Converter/trans problem
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On The Tree
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From: Corpus Christi,Tx
Converter/trans problem I have a blazer Xtreme I recently swapped a 5.3/4l80e into. Blazer drives fine except converter feels really loose. Also I'm unable to spin the tires. I can footbrake and hold the gas pedal floored and stalls to 3000 rpm and doesn't let the tires spin.
So I thought the converter was the problem so I sent it to a converter shop ptc if Texas and try inspected it and told me the converter was perfectly fine. He said it might have been not enough trans fluid or maybe a small crack in the pump of trans which he stated is pretty rare but possible. Anybody have any experience with this situation or any helpful tips. Thanks
So I thought the converter was the problem so I sent it to a converter shop ptc if Texas and try inspected it and told me the converter was perfectly fine. He said it might have been not enough trans fluid or maybe a small crack in the pump of trans which he stated is pretty rare but possible. Anybody have any experience with this situation or any helpful tips. Thanks
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From: Ann Arbor, MI
I'm far from an expert in diagnosing such problem, but I would start with a scanner that can check your TPS, MAP and MAF sensors. Scan for engine and trans codes.
I would also confirm that your trans is starting in 1st and is not starting in 3rd (limp mode) due to an electrical problem like a bad solenoid.
Can you confirm that your trans is shifting?
I would also confirm that your trans is starting in 1st and is not starting in 3rd (limp mode) due to an electrical problem like a bad solenoid.
Can you confirm that your trans is shifting?
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On The Tree
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From: Corpus Christi,Tx
Yea trans shifts fine at cruising and wot. No codes being thrown. The car is acting as if their is not enough fluid in the trans and acting sluggish to take off. Car will not move on its own if put in drive. Takes quite a bit of rpm to move for such a small converter. I have triple checked fluid and is good.
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Joined: Aug 2010
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From: Ann Arbor, MI
Your symptoms precisely match a trans starting in 3rd gear.
So, as you go up to highway speed, you can feel the 1-2, 2-3 and 3-4 shifts?
The converter locking up can feel like a shift too.
I know I'm ask the same question again, but beyond that I am clueless too.
Muffler bearings?
So, as you go up to highway speed, you can feel the 1-2, 2-3 and 3-4 shifts?
The converter locking up can feel like a shift too.
I know I'm ask the same question again, but beyond that I am clueless too.
Muffler bearings?
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Joined: Aug 2010
Posts: 7,323
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From: Ann Arbor, MI
I would next check your TPS, MAP and MAF sensors including the TPS voltage. IIRC the TPS voltage with throttle closed has to be between .25 and .75 volts or the PCM ignores it causing poor driveability.
A quick way to test the MAF is to disconnect it, causing the PCM to switch to open-loop speed-density mode. If the PCM is tuned correctly, you could drive forever that way.
However, I have read advice not to go WOT because the engine could run
too lean if the tune is not correct.
Beyond that, you may need to log the sensor outputs and engine parameter to determine what is going on. Since this is a swap, you may have a broken or missing wire and thorough logging should reveal the problem.
Unless one of the trans experts has other ideas (I know -nuthin- about the 4L80E), I think you have a engine problem and not a trans problem.
Just my opinions.
A quick way to test the MAF is to disconnect it, causing the PCM to switch to open-loop speed-density mode. If the PCM is tuned correctly, you could drive forever that way.
However, I have read advice not to go WOT because the engine could run
too lean if the tune is not correct.
Beyond that, you may need to log the sensor outputs and engine parameter to determine what is going on. Since this is a swap, you may have a broken or missing wire and thorough logging should reveal the problem.
Unless one of the trans experts has other ideas (I know -nuthin- about the 4L80E), I think you have a engine problem and not a trans problem.
Just my opinions.
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