Over the last few months problem has been getting worse - not worse as in symptom but the duration and frequency.

1992 B250 / 318

The engine seems to have a slight miss (no coughing or spitting unless going uphill and gassing it real good)- intermittently

Originally thought I just got a bad tank of gas because it would run fine and then start shuttering. From the start, the problem occurred about 5% of drive time - I could correct it by nailing the gas, and then it would be straight for a while.

As the weeks have passed it has got steadily worse - now it shutters 95% drive time and cannot correct by nailing the gas.

I can sometimes correct by shutting the motor off and restarting.


I posted the problem before and as per ideas people posted here, I started using higher octane gas, octane booster and fuel injection cleaner at every fill up - all to not avail.

Finally today, I replaced the cap and rotor with the brass tipped type, replaced plugs and wires.

Still no change.

I could go outside now and crank it up and it will either run just fine, then get to shuttering again at any stoplight OR it would be shuttering from start up and correct at some stoplight, and then get to stuttering again by the next light and so on and so on.

I recently (2 months ago) had my fuel pump replaced (it did it before and after replacement - did not replace fuel pump because of the shuttering - fuel pump just went out at 260k miles)
They also replaced the fuel filter and the fuel relay @ pump replacement.

Anyway, would like to resolve this with you guys and gals help - many thanks in advance for your input.

 

Partially clogged cat converter.
Stuck/ sticky EGR valve
Plugged fuel filter
fuel pressure regulator
Bad/weak/intermittent grounds.

Bang the cat con and listen.

Take a mirror and flashlight and look to see if EGR pintle moves when throttle applied.

Replace fuel filter along PS frame rail

Hook a fuel pressure gauge up.

Remove and clean and retighten all the grounds and battery cable connections. Engine ground, firewall ground and engine to frame ground. If no frame to engine ground exists, add one.

Check computer ground which might be at base of coil mounting foot.
Do the key dance and post any computer diagnostic trouble codes.

Do the codes before disconnecting the battery to clean the cables and grounds.

 

Thanks landyht for the input.

Last night, went up to advance and bought some plugwires, put them on and nothing better - then I tried a new coil - nothing better (returned coil)

Bouht som b12 chem stuff and wammo!

The guy up at that store that was helping me seemed like he new what he was doing,

after I went through all that above the dude came out to help me a bit, he started off by diconnecting plug wires one by one and connecting a light to them - had fire on all cylinders - he did agree that it really wasnt a miss per se, but a 1/2 miss. Although we could not isolate the 1/2 miss there in the parking lot we figured it was probably a 1/2 clogged injector - I put in a bottle of b12 and ran it for about 15 mins up and down the street, gassing it real good and the stutter disapeared pretty fast and stayed gone for over an hour of just driving around in circles..

 

Aye! Spoke to soon.

Went to get a bite to eat today and it started it again while waiting in the drive thru

would not get right again all the way home...

 

Check you engine codes. That kind of abrupt change in in drivability should be recognized by the ECM and point us in a direction.

The FP regulator is climbing on my list of likelys.

And as always, the grounds.

 

I have no idea how to check engine codes on this van, it has no diagnostic port. I suppose that's what u meant by the key dance *

Thanks for all your help landy - I will check the grounds in the morning.

 

There is a TSB for the Ram Vans of the Magnum engine era. It talks about properly routing the ignition wires in a way to prevent engine stuttering, misses and backfiring. Just check to ensure that the wires don't cross each other and are held by ignition wire plastic looms not to short out on the engine.

That TSB goes into some really lengthy details per each cylinder back to the cap-n-rotor. http://dodgeram.info/tsb/1998/18-48-98.htm

 

Sounds like the engine computer is failing as it heats up.

 

update:

today and the other day-

replaced plugs, wires, rotor carp, button

today:

erg, tps, and idle air cv

no luck.

I am starting to agree with aloro @ ecm

cranked up this morning, drove over 30 miles, ran fine. turned motor off at jobsite for 15 mins - cranked back up and she ran like crap for the rest of the day.

 

Update - FIXED

Ended up taking the van to a real mechanic - versed him on everything that I did already.

He checked the codes - nothing - ECM was fine, he thought it was running real lean because of the smell (mechsnose) and went through all the TSB's and came up with:

TSB 18-03-94 - Issued 3/25/95

Oxygen Sensor Contamination

Models 1993-94 (AS) Dodge Ram Van

Symptom/Condition

Rough running, loss of power, may or may not illuminate cel - may or may not display codes: 51, 52

Repair Procedure
Replace O2 sensor, speed sensor and install jumper harness (that is designed to prevent migration of ATF) between O2 sensor and the sensor lead wire harness.


Basically, the speed sensor wires absorb ATF, the ATF runs down the inside of speed sensor wire to wire harness that is shared with O2 sensor. Shorts occur within the O2.

The new speed sensor actually incorporates the new wiring harness (different than stock)


Van now runs like a scalded doggy once again!

They charged me $294