[cdnram]

The patient is a 95 ram sport 2 wheel drive, 318 with a manual transmission.

The truck is running very poorly, skipping like its running on 7 cyl. It's been at the shop for a day (scanned) and numerous parts replaced. (o2,plugs, wires, rotor, coil, EGR valve) Still no change. Compression checked, ok. When you pull the wires or unplug the injectors it seems to keep running almost unchanged until you get down to two cylinders. (I know that sounds crazy) Scanner was showing a lean condition. (generally)

Anyway, the finger is now pointed at the ECM, and I would like to test it some way before I keep throwing parts at it.

Any help/ideas?? Thanks

 

[chizzle1]

you can source a reman PCM for about $90...you may find one at a junkyard a bit cheaper.
If you know anyone that owns a gen II truck, see if they'll let you swap it.

 

[abossram]

Boy, that sounds like a plenum gasket leak. Ask these mechs if they know what that is. VERY commom on Rams. Have them start spraying carb cleaner or whatever they use to detect vacuum leaks, around the plenum gasket area while the truck is running. look for a change in RPM.

 

[Buzzbass]

Boy, that sounds like a plenum gasket leak. Ask these mechs if they know what that is. VERY commom on Rams. Have them start spraying carb cleaner or whatever they use to detect vacuum leaks, around the plenum gasket area while the truck is running. look for a change in RPM.

How are they going to do that, you'd have to take the manifold completely off to acess the gasket area. have you ever worked on one of these things ?

 

[gcguru]

IAC solonoid or MAP sensor would be my first guess, sounds like the IAC is stuck open since a few dead cylinders dont let it shut completely off.

 

[chizzle1]

IAC solonoid or MAP sensor would be my first guess, sounds like the IAC is stuck open since a few dead cylinders dont let it shut completely off.

The IAC being stuck open would result in a high idle situation, not misfires.
I ran my IAC disconnected for about 8 months until I got around to tuning it to idle right with the IAC connected to the new throttle body.

 

[cdnram]

Thanks for the imput guys/gals?? Been busy lately so I'm just getting back to the problem. And I agree, the plenum gasket should be checked. (have some symtoms but not others :dunno: :dunno: ) I did find the TSB for testing for a gasket leak but is it that easy. If I read it right, it just says plug the PCV line and test for vacuum on the crank case breather hose (on a warm engine) Any experiances on that procedure??

 

[cdnram]

Checked for vacuum as per TSB, no measurable vacuum present. (Assuming I performed the procedure correct). Looked down the throttle body and it looked reasonably clean. But that wouldn't be a good indicater cause just prior to the problem I sprayed mopar cleaner in. I assume that would clean the plenum plate too.
Soooooo, I've still got the problem.

 

[BleedDodge]

It might even be improperly routed plug wires causing the misfire. I don't mean wires routed to the wrong plugs, I mean the route the wire takes to get to the plug.

 

[gcguru]

The IAC being stuck open would result in a high idle situation, not misfires.
I ran my IAC disconnected for about 8 months until I got around to tuning it to idle right with the IAC connected to the new throttle body.

what I meant was that the IAC stuck open is probably keeping his engine running until the last few plug wires are pulled, as he said in his first post. There are few other good reasons besides a immense vacuum leak that would keep that engine running on only a few cylinders.

 

[gramol]

could try swapping the injectors from the bad cylinders to "good" cylinders. if the miss moves with the injectors, you know what to buy. if the miss stays at the same clyinders, i would perform an injector drop test with a scan tool. basically, testing the pcm's ability to fire the injector. after that, i leak down test on the affected cyl's. blowing compressed air into bad cylinder through spark plug adapter with cylinder at tdc compression. listen for air leakage. air at tailpipe..........bad exhaust valve.
air through intake...........bad intake valve.
air out dipstick tube/crankcase...........bad rings.

just some thoughts.

 

[cdnram]

Thanks for the good leads but I've checked the exact wiring as per the dodge TSB. No change.
There doesn't seem to be any "bad" or "good" cylinders. The plugs look the same. On the "day" in the shop they tested all the injectors. All O.K. Compression test done, again all checked out. Didn't do the leak down test though, assuming if if there was a bad valve it would show there.

It seems to be a control item, meaning not just one cyl. but something that affects all cylinders randomly. Now the other day it did give a 32 code which I believe is the EGR, but that has been replaced and no vacuum leaks were found, not to mention rpm is normal.

I'm still all ears.....

 

[cdnram]

SOLVED!!!!! :cheerl: :cheerl: The problem was a very dirty fuel system. In my case I had to take the fuel rail and injectors right out. The amount of rust and chunks of rust was amazing. Two ports on the fuel rail were completely full. (not to mention the small injector holes) Fuel pressure was up and the injectors were firing properly (electronically speaking) so thats why it initially got missed. The crap would be floating around and just generally impeeding fuel flow, and thats why no "one" cylinder would show evidence of it not working.

Another great thing about this repair is it is cheap! Can of brake cleaner and some compressed air. Who doesn't like a happy ending!!!

 

[chizzle1]

glad you got it working...but where did all the rust come from?
May want to get a couple bottles of fuel treatment to get the water out of the fuel system.

 

[cdnram]

Good question Chiz, and you're right, a bottle of water remover is coming right up.

The only theory I can think of is moisture in the fuel (especially over time) has caused both the fuel line AND the fuel rail itself to rust. In my case we're talking 11 years and 150,000 miles.

Moisture could be from a tank of bad gas at the station or from our good friend condensation. The tank is plastic and there is a filter on the pump, so logic would suggest metal somewhere after the pump.

Unfortunately, diagnosis requires pulling the fuel rails to know for sure.