I need some help badly!
I have a 91 Dakota with a 5.2L and I have checked all wiring, connectors and all grounds. I have done a full tune up and have replaced all filters. When it is below 50 degrees outside it go's into ASD but when the temp get around 50 it will start and run but the IAC stopped working and the tac does not read right, today I installed a new hall effect pickup so I will see in the morning if it helps, I dont think it will but we'll see.
Any Help Please!
I'm pulling my hair out on this one!
ECM maybe?

 

OK Read the FAQ page. When you get to the codes section follow the link and check the codes manually if you don't have a scanner. The IAC can be cleaned this links pictures no longer work https://dodgeforum.com/forum/dodge-r...n-the-iac.html
I know it can be hard to resist because I do it but try not to throw parts at it before diagnosing the exact problem. it is cheaper. How do you know the IAC has "stopped"? I don't think the tacs on these are very accurate. My 94 3.9 reads off a bit according to when I had the scanner on.

 

Thanks for the input, I see I only put up part of the info on my truck it is a 91 5.2 TBI auto trans, I have scaned the truck when I got it, (3 or 4 weeks ago)and there are no codes the tac was off a little but not bad and when you shut it off you could see and hear the IAC move, shortly after that it would not start below 50 degrees, when it wont start there is just like 5 mv at the coil so I would think it is going into ASD, I have checked all relays, fuse's, wiring, connectors and all splices and all the grounds, checked and repaided vacum leaks. As soon as the outside temp get to around 50 degrees or higher it starts and runs but there is on high idle (I will try cleaning the IAC)and now the tac is acting very strangly, at idle it shows 100rpm and my scan tool shows around 850rpm and the truck is running a liitle ruff, my scan tool still does not show any codes. I am really at a loss? I dont wont to keep putting money into this rig but allthought it has 210000 mile I think its a nice truck so I really would like to fix it.
I am open to any and all input
Thanks

 

I suggest you try the manual code check anyway just to make sure. That page linked from the FAQ has a code list and instructions. If you can use the scantool to reset the IAC once you clean it. be careful about how far the center piece of the IAC sticks out don't rotate it without rotating it back to the same position. Use TB cleaner. I'm stumped to be honest. Maybe also clean the EGR?