Q: Idles fine in park But won't rev above 2,000 rpm and won't go over 30 mph. 1988 Pontiac Grand Prix

asked by on March 12, 2017

Idles fine in park but won't go over 2k rpms. At 2k sputters bad. In drive won't go over 30mph & if rpms get to 2k sputters loses power badly. Replaced, IAC,tps, plugs, wires, throttle body, catalytic converter, ignition module, coil packs, fuel pump,filter. It's like it's in limp mode. Any help will be appreciated. My car has 140230 miles. My car has an automatic transmission.

My car has 140988 miles.
My car has an automatic transmission.

Hello. This can be caused by a number of things. I usually start by doing a compression test on the engine first. If the compression is low then the engine may be worn or it may need a timing chain. If the compression is fine then I test the fuel pressure and the catalytic converter. Low fuel pressure or a clog in the converter will both cause this. There are a number of other things that can cause this also. If you are thinking of having this looked at, consider YourMechanic, as a certified mechanic can come to to to diagnose why the car has no power and misfires.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

I have a dead short and need to know what to fix.
If you feel certain the problem is related to your repair, relay this information to the mechanic. This will give him a starting point in what can be a difficult and time consuming diagnosis. It is possible the wrong part...
Check Oil Light coming on.
Hello. You are correct that the light can come on for these reasons. If the oil light comes on and there is no engine noise then it is more than likely the oil pressure sensor that needs to be replaced....
Green key light flashing, car wont start.
Hello, from what you describe it would appear to me that you may be having an issue with your vehicle's transponder and key. The green key light that is flashing is actually not related to AC at all, it is...
Valve body replacement
It sounds like you might have an issue with the valve body that you got from the junk yard. It is usually not advisable to pick up internal transmission parts from a salvage yard as their condition is unknown until...
Vauxhall insignia se nav 2.0 cdti - interference or non interference engine
Hi there. Yes the engine is an interference design. This means that if the timing belt breaks the pistons will contact the valve train when not in time. If the belt has broken, I recommend testing the cylinder head and...
Battery the car runs fine when jumped if I shut it off and try to turn it back on it will not start unless jumped
During the most recent episode when the car yet again failed to start, the diagnostic would begin with testing of the battery. If you have a fully functioning charging system (you mention the alternator is new but charging system should...
Rough idle and shakes at stops
What you are describing sounds like a dirty or failing idle air control valve. The idle air control valve (https://www.yourmechanic.com/services/idle-control-valve-replacement) monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds...
Clutch is squeaking after 30 mins of driving, when pressed down or released
It may simply be that the pedal needs lubrication. If you can squeeze up under the dashboard with a can of WD 40 you may be able to sort this out yourself. If not, you can contact Your Mechanic to...
I was to my number 3 coil is misfiring should I change all coil or just that one
Hi Virginia. Thanks for contacting us today. It's always best to first correctly diagnose the source of the misfire before replacing any components. It is possible that the coil pack is faulty, in which it is best practices to replace...

Related articles

Is it Safe to Drive With a Misfiring Cylinder?
An engine misfire can be caused by bad spark plugs or imbalanced air/fuel mixture. Driving with a misfire isn't safe and can damage your engine.
Symptoms of a Bad or Failing Fuel Pump
Common signs include a whining noise, hard starting, engine performance issues, and an inability to start the car.
Symptoms of a Bad or Failing Ignition Coil
Common signs include the Check Engine Light coming on, engine misfiring, rough idle, a reduction in power, and the car not starting.