I have a 1997 Pontiac Grand Am, ~146K, recent fresh spark plugs and coil. It will run, but poorly. Engine “stumbles” on take off from the line and “stumbles” at steady freeway speeds occasionally. It will sometimes stall from a stop and when slowing down to stop. The “check engine” light was on when this problem first started, but has sense gone off. The bulb for the light works; it’s just not triggered on the more recent stalls.
What should I do first? Get the codes pulled and post back? Try cleaning the idle control valve and see what happens? Don’t have much money and I need this car up and running.
Thanks for any help!
You need to take some measurements. If you do a ohms check on the spark plug wires, you may find that some of them read infinity. If so, replace the spark plug wires. Is the engine a four cylinder, V6, or V8?
The fuel filter may be dirty, and dropping fuel pressure. The only way to check fuel pressure, to see if the fuel pressure is where it should be, is with a fuel pressure test gauge.
It is the 2.4L 4cyl…
The wires and checked by my mechanic recently (less than 6-months ago) and were good. The plugs are fresh…I did not replace the IAC valve. Instead, I bought a can of throttle body cleaner and cleaned up the IAC valve and sprayed the cleaner into the throttle body while the engine was running. Things smoothed out quite a bit. The car took off from the line a lot quicker.
The next day, the money light (CEL) came on. No one in the Bay Area (CA) reads the codes for free (not Auto Zone, Not O’Reilly’s, etc.). It looks like I need to buy a code reader. I do (I think) have a electrical tester that measures ohms. So, how does the test work. Car on (scary) or off?
I don’t have a fuel pressure test guage. I’ll likely have to wheel the car over to the mechanic…
Thanks hellokit!
Don’t assume that the mechanic’s check of your plug wires means anything. First, they might have just visually inspected. Second, plenty of time has passed.
Take the ohmmeter and just probe each end of the wire - rule of thumb is that resistance should be less than 5,000 ohms/ft.
If you’re feeling up to it you can get a basic fuel pressure gauge for about $40 or so.
The cheapest and most likely problem with your car is right there along with the coil you said you recently replaced. The part I would suggest replacing is also part of the tuneup on a quad-4 that frequently gets overlooked. I’m not sure what the part is called, but I would call it a distributor or coil housing. It’s that big white plastic thing underneath the aluminum cover that houses the spark plug boots (no wires on this motor), coils, and ignition module. It frequently develops carbon tracking over time, which leads to misfiring or crossfiring and overall poor driveability. The coil housing should come with new boots, but if it doesn’t, spring for new boots as well. They can also develop carbon tracking.
You could pay some one more money to read the fuel pressure, and the trouble codes, ONCE; for more money than what a fuel pressure test gauge, and a code reader costs. The fuel pressure test gauge, and code reader, you can use many times, and just pay ONCE. You might, even, make a little change by reading other peoples’ cars for them.
I’d try something cheap.
You might have been on the right track with the throttle body cleaner. It helped a bit, so let’s try something a bit more deeper cleaning. If you can buy Sea-Foam in the Golden State, buy a can and follow the directions for sucking it into a vaccuum line. Then run Marvel Mystery Oil in the tank for 2-3 tankfuls. This shouldn’t cost more than $15, and if it isn’t the problem, it won’t hurt anything.
OK, I have the receipt out from “tune-up” work back on 08/08/08 (not a lucky day for me…)
My technician replaced 4 spark plugs (@ $13.97 each)
4 spark plug boots (@ $12.45 each)
1 coil ($88.00)
1 coil housing ($133.18)
1 air filter ($24.56)
1 fuel filter ($25.01)
dumped fuel injector cleaner in it ($20.00)
$232.00 for labor
I was fleeced on the parts markup; the labor rate is also high, but that it what you get in CA. I buy AC Delco parts much cheaper at Autozone; the same parts he claims to have used, but I was supporting a local independent mechanic, blah, blah, blah… Anyway, this event took too much cash ($631 + tax).
I am leaning toward getting my hands dirtier with this stuff and am not opposed to buying a code reader. Gas scares me as I have no easy way to dispose of the spilled/left over gas. I just gotta do more work and learn more about autos. (Wife laid off; I could be too…)
Thanks to all who replied!