d21 torque converter won't stay locked

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jaxom28
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d21 torque converter won't stay locked

Postby jaxom28 » Fri Apr 24, 2015 9:24 pm

navara d21 1996 auto 4x4 double cab ute, jap import. From "B" pillar forward are the same as D21 terrano.
Replacement engine is 2.7 (silver top) mechanical diesel with EGR, with throtle position sensor. Original was black top and no egr. Gearbox is re04 with ecu.
Torque converter won't stay locked up. Initially it would drop lock up after 3-5 km. Now it drop lock up after 5-800 metres!!! not km
This trouble started after I changed the engine (died @ 371 k) in late january. Since then I have changed the gearbox (metal filings in the sump), changed TPS sensor for known good, swopped a ballast resistor in the loom, and by passed the gear box temp sensor all to no use. With the old engine every thing was working text book perfect. The new engine and gearbox have done about 180 k each.
Does anyone have any idea what is going on???

BlakeNZ
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Re: d21 torque converter won't stay locked

Postby BlakeNZ » Sat Apr 25, 2015 4:20 am

is it a different torque convertor?

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Crash bandicoot
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Re: d21 torque converter won't stay locked

Postby Crash bandicoot » Sat Apr 25, 2015 6:38 am

You Would probably be best suited getting the TPS etc that match that transmission, although part numbers are part numbers, it has been known for engne trans ecu's to act differently when hooked to replacement senders of the same ilk.

Failing that there is a thread on here about the D21 trans ecu recently (last two weeks) search for it as memory recalls your answer may lay there with how to adjust the TPS to get the trans to shift and hold properly.
Waiter...there is a drought in my glass.

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J_Dub
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Re: d21 torque converter won't stay locked

Postby J_Dub » Sat Apr 25, 2015 7:08 am

I had the opposite problem.
Locking up too early, as well as too early changes, as crash said, play with tps adjustment..

What rpm are the gear changes if you floor it?

jaxom28
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Re: d21 torque converter won't stay locked

Postby jaxom28 » Sat Apr 25, 2015 1:08 pm

The engine and gearbox are out of 2 separate nissan mistrals.
When the gearbox was changed so was the torque converter (matched pair I was told)
The TPS was swopped out of the old engine which worked perfectly with the first gear box.
The nissan dealer has reset the TPS twice now.
The gearbox ecu has been sent away for inspection and returned with "No fault found" also did a test run with a mistral ecu in the gearbox. The result was horrible harsh shifting and I couldn't tell if the T/C even locked at all in 4th.The gearbox came out of a mistral and now won't work with a mistral engine and a mistral ecu, - confusing. The part no of the mistral gearbox ecu is different to the navara gearbox ecu.
The rev counter has not worked for about 5 years. Common nissan fault . I have had the vehicle for about 12 years.

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Crash bandicoot
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Re: d21 torque converter won't stay locked

Postby Crash bandicoot » Sat Apr 25, 2015 7:19 pm

jaxom28 wrote:The engine and gearbox are out of 2 separate nissan mistrals.
When the gearbox was changed so was the torque converter (matched pair I was told)
The TPS was swopped out of the old engine which worked perfectly with the first gear box.
The nissan dealer has reset the TPS twice now.
The gearbox ecu has been sent away for inspection and returned with "No fault found" also did a test run with a mistral ecu in the gearbox. The result was horrible harsh shifting and I couldn't tell if the T/C even locked at all in 4th.The gearbox came out of a mistral and now won't work with a mistral engine and a mistral ecu, - confusing. The part no of the mistral gearbox ecu is different to the navara gearbox ecu.
The rev counter has not worked for about 5 years. Common nissan fault . I have had the vehicle for about 12 years.



see now we get the info.

the rev counter needs to work, the TCU needs a signal from engine speed to detirmine the best time to lock up the TC.

And I'd say it is at the engine side of the tacho circut.

oh and when the say the ecu's are interchangable yeah, they may plug in and the pins may be the same visually, but as found out in other thread, the pinout's do different things.
Waiter...there is a drought in my glass.

jaxom28
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Re: d21 torque converter won't stay locked

Postby jaxom28 » Mon Apr 27, 2015 9:04 am

Hello crash bandicoot, The 4th gear lock up worked perfectly with the old engine/dead rev counter combination. Why should it suddenly not work with a change of engine?There is no engine ecu to talk to.
Also a friend said to try stopping and restarting the engine to see if the t/c would lockup when warm. It did, and dropped out of lockup approx 300m later.
The nissan dealer says the ecu is not maintaining the "lockup" signal (no signal = unlock apparently), which is why I sent the ecu away to be tested.

jaxom28
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Re: d21 torque converter won't stay locked

Postby jaxom28 » Sun May 10, 2015 10:14 pm

Update
The gearbox ecu was at fault, and failing.
Tried several ecu's and the best was a nissan caravan unit. I tweaked the tps to optimise the gear shift points and it is working textbook perfect.

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Re: d21 torque converter won't stay locked

Postby Shugmcm » Mon Feb 26, 2018 5:57 am

Was it the ecu or tcu at fault

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