Help! '91 L98 Loss of Power

[gw71mgb]

'91 L98 Coupe, Automatic Transmission, 96,000 miles. Owned for 4 years now, has run perfect. Friday night, when I got on the highway, I couldn't get it over 50. Shift indicator light would come on around at around 50, if I tried to accelerate, rpms would shoot way up but still wouldn't go over 50.

Immediately suspected transmission, but then as I thought about it yesterday, I started going through and changing fuel filter, cleaning throttle body, putting in new air filter (all of which were due to be done anyways.) Then this morning I pulled the transmission fluid dipstick, it looked clean, but I *thought* it smelled burnt, although I'm far from an expert on things transmission related.

Any obvious suspects?

Thanks!

-gary

 

[vette079]

Did you reset the TV cable after throttle body cleaning?

Or did this happen before you did the cleaning?

 

[gw71mgb]

No, this happened before I cleaned the TB.

-gary

 

[Hib Halverson]

I didn't realize automatic cars had shift lights. Any chance the trans is stuck in second gear?

 

[vette079]

Checked codes?

 

[gw71mgb]

45 and 46

Two codes come up - 45, Left bank O2 sensor and 46, Pass-Key II. Should have been the first thing I checked.

Is left bank O2 sensor the one in the left exhaust pipe? If so, it's practically new.

But boy, it sure feels like a car stuck in 2nd gear.

-gary

 

[vette079]

Two codes come up - 45, Left bank O2 sensor and 46, Pass-Key II. Should have been the first thing I checked.

Is left bank O2 sensor the one in the left exhaust pipe? If so, it's practically new.

But boy, it sure feels like a car stuck in 2nd gear.

-gary

Well, as far as I know a 91 only has 1 O2-sensor and yes it´s in the left exhaust.
Pass key II should not have anything to do with this.
I should clear them by pulling the ECM fuse from the fuseblock on the pass.side door. (that way you will keep the radio-memory)
Then check to see if they come back.
Who changed the O2-sensor? Did you or a mechanic do it.
The code might have been there before the swap.
The trans staying in 2 doesn´t sound to good, if it is that what it´s doing.

 

[vette079]

TC lockup???

Anyone???

 

[gw71mgb]

New Tranny?

Well, I've continued to be stumped, so I brought it to a guy who was supposed to be our local wizard, and he confirmed that the tranny fluid is definitely burnt. He's suggesting we find a used tranny for it.

My question is: are there any other conditions (other than a shot tranny)that could cause it not to shift AND burn the fluid?

-gary

 

[JimBobC4]

My question is: are there any other conditions (other than a shot tranny)that could cause it not to shift AND burn the fluid?

-gary

Can you be more specific about what the car feels like?

Your car has a 4 speed automatic. You should feel 4 distinct " bumps"
when accelerating.(maybe a bark and a wiggle in 2nd )

Do you feel all 4 ? or just 2 gears and it stops ?

What happens when you put it in low gear and manually shift the tranny ?

If you put it in low gear and nail it from a dead stop and pop the shifter into 2nd what happens ?

Also, I don't recommend a used automatic transmission if its needed. Get a crated GM tranny and be done with it. A used transmission is just throwing away money in my opinion.

If its out of the original car, there is a reason. Maybe it took a hard hit, maybe the engine blew as the guy was dropping it into low gear from 6000 rpms. :W

Unless you knew the car it came from , be wary here, ESPECIALLY with a vette transmission.

 

[gw71mgb]

More

My responses preceded by >


Can you be more specific about what the car feels like?

Your car has a 4 speed automatic. You should feel 4 distinct " bumps"
when accelerating.(maybe a bark and a wiggle in 2nd )

Do you feel all 4 ? or just 2 gears and it stops ?

> It feels like 2 gears and then it stops.

What happens when you put it in low gear and manually shift the tranny ?

> In low gear it doesn't over rev.

If you put it in low gear and nail it from a dead stop and pop the shifter into 2nd what happens ?

> It accelerates fine until about 35 mph, where it tops out.

Also, I don't recommend a used automatic transmission if its needed. Get a crated GM tranny and be done with it. A used transmission is just throwing away money in my opinion.

If its out of the original car, there is a reason. Maybe it took a hard hit, maybe the engine blew as the guy was dropping it into low gear from 6000 rpms. :W

Unless you knew the car it came from , be wary here, ESPECIALLY with a vette transmission.

 

[JimBobC4]

I would take it to a tranny shop like AAmco or whoever and have it diagnosed for free. Most shops do that.

I wouldn't spend any money according to what I read on the internet

Free advice is worth what you pay for it.

However, those symtoms are similar to others I've seen in 700r4 trannys when they are about to die. Maybe low internal pump pressure ?

If the shop says its bad. Take my advice and go for a crated GM transmission. That one part is just too complicated and too hard to remove and replace.

Do it once, do it right. its much better than ripping it out twice.