PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

is pcm going?

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Old Oct 20, 2007 | 09:27 PM
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Following tunewith 98 z, bank 2 read -100.0. Tuner claimed pcm going as it could not be reset even though back cats tuned out and both front cats new
and engine just rebuilt. Is this possible???? Upon closer pcm inspection, unit is old and has been rebuilt??? No leaks on engine.
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Old Oct 20, 2007 | 09:34 PM
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get it double checked by someone as its very rare.
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Old Oct 20, 2007 | 09:50 PM
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Originally Posted by jimmorris
Following tunewith 98 z, bank 2 read -100.0. Tuner claimed pcm going as it could not be reset even though back cats tuned out and both front cats new
and engine just rebuilt. Is this possible???? Upon closer pcm inspection, unit is old and has been rebuilt??? No leaks on engine.
Too many pids chosen. 'splain it to him Bill.
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Old Oct 20, 2007 | 09:57 PM
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Originally Posted by edcmat-l1
Too many pids chosen. 'splain it to him Bill.
Its a STRONG possibility which is why I'd have a different reputable tuner look it over

But basically what Ed is saying is 98's have the ability to only scan 24 bytes of info so if the person who was scanning your car with say a config from a 99+ theres a good chance 50/50 that he was logging more than 24 bytes of info which in turn our software will start dropping PID's to get it down to the correct amount of bytes of data...it usually starts with the fuel trims and then onto the others until its down to 24 bytes of data.
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Old Oct 20, 2007 | 10:00 PM
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Not to mention these PCMs are pretty well bullet proof. I've never seen one that "went bad" and just dropped on piece of data.
PS Thanks Bill!!
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Old Oct 21, 2007 | 08:25 AM
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Well, this all began in an effort to get the car passed NC state inspection. I kept getting p0171 codes, bank 1. SO I was getting heads/cam installed and this problem followed the car through to the tuning. THe tuner, CAM, claimed that bank 2 read -100.0 percent.
SO he tuned the car anyhow. But three non-ready codes rom the PCM still existed.
SO, I drive the car all over from cold startup, go to the inspector's and they claim it's not ready to be inspected. THe tuner tuned out the back cats and I haven't had any more
codes thrown( ex P0171) but it still won't pass the inspection even though it makes 400
RWHp on the dyno. WHat should/would you guys do/or go from here???Neeed help....
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Old Oct 21, 2007 | 08:51 AM
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If you send the pcm to me i will check it for free. I dont think it is the pcm. Any tune should be able to make it pass the obd inspection.
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Old Oct 21, 2007 | 08:53 AM
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P0171 code generally isn't a tuning code & can usually be related to a vacuum leak or sometimes even the maf but 95% of the time is not caused by tuning and cannot/should not be corrected by tuning.
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