PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

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Old Jan 29, 2010 | 07:09 PM
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Okay here's is the scenario.

I start the car let it warm up and idle down to the desired (set rpm). I drive the car and everything might be okay until the car is turned off. Next start same thing, let it warm up and idle down....then it decides to have a mind of it's own. I start to drive the car and at the next stop sign/stoplight etc. it decides to rev up and hold rpm's between 1500-1800...will idle down to normal and run fine until the next stop sign/stoplight and does the idle up again.
Now typically it will go through this rev up cycle 5-6 stops before clearing out and not being a problem. THIS happens every other start up only.

No vacuum leaks, no throttle blade sticking...everything has been checked. so I say to you all WTF!! is this a tuning issue??
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Old Jan 29, 2010 | 08:16 PM
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whats your IAC counts and your idle airflow versus desired idle airflow
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Old Jan 31, 2010 | 08:30 AM
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Unknown as the individual who tuned it is no longer in the business nor a sponsor on here, therefore I have no way of knowing at this point...unless I go to another tuner and have them plug in.
I can tell you that I did put in a new IAC valve to see if that might be the issue and it did not correct the problem.

I"ll try and find someone to plug in and get some info .....assuming the prior tuner didn't lock it somehow...who knows with this jerk.
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Old Jan 31, 2010 | 10:41 AM
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It is bizarre that it would only happen every other start-up. Normally a problem like that might be an incorrect value added to the Throttle Follower. I.E., if someone added TF air to the 0% TPS value.

Normally the Throttle Cracker disengages at 1-3 mph (depending on tune), so it is really hard to know if this is tune-related or if something mechanical is contributing.

Did it just start? Tune-wise, you would have to go out of your way to make that scenario happen..especially with it only occurring on every other start.

Good luck.

..WeathermanShawn..
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Old Feb 1, 2010 | 12:15 AM
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Originally Posted by WeathermanShawn
It is bizarre that it would only happen every other start-up. Normally a problem like that might be an incorrect value added to the Throttle Follower. I.E., if someone added TF air to the 0% TPS value.

Normally the Throttle Cracker disengages at 1-3 mph (depending on tune), so it is really hard to know if this is tune-related or if something mechanical is contributing.

Did it just start? Tune-wise, you would have to go out of your way to make that scenario happen..especially with it only occurring on every other start.

Good luck.

..WeathermanShawn..

Been this way ever since he tuned it.....I know it sounds strange but trust me, all mechanical possibilities have been checked.
There seem to be quite a few of us around here with tuning issues because of this guy.

I appreciate the info.
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Old Feb 12, 2010 | 04:26 PM
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Upon request of a friend who runs a local speed shop, I removed by NW TB to have the throttle plate flipped around....meaning the hole was toward the bottom of the plate and he suggested turning it around so that the hole would be towards the top. Not sure this is the fix either on the belief that if it were the culprit, why wouldn't this happen all of the time ..... not every other start up.

Any input/theory on what this might or might not accomplish??
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Old Feb 12, 2010 | 05:58 PM
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I dont know what is causing your problem, but I do know that you need to have someone data log the event and then inspect the data log for parameters that seem out-of-wack.
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Old Feb 12, 2010 | 10:33 PM
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flipping the plate around..... seriously? why would anyone tell you to do that....are they just giving you something to do?
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Old Feb 13, 2010 | 11:30 AM
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My same problem was solve matching Idle spark advance coastdown and base tables.
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Old Feb 13, 2010 | 07:42 PM
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Originally Posted by ZL1Killa
flipping the plate around..... seriously? why would anyone tell you to do that....are they just giving you something to do?

My thought exactly..I'm sure that NW would have designed it the other way if it mattered that much. Hence the question!
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Old Feb 13, 2010 | 07:43 PM
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Originally Posted by Doc99SS
I dont know what is causing your problem, but I do know that you need to have someone data log the event and then inspect the data log for parameters that seem out-of-wack.
Will be done once the snow has decided to stop around here.
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Old Feb 13, 2010 | 07:44 PM
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Originally Posted by kelp
My same problem was solve matching Idle spark advance coastdown and base tables.
Thanks for the info.
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