My '86 has a cam belt auto-tensioner?

[dsmithwc04]

First of all, thanks to everyone so far for helping me with my other issues in a couple other threads. On to the next problem.

So, I was (and still am) having issues with rough running while cold. Checked ICV, replced DME temp sensor and was contemplating on checking the AFM (have not yet as I believe it is not the problem since it idles fine at while warm) and then decided to go ahead and check if I have the updated water pump to order new timing belts since the current ones are unkonwn age.

Low and behold I see an auto tensioner for the t-belt. First thought is WTF, and then immediately went around to check engine code and saw M44 /07. I understand that means this car has an '87 engine in an '86 car...

Can anybody help me figure out if that has anything to do with the cold running condition? Or what else I should be looking for now that I know about this and possible other issues that may come up?

[Chunkerz]

Do you know when in 86 your car was made? They may have started putting the 87 engine in cars built at the end of 86. Or it's possible that your engine was swapped out. The auto tensioner shouldn't have anything to do with your issue. All it does is tension the belt.

Have you checked the wiring for the DME temperature sensor? The wiring might be bad. How are your vacuum lines? When you checked the ISV did you hook it up to 12 volts and verify that it moves freely? There is an oring inside the ISV that can dry out/crack and cause vacuum leaks.

[dsmithwc04]

Yes, I understand the auto tensioning pulley has nothing to do with my rough cold start. I was just stating how I came to find out about the tensioner. My car had the early electric sunroof system so it would definately not be a factory install.

After calling Pelican they said the M44 /07 was definately an '87 engine so it was definately swapped.

My main concern was if there are any electrical connection differences that may be the culprit of the rough cold start and if there is any thing else at all that was different between the '86 and '87 model year engines other than of course the auto tensioner?

I did hook up the ISV and verify it opened/shut freely with 12 volts. What is the easiest way of testing dme temp sensor wiring? And is there a thorough vacuum testing write up with pictures?

[9FF]

Pelican are wrong M44/07 engines were fitted to all US chassis from 85-87.

It still could be an 87 but you need more than the M44/07 designation to find that out. Try and look for a casting mark with a date code. Almost all castings on the engine will have one somewhere, you just have to decipher it. GL

[Chunkerz]

Pull back the rubber boot on the DME temperature sensor connector and checkout the wires. If they're broken/dry rotted then they need to be replaced. Another test you could do is get a reading at the temperature sensor, then go to the DME connector and verify that the reading is the same there. Take a meter and set it to ohms and touch the leads on the two pins on the sensor, then go to the DME connector and stick one of the leads in pin 13 and in one of the ground pins. I believe pins 17, 19, and 28 are grounds. If the reading is the same, then the rest of the wiring should be fine, but you can't really be sure without opening up the harness.

Here's a video how to for testing the vacuum system:
DIY - how to pressurize your 944 turbo intake system - YouTube

[9FF]

...is any thing else at all that was different between the '86 and '87 model year engines other than of course the auto tensioner?

iirc the OPVR is different but you have to dismantle it to find out. I think the oil level sensor was 88 not 87 maybe someone can confirm.