1996 Town Car stalls.

[Topher]

Hi,
Alright, I bought a 96 Town Car a couple of weeks ago. When I first purchased it the check engine light was on. Overall, the car runs smoothly but does seem to surge sometimes, like when stopped at a stop light it will increase in rpm with no pressure added to the accelerator peddle and I have to apply more pressure to the brake to keep from moving forward. When I took the car back to the dealer for the inspection I told them about the stall that occurred while driving on the highway with no previous symptoms. They ran diagnostics and stated that it wasn't "throwing any codes" and they reset the check engine light. I don't believe them about no codes. Had a local mechanic look at the vehicle and all was in good shape. Car starts right up at the beginning of a trip. Car dies while driving and while idling. Range in time for the car to stall is anywhere between 5 min and several days. The battery light comes on briefly right as the car sputters briefly then no power, and then the check engine light comes on. Both lights go off about 5 seconds later. Car will start up about 30 seconds later. Someone had stated the ICM conduction is increasing in resistance and the component can't dissipate the heat fast enough and interrupts signal. Not sure about that because it has died when the engine was warming up and at about half of the normal running temp. It has also died at normal engine temp. MPG is about 20, which I think is about right since the weather temperature has been around the 30's and I do mixed highway/town driving. I have ran sea foam- no help. Another thing, the ignition tumbler is broke; no key is needed to start the car (didn't know until a few days after buying).


Any help would be appreciated,

Topher

 

[Topher]

After more consideration: The car stalls within the first 5 or so minutes of a trip and I believe occurs when the accelerator isn't depressed- stopped, or coasting. It's hard to tell because everything is extremely quite in the car (love it). Wish there was a tachometer. This makes me think either components are cold causing decreased conductivity or a mechanical part like a valve isn't loosened up yet from some build up on it. In idling conditions, low flow, fluid or a gas (not fluid), maybe there is not enough pressure to keep the car running? The car has 180000 miles. With the slight sputter before it dies (only noticed when stopped) I want to say something in the fuel injection system.


Any thoughts?

Thanks so much.

Topher

 

[Town]

Welcome.

Your post #2 suggests that stalling occurs with the throttle at idle position, either stopped at idle or coasting. Under both conditions the air being supplied to the engine is through the Idle Air Control (IAC) solenoid valve. The PCM controls the air flow to provide a high idle speed when cold and to provide for changing engine loads at idle (putting trans into or out of drive, power steering movement, A/C compressor on/off, etc). The valve can get sticky from gas varnish deposits and the PCM cannot position the valve properly through the solenoid. The result is uneven idling and stalling. You can check this by slightly opening the throttle and engine speed should stabilize.

It is easy to replace the IAC usually. I will check on the 1996 model and what is involved.

Another possibility is a vacuum leak. Your problem does not sound like an ignition issue but have the spark plugs and ignition system been checked? At 180,000 miles it is close to needing a spark plug change based upon Ford's 100,000 mile replacement period, but that is a very long interval.

In your first post you mentioned being told about "ICM conduction increasing". I cannot think what that means, any idea?

The ignition lock cylinder can be replaced easily and a new key cut and copied. It is not hard to do, let me know if you want the procedure.

Good luck.

 

[Town]

The procedures to replace the IAC and the ignition lock switch are attached.

Good luck.

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[Topher]

Wow, Town-

That's great! I will be getting to work on this tonight and I'm excited to get it proper running condition.

Thank you for your time,

Topher

 

[McGink]

Wow, Town-

That's great! I will be getting to work on this tonight and I'm excited to get it proper running condition.

Thank you for your time,

Topher

Did this fix your stalling/idling issue?

Welcome.

Your post #2 suggests that stalling occurs with the throttle at idle position, either stopped at idle or coasting. Under both conditions the air being supplied to the engine is through the Idle Air Control (IAC) solenoid valve. The PCM controls the air flow to provide a high idle speed when cold and to provide for changing engine loads at idle (putting trans into or out of drive, power steering movement, A/C compressor on/off, etc). The valve can get sticky from gas varnish deposits and the PCM cannot position the valve properly through the solenoid. The result is uneven idling and stalling. You can check this by slightly opening the throttle and engine speed should stabilize.

It is easy to replace the IAC usually. I will check on the 1996 model and what is involved.

Another possibility is a vacuum leak. Your problem does not sound like an ignition issue but have the spark plugs and ignition system been checked? At 180,000 miles it is close to needing a spark plug change based upon Ford's 100,000 mile replacement period, but that is a very long interval.

In your first post you mentioned being told about "ICM conduction increasing". I cannot think what that means, any idea?

The ignition lock cylinder can be replaced easily and a new key cut and copied. It is not hard to do, let me know if you want the procedure.

Good luck.

I'm thinking I may have this IAC issue with my new to me 96 Town Car. Mine has an occasional RPM surging at idle. It also starts inconsistently. Sometimes she fires right up and other times it'll crank up to 10 seconds. This AM, I gave a little throttle when starting since it stalled X2 on cold start-up. Is there a way to clean or diagnose the valve further or do we just put a new one in? Is the dealer the preferred vendor for this part? TIA

 

[Town]

Hi McGink,

The 1996 model has a number of hoses at the back of the throttle body that could be leaking air, so you need to check them thoroughly. The IAC varies the air flow to the engine at startup and idle and generally is diagnosed as a problem when the engine speed varies noticeably when subjected to a load from trans going into drive, power steering operating while parking, A/C compressor cycling. The hose connecting the air tube to the input on the IAC is nicknamed the hooter hose because it often makes a hooting noise at idle and a non Motorcraft IAC can highlight that issue. You didn't say what happened when you opened the throttle a little on a cold start that failed two times before. If that worked to start the car then it supports the IAC being a problem.

In trying to clean the IAC it can initially fix the problem and then destroy the delicate inner components and the IAC is worse than before cleaning. Ford advise replacement as the only option, and in my limited experience they are right.

Check the vacuum lines for PCV, EVAP hose and the IAC intake hose as common failure points. I think there are some elbows and fittings that can crack and break.

Good luck.

 

[McGink]

Thanks for the info Town. When I added a little throttle at cold start, she seemed to fire up easier. I will check the hoses as you advise and report back. This car was kept garaged way below the rust belt. I suspect that if they're like the rest of the under hood components though (clean enough to eat off of lol) that they will be OK. Still worth checking before replacing the IAC valve though.

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[Town]

Hi McGink,

The problem with the hoses does not only come from the outside, most of the problem is from the inside where oil and fuel vapour deteriorates rubber components. It leads to cracks and rot from the inside out.

Good luck.

 

[McGink]

Well, after being layed-up for a while I finally had to dig into the IAC after a FAIL to run one AM. I took the little plastic cap off and sprayed it with WD40 which got it to stay running. I got a new Valve and will put it in when the weather is better. So far, it's been OK but I won't count on it for too long.