Brian71583
Newbie
1996 454 4L80 Crew Dually
I've been working through some issues since I got this thing a year ago and have been making good progress but there is a nagging intermittent issue and also a new issue that I feel might just be related but don't know how to approach in diagnosing or confirming anything with it.
Background: Trans is a rebuild with maybe 2,000 miles on it. A friend who knows Transmissions inside/out and rebuilds them as pretty much a full time side job did it. Truck was bought and has great bones but whoever owned it prior was def not a mechanic or had severely debilitating attention deficits. Lots of repairs done but parts were all from a similar vehicle but not perfect (like wrong year, or options) Most repairs were put back together and either NOT tightened or POORLY tightened.
Nagging issue:
Transmission would seem to not have one of its upper gears. Not really sure if it was 4th, OD, Lockup or what exactly but it would not have its upper range. It would tach 3,000 just to hit 60mph. Any grade in the road or mph over 60 would climb the rpm's. This was intermittent. Half (Or more) trips would be perfectly fine and tach 2,700-2,800 doing 65-70mph. I had originally thought bad knock sensor wiring I had was disabling lockup.
I recently replaced both knock sensors and the whole wiring circuit and took it out for a ride and now have a clearer picture that there's a problem with the transmission or wiring but the picture is still very cloudy.
New Issue:
I took the truck out for its test ride after the knock repairs and it ran great around town. Smooth and best MPG its ever gotten. Had minimal knock count on the scanner which I attribute to a small exhaust leak it has. I took it for a quick loop on the highway and quickly realized that the missing top end of the transmission range was present again. I was on a highway so I had to continue but didn't want to abuse the truck so I kept it in the 55-60mph range but that still sustained 3,000 rpms for about 4 or 5 miles until I could exit. At the exit I pulled into a parking lot to take some scanner readings.
Upon leaving my parking spot I had a loud sound that sound like a dry power steering pump but from either midship or possibly the rear. Def. was not the steering. I left the lot, pulled back onto the highway I had to take home and still heard this noise so on the ramp I pulled off and tried to check more (scanner and physically) but could not find anything. So I continued to home. Noise was consistent and related to speed/load and NOT engine rpm. Noise seems to be there but quiet off the line but really overpowers engine/road noise once you break the 30mph range. It is worse and louder on deceleration. Once it starts it varies in intensity with speed/load but it is constant when in motion.
That was Friday night. Sunday I took it for another ride for 3 stops I needed to make around town. First two stops where uneventful running great. leaving 3rd stop the noise was present again. This whole round trip was maybe 10 miles max. No extended highway speeds were achieved on this trip but short sections hit highway speed and I do not believe the transmission had its upper range again.
The noise sounds exactly like a dry power steering pump. Even down to the binding like resonation/hum/vibration
I had read some about solenoids and the wiring and such. I know some of the wiring to the round plug on the trans is very sloppy but all looks to be in tact.
In the prior nagging version of the story I think I remember the noise once over the past year but it was once so I never attributed it to the transmission problem. I assumed it was the P/S and it never happened again. But when nagging I would have the problem of missing whatever top gear it wasn't getting pretty often. After fixing a few various issues around the truck it seemed to go away for quite a while so I thought something had fixed it.
This return (and much more frequent/repeatable) has happened since fixing the knock sensors which have wiring in close proximity to the transmission harness, combine that with me already saying how sloppy it is and I would like to think its an electrical issue but I have ZERO clue what to test or how so I am hoping there's some 4L80e guru around here that could give me some insight or direct me what to test.
I've been working through some issues since I got this thing a year ago and have been making good progress but there is a nagging intermittent issue and also a new issue that I feel might just be related but don't know how to approach in diagnosing or confirming anything with it.
Background: Trans is a rebuild with maybe 2,000 miles on it. A friend who knows Transmissions inside/out and rebuilds them as pretty much a full time side job did it. Truck was bought and has great bones but whoever owned it prior was def not a mechanic or had severely debilitating attention deficits. Lots of repairs done but parts were all from a similar vehicle but not perfect (like wrong year, or options) Most repairs were put back together and either NOT tightened or POORLY tightened.
Nagging issue:
Transmission would seem to not have one of its upper gears. Not really sure if it was 4th, OD, Lockup or what exactly but it would not have its upper range. It would tach 3,000 just to hit 60mph. Any grade in the road or mph over 60 would climb the rpm's. This was intermittent. Half (Or more) trips would be perfectly fine and tach 2,700-2,800 doing 65-70mph. I had originally thought bad knock sensor wiring I had was disabling lockup.
I recently replaced both knock sensors and the whole wiring circuit and took it out for a ride and now have a clearer picture that there's a problem with the transmission or wiring but the picture is still very cloudy.
New Issue:
I took the truck out for its test ride after the knock repairs and it ran great around town. Smooth and best MPG its ever gotten. Had minimal knock count on the scanner which I attribute to a small exhaust leak it has. I took it for a quick loop on the highway and quickly realized that the missing top end of the transmission range was present again. I was on a highway so I had to continue but didn't want to abuse the truck so I kept it in the 55-60mph range but that still sustained 3,000 rpms for about 4 or 5 miles until I could exit. At the exit I pulled into a parking lot to take some scanner readings.
Upon leaving my parking spot I had a loud sound that sound like a dry power steering pump but from either midship or possibly the rear. Def. was not the steering. I left the lot, pulled back onto the highway I had to take home and still heard this noise so on the ramp I pulled off and tried to check more (scanner and physically) but could not find anything. So I continued to home. Noise was consistent and related to speed/load and NOT engine rpm. Noise seems to be there but quiet off the line but really overpowers engine/road noise once you break the 30mph range. It is worse and louder on deceleration. Once it starts it varies in intensity with speed/load but it is constant when in motion.
That was Friday night. Sunday I took it for another ride for 3 stops I needed to make around town. First two stops where uneventful running great. leaving 3rd stop the noise was present again. This whole round trip was maybe 10 miles max. No extended highway speeds were achieved on this trip but short sections hit highway speed and I do not believe the transmission had its upper range again.
The noise sounds exactly like a dry power steering pump. Even down to the binding like resonation/hum/vibration
I had read some about solenoids and the wiring and such. I know some of the wiring to the round plug on the trans is very sloppy but all looks to be in tact.
In the prior nagging version of the story I think I remember the noise once over the past year but it was once so I never attributed it to the transmission problem. I assumed it was the P/S and it never happened again. But when nagging I would have the problem of missing whatever top gear it wasn't getting pretty often. After fixing a few various issues around the truck it seemed to go away for quite a while so I thought something had fixed it.
This return (and much more frequent/repeatable) has happened since fixing the knock sensors which have wiring in close proximity to the transmission harness, combine that with me already saying how sloppy it is and I would like to think its an electrical issue but I have ZERO clue what to test or how so I am hoping there's some 4L80e guru around here that could give me some insight or direct me what to test.
