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Automatic gear change problem


flight4
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I have a 1989 3.0 3 door down here in Patagonia! I have 3 issues that I want to try and solve

 

I can only get the change to happen if I lift my foot off the throttle at about 2500 rpm or above, which brings me to the second problem, that the change is far too high!

The rest of the change schedule works, going the other way as well as the gear shift lock.

Is this a speed sensor issue? Vacuum?

 

The other is that when the engine is hot and only after standing for more than ten mins, it starts but very rich, and takes about 40 - 50 secs to settle down. Temp sensor has been replaced.

 

Any guide would be most gratefully received!

 

 

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Thanks for the response... Regarding codes for the auto change issue... There arent any! We will be checking for loose wiring. I was just hoping taht someone else had come accross the same issue at some point!!! Oh, well!

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  • 7 months later...

I have managed to move forward on some of these issues. TPS replaced. However what we need now is info on how to adjust the vacuum with the TPS etc to get the correct change schedule. Does the Haynes manual ($30) cover this?

 

Thanks

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I'm not aware of any vacuum control for the trans--should be all in the trans computer. That said, I don't know if an '89 in Patagonia came with the same equipment that an '89 in the US would've.

 

My understanding of the TPS is that there are two parts inside, a pot (for the auto trans) and an idle switch (for the ECU). The idle switch should make contact when the throttle is fully released. Adjust it to that point and it should be good to go. Poking around with an ohmmeter should allow you to work out which connection is which.

I've got one of the cheap manuals for mine and it's really not great. The service manuals on Nicoclub are much better but I don't think there's one on there for the 80s models with the TBI (again I don't know exactly what you have).

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Thank you very much for the response! The model I have was manufactured in the US, so we should be same. Good info on the TPS. The vacuum I am talking about lives on the left hand side of the engine near the passenger and seems to control the smoothness of the gear change, so we are suspecting that it works in conjunction with the TPS. One simply changes the position of the cable to achieve this... Just wonder if there is some info on the correct setup. I am a bit reluctlant to spend US$30 on a Haynes manual that I have no guarantee that contains the info I seek! I have the Nissan full Maintenance PDF, but that doesn't help either!!!

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I remembered downloading an '89 service manual several years ago (no idea where I found it, but I'm sure it was linked from this forum at some point) and had a look at the AT section, and found that there's a section for a transmission I'm not familiar with: the 71B. That transmission does indeed have a vacuum diaphragm rod/kickdown/etc. The manual should have the info you need to adjust the thing (and an awful lot more besides, it's not just the auto trans section). PM me your email and I'll try and send it as an attachment.

 

Shows what I know about the early rigs!

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