Solved, I believe?
I got down to a possibility which suggested the knock sensor was
defective. If so, the timing would be changed at different times. I
disconnected the knock sensor and the surging disappeared. I haven't
purchased a replacement yet since they are $50 at AutoZone. I also
have no error codes with it disconnected and the car runs super. Gas
mileage has gone up about 2 miles per gallon but this may be due to
other factors as summer time.
I really discovered this answer because I had the cat converter top
cover come loose and rattle at times. I believe the rattle would make
the knock sensor believe it was hearing a ping from the engine and the
sensor would retard the spark. Once I removed the cover, the surging
which had been really bad became less worse. I then asked myself what
would be a relationship between the rattle and surging. The knock
sensor became a possible answer.
Took a hell of a long time to solve this.
p/s, I don't want to hear reply's about the damage to the engine with
the knock sensor disconnected. If you have substantial proof say so
and let's see the testing results.
Dan, And have a good 4th of July
To cut a long story short.
The road master would tow a horse trailer weighing 1650 lbs
and 1 horse of about 1200 lbs without problems. The transmission
shifting issue became apparent when the second horse (another 1200 lbs
was added). The tranmsiison began to growl (my daughters words) when
going up hills.
I ordered and installed another knock sensor and the wagon
runs great, Transports both horses for 1/2 hour or so to shows and no
odd sounds, gets about 14 miles to a gallon when towing. This is what
the road master is used for. We always have all the horsy stuff in
I guess my message is "change the knock sensor if you are
having surging problems" and you have tried the many other things. Or
just disconnect it for a test run. As a caution, the sensor is
inserted into the water jacket and if removed will drain almost all
the antifreeze before you realize it. I took the opportunity to
change both radiator hoses, the antifreeze, and thermostat, also one
My MPG on 600 mile trips without horses is about 19/20 mpg.
P/s roar master has about 176,000 miles on it.
Which I could find an economical electric radiator fan as a
replacement for the existing belt driven fan. The mechanical fan
noise is a little much as I get older and low frequencies are more
prominent in my hearing range. Anyone have one they would like to get
Hope this info helps someone, Have a good rest of the summer. Dan
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