1G 4G37 3.3-3.5k Rpm at 110km/h

[Talonmom]

We were given a 1991 talon (4G37) FWD automatic with no tranny. We put in the tranny and drove home today. All seems well except rpms are at 3300 - 3500 at 110KM/h (68mph). Is this normal?

Sorry if this is a dumb question, my other vehicle is a Durango and rpms at same speed are 1800.
We are worried we did something wrong with the install.

 

[Absit]

Yes, this is normal. These cars aren't super highway friendly on the tach.

 

[Talonmom]

Thanks for the "whew"! Still not quite right as rad cap blew after 40min drive, now over heating. Now comes the little "fixers"

 

[nc_dsm]

The little fixes, that is the life of a dsm'er all the way. If you care to change your rpm / speed issue you can always get a taller 5th gear from the new evo trans'.

 

[Absit]

The little fixes, that is the life of a dsm'er all the way. If you care to change your rpm / speed issue you can always get a taller 5th gear from the new evo trans'.

That sure would be interesting to see installed in an automatic FWD 1g transmission..

 

[LandoAWD]

Thanks for the "whew"! Still not quite right as rad cap blew after 40min drive, now over heating. Now comes the little "fixers"

If you literally overheated to the point of the cap blowing off, consider a compression test. I won't even ask how high the dummy gauge got.

 

[Talonmom]

No, actually car did not overheat. Temp gage didn't move until cap came off. Checked rad fluid before driving, possibly not put on properly. Not looking good though. Had high hopes.

 

[19Eclipse90]

The speed issue really depends on the size of tire you are running as well. For a 25.9" diameter tire (205/55/16), that speed does not make much sense.

 

[nc_dsm]

Correct me if I am wrong but the speedo runs off the transmission on these cars ... wheel size makes no difference on this issue.

 

[Tanro]

Correct me if I am wrong but the speedo runs off the transmission on these cars ... wheel size makes no difference on this issue.

Even if that were true, your rpm at a given speed can change considerably based off wheel size. Total wheel/tire diameter can change the gear ratios

 

[19Eclipse90]

It does make a difference. Understand that a larger diameter tire covers more ground per revolution of the axle, and vice versa for a smaller diameter tire. Even though the speedometer reads off the transmission, it relies on a certain size tire for accuracy. Change the tire diameter and the speedometer will be off.

 

[nc_dsm]

Yes I understand that but this is a thread on the speed that is read on the speedometer versus rpm ... actual speed isn't being questioned. I understand that larger tire size will cause actual speed to be above what is registered but should not alter the reading on speedometer.

 

[dented_coffee]

A larger tire would take more force to turn and a small tire would increase the RPM's when cruising. I preffer to just stay at the OEM size for that good medium ratio of speed/rpm's/mpg's.

 

[19Eclipse90]

Yes I understand that but this is a thread on the speed that is read on the speedometer versus rpm ... actual speed isn't being questioned. I understand that larger tire size will cause actual speed to be above what is registered but should not alter the reading on speedometer.

Ah, I had a bit of a lapse, then. That makes sense.

Even so, with an originally sized tire for a 1.8L (185/70/14) accounted for, the gear ratios should work out to correctly relate the selected gear, RPM, and vehicle speed as read by the speedometer. Running the numbers, it still doesn't make sense as it should read between 2500-2750rpm for 110kph in overdrive.

 

[Talonmom]

At this point it doesn't go any speed. So upset. Car was completely () rebuilt just needed tranny. Ran fantastic until last 2km home. It now warms up, warm air inside then put in gear, blows cold air and antifreeze (quite a bit) comes out the bottom (driver side/over flow). Off to try and find a water pump. Replacing rad cap (which was corroded), and thermostat first but don't think that it is this simple. We did recheck tranny stuff and don't think overdrive is working. Possibly a connection (button?) underneath gear shifter itself? Thanks for all your replys, it is helping alot.

 

[nc_dsm]

I will have to find my paperwork but your TCU, transmission control unit throws codes to let you know if there is a problem with the transmission. It does this I believe in the form of blinking LED and you decode by long and short pulses, I'll look for those codes, its worth a shot.

 

[Talonmom]

That would be great. If we get it up and running with cooling issue, can get back to tranny issue.

 

[nc_dsm]

Do you know if vehicle has a new timing belt? Why you have it tore down to water pump wouldn't be a bad idea if you have the time/ money could save a bit in the long run

 

[DSM1G90]

(I have a 91 base Eclipse with the 4G37 and with auto, so I know where it's all coming from.)

Was your OD switch on or off? Sounds like the OD switch wasn't engaged. In other words you were in 3rd gear and not in 4th at that speed.

It's the button on the side of the shift lever. Button should be out. Also, there should be a dash light that would illuminate "OD off" below the speedo if that button is pressed in.

Also, with automatics, there is that button on the console above the shifter. Its the torque converter, lock-out button that displays "ECO/PWR". That button should be out for "ECO (Economy)" for normal town driving. The "PWR(power)" adds more power for like hills and such (it unlocks the torque converter to allow more power to the tranny..) there should be a light in the instrument cluster in the lower center that should illiminate which postion that button is in. But usually the "Economy" light usually burns out and only the "Power" light will illuminate when that button is pressed in.

At the top of the gear section of the tranny is a harness plate that three wire connectors are mounted there. Check those connections, for one could have been reversed with another connector which would cause the OD not to work, if that's the problem.

110km or 68.2mph and with it being up to 3500RPM on the Tach would show that the OD wasn't engaged.

(why the Durango runs at such a low RPM's at that low speed is that you got a very big motor up there that can run that low of RPMS along with the gearing in the tranny to allow the vehicle to travel at that speed under low RPMS. Little 4cyl motors can't work as strong as them big gas guzzling V8's, thus they have to be gear accordingly to their power, which is usually higher. Thus, at 100KPH, the tach on the Talon should be around 2700 PRM with the OD engaged).

Give that a shot - good luck-DSM

 

[nc_dsm]

I found a method for pulling codes from TCU, it is more involved than the method that I remembered. It is a very interesting article that I found from another dsm forum site. Link is below for their forum, you can click on the second link and go straight to the information.

TCU Code Pulling Page - DSM Forums: Mitsubishi Eclipse, Plymouth Laser, and Eagle Talon Forum: DSMtalk.com
TCU Codes
Again this was not my find, posted by TSI91AT from dsmtalk.com, kudos to him for his excellent find. Hope this helps

 

[Talonmom]

Thank you so much. This is what we were wondering when we saw the button. Once up and running (didn't blow gasket whew!) Doing water pump on Saturday. Quite the job! We (shade tree mechanics) that installed tranny thought the OD wasn't working. Hopefully I will be able to post good news on Monday.

 

[DSM1G90]

Doing water pump on Saturday. Quite the job!

.. Might as well replace the two belts (timing and balance) while doing the pump since you got to take the timing belt off to get to the water pump.

If the balance belt doesn't look too bad, that one can stay on, but at least do the timing belt. They're easy to do on a 4G37-done those many times.

You can PM me if you have any question .. good luck.

-DSM

LATE EDIT: Question: Even though I'm not familar with Canadian releases of the DSM, but the Eagle Talon didn't get the 4G37 motor until 1994 with it being designated as the "DL" (which was the last year of the 1G body styles). Thus, would it be possible that you did get a 1991 but with the 4G63 motor?

Also, what fluid do you put in that thing and I hope it's a SP II, or a ATF+4 fluid, for anything else will destroy the cluster clutch plates.

Also my bad on the button: It's supposed to be in to be in OD, not out - sorry on that ... good luck - DSM