2002 Trans Am 4l60E Help
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Teching In
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From: Idabel, Oklahoma
2002 Trans Am 4l60E Help I just purchased my first Trans Am; and I am new to the motor and tranismission. I have a problem, the car runs a 323 rear end and I am cruising around at 65-70MPH running 21-2300 RPM. I do not think that I should be running that high RPM. shouldn't the torque converter kick in and bump my RPM's to around 17-1800? This is a stock LS1 with the LS6 intake, only 73,000 miles.
If I am not over reacting about the RPM's are there any suggestions for me to look at before I pull the Transmission? I had a MAF code come on but I found that problem and fixed it.
If I am not over reacting about the RPM's are there any suggestions for me to look at before I pull the Transmission? I had a MAF code come on but I found that problem and fixed it.
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From: Ann Arbor, MI
I agree that your RPMs seem too high.
I suspect that your converter's lockup clutch (TCC) is not engaging, as you suspect.
Perhaps someone has a better way, but I can think of two way to test if your converter is locking.
1. On the hwy, give a modest amount of gas (extra 15% throttle) and watch the RPMs. If they immediately jump before the car speeds up, the TCC is not engaged.
2. On the hwy, give about 60% throttle to speed up e.g. 10mph then easy the throttle and watch the rpm. If you see it stable and then drop by 200-300 rpm, that is the TCC engaging.
Generally these cars give a 1870 code if the PCM tried to engage the TCC, but detects via RPM slippage that it is not engaged.
First be sure there are no codes in the PCM, especially not MAF codes. Various codes will cause the PCM to never engage the TCC.
I suspect that your converter's lockup clutch (TCC) is not engaging, as you suspect.
Perhaps someone has a better way, but I can think of two way to test if your converter is locking.
1. On the hwy, give a modest amount of gas (extra 15% throttle) and watch the RPMs. If they immediately jump before the car speeds up, the TCC is not engaged.
2. On the hwy, give about 60% throttle to speed up e.g. 10mph then easy the throttle and watch the rpm. If you see it stable and then drop by 200-300 rpm, that is the TCC engaging.
Generally these cars give a 1870 code if the PCM tried to engage the TCC, but detects via RPM slippage that it is not engaged.
First be sure there are no codes in the PCM, especially not MAF codes. Various codes will cause the PCM to never engage the TCC.
Are you absolutely sure it has a 3.23 gear? if you had a 3.42 that would be about right. Wht size tires does it have on the back wheels, tire heights will affect rpm's a lot.
Thread Starter
Teching In
Joined: Jan 2013
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From: Idabel, Oklahoma
Tires size is 245/45 17 the car calls for 275/40 17. The bin calls for 3.23. I am not sure it hasn't been replaced but this car is stock everywhere else,I am not sure why they would change the rear and leave the rest
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From: So.Cal.
275/40R17: tire diameter = 275*.40*2/25.4+17 = 25.66" <-- what should be on car
245/45R17: tire diameter = 245*.45*2/25.4+17 = 25.68" <-- what you have
at 65 pmh: RPM = 65*336*3.23* 0.696/25.68 = 1911 rpm <-- in 4th with TCC locked
at 70 mph: RPM = 70*336*3.23* 0.696/25.68 = 2059 rpm <-- in 4th with TCC locked
my calculations ^ show you're in the correct range.
edit: sorry, I ballsed up the tire diameter calculation, see my corrections.
245/45R17: tire diameter = 245*.45*2/25.4+17 = 25.68" <-- what you have
at 65 pmh: RPM = 65*336*3.23* 0.696/25.68 = 1911 rpm <-- in 4th with TCC locked
at 70 mph: RPM = 70*336*3.23* 0.696/25.68 = 2059 rpm <-- in 4th with TCC locked
my calculations ^ show you're in the correct range.
edit: sorry, I ballsed up the tire diameter calculation, see my corrections.
Last edited by joecar; Feb 7, 2013 at 09:21 PM. Reason: fixed typo
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From: So.Cal.
You can tell when TCC is locked while cruising at freeway speed...
as you release and reapply the throttle the displayed rpm does not move, and as you increase throttle mph starts climbing noticeably while rpm climbs very little.
as you release and reapply the throttle the displayed rpm does not move, and as you increase throttle mph starts climbing noticeably while rpm climbs very little.
Thread Starter
Teching In
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From: Idabel, Oklahoma
275/40r17: Tire diameter = 275*.40*2/25.4+17 = 25.7" <-- what should be on car
245/45r17: Tire diameter = 245*.44*2/25.4+17 = 25.5" <-- what you have
at 65 pmh: Rpm = 65*336*3.23* 0.696/25.5 = 1925 rpm <-- in 4th with tcc locked
at 70 mph: Rpm = 70*336*3.23* 0.696/25.5 = 2074 rpm <-- in 4th with tcc locked
my calculations ^ show you're in the correct range.
245/45r17: Tire diameter = 245*.44*2/25.4+17 = 25.5" <-- what you have
at 65 pmh: Rpm = 65*336*3.23* 0.696/25.5 = 1925 rpm <-- in 4th with tcc locked
at 70 mph: Rpm = 70*336*3.23* 0.696/25.5 = 2074 rpm <-- in 4th with tcc locked
my calculations ^ show you're in the correct range.
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Joined: Apr 2002
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From: So.Cal.
Thread Starter
Teching In
Joined: Jan 2013
Posts: 33
Likes: 0
From: Idabel, Oklahoma
I agree that your RPMs seem too high.
I suspect that your converter's lockup clutch (TCC) is not engaging, as you suspect.
Perhaps someone has a better way, but I can think of two way to test if your converter is locking.
1. On the hwy, give a modest amount of gas (extra 15% throttle) and watch the RPMs. If they immediately jump before the car speeds up, the TCC is not engaged.
2. On the hwy, give about 60% throttle to speed up e.g. 10mph then easy the throttle and watch the rpm. If you see it stable and then drop by 200-300 rpm, that is the TCC engaging.
Generally these cars give a 1870 code if the PCM tried to engage the TCC, but detects via RPM slippage that it is not engaged.
First be sure there are no codes in the PCM, especially not MAF codes. Various codes will cause the PCM to never engage the TCC.
I suspect that your converter's lockup clutch (TCC) is not engaging, as you suspect.
Perhaps someone has a better way, but I can think of two way to test if your converter is locking.
1. On the hwy, give a modest amount of gas (extra 15% throttle) and watch the RPMs. If they immediately jump before the car speeds up, the TCC is not engaged.
2. On the hwy, give about 60% throttle to speed up e.g. 10mph then easy the throttle and watch the rpm. If you see it stable and then drop by 200-300 rpm, that is the TCC engaging.
Generally these cars give a 1870 code if the PCM tried to engage the TCC, but detects via RPM slippage that it is not engaged.
First be sure there are no codes in the PCM, especially not MAF codes. Various codes will cause the PCM to never engage the TCC.
Thread Starter
Teching In
Joined: Jan 2013
Posts: 33
Likes: 0
From: Idabel, Oklahoma
I put a GPS on it this Morning and the car and GPS were about 1 MPH off. with the GPS showing faster then the car.
