afreeman1984

hi all,

I have a p1300 code preventing my 1997 T100 5Spd 3.4liter from running. Ive changed all the coilpacks, spark plugs, crank sensor, cam sensor, checked timing, swapped mass air flow sensor, ignitor....

I am not sure what to do?

I have gone through the FSM and everything checks out. I found that if i arc the firing wire to the front most coilpack to the rear most coilpack (nearest to firewall), it will run but it seems like its in emergency timing mode and also misfires alot with throttle or above a certain RPM.

I have replaced and cleaned all the ground wires i could find and cleaned up every connector along the way.

Any suggestions?

MF

I just went through similar problem on my 3/4 swap, except I had no spark at all. Turns out the igniter screws had come loose and due to poor contact/grounding it would not start. Make sure those babies are tight. Hope that helps anyway else with similar problems.

afreeman1984

I cleaned the ground connection there along with all of the others i could find. someone has indicated my problem may not be electrical and maybe its related to fuel. any opinions on that?

MF

Hmm... for a minute(s) I thought to consider fuel in my scenario as well, but I had to ground myself... P1300 has nothing to do with fuel. It's something electrical.

I noticed in your first post you didn't mention changing spark plug wires... When was the last time they were replaced?

afreeman1984

Plug wires were done with my refurbishment of the entire electrical system. I did new NGK wires per the many recommendations i found online...

MF

Yeah, those NGK's are good. Only other thing the FSM indicates as a possible failure that you haven't mentioned above is the ECU.

afreeman1984

So i was thinking that could be a possibility but my buddy indicated he had already replaced the ECU previously for the same problem....

MF

If your buddy was experiencing exactly the same problem and solved it by replacing the ECU then I would 100% NOT discount the ECU is the culprit again.

afreeman1984

Im not sure if that was the root cause before. I have found wiring changes and someone had previously swapped coilpacks crankshaft position sensor, camshaft position sensor, in attempt to fix.

afreeman1984

Also i went through the FSM troubleshooting procedures for the ECU and Ignitor. Everything seemed to be within spec.

MF

My suggestion is go to car-part.com and get a junkyard ECU with warranty for 50-100 bucks. Throw it in and see what happens. If the problem persists at least you have a spare ECU and you know 100% without a doubt the ECU is not the culprit. From a troubleshooting stand point of view, in a case like this, it makes sense to me. More sense than spending more time and money chasing "potential" problems, all the while wondering....what if the ECU really is bad!?

Good luck!!

afreeman1984

I think thats a very wise recommendation. I will try and give you the report. Thanks much for your input!!!!

Rocky1

Wow, I'm in the same boat. Thanks for the tip on 'car-part.com' for an junkyard ECU. That is definitely my next step. P1300 is making me crazy!

atcfixer

iTrader: (1)

I'd test a igniter first, it sends a signal back to the ecu to say it is running/sparking and if it doesn't send the signal the ecu shuts down the engine. From memory when I had a similar issue in my case my truck would start then die instantly similar to when the fuel pump relay goes bad or the mass air flow meter on the older trucks doesn't flag to turn the fuel pump on. Igniter was bad in my case, but the truck orig started with a bad ecu and I plugged in a AT ecu instead of a MT and shorted the coils out and such. After repinning and replacing the parts I killed from my mistake, the AT ecu functioned fine.

The basic way to test the ECU is to turn the key to ON and make sure the check engine light is on, if it is, then the "self test" passed, if not the ecu is not powering on or is bad.