miss fire 0201 and 0301

I'm an idiot. I have a 2001 xj. I installed a header because I had an exhaust leak, after installation I felt like my cherokee did not have quite as much power so I was wondering if all of my injectors were firing because I noticed a few had cracked insulation(i did not have a check engine light). I started the engine and pulled the first connector to injector #1. The engine started running like crap. I plugged the connector back in and it kept running like crap. I turned off and turned on and it still runs like crap and throws the 0201 and 0301. I replaced the connector and the injector. I pulled and checked the spark plug. I checked the ground and it has continuity between the injector connectors.

Is there a pin on one of the other connectors i could check to see if there is a break somewhere else in the injector connection #1 to connector power?

How can I check to see if the spark plug is getting spark? It was before i pulled the connector.

If the two wires from the connector made contact what else could be fried?

Can i drive it to work? Any other thoughts.

Thank you for the advice.

I had the same issue with my 98 XJ. I ended up having a short in the wiring going to injector #6 causing it to stay grounded leaving the injector open flooding that cylinder. I took mine to a mechanic since I don't know squat about wiring. The mechanic had to take the wiring harness apart and find the short and replace that section of wire. After that it ran great. Cost me 550 dollars. So if you have knowledge about wiring and have the time save the money and do it yourself. Hope this helps you out.
-Kevin

They make a test light that can be plugged into the injector harness called a NOID light. Its basically an LED in a fancy plastic housing that has pins configured to match different injector harness plugs.

http://www.autozone.com/autozone/accessories/OEM-6-pcs-noid-light-set?itemIdentifier=948078

To check spark on the 00 and 01 is a pain since its the coil rail and not a distributor style. You could try pulling the whole coil rail and leaving the wiring harness hooked up and having a buddy crank the engine. The coils should jump spark to ground.

The noid light was a great idea. i made a noid light and check to see if it was firing. All the others injectors are working but #1 is not getting power to the injector. Then i check continuity to the box right be the air filter middle connector.

https://picasaweb.google.com/njinnv/20111103#

Any suggestions on what got fried? Is there a fuse for the injectors?
Where is the control circuit?

Thank you,

Nate

The pic you posted isn't showing up but I don't recall a fuse for the injectors. The engine computer has whats called drivers inside that power the injectors. I'm not 100% on if its one driver per injector or how they are set up.

When you say that you checked continuity I am taking it that you unhooked the computer connector and tested between the #1 injector plug pins and the computer plug pins for it. If you show good continuity doing that I'd say that the computer could be bad.

When you made the noid light was it an LED? Reason I ask is that the injectors dont use much amperage and may not illuminate a regular bulb which could make you think its not working or actually burn up the driver circut for that injector.

noid light

http://www.youtube.com/watch?v=EeLFqC2UabY

Looking at the FSM for my 00 there is a fuse for the injectors but it is a 15a for all of them. The computer controls the ground to activate the injector.

You should have power coming in on the dark green with orange tracer and ground on the white with dark blue tracer.

The green wire is continuous to all of the injectors. I traced the white with blue to the middle connector on the pcm (powertrain control module-is that right) and checked continuity. Is there a good place to buy the pcm. Is it ok to get one from jy?

Yep the computer is also called the PCM. You can get a junk yard PCM but you want one with all the same options as your jeep. The big one that I can forsee being an issue is if the donor jeep has the security ignition keys that are specific to that vehicle. The security keys will have a grey head vs the non security keys are black.

thank you

PCM

Napa, Oreilly, and autozone want 255 ish for the pcm. The Dealership wants 560 for the pcm. No local jys have it. I'm going to order through: http://www.autocomputerexchange.com/

I hope I diagnosed correctly.

Nate

http://www.daveysjeeps.com/index.html

I've gotten stuff from here in the past with good results.

Thank you wheeling365!

PCM was bad. 250 over night delivery. Good customer services.

So now all of the cylinders are firing most of the time. I'm experiencing heat soak. Does anyone have a set of hood vents for sell? I have checked the local junk yards and i will keep looking.