Mechanics

ROUGH IDLE, NEW A/C COMPRESSOR

1998 Mercury Tracer

Noises problem
1998 Mercury Tracer 4 cyl Front Wheel Drive Automatic 79000 miles

Hi,

I purchased a used Tracer GS last year and since I got it, it’s had a low idle. After I purchased it I had a local (trusted) mechanic have a look at it and he said everything was fine apart from the thrust motor mounts (front and rear) he also mentioned the transmission mount should be replaced, a small leak in the a/c compressor and he had some concerns about the low idle. We recently had the A/C compressor and the thrust motor mounts (not the transmission mount) replaced and the low idle turned into a very rough idle. The entire car would shake quite badly when using the A/C while in Drive but not so much in Park or even in Reverse it’s much less! This shaking will die down quite a bit when I turn the A/C off, I’m in Florida so the A/C is critical! Although driving without the A/C is now very smooth compared to before.

I asked him to double check the car again and he flushed out the A/C system and increased the idle slightly. He showed me how he increased the idle and the screw used to make the increase is rusted in place so I’m stuck at what I’m at. He said the car did stall once as he was taking it around the block before increasing the idle. The car still shakes quite a lot when stopped but 100% file while driving? I sat in the car as he manually increased the idle with the A/C on and the shaking disappeared? He also checked all the usual, fluids, computer for codes, he actually showed me the results as he searched for an error codes. There where no errors reported from the computer.

Is there something else that’s missing? Something obvious that a more seasoned mechanic might have spotted that our mechanic hasn’t seen too much before or at all before in the shop or is our mechanic on the right track?

Thanks for your help!
Avatar
Aidan_80
May 13, 2008.



First if you have any mounts that are bad, it will vibrate regardless. The torque mounts go out it places extra stress on the other mounts to try to keep the engine in check. Have him clean the throttle bore around the butterfly with carb cleaner and a rag, also clean the Idle Air Control Motor the same way, this should help stabilize the idle, is the tune up in good shape?

Tiny
Jack42
May 15, 2008.
Hi,

Thanks for the response! I intend to have the other mount replaced in the coming weeks. I actually took the car back in today as the check engine light came on. He checked for error codes and found the Idle Air Control to be giving an error? He cleared the code and set it up to come in next week, the light came on again on the way home. Tune should be fine, it had fresh fluids, new battery, plugs and wires when I bought it, I also had it checked when I got it. I do intend to have it checked out back to front next week to try and nail this problem. It's also now revving up quite a bit when I start the car, I've no meter to see how high but I was told not to worry about it for just this week unless it revs really high and loud, in which case I should turn it off. I will of course pass on your suggestions.

Thanks again for responding! : )

Tiny
Aidan_80
May 16, 2008.
A new IAC will most likely take care of the problem

Tiny
Jack42
May 19, 2008.
Thanks again for the response! I'm sure between you and my mechanic you've saved me a lot of stress and a lot of cash!

Tiny
Aidan_80
May 22, 2008.
Well I got it back into the shop and long story short, they replaced the trans axle mount (I now have 3 new mounts in total, 4th is in good shape) and the thing is still shaking but no where near as bad. It also feels more together taking off? There is a lot more power maybe due to the A/C being flushed out?

They checked for vacuum leaks, they double checked the A/C to ensure it was working correctly and flushed any and all air out of it. Cleaned the IAC (which needs replaced now at $200 for the part?) So I still have a high idle starting then dropping down and the shaking starts.

I've had our mechanic, his boss look at the thing and they double checked everything and still it shakes when stopped! They can't find whats wrong and have mentioned it could be the motor? They don't think the IAC is causing it to shake as bad as it was?

I mean ok this car is 10 years old but before the A/C and mounts where replaced I didn't feel as much as a rattle inside, not a bump. It's a lot better now but not as it was when I bought it before any work was done.

Am I asking too much or should I just get used to it?

Thanks again!

Tiny
Aidan_80
Jun 23, 2008.
Well I agree with Jack, it's either a vacuum leak, or the IAC, Fords are known for them.
You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody

Merlin2021
Jun 28, 2008.
Thanks again for responding!!.. I'll head off to the local wal-mart/autozone and get a can of spray gumout and spray the vacuum lines. I don't have a tachometer, I'm assuming I'll hear the idle change if I find the leak?

This might sound stupid but.. when I first got the car I noticed some duct tape wrapped around one of the tubes/lines (see attached image, highlighted in red) hidden under a plastic sleeve, highlighted in green. I never thought anything of it really until now?


http://www.2carpros.com/forum/automotive_pictures/190115_Tracer_Eng_1.jpg



Sorry if this sounds strange but I'm not much of a car person! After this I think I'll be learning a bit more on basic maintenance.

Thanks again, I'll post back my results, if any!

Tiny
Aidan_80
Jul 1, 2008.
They most likley put tape there because a rub spot was developing. To put your mind at ease you can take a peek under there and re-tape it.

Merlin2021
Jul 2, 2008.
I already did, it looks like the rest of the tube, didn't look worn, cracked or damaged. Actually just sticky from the tape? I'll trust your judgment on it!

Tiny
Aidan_80
Jul 2, 2008.
Ok I got the gumout, sprayed every single vacuum line I could find and didn't get anything. While I was in there I checked the oill so filled it up. I removed the air filter and knocked out the dust, there was deposit in the tube. I also used some Carburetor/Fuel Injector additive to my last fill. In the hope that maybe something might have an effect and. Something has, I think? (Air filter maybe?) The rough idle is now bearable? I mean my teeth don't chatter at a stop light anymore? I'm going to replace the air filter with a new one this week and I'll have the IAC replaced when funds allow. I still get the high RPM's when starting but thats due to the IAC?

I do have another question. I had the brake switch, that controls the brake lights and shifter release replaced a few months ago as I got stuck in Park one day! I've been driving along quite happily until now. I'm getting stuck in Park again. Is there something that could be causing this? The old switch was melted inside? The mechanic that installed it said I might want to replace or disable the solenoid that controls the shifter release but I need to know when I have brake lights!

Tiny
Aidan_80
Jul 7, 2008.
Page 1 of 3