cowboysmoke

1994 12 valve dodge automatic...
When i am driving down the road at freeway speeds the engine (reading it at the tach) surges about 200 rpm and then drops back down to normal. I pulled the obd 1 codes and it says battery voltage is too low but the batteries seem to be fine. Im not sure when they were replaced but there do not seem to be any starting problems related to the batteries being low. It has a brand new alternator so i am reasonably sure that is not the problem. Thanks in advance.

Nsomniac05

I am not too savvy with 1st gens in particular, but heres some food for thought that will hopefully help with troubleshooting. Unless there is something about your setup that is different from other mechanically injected diesels, or fundamentally different from diesels in general, The only component that depends on your battery that would affect your motor, is if you have an electric fuel pump supplying fuel to the injection pump.

BC847

That'd be a 2nd Gen.

cowboysmoke

I know its a second gen...just tryin to figure out whats wrong with it...

Nsomniac05

I think he was speaking of when I referred to it as a 1st gen. I saw the year, I don't know why but I think It was your signature and the power of suggestion that made me think it was a 1st gen. that being said, It is still the same concept except the VP44 may have some electronics on it.

kthiemann

Have you checked your fuel filter and the filter screen at the fuel heater?

DieselLady

Are you sure it's the engine and not the trans going in and out of Lock up?

torquefan

That was my thought. It's a common symptom of the TP sensor starting to fail. Could also be a bad connection, misadjusted brake light switch, binding throttle linkage, or internal transmission problem.

cowboysmoke

It does seem like the lock up is engaging and then disengaging...we changed the alternator, replaced the cross over battery cable, cleaned all the grounds, and cleaned any other connections that we found. One thing that puzzles me is that the batteries test as good and the alternator is new but it only shows around 11-12 volts at the guage when the truck is running.