I thought it might be best to see if anyone on the forum has an idea of what could be causing my van trouble. I've owned this van for nearly 5 years and it has been an amazing vehicle. The last 2 years it has been doing something that I can't seem to figure out.
The van always cranks and runs and has never stalled. If I drive 55 mph I never have a problem, but when I go to 65 or 70 mph it will lose power intermittently. This meaning sometimes it does continue to run without losing power and sometimes it may happen after I've been driving for 5 minutes or longer at the higher speed. When this happens I have no accelerator pedal unless I floor it. Then it responds and accelerates until it loses power again. It does not stall. I usually exit the freeway or pull to the side and start again. Staying under 55 mph it runs as normal. There have been time recently when the engine continued to run rough even after I started slowly. In these cases I turned the van off, waited a couple of minutes, and restarted and it ran fine again. I have replaced the wires, distributor cap and rotor. Cleaned the throttle body. Had the engine scanned by a mechanic - no code errors and all cylinders firing correctly. The check engine light does not come on when this occurs. Has anyone ever had this problem or heard of something like this before. Thanks

 

Your ignition coil may be getting old and shorting out under certain conditions. Make sure your cap and rotor are brass, not aluminum.

Just my $ .02.

 

it could be anything.

along with the coil

first things that come to mind are


flakey CPS
flakey O2 sensor


weak fuel pump


dead or cracked spark plug


clogged cat


weird ground strap


transmission pressure fluctuation

 

Thanks for the information.
I think I'll start with the cap and rotor in brass. I know the ones on the van are aluminum. I have had bad coils before on other vehicles and I'll see what the shop manual says on testing. I'm trying my best not to get into a pull and replace situation. Can't really afford it. One thing I didn't mention about the problem is that the engine backfires when losing power. A friend told me if it backfires it's an electrical problem. I just replaced the wiring harness to the back oxygen sensor (chewed by groundhog). Thought that might have been the problem, but it still remains. I'll keep plugging away, but any other ideas that come to mind would certainly be helpful and appreciated. Thanks folks!

 

To me it sounds like it could be your distributor, are you friendly with a local salvage yard?
If you could swap it in another then go for a short ride you could rule it out.


As others have mentioned ignition coils become finicky with age in regards to heat sensitivity.

 

when I was using that crappy Bosch O2 sensor, my van did the same thing...lose power then start backfiring. I had to floor it for it to stop and then the engine started running again...



also--the Bosch o2 sensor was responsible for clogging my cat...

only the NTKs (OEM) or (I think) Denso are the only ones that work right with our PCMs. I changed to NTK and never saw this problem again.

 

Starting in 1994-1/2 to 2003 all Magnum engines are computer controlled distributors. When you pull out off the cap-n-rotor and then undo the two bolts, there is only a sensor under there. No matter how much you turn it, nothing changes for the timing. LOL

Prior to 1994, those LA engines could be tweaked that way.

 

In the order of good O2 sensors ...

NTK (NGK) - works well, a slight mpg gain, a little more money though
Delphi - works no problems, mpg alright
ACDelco - (same Delphi product)
Denso - usually pricey
AIRTEX / WELLS - low cost, it works

Never use Bosch on a Magnum engine for O2 sensors.

The ACDelco can be used in both the USA and Canada. Oddly, the Delphi is shown only for the USA. Both are the same manufactured part. Go figure.

 

Thanks again for the input. I assumed that a bad oxygen sensor would show up with a check engine light. I haven't had a check engine light come on in the last few months. When I did have one - the scanner at Autozone gave a misfire code. I don't think it came on during my stated problem, and after it was reset it did not come on again. However, yesterday the problem occurred during driving at lower speeds. So whatever it is might be starting to fail completely. The oxygen sensors may be the problem, I'm going to check on the price for replacing them both. It might take me awhile to accomplish this, but I will report back when I have found, or not found the problem. Much thanks to all.

 

IMO whether the conductors are steel/brass/aluminum is not the issue.
BUT I would clean the cap with alcohol 90% mix and let it dry before starting
The O2 sensors are also probably not the issue and they will throw up a code.
Our 99 chevy had all O2 sensors bad in code but engine still ran without a miss.
The back fire means you received a spark at the wrong time.
I would look at the crankshaft position and the cam position sensors.
These sensors also throw up a code but do not necessarily light the code idiot light.
The losing power under load is normally associated with the fuel system before the injectors. Check the rail pressure when it is losing power to see if there is sufficient pressure/volume. Glowshift gauges has a FI pressure gage cheap, Hokey looking but is accurate.
Yes we do have a 2001 V360 powered A1500 conversion currently with no issues.
Good luck with your van.