BacktheBlu

Just wanted to relay my experience I had with downloading a 2 bar speed density tune for a 98 C5. I had a very experienced and knowledgeable tuner acquire a 2 bar speed density tune from HP Tuners. After a number of mods to the car, it was time to tune it. The initial rewrite with the usual mods ( fan temps, delete cats..) downloaded and was accepted by the PCM. The speed density program was then downloaded; however, the car started, but the gauges did not work. The original modded program was then again downloaded. The car started and ran fine. The 2 bar speed density tune was again loaded and accepted by the PCM. The program was never interrupted and power was ensured by a new battery. The car failed to start and provided two codes, including P1518 and P0601. After reflashing the stock tune the car turned over, but would not fire.

In the end it was a fried PCM and Electronic Throttle Module that needed replacing. HP Tuners make a very good product and provide support to back it up, but the tech support was even baffled at what could have caused the melt down.

I have since used their basic software and have had the car tuned with excellent results.

I hope my expensive lesson can perhaps save someone else from
experiencing what I did. Caution should be used when considering a speed density program with early C5 PCM's.

Attached is a link to the original HP Tuner forum....

http://www.hptuners.com/forum/showthread.php?t=12242

caseyse

I'm sorry you lost your PCM. This also happened to my '99 when installing a custom OS for 2-bar just a few weeks ago. Swapping the entire firmware isn't trivial, and can cause occasional problems.

tjwong

I can beleive that it fried the PCM but it concerns me that it also fried the TAC module. Normally that device is very robust as I have yet to see any failures of a TAC module. When you initially installed the 2bar OS and when the instrument cluster was inop, did you try disconnecting the battery and restart the engine? In the early 97 to 99 Corvettes, I often will get a cluster inop, but after disconnecting the battery for a few seconds and a restart the cluster always comes back to life. I also use a GM J tool to isolate the serial bus when flashing the PCM in the car. To use this tool, you connect it to the two star pak connectors located in the passenger floor compartment where the BCM resides.

RJW

I heard that the 98's are the worst as far as frying goes.

I did an entire write on my 03 and it failed . I was told by hpt support that it was fried, but I kept at it and eventually it took, mind you at low speed and probably 30 to 45 minutes of thinking and switching from hi to low speed. I thought it was cooked, but luckily it survived

Haven't had a problem with it since, but a make sure battery is ful charge and laptop plugged in ac outlet with NO sleep mode.

In my case, I bought a brand new battery and it was defective. voltage dropped to 3v during the write

Sorry to hear about your problem

fisheson

why are the 98's the worst??.