Rough idle, car jerks and sputters when accelerating. Is is the new timing belt? - Mazda MX-6 Forum
 
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post #1 of 10 (permalink) Old 10-16-16, 21:07 Thread Starter
 
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Rough idle, car jerks and sputters when accelerating. Is is the new timing belt?

I just had timing belt, water pump, pulleys etc replaced on my 95 mx6 ls with v6.
The car ran fine for about a month, but started having rough idle at stop just recently.
It also feels like car jerks and sputters when accelerating. I can still drive the car fine. The symptoms are not severe yet, but the loss of power is noticeable.

No check engine light, starts fine. It seems like the symptoms appear when car gets warmed up. I suspected maybe timing belt being off by a tooth, but that doesn't explain how the car ran just fine for a month. I'm not mechanically inclined and spent a lot of money already. Any help/suggestions would be appreciated!
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post #2 of 10 (permalink) Old 10-17-16, 16:48
 
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Very unlikely to be the timing belt, if it runs fine until it warms up.

I would suspect plug wires, or distributor.
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post #3 of 10 (permalink) Old 10-17-16, 20:09 Thread Starter
 
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Thanks, it ran fine for about a month, and it seems to run ok before it gets warmed up.
I know it's probably best to replace all three, but if I want to replace one by one, which one should I replace first out of plugs, wires and distributor?
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post #4 of 10 (permalink) Old 10-18-16, 18:41
 
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Plugs are cheapest, but you can usually tell just by looking whether they need replacing. So look at them first, and replace if they look worn.

Wires are second cheapest, and easy to replace. But if they look newish, they are probably OK.

Distributor last.

But just on a hunch, disconnect the engine coolant temperature sensor first, and see how the car runs with it disconnected. It's the 2-wire sensor, just next to the timing belt cover, next to the fuel injection rails.
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post #5 of 10 (permalink) Old 10-18-16, 20:25
 
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Just curious how much was a lot of money ?
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post #6 of 10 (permalink) Old 10-18-16, 21:03 Thread Starter
 
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Ok, I tried to get the spark plugs replaced today. The socket I have (5/8 spark plug socket) can't get the plugs out for some reason. It seems too big to get those out. I'm not sure if I need a special socket for it.
I will try the coolant temp sensor tomorrow. What's the reason behind it?

As far as money goes, I meant that I've spent more than I should have on this car. The car is probably only worth $1000-$1200 if it was good running condition. When water pump went out, I seriously thought about selling it to the salvage yard for $200-300. I've put close to $900 so far. I still need to replace one of rear brake caliper due to locking problem, there is gas smell in and out of car. The list just goes on.
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post #7 of 10 (permalink) Old 10-20-16, 17:52
 
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Regular 5/8 inch plug socket is the right size. (But you need a long extension to get the rear plugs.) Sometimes the wires fall apart when you pull them of, and part of the wire (a rubber insulator) stays on the plug, so you can't get the socket on the plug. Inspect the wire closely, and shine a flashlight down the spark plug hole.

There have been some cases of engine coolant temperature sensors going bad, so the computer thinks the engine is cold even after it's warmed up, and giving too rich a mixture, causing low power and a misfire when warmed up. Disconnecting the ects is a relatively easy way to check for this problem, since the computer reverts to a standard default setting, and the car runs better (except for cold starts).
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post #8 of 10 (permalink) Old 10-20-16, 23:13 Thread Starter
 
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I can't thank you enough RickR!

If the rubber insulator is stuck, how do I get those out?
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post #9 of 10 (permalink) Old 10-22-16, 21:58 Thread Starter
 
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NickR, I tested the coolant temp sensor. The fan turned on high and the rpm became stable. I replaced the sensor thinking that's what causing the problem. But it didn't fix it.
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post #10 of 10 (permalink) Old 11-10-16, 16:56
 
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Check your intake boot from the MAF to the intake, these get dry and crack causing the exact symptoms your describing, extra air getting in after the MAF sensor causes a lean condition and loss of power, hesitation, rough idle, jerking when driving, etc. It runs fine cold because the computer isn't using sensor readings just a programmed baseline setting.
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