Custom tune problems

**bohnseye** · 09-06-2015, 06:58 AM

Have 1998 Camaro ss. Had o2 sensor go bad. Was told by tech person that car goes into trip mode when this happens. My car being a 98 it had to be tuned
with laptop What is proper way to reset back to custom tune. Noticeable difference in performance.

Thanks guys for any help

**pajeff02** · 09-06-2015, 08:58 AM

The PCM has a "limp mode" when a serious fault occurs. Once corrected, simply clear the code with a scanner and you should be good to go. Usually, the SES flashes when things are really bad.

**bohnseye** · 09-09-2015, 08:34 PM

Originally Posted by pajeff02

The PCM has a "limp mode" when a serious fault occurs. Once corrected, simply clear the code with a scanner and you should be good to go. Usually, the SES flashes when things are really bad.

Is this something advance auto or AutoZone can handle with their scanners? And what do I tell them to clear Limp Mode?.......Just asking in case I get that look.Im sure you know that look. I wish my car was a 99 or newer so I could use a handheld.If this works I owe you one big time. You live pretty far away, I live 90 miles south of Pittsburgh. Guess I will mail it to you

Thanks a lot for your knowledge and help
Mike

**35th-ANV-SS** · 09-09-2015, 11:09 PM

Simply clearing it will not solve the problem unless you've already fixed the issue which caused it to go into limp mode already?

**Firebirdjones** · 09-10-2015, 07:17 AM

If Jeff is offering to look at it for you, 90 miles is nothing. Hour and a half drive tops.

Otherwise reading the code at autozone with a scanner is your only option unless you want to hit the dealer. Then you can address the issue properly with the code pointing you in the right direction, buy what's needed, and fix it.

**bohnseye** · 09-11-2015, 08:56 PM

No codes. Fixed problem.Had two weak o2 sensors. My question is if go to autozone or advance and tell them to clear limp mode are they capable of doing that for me? Is that a common thing? Im sorry but im new at the tuning scene. My last muscle car was a 67 ss 396 Camaro. And I also have a custom 51 Buick with a 425 nailhead with two fours.So im not at all familiar with computer tunes. Im asking for help with my arms wide open.......Tim put a great tune in it,i would love to get it back

Thanks
FirebirdJones

**bohnseye** · 09-11-2015, 09:00 PM

I am a car guy. Been a Goodguys member for 20 years. But dumb as a rock when it comes to tunes.

**pajeff02** · 09-12-2015, 05:21 AM

The staff at the 'Zone is allowed to read the codes, but not clear them. That's my understanding from past conversations and seeing them in action. This being said, you can pick up a decent scanner to around $150, and one with all the bells and whistles for about $300. I have a middle of the road Actron that works great, just wish I had spent the coin for one that could read live sensor data.

**bohnseye** · 09-13-2015, 08:24 PM

Originally Posted by pajeff02

The staff at the 'Zone is allowed to read the codes, but not clear them. That's my understanding from past conversations and seeing them in action. This being said, you can pick up a decent scanner to around $150, and one with all the bells and whistles for about $300. I have a middle of the road Actron that works great, just wish I had spent the coin for one that could read live sensor data.

Advance will know what a trim code is? I can get them to clear it off. Ive just hever known anything about trim codes before. If you think they will know what im talking about,i should be ok.

Thanks a ton Jeff
Mike

**pajeff02** · 09-14-2015, 03:23 AM

I assume by "trim codes" you are referring to your fuel trims? If so, a basic code reader will only let you know if the PCM has set the SES light due to a lean or rich condition, or if the O2 sensor data does not comport with what it thinks it should. Pricier scanners with actually allow you to see the STFT (Short Term Fuel Trim) and LTFT (Long Term Fuel Trim). These numbers represent fuel adders and subtractors -- a positive number means that the PCM is adding fuel by upping the injector shot (holding it open longer). Negative numbers mean that the PCM is subtracting fuel by shortening the pulse to the injectors.

Bank 1 is the driver side and Bank 2 is the passenger side when you look at these numbers. Ideally, the STFT's and LTFT's should be as close to zero and maybe +/- 3. The closer to zero the more accurate your tune as the PCM is not compensating for improper fueling. Worn parts, defective sensors, and modifications can all alter fueling. If you maybe cross up your O2 sensors harness from left to right after some major work (not that I know of anyone who would do this

), you will immediately see your trims max out at 25 as the PCM fights with itself to properly fuel the engine.

**bohnseye** · 09-14-2015, 06:38 AM

First I was told by a Summit tech that when enginge light comes on computer goes into (trip)mode. So the all the money i spent to have car tuned is set aside by computer till problem is fixed. Weak o2 set it off. Fixed problem. Just want my tune back. I thought unplugging battery would reset back. I wish my car wasnt a 98. Cant buy ny own tuner. Only 99 and up

**pajeff02** · 09-14-2015, 06:39 PM

The SES light does not automatically result in "limp" mode for every issue. Generally, a transmission related code, or maybe something like the crank position sensor failing, will cause it. Other than that, your tune remains intact. If the engine is not running right you have something else going on.