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sprinkles08, Chrysler/Dodge/Jeep master tech
Category: Dodge
Satisfied Customers: 22361
Experience:  ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans and Hybrid Specialist
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My 1999 Dodge Ram 1500 with 5.9L began running rough soon

Customer Question

I'm Bill. My 1999 Dodge Ram 1500 with 5.9L began running rough soon after using gas from a different gas station. Got so bad that it wouldn't idle. Threw codes p0203 p0204 p0206 and p0208. Ran injector cleaner through it while using the accelerator to keep it running. Codes changed several times from injector to injector but finally settled on p0203 and p0204. I pulled those two injectors and they tested OK. I switched them with two others and afterward, it still shows #3 and #4 as faulty. Got a new PCM, same problem. Disconnected battery and PCM checked continuity of wires and found no short. However, the ASD wire (DR GRN/OR) shows a low resistance short to ground. Although I would assume that it's an O2 sensor, since they share that ASD wire, but that should affect all injectors, not just two. Still puzzled, need advice.
JA: Thanks. Can you give me any more details about your issue?
Customer: Just thinking that I didn't check for crossover short between #3 and #4. I need to try that.
JA: OK got it. Last thing — Dodge Mechanics generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: Dodge
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

Without knowing how testing was done I doubt there is actually a short to ground on the ASD circuit. If the circuit was actually shorted to ground then the fuse would blow which would prevent the engine from starting at all.

You may or may not actually have injector circuit issues. I've seen many cases of a failed TPS or valvetrain issues cause injector driver codes on these older JTEC PCM'd vehicles.

The proper preliminary tests to do for these codes would be to check for power on the ASD wire at the affected injectors while running and check the driver wires for pulsing ground. Have either been done?

Customer: replied 1 year ago.
I don't have a noid light but I did test the injector connectors using a digital multimeter. Set on VDC I get pulses of different voltages down to Zero. There is a difference in the pattern of voltage pulses from the two affected injectors, they seem less regular, no pattern that I can detect vs. the other injector connectors that have a pattern/rhythm to them. It's almost impossible to get the engine to idle so that I can test the active circuits. I did check the voltage on the ASD wire at the injector connector, key-on-not-running, and got nothing. However, that makes sense since the ASD should shut power off if there's no input from the tach or cam sensor. I only did it because it was recommended on a blog. So in answer to your question, I didn't measure the ASD voltage wire 'to ground', only to the 'control wire' in the connector.
Expert:  sprinkles08 replied 1 year ago.

An incandescent test light should be used to test ASD voltage and the injector driver. Even if two injectors were down though it should still idle.

Are you hearing any abnormal noise from the engine?

Customer: replied 1 year ago.
It was backfiring before the new PCM. Now it's just misfiring badly. Can't hold steady RPM. When it sort of idles, it drops to 400 RPM then lurches up to 800, up and down between about 400 and 800 RPM. Pretty random. Even if I hold the accelerator at a higher RPM, say 1,800, it sill fluctuates up and down a hundred RPM or so. Other than that, there's no sound per se that I can detect.
Customer: replied 1 year ago.
Oh. I did install a new TPS tonight but no effect.
Expert:  sprinkles08 replied 1 year ago.

Do you have a compassion gauge?

Customer: replied 1 year ago.
Compression gauge? No, but maybe I can rent one from the local auto parts store.
Customer: replied 1 year ago.
Had a new code last night after replacing the TPS, P0500. However, I didn't move the vehicle, so I can't imagine that would effect the idle or the surging, shaking, and misfire. At least it feels like misfire, there's actually no code showing for misfire.
Expert:  sprinkles08 replied 1 year ago.

Let's either do a running compression test and compare all cylinders or pull the valve covers and take a look at the springs.

Customer: replied 1 year ago.
Thanks. I'll do that Monday, my day off. I'm working overtime this week because we're understaffed.
Expert:  sprinkles08 replied 1 year ago.

You're welcome!