Pontiac Grand Am Runs Bad At Low Speeds

1997 Pontiac Grand am se 2.4L engine light on, multiple misfire. We changed spark plugs, plug wires, map sensor, o2 sensor, coil housing, coils, control module,cam sensor, checked fuel injectors, checked compression 150%. New computer. Had fuel injectors cleaned out.

Question:
Car runs perfect if your driving on interstate. Driving through town car won't stay running, stalls constantly and shakes like crazy. Had it to two different mechanics and neither one of them could figure it out. Tried everything. Car barely runs or starts now. It started running bad a few weeks earlier and the problem gradually just got worse. Can't drive it at all now. Did find a broken line to the gas tank, no fuel in line more like a vacuum line, fixed that and car ran worse after I fixed it.

pontiac grand am

ANSWER:

The line you are talking about sounds like the EVAP emissions vapor line. That would have nothing to do with the way it is running. Must just be a coincidence.

You said that the injectors were checked? Were they checked for proper fuel flow? There is a test to see it the injectors are restricted by using a pressure gauge and comparing the flow rate of each one.

You need to get the gas checked. You may have gotten a bad tank. Have a fuel sample taken and then let it sit a few minutes to look for any separation or settling. If there is any, then it is contaminated. Usually it is from water.

If the gas is fine and still wont run at slow speeds, it sounds like the timing has jumped. Especially is the misfire code is showing up on all four cylinders. This will not always show up on a compression test. Best way to check that on this engine is to remove moist of the top timing cover bolts, turn the engine to line up the cam gear marks and see if the crank mark is lined up.


Live Chat:

Question: Joe, I have a question regarding idle on cold start. Give me your opinion? Pontiac Grand AM 2005 3.4l. It is sort of a pressure relief noise. The dealer said its because overnight it loses pressure and it takes a while to rebuilt that pressure.
 What pressure are they talking about?

lol no idea man. he was talking about a spring part... I have a hard time hearing his because his english is not too good.
 Does the engine make noise also under the hood? Does the exhaust smell? Do you think it smells like burning antifreeze, oil, or gas.

Only when cold before the exhaust heats up. Nothing bad. Just burnt gas.
 Ok. If you have not done so already and you have the car with you, check the coolant level and condition. Also pull the dipstick and see what color the oil is. And one final thing, remove the oil filler cap to see if it is full of sludge.

I was thinking more like it could be the MAF or PCV or IAT causing the issue.
 No, probably not one of those. Bear with me while I type a pretty big paragraph of some things I think it could be. it sounds like the mechanic is trying to describe that the lifters are taking too long to pump up. All the lifters have springs inside them. Or he was trying to tell you one of the valve springs is broken. The engine has a bad miss fire. Some possible causes and the reason I told you to check the fluids is possible lower intake manifold leaking coolant into the oil. Contaminated oill will cause the lifters to bleed down and engine will run bad until they pump up. Another possibility is that the fuel pressure regulator is leaking gas internally very badly. This will also contaminate the oil and wash the cylinders which can cause engine misfires. Neither of these things will cause a broken valve spring though. So I think the most probable cause is that the coolant and oil are contaminated, mixed together. Lower intake manifold leaking coolant is very common on the 3400 engine.

Ok. I will keep and eye on the coolant and the oil. Thank you for your help Joe.


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