Start with the obvious I guess, was the spark plugs ever replaced? 60k miles is getting around that time. How about the plug wires? Spray some water on them in the night time while the engine is running, and see if there is are any sparks. That will eliminate that problem.

Another possibility is to hook up a dignostic hand held, which can be purchased at your local auto part store for about $100.

This is not an all-inclusive list, and it is possible under some circumstances to add or delete items. It is a basic performance testing menu.

Basic testing sequence:

Physical inspection of underhood components; condition of plug wires, wiring, fuel injection,

other engine performance components.

Pre (cold) start attempt:

Check for proper battery voltage

Install fuel pressure gauge

Check for pressure and volume (check spec table in repair manual)

Install engine analyzer

Check for spark at a minimum of two cylinders

Check for injector pulse at a minimum of two cylinders

Pull codes

Check ECM/ECU data stream

Attempt to start: if starts and runs:

During running, recheck:

Fuel pressure/volume

Primary/secondary ignition scope traces

ECM data stream

There have been some specific problems with GM performance issues. For example, the CFI injection systems used on some GM trucks (which features a electro-mechanical injection system) has presented internal leakage issues with the feed tubes from the central injectors to the individual injector poppets. Also, EGR sticking issues are well documented. Vacuum leaks are also possible.

Let us know what you find.

See if someone new just filled it up at the gas station (Petrol Bunk for Del and others) and left the gas cap loose. It needs to be tight. That's why they have a clicker to make sure you get it tight but not over tight. This affects the emissions control system and the computer may be trying to adjust timing to compensate for the loose cap.

Oxygen sensor bad or loose wire? Look in your exhaust system under the car and see if the O2 sensor wire fell off or is dirty. The sensor is just downstream of where the two exhausts collect into one. Pull the plug off, spray some contact cleaner (Radio Shack) in it and replace, or at least plug it in/out/in to scrub off any corrosion or gunk from the pins. DO NOT attempt to remove the O2 sensor. It takes a special tool at times.

As already suggested you can get a code reader from any auto parts store and read the codes 'thrown' by the computer. There is a plug near the steering wheel or under the hood (bonnet for Del). Those code readers are not 100% accurate but cheap. If you know a professional mechanic he will have a $8,000 code reader where they work and will be able to read a very detailed code (fault code).

Generally look for loose connectors under the hood. Any loose senor wire will give a false reading (like water temp) to the computer and the computer will attempt to keep the engine in "Emissions Compliance" by screwing with the timing automatically.

Good luck.

That is the orginal engine ?

Has a Bow tie on the front!

Hello imintowater,

When I purchase a used vehicle that seems to be in excellent condition with unusually low mileage that is billed as a one owner vehicle, I get very suspicious regarding the wonderful claims being made regarding the real condition.

All to often vehicles are wrecked and spend a long time in storage facilities awaiting for the salvager's to acquire sufficient parts to repair said vehicles without a huge investment in parts and labor. You live in Phoenix, so there is a lot of green card labor available there. The odometer isn't turning while this vehicle is in waiting.

And worse than that, there was this hurricane named Katrina that flooded much of the Gulf coast and another that landed in the greater Galviston Island area, both filled many vehicles with salty flood water. I am aware that there are at least two states that do not require that insurance companies report vehicles that have been totaled or significantly damaged.

I will guess that because this vehicle appeared to be in such great condition, with only "60,000 miles on a 7 year old vehicle", and only one traceable owner, You determined that you need not get a carfax report. I truly hope that I have guessed wrong.

I suggest that you attempt to determine the true history of this vehicle before you go spending a lot of money attempting to repair it. If the history is clean then the repairs should not be very expensive, on the other hand, if this vehicle was a floater, "get rid of it before it overwhelms with repair costs and un needed head aches.

TMF

FIRST thing to do is take it to Autozone or what ever name brand autoparts store and ask them to read the code that turned on the 'check-engine' light or 'malfunction indicator light' (MIL) Your vehicle has OBD II and will give very specific error codes, indicating the misfiring cylinder and the cause-ignition, fuel or?. Then it is much simpler to sort out the root cause. It may be as simple as a fouled spark-plug, a faulty ignition coil, or as complicated as a failed fuel injector requiring removal of lots of parts to get to.

You have received some good answers so far. I would only want to add that once you have gotten the computer read out, take a step back and look at the results. Are you seing causes, or results? Take a defective check valve at the brake booster. If it allows too much flow of vacuum, the engine will detect this as a lean condition. The computer will adust the mixture to compensate. The comouter also knows jst how far the normal range of mixture adjustments should be. That vacuum leak will require an adjustment that is "out of normal range" This will set the check engine light. But you do not need to change anything in the mixture control system, your problem is elsware. Use the stored codes as a guide, not as an all perfect answer.

Another thing to remember. Do your routine maintenance before you start replacing components because the codes say so. tell us the codes, and some of the gearheads will hwlp guide you. Please do not guess. Just because your second cousin had a desoto that had a dead cylinder becaese the sparkplug wire was destroyed from gas dripping on the spark plug wire does not mean that that is your problem. Good luck, and stay in touch.

It could be the crankshaft position sensor. This fault does not record in the OBDII memory. The behavior is the engine will skip / misfire as it warms up (eventually getting bad enough to stall out) as the temperature goes past the trouble zone it clears back up. GM dealer installed a recording device that i drove around with until it acted up and i activated the record function and took it back to the dealer. A subscription to ALL DATA will let you know all the technical service bulletins and other issues associated with your vehicle.