Mail order tune using a new PCM.
10-01-2009, 05:22 PM
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Mail order tune using a new PCM. Well so far I'm not impressed, but in want to make sure I'm not overlooking something.
During my first drive I get a surging effect after accelerating to higher rpm. Also just general shifting and performance is not what I was expecting. When I do a hard acceleration it acts like the trans is slipping, rpm goes up speed lags behind substantially. Car has 38k mi and runs perfect with the stock tuned PCM.
So is a crank relearn a must and will it remedy some of this?
Also is there a learning period for the PCM itself, that would affect fuel management and shifting?
During my first drive I get a surging effect after accelerating to higher rpm. Also just general shifting and performance is not what I was expecting. When I do a hard acceleration it acts like the trans is slipping, rpm goes up speed lags behind substantially. Car has 38k mi and runs perfect with the stock tuned PCM.
So is a crank relearn a must and will it remedy some of this?
Also is there a learning period for the PCM itself, that would affect fuel management and shifting?
10-01-2009, 05:43 PM
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I am not sure on the Crank Relearn. I think that depends on how your VIN was transferred from PCM to PCM. I purchased the "RoadRunner" PCM and did not have to do a Crank Relearn. Normally you would get a MIL light if that was the case (unless it was disabled).
And I believe a Crank Relearn is not performance related, but to help monitor misfire, engine diagnostics, etc., so not likely to be the cause of your current problems.
Yes the PCM was removed from your car's power source so it will have to re-learn Fuel Trims, depending on what kind of tune your purchased.
Quite frankly it does not sound like fuel trims. You can give it another 50-100 miles, but perhaps it my be related to the shift points of your automatic transmission.
No offense, but I must ask the obvious question..if it was running great before..why did you change it? In any case without viewing the tune via software it is simply a guess at this point. But maybe the shift points were not done in the manner you wanted.
Good luck..
..WeathermanShawn..
And I believe a Crank Relearn is not performance related, but to help monitor misfire, engine diagnostics, etc., so not likely to be the cause of your current problems.
Yes the PCM was removed from your car's power source so it will have to re-learn Fuel Trims, depending on what kind of tune your purchased.
Quite frankly it does not sound like fuel trims. You can give it another 50-100 miles, but perhaps it my be related to the shift points of your automatic transmission.
No offense, but I must ask the obvious question..if it was running great before..why did you change it? In any case without viewing the tune via software it is simply a guess at this point. But maybe the shift points were not done in the manner you wanted.
Good luck..
..WeathermanShawn..
10-01-2009, 06:27 PM
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Not getting any lights or codes and the PCM came off another car and was provided with the tune. I really did'nt expect to have these issues considering it's a stock engine. The tuner is reputable and has been trying to help but i wanted to post my experience to get some more input. I guess I'll drive around for a bit see if it get's better.
I did it because i was looking for some better performance than stock. In the way of both some HP increase and shifting. My understanding is that these cars are tuned down from the factory and even a mild tune on a stock car provides benefit, although now I'm not sure it's worth it. 
No offense, but I must ask the obvious question..if it was running great before..why did you change it?
Last edited by Alex212; 10-01-2009 at 06:46 PM.
10-02-2009, 01:07 AM
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I did it because i was looking for some better performance than stock. In the way of both some HP increase and shifting. My understanding is that these cars are tuned down from the factory and even a mild tune on a stock car provides benefit, although now I'm not sure it's worth it.
Even though you are still basically 'stock', you could benefit from a good tune. There are several outstanding mail order tunes available from various LS1 Sponsors on this board. There is one individual who is on this board all the time that almost everyone speaks highly of. In fact, I probably do not even have to say his name he is so well known and respected.
If you run out of luck with your local tuner, at least that is another option.
..WeathermanShawn..
