarted.

I have replaced the HEI coil, the ignition control module, plugs, spark plug wires, knock sensor, CTS, etc. MAF and TPS values are normal. I am running the engine long enough to get into closed loop. I had the ECU tested and was told it is fine. I am not getting anything strange with the knock counts and no error codes. The distributor has been removed and re-installed (could anything go wrong here?). Could the Electronic Spark Control module be defective?

Any ideas what to check next or what to look for in TunerPro? Thank you in advance.

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Joined: Tue Jun 22, 2021 3:38 pm

Re: Ignition Timing Advance in tuner and in reality

Post by dedodson »

Sounds like it could be your injectors. Take a look at this video: https://www.youtube.com/watch?v=G8M5jNy9KrA

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