Hi, I acquired a m6 97 camaro ss. The motor specs are unknown and I got it untuned. It does have a small cam for sure and roller rockers I believe. I was told it was port/polish as well. Tomorrow I’m swapping ecm to obd1 so I can tune for free. Currently, it starts right up no problem. Idle is a little rough but not bad. It has longtubes y pipe and a dump right after that. But the issue is when I get on the gas it pops and bangs like hell. Nasty backfires in the 25-45k range usually clears up a little afyer that. I got the computer generated tune from an lt1 site that I plan to put in it. Mild cam timing, delete all the emissions and stuff. Just curious why it’s running like *** with such a mild cam and headers. I was told that the cam was a small lt4 hot cam which should be fine no tune. It’s also open maf (no filter or anything Bc they took it off for a strut brace) what could be causing the insane backfires that I’m missing?

also. Last time I drove it, I took it on the interstate and it overheated like hell. It still starts and runs fine. Hauled it home. If I start it wnd let it sit it overheats. I’m assuming it’s a stuck thermostat. What else could it be?

thanks!!!

 

I also have to two foot it at stop lights usually

 

Are you saying that under heavy throttle, it misses and backfires between between 2,500 and 4,500 RPM? Also idles poorly to the extent you have to struggle to keep it running.

With no tune, unknown head work, the LT4 HOT cam (every aftermarket cam needs a good tune for best results), and an open, probably dirty from no filter MAF likely screwing up the calibration of the sensor, it's pointless to try and guess what's going on. I could guess, since it starts OK (open loop), but won’t idle or run right (closed loop), you have issues with the O2 sensors and A/F ratio problems, but that’s just a guess. Pointless to even guess if you are changing the PCM and tune in a few days.

Once you get it running with the new OBD-1 PCM, and your downloaded tune, probably still a mismatch for the engine, download GaryDoug’s Scan9495 software, so you can scan and data log the PCM. With a data log you gain insight as to what is going on in the PCM and what is right and wrong.

If the overheating increases the faster you go on the freeway, it could be due to the air dam that's under the front bumper is missing or broken. What temperature does the coolant reach on the freeway? ….. at idle? Does it get into the red?

 

Sounds like I know what to do now. I had an lt1 swap before and never had any issues but built the motor. Was worried it may be opti or something. Since the freeway overheat, it will peg the gauge if I let it sit at idle for to long or anything. I live 3 hours away from where I leave the car so I don’t usually get to tinker much. Thanks for the insight 👍🏼

Yes backfire under heavy throttle, and before the over heat it would backroad cruise and stop light to stop light just fine. Which is what confused me

 

Fan(s) may have failed. They get power direct from the battery, through a fusible link and a relay system. If the relays fail it sets a code, but a fan failure or blown fusible link does not set a code. Also the obvious check for something blocking the front of the radiator, plastic bag, etc.