89 GMarq Power Plummets on Summit

[shebe]

Hi... My '89 runs fine around town, but when I try
to climb a hill the car struggles. At best, after dropping
into OD I can do around 50 or 60. I also try to avoid
putting the *petal to the metal* because it causes
substantial smoke. (leaky oil pan and valve cover gaskets.)
(I try not to run the AC when freeway driving, but when
I do the engine seems to have a bit of what I'd describe
as a surge to it.)

The car has about 93,000 on it, with a rebuilt tranny. The
car doesn't really seem to burn oil though the puddle under
the car is noticeable. It had a tuneup (plugs and wires
changed ect.) about 13,000 miles ago and before my last
trip I had the fuel injectors cleaned, along with an oil change.

Other then the obvious, *stop driving up hills,* which isn't
too fesible. I need to know if it's worth putting *more money
into the car? (I would like to keep her at least another year
or so.) I've already spent what the car is worth by rebuilding
the tranny and I was quoted 450 to 500 on the oil pan gasket
and 250 to 300 on the valve cover gaskets, but then these
won't address the *power* problem.

So... Is this just *age* or can it be fixed or improved? Any
suggest or insights will be greatly appreciated. Do you
believe it's better to keep a car you know vs buying a
newer used car you don't?


Well, thanks ever so for your assistance, Sheila


BTW - I don't mind spending the money too fix the situation,
but as a female, I just hate getting *ripped off.*

[fredjacksonsan]

Couple things come to mind.

When the plugs were changed, did you get a new distributor cap and rotor also?

Air filter. When was it last changed?

On the 5.0 motor, sometimes you will get a carbon buildup in the intake which could be contributing.

I wouldn't rule out a partial clog in the catalytic converter; when the engine is idling, put your hand over the exhaust; does it seem that a lot of air is coming out, or not? If you put your hand ON the exhaust, is there a large pressure buildup? If not, you may have a restriction in there somewhere.

Hope those help, if you could give a little more description about the surge/loss of power it would help.

[shebe]

<When the plugs were changed, did you get a new distributor cap and rotor also?

Yes

<Air filter. When was it last changed?

About 3000 miles ago.

<On the 5.0 motor, sometimes you will get a carbon buildup in the intake which could be contributing.

I ran a finger into the tail pipe and it was came back covered in black soot.

<I wouldn't rule out a partial clog in the catalytic converter; when the engine is idling, put your hand over the exhaust; does it seem that a lot of air is coming out, or not?

Yes, a lot of air.

<If you put your hand ON the exhaust, is there a large pressure buildup? If not, you may have a restriction in there somewhere.

I'm not exactly sure what you meant by pressure build up, but when I pressed my palm over the opening the idle dropped significantly.

<Hope those help, if you could give a little more description about the surge/loss of power it would help.

When I was driving from Vegas to Los Angeles the car was doing 70 using cruise control with no problem. Then I hit the first incline and the speed dropped to 50 or so. I kicked off CC and dropped it into OD. As I stated before I try to avoid pressing the pedal to the floor instead I just ease it down. I could sustain 55-60 mph, (it gives ya the feeling being a turtle - slow and easy wins the race).

Once I'm over the hill (figuratively) I put it back into Drive, an all is fine until the next climb. (I only have idiot lights. so I don't have a clue about temp etc.)

The surge is more like the engine racing (sorry!) When I'm on the freeway and turn on the AC it feels like it's pulling hard and then the engine tries to compensate.

Well, I hope this makes sense and helps with the diagnosis. I really appreciate your help.

Thanks, S

[fredjacksonsan]

Originally Posted by shebe

<On the 5.0 motor, sometimes you will get a carbon buildup in the intake which could be contributing.

I ran a finger into the tail pipe and it was came back covered in black soot.

<Hope those help, if you could give a little more description about the surge/loss of power it would help.

When I was driving from Vegas to Los Angeles the car was doing 70 using cruise control with no problem. Then I hit the first incline and the speed dropped to 50 or so. I kicked off CC and dropped it into OD. As I stated before I try to avoid pressing the pedal to the floor instead I just ease it down. I could sustain 55-60 mph, (it gives ya the feeling being a turtle - slow and easy wins the race).

Once I'm over the hill (figuratively) I put it back into Drive, an all is fine until the next climb. (I only have idiot lights. so I don't have a clue about temp etc.)

The surge is more like the engine racing (sorry!) When I'm on the freeway and turn on the AC it feels like it's pulling hard and then the engine tries to compensate.

Well, I hope this makes sense and helps with the diagnosis. I really appreciate your help.

Thanks, S

You're more than welcome. The thing that puzzles me is that you say "I drop it into OD". If you're on the highway, aren't you in OD already? You've got the setup where you have it in "D", and a button on the end of the shift lever to turn OD off, right? When it surges, is the engine running faster? Then it's probably shifting down to Drive from OD when you're going up a hill, which is normal if it's any grade at all.

On my old MGM (86) I would have to give it some gas and speed up prior to a big hill, so you may have to do the same. You said the car does fine around town, right?

Does the transmission seem to work ok at all other times?

And the soot in the tail pipe...is it a large buildup or just a sort of greasy grime? Is it really really oily/gassy? What is the mpg that you're getting?


I'm not sure why you're losing power; it could be a lot of things, including just age. Everything on your car is 16 years old. Your odometer may say 92000 but it may actually be 192000(unless digital).

[shebe]

Originally Posted by fredjacksonsan

You're more than welcome. The thing that puzzles me is that you say "I drop it into OD". If you're on the highway, aren't you in OD already? You've got the setup where you have it in "D", and a button on the end of the shift lever to turn OD off, right? When it surges, is the engine running faster? Then it's probably shifting down to Drive from OD when you're going up a hill, which is normal if it's any grade at all.

On my old MGM (86) I would have to give it some gas and speed up prior to a big hill, so you may have to do the same. You said the car does fine around town, right?

Does the transmission seem to work ok at all other times?

And the soot in the tail pipe...is it a large buildup or just a sort of greasy grime? Is it really really oily/gassy? What is the mpg that you're getting?


I'm not sure why you're losing power; it could be a lot of things, including just age. Everything on your car is 16 years old. Your odometer may say 92000 but it may actually be 192000(unless digital).

Okay, can I just *Oops*

I do not have OD what I meant too say was I would drop the gear down manually. I'm sure the transmission would shift if I gunned it, but like I've mentioned ad-naseum, I hate pressing down hard on the pedal because I smoke everyone behind me.

The car is great around town and the rebuilt tranny only has about 600 miles on it, but it seems fine. (The power problem has been around for a while, but only when climbing.)

As for the soot, it's just a dry, black soot. The gas mileage for the last freeway trip was about 18mpg. (I made it from Vegas to near Angeles (261 miles) and still have a quarter tank left.)

The person I got the car from was a (old) family friend, so I don't think the odometer is off.

I'll be heading back to Vegas and I'd like to have a mechanic look at it before I drive it again. What would you suggest I have him/her check out? In other words, what would you do?

Thanks once again, S

[fredjacksonsan]

If I were to have someone look at it, I would first tell them what the problem was, and go on them while they took a test drive. Find a suitable hill so that they can reproduce the problem.