Question about 1995 Pontiac Bonneville

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Car stumbles driving uphill

Replaced gas tank, fuel pump, catalytic convertor, muffler, an ignition coil died, so one was replaced but the module had to be replaced as well, intake manifold gaskets replaced and oxygen sensor was the most recent. There are no issues driving short distances, but when driving say 60 miles and then driving back some point in the drive the engine light goes on and a loss of power occurs. there seems to be a dead spot in the pedal if you press it to floor u can get power, turn off engine turn back on light goes off and car runs fine. last few long drives no check engine light but stutters (kinda like the car is coughing) going up inclines and a few take offs. Any suggestion of what is happening or what to look at next?

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  • melissa Dec 14, 2012

    i do not have the symptoms of a faulty ecu



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  • 20 Answers

Try a new ECU !

Posted on Dec 11, 2012


6 Suggested Answers

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SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

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Posted on Jan 02, 2017

  • 320 Answers

SOURCE: Car not running on all cylinders

the first thing that comes to mind is ignition system faults. Are the spark plug wires connected properly, in the right firing order? Has work been done on the distributer, or the engine head, recently? Ignition timing can be 180 degrees out, and the engine will still run, sometimes. If it is not the ignition system, the next most likely culprit is the head gasket, which seals the head to the block of the engine. If this gasket is breached seriously, it can cause a cylinder(s) not to fire. Is there water in the oil, as evidenced by a thick, white foam? Is there oil in the coolant? Either of these are symptoms of a leaking head gasket. 
Basically, one cylinder isnt firing for one of a number of reasons. The most common cause is an igntion fault. This will cause the engine to feel and sound "lumpy", and the power would be greatly reduced. The best way to find the cylinder which is responsible is quite simple but care must be taken. Firstly if you hate electric shocks as much as I do, find a proper pair of electricians insulated pliers, and even some decent rubber gloves if you can aswell. Start the engine, and one at a time, use the pliers to remove a lead from the top of one spark plug, if the engine almost stops, or gets worse in any way, it is not that piston which isnt firing. Repeat the proccess, one at a time, you will know which piston ISNT firing when you remove the plug lead, and there is no change in the engine sound, this is your defective cylinder. Its just a case then of looking at the condition of the spark plug and asessing the cause of the misfire before carrying out repairs. BEWARE:- THE LEADS WHICH CONNECT TO THE SPARK PLUGS CARRY SEVERAL THOUSANDS OF VOLTS - HENCE RUBBER GLOVES AND INSULATED PLIERS 

Posted on Mar 05, 2009

  • 1 Answer

SOURCE: service engine soon light keeps coming on. Now low coolant light

I would start by doing an oil change myself so you can examine the oil and look for water/antifreeze in it. You will be able to see it separate from the oil and you can smell the antifreeze. If there is then you have a leak between the water jacket and the heads somewhere. More than likely the LOWER intake gasket is leaking into the head. You said they replaced a gasket but was it the UPPER or LOWER? If it was the LOWER did they use RTV in the correct areas? Did they torque the intake bolts to the correct pressure and install the bolts correctly? I know you don't have these answers but these could all be part of the problem. It may be leaking more at #2 cylinder and causing it to foul more than the others. Also just because a mech pressurized the coolant system and didnt see any change in pressure (hopefully he wasn't just looking for visible leaks) the issue may not happen until the engine is hot, as metals behave differently when heated, especially aluminum which the LOWER intake is made. Have a mechanic or mechanically inclined friend (gearhead) remove the #2 plug wire, then kick the engine a few times without starting it, enough to let any fluid get into the chamber, this would include gas btw. Then remove the plug and look for any wet residue on the plug, gas will evap. quickly, antifreeze/oil won't. again try to smell the residue and if necessary, lightly touch some to your tongue, antifreeze has a sugary sweet taste that is easily detectable. Remember any time you are working with chemicals such as waste oil and especially anti freeze, minimize spills and clean them up quickly and completely and place the spent fluid in a sealable container and take them to a collection center for disposal. Waste oil is a carcinagin (cancer causing) agent and antifreeze (glycol) new or old will kill any animal (child, dog, cat,etc) that ingests it. Many auto parts stores and some other retailers that sell oil and antifreeze will take your wastes if you bought the replacement fluid from them, check before you buy.

Posted on Apr 04, 2009

  • 3 Answers

SOURCE: 1991 Pontiac Transport Engine stall

Problem mayby ECM control unit and couple fuse (EGN)
But your start motor working???
Code 12 meens "No distributor reference pulses to ECM/PCM"

Posted on Aug 21, 2009

  • 17970 Answers

SOURCE: My 2004 Sunfire check engine

DTC P0442, P0455 or P0456 are all diagnostic codes indicating a leak has been detected in the EVAP system:
- P0442 EVAP Leak Monitor .040 Leak Detected (Medium Leak)
- P0455 EVAP Leak Monitor Large Leak Detected
- P0456 EVAP Leak Monitor .020 Leak Detected (Small Leak)

What this code means is that the computer has tested the evap system and was not able to draw a vacuum on the fuel tank. it does this by turning on the evap vent valve which closes the fuel tank vent off, It then opens the vacuum solenoid and allows engine vacuum to be drawn on the fuel tank. A sensor in the fuel tank monitors the Pressure/Vacuum levels on the tank and reports this to the computer.If the computer does not see a change in pressure/vacuum on the tank then code P0455 will set.

Check under the hood to make certain no vacuum lines are disconnected, check your fuel cap if it isn't sealing correctly or is missing or the wrong one this will cause that code to set, You may have a bad vent valve in the gas cap causing the problem.

If you first get a P0442 or P0456 then a while later get a P0455 it is a sign a hose is going bad.
It is common for the hoses over the gas tank on Jeeps and some other chrysler cars to go bad, which requires removal of the gas tank to repair. Could also mean a piece of charcoal from the vapor canister is stuck in a line. Blowing the lines out can fix it.

If you get a P0455 (large leak) at the outset it more likely a stuck valve or a hose which came loose. A smoke machine is the fastest way to finds leaks in these systems but not a common tool for do it your selfers (click image diagram for zoom).


Additional details could find in this TSB procedure DTC P0440 (click over link).

If you have additional comments about this, keep in mind also send us exactly what faulto code found there.

Keep us updated.

Posted on Jun 20, 2011

SOURCE: I have a pontiac grand prix gt 3800 non turbo is

I have a 2003 Pontiac grand prix...I've lost power, it won't go over 30mph, it doesn't shift thru the gears smoothly. The service engine soon light goes off and on, more so when I'm trying to gas it. Its seems as tho it's 'being choked' not getting gas or air. So far, I've flushed the ******, changed the plugs, wires, air filter, fuel filter. I suspect the problem is a clogged cat convertor. I've been told that the exhaust can be opened a little near the cat to allow air to flow in....that should confirm if the problem is the Cat or not. I'm testing that theory today.

Posted on Mar 12, 2012

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Your request for help has some different elements that are not common with how repairs are usually made. To open a catalytic converter to inspect the honeycomb and then remove the insides destroys the converter.

Some of your problems should have thrown a trouble code and the lack of a code can mean the diagnostic system is not working. This can mean the brain is not processing signals from various sensors.

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· other symptoms may also be present

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