1994 454 TBI runs rough, misfires, backfires, dark exhaust

[Rickf1985]

RTV would not be my first choice there, I prefer to use Permatex #3 aviation cement on all paper type gaskets. It is a semi-liguid and can be put on nice and thin. When you do get a new gasket then this stuff will wipe off with carb cleaner. Sparky, why do you say no sealer? I have been using it for 45 years. I use it on all paper and fiber gaskets and also on all hoses. It prevents corrosion on the fittings for the hoses and acts as a lubricant as well as a sealer for getting the hoses on and off without damaging soft copper fittings on heater cores. Will not damage O2 sensors as long as you use common sense putting it on and use a very thin layer. Also this sealer does not harden so it is not a bear to get things apart again when needed.

RTV is a gasket maker and not a sealer to add to a gasket. It will generally cause a gasket to slide out of place.

[bluebird]

Have to make sure any sealer used is sensor safe. Some sealers on the market will mess up some of the sensors.

[kennyrodgers]

Thanks again guys,
I'll look into some sensor safe sealant and re do it.
Any views on the water pump ??

[Rickf1985]

Stock pump should be fine. You can actually move water through the system too fast and it does not have time to draw off the heat.

[kennyrodgers]

Cheers Rick.
I took the back plate of this morning and they both have eight vanes. The old ones are bigger than the new ones though. Hey ho, fitted the thing anyway lol.
All done from the doghouse except for one bolt at the bottom of the PS bracket,  being 5'7" has it's advantages sometimes. Just the alternator to refit tomorrow then bar any leaks etc we'll be back at the high idle.
Thanks again Buddy.

[bluebird]

Make sure you haven't bent the throttle bracket, laying on the engine while working on it. Don't ask how I came up with that answer.

[kennyrodgers]

Will do Bluebird, thanks.
PS, love your rig btw. I might have to do the bottom half of mine white, it really sets it off.

[bluebird]

Will do Bluebird, thanks.
PS, love your rig btw. I might have to do the bottom half of mine white, it really sets it off.

Thank you, I like it a lot too. Looked quite a while for a replacement for the Challenger, I knew this was the one for me as soon as I seen it. It needs a bit more TLC than I wanted but I got it for a real good price. I'll still be in it for a very good price when I get it done the way I want it. It's a good runner, we drove it back home 350 miles the day I bought it pulling a S10 on a 18 ft trailer. Running 65 70 mph she got right at 9 mpg, pretty happy with that. 

[kennyrodgers]

If i get the same mileage Bluebird I'll be a happy camper. Our imperial gallon is 10% more so hoping to get 10 -12.


Well we're very nearly at road test time.....
Got a pair of 225's for the front fitted today and picked the best 4 for the rear. I'm only doing shakedown runs over the next few weeks so nothing over 40 for the time being.
She's still running very rich for some reason but she starts and idles fine. Re the high idle...... I noticed that the throttle was hanging ever so slightly on the throttle kicker. I adjusted that today and it's a lot better so maybe you were right Rick when you said the PO could have adjusted something. I can easily see how someone could mistake the kicker for an idle adjuster,


Anyway, just the new o2 sensor to fit tomorrow then we'll see how she goes. I'm hoping a run out will sort out the rich problem as the ecu relearns it's thang.
PS, new Firestone  4100 airbags en route from summit, not looking forward to that job at all,

[kennyrodgers]

It seems we now have another problem........The tranny, a 4L80E is not shifting into 3rd. Does it ever end.
I took the coach out for a quick blast tonight and now that the engine is running something like I managed to get up to 30 / 35 mph. I'm getting 1st and 2nd fine but no 3rd. After about 3 miles I decided to turn back.
I'm wondering as the coach sat for 7 years if something could be stuck, maybe a solenoid or valve for example. I've absolutely no clue when it comes to transmissions and wouldn't know where to start.
I have good fluid level and it's a nice colour. Would a change of fluid and a filter be a good place to start. There's 43000 miles on the coach.
Cheers.

[legomybago]

Make sure your clutch fan isn't just stuck making a lot roaring under the hood.
I'm curious what the O2 sensor replacement did for your running rich symptoms?

[Rickf1985]

Considering it is an electronic transmission you have to determine if it is a computer operated issue or a mechanical issue. I am assuming you have no codes? Have you fun a code reader on it yet? If no codes then it could be a stuck governor. It could also be a bad speed sensor but that should set a code. Be aware that these codes may NOT show a check engine light on this unit depending on how it has been rigged by the coach manufacturer. Technically the engine/transmission are both tied into the OBDII computer.

[legomybago]

The rig is a 1994 Rick, no OB2 I'm sure. You probably have to cross two wires, shake a stick, and talk dirty to it upside down to retrieve any codes. I don't think it would shift into 2nd with a bad governor. It's hard to believe how much stuff can go wrong on these RV's just from setting. Goes to show, drive um as much as you can.

[SLEETH]

need pic of ald connector= all 4l80e have a ecm=obd2
should not be obd1 if so=that means it would have a stand alone controller= and I have  never seen that but in aftermarket only

[kennyrodgers]

Hi Guys,
appreciate the replies.
Firstly the o2.
I've was swinging on the damn thing today for a good hour and couldn't get it out, i mean it's in there. I'm pretty sure that it's the original one from 94.  I wire brushed it and used copious amounts penetrating spray, big hammer, long bar, you name it.   I was tempted to cut the tail of and put my impact hammer on it but held off. My buddy is coming over on Monday and he has the correct deep socket with a hole for the wire. If that doesn't shift then it's over to Mr Dewalt.


Re the tranny,
I'm pretty sure my coach is OBD1 and all I'm getting up to now is a code 12 so nothing showing up fault code wise.  1st to 2nd is a nice firm shift then nothing.  I've spent the evening doing my research and I think a fluid and filter change will be first on the list and now that I've found out how the solenoids work I can check those whilst I'm in there.
The plan is to get the o2 sensor done Monday morning then hit some decent roads then we can get the speed up and see if that does anything. I'm in a pretty rural location hence the not managing to get much over 30 this afternoon. 


I've found this as well. I'm pretty confident I could rig this up to try and force the shifts without the computer.
http://www.atraonline.com/manuals/general/tetdv/tetdv-c3i.htm


Thanks again guys, your comments and suggestions are helping more than you know.
Cheers.

[cncsparky]

The 4L80E first out 1991, I believe.  Most likely OBD1.  Diesel trucks in early years had a stand alone controller for the 4L80E. Early GM implementations of OBD2 started around 1994, but heavy duty vehicles probably much later. 

[cncsparky]

Sparky, why do you say no sealer? I have been using it for 45 years. I use it on all paper and fiber gaskets and also on all hoses.

I was referring to Kenny in post #48, he wanted to use RTV on a TBI base gasket.  I would never use RTV there, gas breaks it down. 

[kennyrodgers]

Hi Sleeth,
I'll get a pic of the connector up tomorrow so we can check which one it is.
Cheers.

[bluebird]

need pic of ald connector= all 4l80e have a ecm=obd2
should not be obd1 if so=that means it would have a stand alone controller= and I have  never seen that but in aftermarket only

That's not correct. They were obd 1 until mid 96 or later. My buddy has a 96 Storm that has a obd2 port but is in fact a obd1 system. They were still ecm controlled. If it were a speed sensor it would throw a light, but would reset with key off automatically.


There are 2 speed sensors on the trans, one on the tail housing and one right behind the bell housing on the drivers side. Unplug them and plug them back in, and make sure the ground cable going from the left rear of the block to the frame is good and clean. Does the speedo jump around or erratic ? The speed sensors are actually ac generators that work off of reluctor wheels. The currant is then feed to the vss module where it is changed to DC and goes to the ecm and the speedo. The ecm does all the control for the trans. You really do need a scan tool to know what is going on. Be careful using those jumper wires. I would be trying the grounds deal before any thing else. The vss module is under the dash and is a yellow box. You may try reseating the plug in that too.

[SLEETH]

These transmissions have issues with early style 12 pin harnesses in which transmission fluid leaks around the harness and shorts the pinouts causing transmission to go into "limp mode" This issue can be easily rectified by simply cleaning the plug

[Froggy1936]

It is a OBD1 for sure OBD2 started in 96 My 95 is OBD1 Since you were working on TBI .The Throttle position switch is part of shifting program also distributor (for rpm) The two plugs on the left side of trans case are for shifting control also The plug on the tail shaft is for Vss and speedometer All are used for shifting controls  As are the solenoids and internal wireing  The large connector on the L/S of the case is also involved But I would start at the throttle switch because you were there ! If the fluid is clean that would be the last suspect ! Frank

[kennyrodgers]

Hi Guys,
From the replies do far...
We had bad earths all over the place when we were getting her ready for the annual test and I'm pretty sure we did the one on the block near the bell housing. I will re check it though, also,  the speedo is also nice and steady.
It wouldn't surprise me in the least though if it is a bad connection somewhere as we still have quite a few electrical issues to sort out.  That's what we're hoping anyway.
From what research I've done if the tranny goes into limp mode you get Park, Neutral Reverse and 2nd. We're  definitely getting 1st then and up shift to 2nd.
Frank, could you tell me how we can troubleshoot the TPS to see if it's connected with the issue.


I can't think of anything else at the moment guys......

[SLEETH]

if the  tps was out of perimeter it usually sets a code

[bluebird]

There are many codes the get erased with the key cycle on OBD l, so you have to check it before you turn off the key. I don't have my books on the OBD l system anymore or I'd look it up. I gave them to my buddy after I sold my Challenger.

[Rickf1985]

Unplug the electrical plugs on the transmission and plug them back in a couple of times to make sure there is good contact. Try the easy cheap things first.