Please help running on two cylinders on idle, sorry long!

[WickedV6]

Please help, I hope I am at the right place to ask for assistance, I have a 1990 Legacy with 122K miles. A few days ago on a 98 degree day with AC on the car started running funny at idle. The temp gauge also stopped working; the check engine light also came on.

 

First of all I don’t know how and were to get the trouble codes out. The car runs beautifully above 1500-2k RPM. Sounds like on idle it only runs on two cylinders.

 

I checked the power two the front two injectors and there is no power to them on idle. I switched the fuel injector harness from the rear two to the front two so the front two cylinders fired up. I swapped out the coil unit, mass air flow, wires, plugs etc (I have a spare 1991 legacy sitting around with a busted timing chain).

 

I don’t know much about these cars but it sound to me that the car is set up as sequential fuel injection on idle and after certain RPM it goes to batch fire, just a guess is to why the car runs fine after certain RPM. Is there a cam sensor that works with the injectors?

 

 

 

Sorry for the long post and any help in this matter is appreciated.

 

 

 

Thanks

 

[beezer]

I would check out Legacy777 website for details on retrieving trouble codes. It's quite easy.

 

How did you check to see if the injectors were receiving power at idle? I thought you could test them with the key in the "On" position, not with car running. (could be wrong don't know for sure)

 

Normally I would say check the wires, plugs and coil pack. I would also check to see if the knock sensor is cracked. All this is guessing, check the codes first and see what shows up.

[WickedV6]

Thanks for the reply, I am new at this, where do I find Legacy777?

[beezer]

You can just click on his name, you can find it in a box named "moderators", you will see his website address there.

[camosuba]

if you have a complete car spare try swapping the computer as well.

regards camo

[WickedV6]

I also swaped out the computer as well, no luck. Does the coolant sensor have anything to do with the idle?

 

Thanks again for the input.

 

Prasad

[blitz]

Here's some things to check:

 

Measure the output of the throttle position sensor. With the ignition on, but engine not running, it should provide a smooth analog output voltage that swings from .5V - 4.5V as the throttle is moved from idle to wide open.

 

Check for vaccum leak(s) anywhere.

 

Make sure the PCV valve, throttle body, and IAC valve are clean and free of gunk.

[WickedV6]

Thanks for the input, I will check those items.

 

Prasad