LS1 engine misses when cold

**jdbenn09** · 01-12-2017, 04:18 PM

I have a 2001 T/A and it has started missing until it gets up to operating temperature. If i give it full throttle it will hesitate and eventually kick in and i have full power, but as soon as i let out of it it will go right back to missing. What could be causing this?

**bigrondownhiller** · 01-13-2017, 01:18 PM

Are there any codes being thrown?

**cammed goat** · 01-13-2017, 03:11 PM

Do you have any modifications ie cold air intake, headers, aftermarket exhaust?

**jdbenn09** · 01-13-2017, 06:05 PM

I don't have a way to check the codes. It has a full exhaust system, headers back. Also the guy I bought it from told me it had been tuned.

**bigrondownhiller** · 01-13-2017, 07:43 PM

Is the check engine light on?

**pajeff02** · 01-14-2017, 02:31 AM

Best bet is to either invest in a hand held scanner or take it to a chain parts store and let them plug in theirs. You can get a basic code reader for around $30 these days: Wilmar CAN OBD II diagnostic scan tool W2977 - Read Reviews on Wilmar #W2977

This is a handy tool and will work on most any 1996 and up vehicle. The more expensive units offer additional features such as the ability to see live engine data. In either case, reading and posting the Diagnostic Trouble Code (DTC) will allow us to help you narrow down your issue. As a general rule, a misfire will be the result of a lean condition or faulty components. The fact that it only happens when cold is interesting as the engine is in open loop and the PCM is not accepting input from the oxygen sensors to adjust fueling.

**Whamhammer** · 01-14-2017, 10:19 AM

If you have headers back, the O2 is set further back in the exhaust, thus the exhaust is cooler , takes longer to heat up than before, the 02 feedback may be part of the problem. Have you had a tune yet? My tuner took the info into account, and gave the sensor a longer time to warm up before setting a code/reacting etc.

You might have a slight vacuum leak too.

**jdbenn09** · 01-17-2017, 04:28 PM

Alright great! Thanks for the info! It was supposubly tuned when I bought it. I had a 2000 that was identical to this and i did all the work myself and then had it tuned and had no issues with it. I will invest in a reader very soon!