1998 Mercury Tracer Rough Idle, New A/C Compressor

AIDAN_80

MEMBER
1998 MERCURY TRACER
4 CYL
FWD
AUTOMATIC
79,000 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!

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Tuesday, May 13th, 2008 AT 10:39 PM

30 Replies

2CARPRO JACK

MECHANIC
11,533 POSTS

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?

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Thursday, May 15th, 2008 AT 8:06 AM

AIDAN_80

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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! :)

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Friday, May 16th, 2008 AT 7:46 PM

2CARPRO JACK

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11,533 POSTS

A new IAC will most likely take care of the problem

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Monday, May 19th, 2008 AT 7:47 AM

AIDAN_80

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41 POSTS

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!

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Thursday, May 22nd, 2008 AT 10:46 PM

AIDAN_80

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41 POSTS

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!

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Monday, June 23rd, 2008 AT 10:27 PM

MERLIN2021

MECHANIC
17,250 POSTS

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

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Saturday, June 28th, 2008 AT 3:15 PM

AIDAN_80

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41 POSTS

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?

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!

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Tuesday, July 1st, 2008 AT 8:54 PM

MERLIN2021

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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.

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Wednesday, July 2nd, 2008 AT 6:19 AM

AIDAN_80

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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!

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Wednesday, July 2nd, 2008 AT 8:05 PM

AIDAN_80

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41 POSTS

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!

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Monday, July 7th, 2008 AT 9:28 PM

AIDAN_80

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41 POSTS

I wanted to post back on this. Just incase another poor soul ends up in my boat with one of these wee cars!

Shaking Issue = Timing Belt jumped a tooth or too and finally jumped enough to cause the car to stop running. New timing belt and the rough idle dropped down to a buzz. Shakes up a bit sometimes but not too bad.

Still have the IAC Check Engine Light on. Going to pull it myself (seeing how easy it is) and put in another. That should finally put to bed the rough idle.

If your in the same boat as me owning an older Ford/Mercury Escort/Tracer with a rough idle and normal mileage you may want to keep an eye on the timing belt if it hasn't been done and of course error codes!

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Friday, January 16th, 2009 AT 9:09 PM

MERLIN2021

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If the belt jumped time, then it may have also backfired thru the intake, and this only needs to happen once to ruin an IAC. Most of your remaining idle problems can trace back to it.

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Tuesday, January 20th, 2009 AT 4:59 PM

AIDAN_80

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41 POSTS

Ok I replaced the IAC and started up the car. Car ran perfect, idle was back to normal. Took it out for a test drive and it still shakes just a bit but still shakes up a bit now and then when in gear. The shake is just a buzz when in park. It's also stalled on me while reversing. It was like the idle dropped so low it cut out the engine? I have to say it's night and day difference compared to what it used to be with the idle.

I should mention and please remember I'm a novice here lol. Check engine is still on I assume this needs to be cleared! I also noticed some black oily buildup on the shallow hole on the throttle body. I'm going to remove the throttle body and clean it just in case.

At times when driving it today it felt like the computer didn't know what to do with the new IAC it'd had the old one messed up one for so long now like it was revving up now and then and dropping down once and a while. Is it relearning how to use the new part maybe?

Any suggestions would be excellent, thanks again! :-)

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Saturday, January 24th, 2009 AT 8:48 PM

AIDAN_80

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41 POSTS

I disconnected the battery and drove around for a while. Check engine came back on with the used IAC I put in. I had the check engine codes pulled at an auto store and this is what they found:

* P1504 IAC circuit fault
* ECM has detected an electrical load failure on the IAC circuit.
* Causes Open or shorted circuit or failed IAC valve.

I've also tried:
Installed used IAC car started with a buzz and very low idle almost to the point of stalling while in P. Reinstalled the old IAC car started up with a roar and the usual high idle it had! I started the engine, let it heat up and pulled the electrical connection from the IAC while the engine was running. No change and no stall or drop in RPM's! Tapped IAC with a hammer (both of them) while running and no change. Wiggled the electrical connection and the wires leading to the IAC without any change in idle.

Any other suggestions are very welcome!

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Sunday, January 25th, 2009 AT 11:16 PM

MERLIN2021

MECHANIC
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A used IAC? Not on my ride thanks. The other thing is yes clean out the throttlebody, with TBI cleaner ONLY, these have a teflon coating and other cleaners destroy it. Also check the PCV.

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Monday, January 26th, 2009 AT 3:14 PM

AIDAN_80

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41 POSTS

Well used IAC at $25 or a new one from Ford at close to $200. I had to try the used one first just incase. I went a bought a new IAC from an auto store today but before I install it I checked all three IAC's with a multimeter just to be 110% sure it really is the used IAC and save myself some cash. Maybe?

I tested resistance (lowest setting), polarity in both directions with all three IAC's here's what I got.

* Original broken IAC 11.7 in both directions - high rev every time I used it in the car
* used IAC 12.1 in only one direction - buzz no high rev, very low idle still installed in car
* new IAC 11.8 in both directions - never installed, prefer to return if it's not needed

Now where I'm stuck at ruling out the IAC issue is. I assume it should be allowing the test to run both ways I'm worried that it's only running one way in the use IAC. I'm thinking it maybe shorted? Then why is the my original IAC showing expected resistance in both directions. Mechanical failure maybe?

I'm just thinking out loud here as I'm very much a novice but would like to try and figure out this one if I can.

Thanks again! :-)

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Monday, January 26th, 2009 AT 7:43 PM

AIDAN_80

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I ran one more test. I disconnected the power to the IAC, the used one and put one of the multimeter probes on one of the IAC terminals and the other one the IAC body per the instructions found in a repair book. The reading was 1, I reversed the polarity and still reads 1. I tried this out with the other two IAC's and again it reads 1. I tried this on all resistance settings starting from lowest all the way up to highest? The repair book said I should be reading at least 10,000 ohms?

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Monday, January 26th, 2009 AT 9:09 PM

AIDAN_80

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41 POSTS

I installed the new IAC and it works exactly like the used IAC I put in, no difference. Still keeps the check engine light on. The check engine light will stay on all day then every other day it'll knock off for a few hours and come right back on again. Still have error 1504 showing up.

I did the same tests as before on the new IAC when installed, even pulled the electrical connection from the IAC while the car was running.. the idle didn't change one bit? I wonder if the IAC is even getting any power? I may have that electrical connection checked out?

I checked again for vacuum leaks and again I sprayed carb cleaner on all the lines.. only one area gave a slight increase in idle when sprayed. I sprayed the same area over and over again and each time without fail the idle would go up just a small bit but not much. I sprayed a line to the right between the engine and battery as pictured..

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Tuesday, January 27th, 2009 AT 8:27 PM

MERLIN2021

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TESTS W/CODES (SOHC) -1998 Mercury Tracer GS
Page 1 of 5
Diagnostic Aids
Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:
� � � Throttle linkage.
� � � Wiring harness circuits (IAC and VPWR).
� � � Faulty Idle Air Control (IAC) valve.
� � � Faulty throttle body.
� � � Faulty Powertrain Control Module (PCM).
Fig. 52: Identifying IAC Circuit & Connector Terminals
1) Check For DTCs

Retrieve and record all Continuous Memory DTCs. Perform KOER ON-DEMAND SELF-TEST . If DTC P0505, P1504 or P1507 is present, go to next step. If DTC P0505 or P1507 is not present, IAC system is okay and testing is complete. If symptom exists, go to TESTS W/O CODES - EEC-V article.
2) DTC P0505, P1504 & P1507
DTCs P0505 and P1504 indicate IAC system malfunction has been detected. DTC P1507 indicates that IAC system under speed fault has been detected. Possible causes are:
� � � IAC circuit open or shorted to PWR.
� � � VPWR circuit open.
� � � Contaminated IAC valve assembly.
� � � Damaged throttle body.
� � � Faulty IAC valve.
� � � Faulty PCM.
Turn ignition off. Disconnect IAC valve connector. Turn ignition on. Measure voltage between VPWR terminal at IAC valve wiring harness connector and battery ground terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in VPWR circuit.
3) Check IAC Valve Resistance
Turn ignition off. Connect DVOM positive lead to VPWR terminal at IAC valve. Connect DVOM negative lead to IAC terminal at IAC valve. If resistance is 6-13 ohms, go to next step. If resistance is not 6-13 ohms, replace IAC valve assembly.
4) Check IAC Valve Internal Short To Case

Turn ignition off. Measure resistance between each IAC valve terminal and IAC housing. If both resistance readings are more than 10,000 ohms, go to next step. If any resistance reading is 10,000 ohms or less, replace IAC valve assembly.

1/29/2009
TESTS W/CODES (SOHC) -1998 Mercury Tracer GS
Page 2 of 5
5) Check Air Inlet System

Turn ignition off. Remove air filter. Inspect air filter, MAF sensor and air inlet system for excessive dirt or contamination. Repair as necessary. If air inlet system is okay, go to next step.
6) Check For Vacuum Leaks

Start engine and allow to idle. Inspect air inlet system any of the following possible faults:
� � � Cracked or punctured air inlet tube.
� � � Loose inlet air tube or air cleaner housing.
� � � Loose or damaged throttle body.
� � � Contaminated or damaged IAC valve assembly.
� � � Faulty EGR valve or gasket.
� � � Faulty PCV valve or hose.
Check entire system for vacuum leaks. Repair as necessary. If no vacuum leaks are found, go to next step.
7) Check IAC Circuit Continuity
Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between breakout box test pin No. 83 (IAC) and IAC terminal at IAC valve wiring harness connector. If resistance is 5 ohms or more, repair open in IAC circuit. If resistance is less than 5 ohms, go to next step.
8) Check IAC Circuit For Short To Power

Turn ignition on. Measure voltage between test pin No. 83 (IAC) at breakout box and chassis ground. If voltage is one volt or more, repair short to power in IAC circuit. If voltage is less than one volt, go to next step.
9) Check IAC Circuit For Short To Ground
Turn ignition off. Disconnect scan tool from DLC. Measure resistance between test pin No. 83 (IAC) and test pins No. 51 and 103 (PWR GND) at breakout box. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground in IAC circuit.
10) Check IAC Signal From PCM

Connect PCM to breakout box. Connect IAC valve to wiring harness connector. Connect DVOM between test pins No. 83 (IAC) and No. 51 (PWR GND) at breakout box. Start engine and slowly increase speed to 3000 RPM. If voltage is not 3.0-11.5, replace PCM. If voltage is 3.0-11.5 volts, proceed as follows:
� � � If Continuous Memory DTC P1504 or P1507 is present, go to step 30).
� � � If Continuous Memory DTC P1504 or P1507 is not present, check throttle body for damage.

1/29/2009
TESTS W/CODES (SOHC) -1998 Mercury Tracer GS
Page 3 of 5
Repair as necessary. If throttle body is okay, replace IAC valve.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 20). No test procedures have been omitted.
20) DTC P1506

This DTC indicates IAC system has reached over speed malfunction. Possible causes are:
� � � IAC circuit short to ground.
� � � IAC assembly stuck open.
� � � Air intake leaks or restrictions.
� � � Damaged throttle body.
� � � Contaminated or damaged IAC valve assembly.
� � � Faulty Powertrain Control Module (PCM).
Start engine and allow to idle. Inspect air inlet system any of the following possible faults:
� � � Cracked or punctured air inlet tube.
� � � Loose inlet air tube or air cleaner housing.
� � � Loose or damaged throttle body.
� � � Contaminated or damaged IAC valve assembly.
� � � Faulty EGR valve or gasket.
� � � Faulty PCV valve or hose.
Check entire system for vacuum leaks. Repair as necessary. If no vacuum leaks are found, go to next step.
21) Check EVAP System

Turn ignition off. Disconnect hoses from EVAP canister purge valve. Connect a vacuum pump to carbon canister hose port. See Fig. 53 . Using vacuum pump, apply 16 in. Hg to port. If vacuum bleeds off within 20 seconds, replace EVAP canister purge valve. If vacuum holds, go to next step.
Fig. 53: Identifying EVAP Canister Purge Hose Ports
22) Check IAC Valve Function

Start engine and allow to idle. Ensure transmission is in Park or Neutral and engine is warmed to normal operating temperature. Disconnect IAC valve wiring harness connector. If engine speed drops, go to next step. If engine speed does not drop, check throttle body for damage. If throttle body is okay, replace IAC valve.
23) Check IAC Circuit For Short To Ground
Turn ignition off. Disconnect scan tool from DLC. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box

1/29/2009
TESTS W/CODES (SOHC) -1998 Mercury Tracer GS
Page 4 of 5
(014-00950), leaving PCM disconnected. Measure resistance between test pin No. 83 (IAC) and test pins No. 51 and 103 (PWR GND) at breakout box. If both resistance readings are more than 10,000 ohms and idle speed is normal, go to step 30). If both resistance readings are more than 10,000 ohms and high idle speed is present, replace PCM. If resistance is 10,000 ohms or less, repair short to ground in IAC circuit.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 23) to step 25). No test procedures have been omitted.
25) DTC P1505: Check Inlet Air Supply

This DTC indicates IAC system has reached the adaptive learning limit. Possible causes are:
� � � Air intake leaks or restrictions.
� � � Throttle body linkage binding.
� � � Contaminated or damaged IAC valve assembly.
� � � Damaged throttle body.
Inspect air intake system for leaks. Repair as necessary. If air intake system is okay, go to next step.
26) Check Air Inlet System
Turn ignition off. Remove air filter. Inspect air filter, MAF sensor and air inlet system for excessive dirt or contamination. Repair as necessary. If air intake system is okay, go to next step.
27) Check Throttle Body & Linkage
Disconnect accelerator cable. Remove air cleaner tube from throttle body. Check cable and throttle body linkage for binding or interference. If faults are present, go to CIRCUIT TEST HU , step 3). If no faults are present, go to CIRCUIT TEST HU, step 8).
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 27) to step 30). No test procedures have been omitted.
30) Check IAC System For Intermittent Open Or Short Circuit
Connect scan tool to DLC. Start engine and allow to idle. Ensure all accessories are off and engine is warmed to normal operating temperature. Using scan tool, select IAC and RPM PIDs from PID/DATA monitor menu. IAC duty cycle should be 20-45 percent. Observe IAC and RPM PIDs for indication of fault while performing the following:
� � � Wiggle and bend wiring harness starting at IAC valve and work toward PCM.
� � � Lightly tap on IAC valve to simulate road shock.
Fault will be indicated by sudden change in IAC PID or RPM PID value. If any faults are found, isolate fault and repair as necessary. If no faults are found, problem cannot be duplicated at this time. Go to CIRCUIT TEST Z .

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Thursday, January 29th, 2009 AT 11:24 AM

AIDAN_80