CEL 31 Fuel injector #2 whenever heat soaked

[Spoolin4Ever]

EDIT: I apologize, I just realized 31 is the knock sensor not the fuel injector. Well it's been a while since I read the code, but it is fuel injector #2, the injector code thingy when heat soaked.

So when the car has been sitting after being driven, if you start it up after it sits and "heat soaks", I get the CEL and it said it was injector #2. Once it cools off it goes away. So cold starts are a breeze, as well as long trips, even sitting in drive-thru it will still run fine as long as you leave the engine and fan on.

I have not swapped out the injector quite yet, I was wondering if anyone else has had this happen under this exact same scenario?

I inspected my ECU and noticed it has one capacitor replaced with the new kind, but the other 2 Caps are the older style. Kind of strange, it is the original ECU and I don't think ever replaced or worked on. No fish smell present.

I have seen other threads from searching that other people had the same code, but not heat soaked and runs normal after cooling off, mostly the opposite in fact in the other threads.

 

[Ceddy]

I never heard of heat soaking injectors on a DSM.

Its a common problem on some of the 4.0 Jeeps. I get it on my 2000 XJ, but the exhaust manifold is right below the injectors. Jeep did a recall and added a heat shield and little injector heat shield sleeves.


I would swap injectors, and check the injector wiring for breaks or dry rot.

 

[steve]

I've had DSM injectors go bad and have the coil open once the injector gets hot. If that happens you have to replace the injector.

I've never seen 1G ECU throw a 41 fault code and tell you which injector but disabling them one by one until you find the one that doesn't act differently when turned off narrows it down quickly.

 

[Spoolin4Ever]

Hey guys; driving to work, after about 30 miles, it started running rough as if on 3 cylinders. No CEL. THink it could be the injector?

Which one is injector #2?

THanks!

 

[steve]

Which one is injector #2?

Ah, the second one in from the timing belt.

 

[Spoolin4Ever]

Do both the blue top and the black top injectors work on a 1G? Assuming they're DSM injectors that is.

Do all injectors say on the side of them what CC they are?

I've had DSM injectors go bad and have the coil open once the injector gets hot. If that happens you have to replace the injector.

I've never seen 1G ECU throw a 41 fault code and tell you which injector but disabling them one by one until you find the one that doesn't act differently when turned off narrows it down quickly.

Yeah you're right come to think of it; I had the injector pulse code, and I narrowed it down by disabling various injectors using a logger on laptop pc. Turned out that injector 2 was at fault.

So does this sound normal now? The injector apparenttly failed, but there is no CEL.

 

[steve]

If the injector clogs or locks up but the coil is still good no CEL gets thrown.
All the original DSM injectors have the cc's in the part number but not all injectors.