Transmission slips

Tiny
PHAZERCIL
  • MEMBER
  • 1996 MITSUBISHI 3000GT
  • 3.0L
  • V6
  • 2WD
  • AUTOMATIC
  • 165,000 MILES
I had two error codes on my car listed above SL model.
#1 Cylinder four misfire.
#2 P1750 (Transmission Solenoid problem).

I had a hard time shifting between gears (gears would be rough but would shift). First gear didn’t give me problems but the other gears would have a hard time shifting on hills. And the engine would rumble because of only running on five cylinders.

So I parked my car and replaced all the spark plugs (front and rear). I had to take off the intake manifold and throttle body.

When I put everything back together, the car wouldn’t shift at all. You would have to get it to go in high rpm's to get going. (This was before draining the transmission fluid. )

I then replaced the transmission solenoid pack and the P1750 error code went away. The transmission fluid was drained and replaced. (Not flushed out)

It still had the loss of power in the drive and first gear doesn’t have any power. You only get power when you give it a lot of gas.

Once you have a high enough speed, you can let go of the gas and it’ll fall/shift into second gear and then it drives like normal above first gear. The bumpy/struggling shifting is gone and it shifts wonderfully. When it’s in the air, it shifts fine in first gear. But when you put torque on it, it doesn’t have any power.

Reverse works perfectly as well.

The Throttle Position Sensor works just fine and has a current flowing as the manual says.
I adjusted the throttle cable as well.

What could possibly be the problem? I don’t think it’s anything with the transmission because it started acting up when I removed the intake manifold and throttle body.
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Tuesday, April 23rd, 2019 AT 6:26 PM

9 Replies

Tiny
MOTOR MASTER
  • MECHANIC
  • 279 POSTS
Hello my name is Dave.

I have a lot of experience with these cars as we specialize in complete builds, usually the VR-4 model but quite a few of the SL models as well. There are a few things that are common causes of issues with these cars. The first question is what kind of plugs did you put in ti? We have found that they don't do well with platinum or iridium plugs as they cause miss fires and pour performance. The other issue we find so common that we always recommend replacement is the coil pack and the PTU which is the module directly under the coil pack. I would highly recommend replacing both of those and also using NGK copper plugs. And if you need any parts that you have a hard time finding 3SX. Com is the 3000 parts specialists and can help you find anything you have trouble finding. If you can make sure you have copper plugs, good plug wires and the coil pack and PTU and that none of the connectors got knocked loose I feel that your odds are good your issue will go away, if not please let us know and we can assist you further. I hope this is helpful and thank you for using 2CarPros
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Wednesday, April 24th, 2019 AT 11:17 AM
Tiny
PHAZERCIL
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  • 5 POSTS
I did put platinum spark plugs in when I got them.
I’ll have to buy the copper ones and the other parts and install them on Saturday to see if that works.
Thanks for the advice! I’ll keep you posted on how it goes.
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Wednesday, April 24th, 2019 AT 2:14 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,554 POSTS
Please let us know what you find. We are interested to see what it is.
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Monday, April 29th, 2019 AT 12:16 PM
Tiny
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  • 5 POSTS
So I changed the parts and it still won’t operate normally in first gear.
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Sunday, May 19th, 2019 AT 6:45 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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It sounds like you have a pressure control solenoid that is not working right, do you have a check engine light on? Here is a guide and diagrams below to show you the solenoid location:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Check out the diagrams (below). Please let us know what happens.
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Monday, May 20th, 2019 AT 11:30 AM
Tiny
PHAZERCIL
  • MEMBER
  • 5 POSTS
I did have previously error code P1750. I replaced the solenoid pack already and there are currently no error codes on my car
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Monday, May 20th, 2019 AT 3:06 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,554 POSTS
How is the condition of the fluid? Smell burnt? Brown or black in color? Can you please shoot a quick video with your phone so we can see what's going on, that would be great. You can upload it here with your response.
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Tuesday, May 21st, 2019 AT 12:30 PM
Tiny
PHAZERCIL
  • MEMBER
  • 5 POSTS
Before I changed the fluid, the original transmission fluid was a medium dark brown, no burn smells and no particles/sediment whatsoever.

As for the video I’ll have to get a recording of it in a couple of days when I get back home.

But it acts like it hesitates when you have it in first gear. To get it to engage and to get it to slowly crawl forward you have to get it to be in 7,000 RPM's.

Reverse works perfectly and all the other gears.

Could it possibly be the TCU?
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Tuesday, May 21st, 2019 AT 6:20 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Yes it can be. Lets try swapping it out for a used or rebuilt unit. Here is the location. Check out the diagrams (below). Please let us know what happens.
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Thursday, May 23rd, 2019 AT 11:02 AM

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