Rpm

[Rickabod]

what rpm's should an automatic sho be running at 55 miles per hour. i just recently fixed my overdrive by replacing a broken E clip, it gave it 4th gear back, but it seems to only have dropped the rpm's on the engine by 500. my car is running around 2,500 rpm (give or take a couple hundred) at 55 mph.

 

[Val]

thats about right cat

 

[Axianator]

2500 rpms seems a little high for a typical ATX running at 55mph. Once warmed up, my '95 runs around 1800-2000 rpms at 60mph with no throttle applied. Is this 2500 rpm reading with throttle lightly applied or with none at all? Can you tell if your converter is locking up after you take your foot off the gas and then lightly reapply it (the RPMs should kick up a couple hundred RPMs when you let off, and then stay up and dip back down once you re-apply the throttle)?

 

[Val]

true i could be wrong cuz my vss is way off. but my tcc does lock up in 3rd and 4th

 

[SHOtimer]

Yea, I'm with Adam on this one. At 55mph I am tachin 1800-2000 with the TC locked up. Now, in the morning with the TC unlocked I am at 2500 at 55mph. You need to find out whether you are having a tranny problem or a TC problem. At 55 when you apply the gas does the RPM change quickly and the car respond slowly, or the tach not respond quickly but it is in close tune to the car. I hope that makes sense, it does in my head at least. IMHO, it sounds like your TC is not locking up. Oh, I just thought of another simpler way, at 55 when you let off the gas does your RPM drop to 2k? If it does then your TC is the problem, if it doesn't you do have a tranny issue.

Doug

 

[ctm78]

Yea, I'm with Adam on this one. At 55mph I am tachin 1800-2000 with the TC locked up. Now, in the morning with the TC unlocked I am at 2500 at 55mph. You need to find out whether you are having a tranny problem or a TC problem. At 55 when you apply the gas does the RPM change quickly and the car respond slowly, or the tach not respond quickly but it is in close tune to the car. I hope that makes sense, it does in my head at least. IMHO, it sounds like your TC is not locking up. Oh, I just thought of another simpler way, at 55 when you let off the gas does your RPM drop to 2k? If it does then your TC is the problem, if it doesn't you do have a tranny issue.

Doug

Does this play true for a MTX as well? Do I even have a torque converter? I run at about 2700 at 55.

 

[Val]

Manual trannies have no tq converters. Your rpms are were they should be. On atx tq converter lets the tranny slip when its not locked up thats why Rick was running at higher RPM.

 

[Coil99]

At 55mph I am tachin 1800-2000

I checked it on the way to work this morning and I am too.

 

[SHOtimer]

ctm78,
I do not own an MTX but I have driven one. It sounds to me that you are in 4th @ 55 if you are tachin 2700rpms. If you are in 5th at 55 and you are tachin that high you have a problem. Your tach might be off, or by that matter your speedometer, or a really bad problem with a clutch. No, you do not have a torque converter, you have a clutch. Which you are always in complete control over, unlike my ATX which decides what it wants to do....

Doug

 

[Axianator]

Doug is correct on this. The EEC will not lock-up the converter unless the tranny fluid is above a certain predetermined temperature (hence why you may be doing 2500 rpms @ 55mph in the morning if your tranny fluid isn't warmed up to temp). After the tranny fluid has warmed up, the EEC will lockup the converter at the appropriate speed and throttle position (lockup is determined by tables that are referenced by speed and TP, FWIW).

Even if your ATX is running at 2500 rpms @ 55mph with your fluid warm and your converter locked up, don't think that you have a tranny problem. Remember that the EEC is the main controller/dictator of the tranny, regardless of how "out of touch" we may feel driving our ATXs. Your problem may be nothing more than a failed lockup solenoid in the valve body - very easy to get to and fix, assuming this was the problem.