Code P0203 (please help me)

[thinkV]

Hi everyone,

I have Deatchswerks 900cc injectors (on my turbo setup).

I have code P0203 (Injector circuit/open - Cylinder 3). I have had this code previously (6 months ago) and I replaced all of the injector harnesses however my engine blew up and I have spent the last 6 months rebuilding and getting the car back on the road.

The error has come back, I can clear the error and drive and it may not re-appear, it is very random.

I have tried:
- Moving the injectors around
- Replacing all of the adapter harnesses, including using a shorter version from Counterspace Garage

What is this error and how can I fix this? I am so tired and defeated by this car, but have just spent so much for a full rebuild that I can't quit now.

[RZNT4R]

If you've moved the injector and the code remained on cyl 3, it's probably not the injector. If you've replaced the adaptor, it's probably not the adaptors.

Have you considered that it may be in the engine harness or ecm? The"injector circuit" is anything between the 12v supply and ground. If it's tripping the code for a single injector, that eliminates the efi relays and fuses and ecm ground (basically anything that is in common to all 4 injectors), so it's between (and including) the concerned injector's splice on the red efi main1 12v rail and the driver in the ecm.

[Ultramaroon]

^^^this^^^


I suggest starting with the connector where it plugs into the adapter and working upstream.

[thinkV]

Originally Posted by RZNT4R

If you've moved the injector and the code remained on cyl 3, it's probably not the injector. If you've replaced the adaptor, it's probably not the adaptors.

Have you considered that it may be in the engine harness or ecm? The"injector circuit" is anything between the 12v supply and ground. If it's tripping the code for a single injector, that eliminates the efi relays and fuses and ecm ground (basically anything that is in common to all 4 injectors), so it's between (and including) the concerned injector's splice on the red efi main1 12v rail and the driver in the ecm.

Originally Posted by Ultramaroon

^^^this^^^


I suggest starting with the connector where it plugs into the adapter and working upstream.

Thank you for so much for the replies guys, the frustration has never been higher.

What is the best way about diagnosing this? Given it occurs randomly, how can I find out at which point fro the injector plug to the ECM it is occurring?

My first plan is to remove the plug and hardwire in the injector plug.

[Ultramaroon]

Originally Posted by thinkV

Thank you for so much for the replies guys, the frustration has never been higher.

What is the best way about diagnosing this? Given it occurs randomly, how can I find out at which point fro the injector plug to the ECM it is occurring?

My first plan is to remove the plug and hardwire in the injector plug.

Pshh. First thing I'd do is give that connector a little wiggle.


Ok, here's my one experience with injector adapters. I was helping a buddy with his when, as I was studying the connectors, I noticed that the spades on the adapter never fully seated with the sockets because they were too short.


I tested my theory by bending the spades a little outward right at the tip. Boom. engine quit missing.


I told my friend to get the correct connector for his adapter and I'd help him mod his mod. He never got back to me. Just drove it that way. :/

[thinkV]

Originally Posted by Ultramaroon

Pshh. First thing I'd do is give that connector a little wiggle.


Ok, here's my one experience with injector adapters. I was helping a buddy with his when, as I was studying the connectors, I noticed that the spades on the adapter never fully seated with the sockets because they were too short.


I tested my theory by bending the spades a little outward right at the tip. Boom. engine quit missing.


I told my friend to get the correct connector for his adapter and I'd help him mod his mod. He never got back to me. Just drove it that way. :/

Interesting! I have actually used two different types of adapters on this car and the error came up the same on the same injector port.

Do you mean the pins in this part of the adapter? or do you mean on the actual injector lead in the car? What kind of modification would I need to do?

[Ultramaroon]

Originally Posted by thinkV

Interesting! I have actually used two different types of adapters on this car and the error came up the same on the same injector port.

Do you mean the pins in this part of the adapter? or do you mean on the actual injector lead in the car? What kind of modification would I need to do?

Let's not get excited but yes. It's possible that one of the sockets in the other side of the connector is damaged. Maybe a wire is broken. Blah blah...

[thinkV]

Originally Posted by Ultramaroon

Let's not get excited but yes. It's possible that one of the sockets in the other side of the connector is damaged. Maybe a wire is broken. Blah blah...

Out of curiosity, do you know exactly where the other endpoint is of the injector plug? I'd like to see if it's plugged in properly at the other end.

[Ultramaroon]

Originally Posted by thinkV

Out of curiosity, do you know exactly where the other endpoint is of the injector plug? I'd like to see if it's plugged in properly at the other end.

Other end is inboard one of two main connectors for the engine harness. Doubt it's there. Bet you dollars to donuts that it's the injector plug.

[thinkV]

Originally Posted by Ultramaroon

Other end is inboard one of two main connectors for the engine harness. Doubt it's there. Bet you dollars to donuts that it's the injector plug.

Thanks, guess my only option is to cut the cable and hardwire it to a plug, the plug itself looks fine at the moment.

[Ultramaroon]

Originally Posted by thinkV

Thanks, guess my only option is to cut the cable and hardwire it to a plug, the plug itself looks fine at the moment.

Jesus, no. Be sure that's your problem before you cut anything. Make jumpers with some skinny wire. Be careful not to short anything.

[RZNT4R]

ThinkV G-damn STOP holy crap!

Always start with non-intrusive test first! with the car running wiggle every part of the engine harness, from the injector to the ECM, wiggle those plug, wiggle those wires.

You're tired of wiggling crap? Good, NOW you can think about unplugging things. wiggling the plug did nothing right? well, you're going to unplug it and visually inspect it anyway, you're going to take a needle and insert it in the female part of the terminal and feel for a good amount of friction. You're not sure how it should feel? well it's perfect that you have 3 other known-good injector circuits to feel the difference with. It feels fine at one end? Check the ECM end! And at every other connector between the injector and the ECM! Everywhere a wire is crimped into a connector, you're going to give it a gentle tug to see if it's weakly crimped or if it's only holding on by a strand and a half.

Now you've wiggled it and it was fine, you've checked every terminal along the way and it was fine? OK, you're going to BACKPROBE the circuit at the ECM and OVERLAY wires to the injector over the engine harness, effectively running a new circuit in parallel, and you're going to drive the car like that. And then you're going to drive it some more, until the code comes back. If it doesn't come back, well, there was your problem: a wire somewhere deep under layers of tape and loom, hidden where wiggles don't trigger it enough. Find it and fix it.

And if everything is fine and even with an overlay it still throws a fault, well the driver in the ECM isn't free from suspicion. Why do I say it in such a dodgy way? because calling the shot on an ECM for an intermittent problem ALWAYS sucks. ALWAYS, and I don't want to be the one to say "replace your ecm" without having put a finger on the car.

[Ultramaroon]

Originally Posted by RZNT4R

ThinkV G-damn STOP holy crap!

I see that you are an experienced kindred spirit. I couldn't have said it any better.

[thinkV]

Originally Posted by RZNT4R

ThinkV G-damn STOP holy crap!

Originally Posted by Ultramaroon

I see that you are an experienced kindred spirit. I couldn't have said it any better.

You guys will hate me haha, I think the car has just caused so much stress to me that I am tired of chasing issues. I actually just cut the plug off and spliced on the injector adapter, the error hasn't come back YET. I was a little desperate.

I do have some questions though, where do the injector wires plug back into the ECM? If I ever had to replace the entire loom to the injectors what kind of work/parts would I be looking at?