Can a MAP sensor cause problems at idle and not cause a SES light to show? I have been having a problem at idle for a long time now; I even rebuilt the entire motor and installed a ltcc ignition with new ignition parts. I have double checked the ignition and fuel system, but I can not find any thing wrong. The Idle is rough and tries to fix it self but surges up and down. I am thinking I might have a problem with the MAP or some other sensor. If I can not find the issue soon I am going to install eficonnections 24x ignition and have the car d=tuned by CMS.

 

Use a scan tool for diagnosis.

 

^ That is my problem I do not have the correct scan tool like autotap.

 

I would find out what the issue is first before i install a 24x conversion on it. Do you at least know what code the SES light is showing?

 

You can't troubleshoot modern cars without some kind of diagnostic equipment.

 

If he has a laptop, couldn't he order a usb to obd2 cable and download a free scanning program? I do this with my car and it works awesome. Would guess that its the same for obd2 cars.

.02

 

OBD-II stuff generally is not free.

 

Ah, I was un-aware! good to know. I've been shbox'ed again! lol

 

Here is what I did I installed a new map and the car is running better at idle but something still seemed off. So I started to move the wires on the injector plugs around and when I got to cylinder number 2 the motor surged up and down. After this I went into the car and noticed the SES light was on and it was not on when I started the car; I read the code and found it was as injector circuit malfunction. I think the number 2 injector might be causing a problem so I am going to go ahead and solder in a new injector plug from a second harness I have. I hope that fixes everything; I have been fighting with this car for too long. The map sensor did seem to help because the car is not stalling out completely like it was. I really should go ahead and order autotap so I don't have to take the shotgun approach any more.