Low power at high rpms, slight missing feeling in mid range
10-21-2011, 10:26 AM
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Low power at high rpms, slight missing feeling in mid range Hey fellas, I've got a t56 ls1 99 t/a that has about 1800 miles on a brand new gm crate motor. I pulled codes on it and came up with P1626 and P1637.
It seems like i get normal power at low rpms <2500, then a slight missing feeling at 3k, then once i get to high rpms i loose alot of power. other than that i can drive around all day under 3k and it purrs like a cat
There are a few little things that goes on that may help yall figure it out.
one or two times a month on my car i have a problem were ill hop in and turn the key and nothing will happen, security light is on, wait 10 mins or so. and it turns off and im good to go.
my ABS INOP, and TCS OFF lights come on simultaneously about 80% of the time. whats this?
I have a slight ps leak on my new alternator. I get great voltage though.
new fuel filter.
and the car has 160k on it. 1800 on motor, 20000 on built t566.
i am really trying to figure out what the deal is with the low power and missing feeling.
weak fuel pump? ignition?computer issues?
HELP PLEASE> 9797333426 if u really think u can help me.
help is greatly appreciated!
It seems like i get normal power at low rpms <2500, then a slight missing feeling at 3k, then once i get to high rpms i loose alot of power. other than that i can drive around all day under 3k and it purrs like a cat
There are a few little things that goes on that may help yall figure it out.
one or two times a month on my car i have a problem were ill hop in and turn the key and nothing will happen, security light is on, wait 10 mins or so. and it turns off and im good to go.
my ABS INOP, and TCS OFF lights come on simultaneously about 80% of the time. whats this?
I have a slight ps leak on my new alternator. I get great voltage though.
new fuel filter.
and the car has 160k on it. 1800 on motor, 20000 on built t566.
i am really trying to figure out what the deal is with the low power and missing feeling.
weak fuel pump? ignition?computer issues?
HELP PLEASE> 9797333426 if u really think u can help me.
help is greatly appreciated!
10-21-2011, 12:14 PM
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Man sounds like a lot of electrical issues to be honest. The BCM controls the fuel enable signal to allow the PCM to start the car and also issues the lights for ABS, TCS etc so that could explain your security light and the ABS lights. I would start with the BCM and check out the connectors or swap it if you can. It sounds like some kind of intermittancy, broken wire etc. Are those mornings when it doesn't want to start cold?
I would check the ECM harnesses as well and probably swap the alternator.. if you aren't getting enough power to the pump/injectors you would definitely lose power on the high end. If you can rule out power issues, you should find a way to do some data logging to nail it down , to test the fuel pump I would log injector pressure and delta pressure among other things in those RPM ranges you are talking about and see what is going on, if it's the pump I would expect to see injector pressure and delta pressure drop as RPM increases. I have had the same high rpm issues and the pump was the culprit.
If the BCM doesn't help the ABS/TC lights it could be the ABS sensor on the hub, I had the same issues on my Pontiac, the sensor ended up getting replaced and the problem went away.
I would check the ECM harnesses as well and probably swap the alternator.. if you aren't getting enough power to the pump/injectors you would definitely lose power on the high end. If you can rule out power issues, you should find a way to do some data logging to nail it down , to test the fuel pump I would log injector pressure and delta pressure among other things in those RPM ranges you are talking about and see what is going on, if it's the pump I would expect to see injector pressure and delta pressure drop as RPM increases. I have had the same high rpm issues and the pump was the culprit.
If the BCM doesn't help the ABS/TC lights it could be the ABS sensor on the hub, I had the same issues on my Pontiac, the sensor ended up getting replaced and the problem went away.
Last edited by redlightrampage; 10-21-2011 at 02:36 PM. Reason: EDIT: PCM = ECM
10-21-2011, 05:21 PM
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What is BCM? I am pretty sure I have a weak fuel pump. I have had many cars and trucks with weak fuel pumps and it is starting to act the same as they do.
I believe the anti theft 1626 is from the times it has had the security light on and wouldnt turn over. i mean **** the fuel pump has 158000 miles on it. bout time for a new one anyhow.
I believe the anti theft 1626 is from the times it has had the security light on and wouldnt turn over. i mean **** the fuel pump has 158000 miles on it. bout time for a new one anyhow.
