Engine idles rough in gear/misses more when put in gear.

[Jjbiskup]

Engine idles roughish. Misses but not as rough when it is in gear. It still runs and drives but any clue on what it is? It started doing this an hour into a 2 hour drive, started running really rough. Just changed spark plugs and all of them look good. Truck is a 94 1500 with a 305.

 

[Schurkey]

What is the fuel pressure? How old is the fuel filter?

How old are the usual tune-up parts/services? Cap, rotor, plug wires, plugs, air filter, initial timing, PCV service, EGR inspection, etc? Inspect the magnet on the distributor shaft.

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Connect a scan tool, verify EVERY sensor and computer output--including but not limited to the IAC valve.

Clean the throttle body including the throttle plates and IAC passage.

Check for vacuum leaks--failed intake gaskets, failed throttle body base gasket, etc.

 

[Jjbiskup]

What is the fuel pressure? How old is the fuel filter?

How old are the usual tune-up parts/services? Cap, rotor, plug wires, plugs, air filter, initial timing, PCV service, EGR inspection, etc? Inspect the magnet on the distributor shaft.

You must be registered for see images attach

You must be registered for see images attach

Connect a scan tool, verify EVERY sensor and computer output--including but not limited to the IAC valve.

Clean the throttle body including the throttle plates and IAC passage.

Check for vacuum leaks--failed intake gaskets, failed throttle body base gasket, etc.

I took the air filter off to inspect the egr valve and discovered a piece of black electrical tape wrapped around the vacuum line leading to the egr, the tube was broken. I unplugged the vacuum line but didn’t cap either side and started it up and it seemed to run a lot better than before BUT it was still having a small random misfire at idle. It runs even rougher when I’m in drive but on the brake as I stop at a red light or something. While I had the air cleaner off I inspected the distributor cap and it seemed fine but when I put it all back together I did notice a ticking and saw an arc out of the corner of my eye coming off of the coil. The actual plug wire on the coil side and the top of the coil were slightly corroded. Would this most likely be my problem? The hesitation during acceleration stopped after I unplugged the egr valve, also do I need to cap the vacuum lines or do I NEED to replace the EGR valve. Thanks

 

[WICruiser-97]

Defintely cap the vacuum lines, if left open whenever those lines are opened you will have a vacuum leak. Your coil wire should be replcaed but probably not the cause of your problem.

 

[Schurkey]

Inspect the COIL, the COIL WIRE, the DISTRIBUTOR CAP including the carbon button in the middle, underside, and the PLUG WIRES. All the wires need to be checked for resistance--no more than ~4000 ohms per foot of wire. Less is better.

Kinda guessing the coil is damaged--cracked or carbon tracked--from excessive voltage due to failed coil wire or plug wires, which may have destroyed the carbon button of the cap as well.

If the EGR valve is damaged, it has to be replaced. Typically, the "broken" piece is a plastic nipple from the EGR solenoid. WHAT is actually broken?

 

[Jjbiskup]

Inspect the COIL, the COIL WIRE, the DISTRIBUTOR CAP including the carbon button in the middle, underside, and the PLUG WIRES. All the wires need to be checked for resistance--no more than ~4000 ohms per foot of wire. Less is better.

Kinda guessing the coil is damaged--cracked or carbon tracked--from excessive voltage due to failed coil wire or plug wires, which may have destroyed the carbon button of the cap as well.

If the EGR valve is damaged, it has to be replaced. Typically, the "broken" piece is a plastic nipple from the EGR solenoid. WHAT is actually broken?

The actual hard plastic line was broken in half and whoever had the truck before me just patched it with black electrical tape. The truck was running better after I unplugged the egr but when I started messing with the distributor I discovered the arcing from under the boot on the coil. This is when it started missing again. The distributor cap looked fine and I’m looking for somebody who sells just the coil wire but it seems like nobody has one. I will update after I plug the lines and get a new coil wire.

 

[Schurkey]

Have you looked at the plastic of the COIL where the coil wire plugs-into it? Really common for that to be scored/cracked/carbon tracked between the tower and the connector for the primary wires.

 

[Jjbiskup]

Have you looked at the plastic of the COIL where the coil wire plugs-into it? Really common for that to be scored/cracked/carbon tracked between the tower and the connector for the primary wires.

That might be the case but the actual coil to distributor wire would not click onto the stud for the coil. When I pressed down onto the wire the ticking/arcing stopped so I’m assuming it is just the wire

 

[Jjbiskup]

What is the fuel pressure? How old is the fuel filter?

How old are the usual tune-up parts/services? Cap, rotor, plug wires, plugs, air filter, initial timing, PCV service, EGR inspection, etc? Inspect the magnet on the distributor shaft.

You must be registered for see images attach

You must be registered for see images attach

Connect a scan tool, verify EVERY sensor and computer output--including but not limited to the IAC valve.

Clean the throttle body including the throttle plates and IAC passage.

Check for vacuum leaks--failed intake gaskets, failed throttle body base gasket, etc.

A check engine light popped up for like 20 minutes today, I did the paper clip truck and got codes 12, 32, 45. It was also running ALOT smoother while it had this check engine light if that means anything. The check engine light comes on once in a blue moon but goes away. Mean anything?

 

[scott2093]

It still runs and drives but any clue on what it is? It started doing this an hour into a 2 hour drive, started running really rough

My 93 did that for a bit when I'd get off the interstate after a 2 hour trip I was taking every week. It would only act up in that scenario...be fine around town when I was home or after it sat usually..it was random but only started after on the highway at those speeds...

I replaced some things with no luck and finally read something with the egr getting stuck or passages iirc....I think I took it (egr) out and revved the engine really good or, maybe I would just put it in neutral while at a stop if it was acting up and rev it good. Problem just went away and has never returned... but been meaning to get in that area one day....probably needs attention..