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I am having a problem with my 2001 Mercury Sable. A few times, over the past month, the car has idled very poorly at start-up but then, as soon, as I gave it a little gas, it was fine. It has been fine recently, but this morning, it again idled roughly at start-up and the Check Engine light came on. I drove to my local auto parts store to get the codes read. It came back P0301, Cyl #1 Misfire. But, as I drove to the store, the car ran fine. It’s only at start-up that this problem occurs. It has never happened at any other time. I changed the plugs about 3 months ago and it was ok until about a month ago… when the problem popped up again. It started up rough last night and, then today, another rough start and the light came on. I will appreciate any help! Thanks!
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thanks, I’ll give that a try. any ideas as to why the problem only shows up at start-up and not every time then?
I’m still fighting this one. I took the car to a local shop… twice. First time, they found that the coil on the #1 cylinder was bad (wire and plug ok) . So they replaced it. The car was ok for a couple of days then.. back to the rough idle at startup. Back to the shop.. this time, they checked all the sensors and updated the computer program. Once again, the car was fine for a couple of days… then…. rough startup idle again! Any other thoughts?
could be intake gasket by #1 try spraying with carb
spray or a spray bottle with water. also try doing a
power balance test with the injectors.Thanks! How about the possibility of a leaking injector on #1 that would let excess gas into the cylinder after shutdown? Someone mentioned that to me. Any thoughts?
If you had a leaking injector, more then likely, you wouldn’t get a misfire code. We had the exact same scenario happen at my shop. Mis code, replaced coil, 3 days later they are back, checked wiring and firing order like 6 times, found out the coil was bad. Same problem on another forum about a month ago. My money is on a bad coil. Unfortunately not all aftermarket parts are created equal.
Could a bad coil cause a problem like this that only shows up in startup? After it gets going it runs fine….. until I let it sit for an hour or two.
the shop did a smoke test to check for leaks. None found. I’ll have to check out the power balance test. I’m not familiar with that. This just occurred to me… if the injector was leaking after shutdown, wouldn’t that cause a running problem? Excess gas flow? As I wrote before, after the initial rough startup idle, it runs fine.
3.0 pushrod motor? Common for the head gasket to leak into a cylinder after sitting. It will miss until the coolant is burned out of the cylinder. For whatever reason, it is usually cylinder 1 too. Get somebody to start it for you while you sniff the tail pipe. If it smells like coolant/cat piss, you have your answer.
[quote=”Monte” post=66521]the shop did a smoke test to check for leaks. None found. I’ll have to check out the power balance test. I’m not familiar with that. This just occurred to me… if the injector was leaking after shutdown, wouldn’t that cause a running problem? Excess gas flow? As I wrote before, after the initial rough startup idle, it runs fine.[/quote]
A leaky injector could cause the rough start.You would need to
do an injector leak down test.Before you (with no evidence) jump to head gaskets and bad injectors, why don’t you swap out the coil, since none of the aforementioned items would give you a misfire code.
the shop replaced the coil for the #1 cylinder. Do you mean I should replace it again? or swap it with one of the others to see if I get a misfire on a different cylinder? I don’t always get a misfire code though and last night, when I started the car after it has been siting for about a week, I was unable, for the first time, to get it to idle smoothly. Seems like whatever the problem is… its getting worse.
Try removing the plugs with a cold engine and disable the fuel and ignition and crank the engine over and check around the plug holes for coolant.
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