Ok so none of the solutions thus far have corrected the problem. Hopefully the other people were helped even though I haven't heard the problem being solved yet. In fact to me while I don't think my efforts were making the problem worse it was getting worse. Knowing that without a doubt in my NON-mechanics mind that something was awry with the timing. I have since discovered that the timing can't be adjusted even though the manual tells everything one needs to know to set the unsettable timing. Out of exasperation I loosened the distributor bolt and with the engine running I made very small counter-clockwise adjustments, revved it up and repeated until the backfiring and hesitation stopped. I read that doing this adjusts the fuel sync. On the road the problem is almost gone. I may have to go another smidge CCW.

Whatever I'm doing makes the van usable. Am I doing some irreparable harm or is there a better way to accomplish this aside from trial and error? Does this sound like something getting stretched, skipping or missing teeth, or some previously failed effort? Hopefully I'm on to something that will help quite a few others who have described this problem but never let us know if they got it fixed.

 

What year engine is in your van? Also is it a V6 or V8?

The V8 Magnum engines were not available until 1994-1/2. So, a 1993 should be able to adjust the timing via the distributor. Or if it's a V6, the 3.9L arrived early for the Ram Van and Ram Truck. the distributor adjustment for the V6 should do really nothing. The Magnum engine distributors are ECM/PCM controlled.

 

It is a conversion van billed as a 94 but the engine is definitely a 93 V8 318 5.2L. She sure runs nice with all the stuff I've been doing and I may be close having a resolution to the original problem. Turning the distributor seems to have the effect of changing the timing but maybe I can't tell the difference from the fuel sync being adjusted.

The info I got regarding the fuel sync is from http://www.bionicdodge.com/bionic%20downloads.htm

 

Ok adjusting the timing via the distributor had no effect overall. It did expand the range at which I have power but the lack of acceleration problem remains. I found 3 ground wires in the vicinity of the auto shutdown relay.

Can someone tell me where other/all grounds might be?

Should I remove all paint from the connector and the van body?

 

Well, I know there is a ground strap from the engine to the van body located just behind the alternator.

I'm not sure for your year, but the fuseable links are under the brake booster mainly.

 

Checked and cleaned all grounds I could find; no change. When cold I have good responsiveness. The warmer it gets the less acceleration I have, in fact I may not be able to get over 40MPH when at operating temp and it takes too long to achieve even that. So to recap:
Engine idles and revs fine hot or cold
When cold the the engine is very responsive
The warmer it gets the less acceleration I get and more frequent popping and backfiring from the engine when accelerating
The problem used to require that I drive >20 miles now the engine only has to be warm
The popping and hesitation can be lessened by backing off on the throttle slightly

Removed catalytic converter
Replaced ASD relay
Cleaned fuel tank and filters
Fuel pressure tested good

Replaced:
Speed sensor
TPS (tested, within specs)
O2 sensor
Camshaft position sensor
Crankshaft position sensor
Ignition coil
Ignition wires
Cleaned the IAC
PCV Valve

I'd hate to scrap this vehicle especially since she shows only 117K but I'm about out of ideas.

 

Not sure if the original poster has ever found a solution...
But this sounds kind of like my van (see transmission issues 93 B250).
Sounds like a no-brainer, but have you checked the transmission fluid as well as the rear diff. fluid? My van runs beautiful in park...But has trouble getting up past 15mph.

Good Luck

 

Would the transmission really cause it to run lean and backfire? I have since replaced the timing chain but still the fuel delivery does not speed up as the spark frequency increases. There is only the distributor itself to replace, then every component will be new but none have solved the problem. In spite of 5 months of research and effort, 4 mechanics, and replacement of every related part, I think it's time for the tow truck to get this thing out of my life.

I have been looking for someone with a computer that is capable of setting the fuel sync, but those ODB1 computers are rarer than my success so I don't hold out much hope for this van being saved from the junk yard.

 

I'm sure you know this already, but in case you don't -- I cruise EBAY occasionally for good deals on used parts. I'm running a $65.00 EBAY computer now in my 94 B250. (My original is in the bag as a spare.) Sure beats parts house prices.
Just my $.02 worth.

 

Only the DRB scan tool that are 99.99% owned by dealers, can do the sync.