Mechanics

CAR HAS NO POWER UP HILLS, BUT GOES DO

1992 Pontiac Sunbird

Engine Performance problem
1992 Pontiac Sunbird 4 cyl Front Wheel Drive Automatic 122000 miles

I just got this Sunbird from a buddy. I bought it knowing it needed a cylinder head, which I did and the car is back together and running.

i went to take it on it's first drive in probably a year at the least, and the car has very little power. It barely makes it up hills, and then on the way down a hill it will wind out just like it should and shifts just fine. Soon as there is another hill I lose power again and no amount of pumping the accelerator makes anything different whatsoever.

The timing is within a tooth, so I know it's not that. The transmission fluid is at the full line as it should be.

Essentially, I have no power under load, especially when trying ANY kind of hill (even small ones)

Any ideas?
Avatar
RyanVee
April 26, 2010.



Hi RyanVee. Welcome to the forum. One tooth off on the timing belt WILL definitely cause this problem. It must be exactly correct.

If you were just generalizing, and the belt really is right on the money, suspect a partially plugged catalytic converter. Also look at the exhaust manifold after a test drive or after the engine has been idling for a while. If it's glowing orange, the ignition timing is retarded. That will cause the fuel to start burning long after the pistons have passed top dead center, and it will finish burning in the exhaust system. It doesn't produce any power there.

Caradiodoc

Caradiodoc
Apr 26, 2010.
Any way to really narrow it down? I'm doing the work myself, so I hate to just throw parts at it without much of an idea as to why.

I don't know when the last time the car was " in service" but this was not one of the problems it was having then. The gas in the tank was probably a mix of both 1 year old, and god-knows-how-old gas as well, so I don't think it was real high octane anymore. Probably varnish.

The next thing I " want" to try is the fuel filter (thinking maybe I'm not getting fuel pressure because of a blocked rusty filter), but other than I I'm not sure. My buddy who ran much of the gas out of the vehicle (both by siphon and by running it) said the " Service Engine Soon" light is now on. Not sure what that is supposed to mean.

I will also take off the timing cover (I did one of those insanely stupid " Previous Owner" modifications to the timing cover so I could remove it with the car still in running condition) and check the timing marks. Near as I can tell, the notch on the cam sprocket lines up with the backing plate " arrow" and the " keyway" on the crank pully should line up with it's respective arrow on the backing plate. If that is incorrect then that is my problem because that is how I assembled it.

Thanks.

Tiny
RyanVee
Apr 26, 2010.
Ok, the first piece of dandy news is the Check Engine light. That means the Engine Computer has detected a problem and has set a diagnostic fault code in memory. Auto Zone, and probably some other parts stores can read those codes for you. There is a way you can do it yourself by watching the light flash two-digit codes. I can tell you how to do that, but I only have service manuals to tell what the numbers mean for Chrysler products. Having someone else read them will give you the actual description rather than just a number.

The codes will indicate the circuit or system with the problem, not necessarily the defective part. That will be a perfect starting point.

I doubt the fuel filter will help but I'm basing my opinion on previous Chrysler experience. The largest volume of fuel flows during coasting. The largest percentage of that fuel just circulates back to the tank, but it has to go through the filter. The lowest volume flows through the filter when the engine needs it the most, during acceleration. I know that sounds backwards, but a partially plugged filter will first cause stalling problems when you begin coasting from highway speeds.

Ignition timing didn't magically change from sitting for a long time, but changing the timing belt could result in retarded timing if a sprocket is retarded by one tooth. Besides rechecking the belt, have the fault code(s) read and we'll go from there.

Caradiodoc

Caradiodoc
Apr 26, 2010.
Turns out I did have the timing off. I aligned it to the " keyway" when it should have been aligned to 10 degrees BTDC. I changed it and am now driving it every day just fine. Thanks!

Tiny
RyanVee
May 3, 2010.
Wonderful news. I needed some of that today! Come back and see me again.

Caradiodoc

Caradiodoc
May 3, 2010.