TSI AWD Automatic

[92AWDTalonTSI]

Ok, I bought a 1992 TSI auto and it is stuck in limp mode. We located the TCU and opened it up. No leaking caps and no foul odors. So I'm assuming it is good. The 4 A/T fuse is good also. tested the power wire on the TCU and we had power. The transmission does not shift hard into drive or reverse and there are no metal shavings in the transmission fluid. Nor does it have any metallic shine. We checked the transmission fluid and it is over filled. The fluid comes up about 4 inches past the "Full" mark. Also the oil and coolant light is on.

Is there any correlation between these lights and the limp mode?
Or even just the high amount of ATF?

Solenoid A and B inside the transmission is the next thing we are looking at. It there any way we can check to see it they are functioning before cracking the case? Also someone mentioned the harness going to the transmission could be wicked up with transmission fluid and causing errors.

Would you recommend looking into anything else?

Also, as I'm new to the DSM scene. I was wondering if the oil soaked hood is normal. The PO said the head gasket went out and the big turbo they had on the car had to be replaced as well. They purchased a JY head and had it refurbished. And replaced the big turbo with a stock TD05H I believe. The lines going to and from the turbo (Hard lines) are soaked in oil. The turbo is brand new. The motor also vibrates when you let off the throttle. Maybe caused by a loose timing tensioner?

Other than that it is a solid car. Minimal rust in front of the back tire and one little spot on the hood.

Let me know if you have any concerns. I want to drive this car as an every day driver.

^^----------------------------------------------------------------------------------------------------------Original Post------------------------------------------------------------------------------------------------------------^^

I've decided to alter this post more as informational than requesting help. As no one can help me I am narrowing the problems down one by one and I am going to post them above with all sorts of information. Since this appears to be a common problem I hope I can help everyone else all the while solving my problems.

Causes for limp mode:

Pulse Generators A and B.
Throttle Positioning Sensor.

Connector 1 (4pin) (*A51* in 2nd diagram below) (*A39* on Alldata) is to the Pulse Generator.
Colors: Black, White, Green, Red.
Connector 2 (1pin) (*A38* in 2nd diagram below) (*A38* on Alldata) is to the Kick Down Servo.
Colors: Brown with Green.
Connector 3 (3pin) (*A37* in 2nd diagram below) (*A37* on Alldata) is to the AT Fluid Temp Sensor.
Colors: Light Yellow, Brown with Red, Brown with Blue.

You can test the pulse generators on Connector 1. For PGA check the resistance between pins 1 and 2. For PGB check the resistance between pins 3 and 4. Both should read out from 215 to 275 ohms *With a cold transmission*.

To test the TPS, Pull the connector and inspect the pins for debris or gunk. With a multimeter, ground the negative probe to the chassis and probe pin 1 with the positive lead. Turn the ignition on. It should read 4-5 volts. Now with the ignition still on jump pin 1 with pin 2. Ground the negative probe to the chassis and probe pin 4 with the positive lead. If you have 4-5 volts your TPS is bad. If not your TCU is bad. To double check the TPS it should output a standard value of 0.48 - 0.52 volts.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

Here are the diagrams.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

I will elaborate more on everything after I check more information and crawl around my car more

After further investigation. The transmission was not in limp mode. I took the car out yesterday and I have no issues so far. I just have to figure out why it makes a grinding noise when I let off the throttle. ^^^ The above information could help someone and if I have time after solving my other problems I will finish the post.

 

[AK Maniak]

We checked the transmission fluid and it is over filled. The fluid comes up about 4 inches past the "Full" mark

I'm gonna go out on a limb here and say he already knows that...

 

[ramsack]

why would the torque converter be drowned in fluid? it's outside the case and it gets pumped in the from the oil pump. check the codes on the tcu.

TCU Codes

 

[DSM1G90]

It's an electronically controlled, 4sp transmission called an "F4A22" tranny. They're the basic same tranny that is in the Dodge/Plymouth minivans that has the Mitsu 6G72 V6 motor. They're known to get a pelore of issues with them when they get mileage on them - and going into limp mode is the result of these issues.

"Nearly every system in your automobile is controlled by onboard computers these days, especially your engine and transmission functions.

'Fail Code' conditions, or 'Limp Mode', happens when the vehicle computer recognizes a problem in it's logic. When an expected signal value from a sensor is sent to the computer and is not within the computer's programmed specifications, 'secondary' programs are activated by the computer to strive to protect the transmission from any damage the improper sensor signal might cause to occur, be signaling, or contribute to.

In other words, the computer is always expecting certain signal values from certain sensors i.e. the temperature sensor, the speed sensor, the throttle position sensor or MAP sensor, etc. As long as these signals are what it would normally expect for the current operating conditions and are normal based on all the other signals it is receiving from other sensors, it acts normally and accordingly.

If the computer, all of a sudden, receives some crazy signal from one of the sensors that is out of the normal range expected from this sensor, it is programmed to go into 'emergency' or 'secondary' measures.

These emergency measures vary depending on the severity of the defective signal. All of this is preprogrammed into the computer's logic by the manufacturer. The manufacturer has decided that as long as a certain parameter of a particular signal is sent from a sensor to the computer, all is well. The manufacturer decided that if this signal is higher than their highest parameter or lower than their lowest parameter, something is wrong with that sensor and the computer should make someone aware of the situation and take action to try to 'save' the vehicle systems or powertrain. "

Since there is no extra linkage to come from the throttle to the transmission to control fluid pressure to make the clutches shift per load requirements, it's dependent of the signals from the ECU.

usually what happens is that the two plugs on each side of the small plug gets crossed and this usually shoves the unit into limp mode. But, if this isn't the problem, it's an internal issue that requires tranny rebuild or replacement. Auto trannys are actually a very delicate device that only works normally when everything inside of it functions as it should.

On each plug, look at the color of the wiring and see if the color matches the color on its representive socket.

good luck-DSM

 

[92AWDTalonTSI]

Tell me what you guys think so far. ^^

 

[ramsack]

to summarize what he said:

the trans will go into limp mode if a clutch or band is slipping, or an electrical problem. when it goes into limp mode it changes to 100% line pressure and slippage may not show then. it only knows that from being driven, though, so if you get limp mode right off the bat, it's most likely just electrical.

 

[92AWDTalonTSI]

I know what he said. He copy/pasted it from another site. Also I know what limp mode is. And I'm only trying to narrow the cause of it down. One by one.

 

[92AWDTalonTSI]

Thanks for everyone's input.