Motorhome 6.2l class A 4L80E

[stone]

Well oldman old rv old mechanic new to chevy 6.2..This is a Brave 27 ft winnie 1993 I'm owner #2 175,000 miles.The eng.has a larger exhaust the pump set breather is fairly big but not sure if good enough.I had the trany rebuilt and know this to be the third in five years,expect low power and last owner getting older too added to losses but am trying to upgrade all and enjoy this old girl till we both join the 1st owner.I have a snapon mt 2500 scanner and can scope the trany functions and tsp.The engine seem sluggish and low on power and I know its not a charger I drive a cummins powered up some so I don't expect or want that but efficency is my goal.New fuel filter and added some cleaner and felt some improvement and got 11 mpg on trip 900mi.not bad but hope to get some better and the trany has some hard shifts but seems to be more from shift points and sluggish eng.power.and the thing down shifts with a very slight throttle touch.I know this scattered but just trying to give an overview and let you see what it is that I have and maybe give me some ideas on where and how to best approach the improvements and I'm new to site so if I miss some correct input please advice.The other item I am trying to get working is the vaccum the pump is belt drive and located under the alt hard to get to it runs the heater vents and the cruise when it worked which I need to replace too and maybe an electric vaccum pump and electronic cruise don't know.Ok enough I have the 6.2L 1 & 2 and the GM books and winnies books on electric so any ideas on the power the vaccum the cruise....Thanks if you can

[stone]

If I have all the correct things set right what would be the power I should feel on this 14500lb rv?If running at 60 on level and come to a rise it drops to 40-45 in short order and unless down shifts to 2nd it continues to drop but there is no ruff engine but doesn't seem to have any power to hold,after the fuel additive it did improve some enough to notice would this suggest injectors replaced might help?What is the best way to see if the inj pump setting is where it was upgraded to and if it is holding?I don't have any smoke white or black as this is happening that I have seen.I don't want to start adjusting swapping and make random changes,I hope to do some things to improve it and know which do help.If anyone can tell me about the inj pump changes that are done and what to look for on it maybe I can start there,I was told "BUD" had it done, the exhaust was increased,an egt was put in and the air filter was modified.Has anyone got some information I may start with or something I can look into?

[john8662]

14500 lbs is a big load for a 6.2, been there done that. You basically get in practice of leading harder on the accelerator petal before a hill.

I'd be curious what your rig is geared as well, gearing can help towing ability. I'd wager it's a 4.10 gear ratio, hopefully.

To help power you really should invest in a new set of injectors. Anything over 100k miles and the injectors really are not that healthy any more. They physically wear out and need to be replaced to regain everything that the engine originally had.

For the transmission, take specialy care to adjust the TPS (Throttle Position Sensor) that resides on the side of the injection pump. Check to make sure while you're performing this adjustment that your fast idle solenoid isn't always engaged when the engine is up to operating temp. If you adjust the TPS and you have an engine where the fast idle solenoid is always on, your adjustment will be slightly off.

Basically, proper adjustment of the TPS should give you the best shifts (pressure wise) and the right timing. The TPS is adjusted by having the ignition on and using a volt meter to probe the return sense wire. There are three wires, one is a constand 5v, one is a ground, and the other is the sense wire. You will measure the sense wire and get as close as possible to .5v at idle (engine NOT running of course while doing this, just ignition swith on to provide power).

From the past troubles with the transmission I'd look into upgrading the cooling for the transmission. Look into installing a transmission oil temp gauge so you can monitor the temperature. If it's high, then you'll need to find a way to install an aftermarket oil cooler for the transmission itself.

Some of your harshness in shifting (after you've established that the TPS is properly adjusted) could also be from past remans, resulting in the installation of shift kits to increase line pressures.

Cruise, I'm surprised that it's still vacuum in 1993, but this is a G30 chassis most likely. You'll be pretty much reliant on the existing system. Start with the vacuum pump replacement, only after verifying you have no vacuum. This is a high failure item. I still don't know why the entire auto industry created accessories that relied upon vacuum. Ford still does it today not many many of their vehicles, stupid, stupid. Vaccum sucks, literally.

Hope this helps...

J

[stone]

Thanks J, I am sure the Vaccum pump is bad it has zero suck on the line from it.I am going to get new injectors it seems I hear that is about the miles they get bad.This is a P-30 chassis with 5.13 gear ratio listed in the equipt option sheet it has four wheel disc brakes and 19.5 rims. it does have an added trans cooler and using the snap on scanner the temp is doing pretty good but I do believe the tsp is not doing well it is new but the adjustment seems touchy.The idle stop solenoid add system is not doing right I am trying to test the heat sensor that they get power from but part of it is mechanical the solenoid is worn the spring is broken that holds it up but they are 175.00 unless I find a used good one somewhere.I hope the tps adjustment in the shop manual will answer the fine issues with the new updated trany 4l80e it probably does have different pressures and valve movements,I don't mind the robust shifts as much as the too fast down shift before fuel increase has a chance.I will do the tps adjustments first and the injectors. towing is not as needed as just power to pull itself and hold a fair cruise,the 14500 is the braves GVW.So far I like this older MH and the 6.2 should offer the best shot for economy and dependability if not pushed.

[john8662]

.The idle stop solenoid add system is not doing right I am trying to test the heat sensor that they get power from but part of it is mechanical the solenoid is worn the spring is broken that holds it up but they are 175.00 unless I find a used good one somewhere.

There isn't a spring associated with the fast idle solenoid. The only spring on the injection pump is on the throttle arm that attaches to the injection pump bracket the holds the physical accelerator cable.

My only caution about the fast idle solenoid is that you don't want to make your adjustments on the TPS setting for idle, only to have the fast idle solenoid engaged all the time throwing off your TPS readings when actually driving. You want the system to work as designed, fast idle only when cold, turning off after around 5 minutes or less of running. If the fast idle and associated switch aren't been engaged, you only have no issues with the TPS, just harder starting.


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I hope the tps adjustment in the shop manual will answer the fine issues with the new updated trany 4l80e it probably does have different pressures and valve movements,I don't mind the robust shifts as much as the too fast down shift before fuel increase has a chance.I will do the tps adjustments first and the injectors.

You'll be pleased with the outcome when you do.

[stone]

thanks again, I thought there was a spring on the shaft that held it up when not energized like several on gas units.As far as I can tell it has no voltage applied even when cold so that problem is one the only time it has caused any trouble is if cruising at a speed it does seem to mechanically hang on the pump lever and keep the unit from dropping back to idleI can stop this by physically moving it for any tps adjustments.Any ideas or suggestions you or anyone else still up on the 6.2 would help as I said I am an old mech and did work on diesels but not a 6.2 or many auto style,not very nimble anymore but still got grease in the blood and enjoy when the thing works right nothing feels like making an old engine make music and nothing makes an old mech feel better.Smooth soft and solid that what I always thought was the best it could be.Enough old garb As I go through the fixing it will be great to have some other input.