Help! Replaced CPS, but the problem has returned

[dfinley]

On Sept. 4 I posted the message below. After numerous contacts from members, I narrowed the problem to the cam position sensor. I replaced it last week and it seemed to solve the problem. This weekend, the problem returned. DRAT!
Anybody have a suggestion for what to do next? I have gotten a readout for MAF, but I have two and the problem exists with both. It's hard to believe I have TWO defective MAFs.

Here's a restatement of the problem:

I have a '95 Taurus SHO 5-speed. It's in great shape with 70,000 miles and I take extremely good care of it.
About six weeks ago it developed a very unusual and intermittent problem.

Here it is: The car stops accelerating as soon as it hits 3,000 rpm. It feels like it has a governor on it and just stops accelerating and falls flat on its face. Sometimes it will buck a little, but mostly it just kind of decelerates. It does continue to run however. If this happens on the highway, I have to back off the accelerator, gear down and then slowly bring it back up to speed. Needless to say, this is dangerous. It will do about 55 mph, (eventually), and I can run it around town as long as I don't drive it aggressively. If I turn off the car and restart it, the problem usually goes away. It might come back in an hour or a few days. Lately, it's been there every day. I have had four mechanics, including two Ford dealers, look at it and none of them can figure out what's wrong. Ford couldn't even generate any error codes. I've had a new fuel pump put in the car. I put in a new ICM myself. It's a Borg-Warner part, not a Ford part. The latest mechanic I have working on it got a 219 error code and replaced the spout circuit. All to no avail.
In addition, the car occasionally loses the tach while the car continues to run. The tach just sits at zero for a while and then suddenly it resumes operating. Check engine light comes on occasionally.

 

[SolidState]

Cam Position Sensor, or Cam ID (CID) is different from the CPS, or Crank Posiiton Sensor.

The way the tach works is the engine speed is read by the CPS (below the waterpump, by the front main seal) and sends it to the DIS, which is on the crossover tube, which then relays it to the tach.

If the tach is going dead, it is a CPS problem or a DIS problem. I am leaning towards the Crank Position Sensor.

If the CID was no good, the car would start really really hard, because it doesn't know what cylinder to fire first.

Hope this helps. beer

 

[sdpatt]

By the ICM, do you mean the distributorless ignition system (DIS) module mounted on the intake's crossover tube or are you referring to the black box over the radiator? The former may be the problem, but the latter contains the relays for the fuel pump, raditor fan(s) and the A/C compressor and will not cause the problems you have described. The 219 code tells me that there is a problem either with the DIS itself or with the electrical connectors or the ground circuit through the intake to the DIS module.

If there are no codes generated during this event, there are only a few causes that will not set an error code. A couple of them involve the spark plugs and plug wires but they almost have to be downstream of the coil pack. How are those components doing? Are the Motorcraft parts and have they been replaced in the last 60,000 miles (plugs) or 120,000 miles (wires)? Have you checked the plug wells for oil or water?

 

[dfinley]

Thanks for the response. I have been told that a faulty Crank Po Sensor will cause the car to shut down, while a faulty CID will cause the problems I described. Do you understand otherwise?

The DIS is new. My old one was cracked so I thought that was the problem.

 

[stevetatro]

Don't pay money to have a mechanic diagnose the codes. Do it yourself with a paper clip, or wire lead as SDPATT has described, and post the codes - all of them - here so we can help you further.

If it really is a 219, you shouldn't have wasted your money on a CID, IMO.

 

[luigisho]

The dead tach is indicative of the crank sensor or the DIS. I'm wondering how the old one cracked and if there was any damage to any of the wires/grounds in addition to the damaged outer casing. Are the bolts that ground the unit connected properly?

 

[gc4vette]

I'm having the same problem and I'm waiting for you to get it fixed so i know where to start with this problem . I'll just keep on reading the posts on this topic until the problem id fixed. I think i'm going to try thr crank sensor first.

 

[dfinley]

Well, next I plan to do a KOEO as suggested by SDPATT and post the codes as suggested by STEVETATRO.
If you replace the Crank Position Sensor, let me know the result.

 

[Blast7]

You could always head to Autozone and have them check the codes for free if you have trouble doing it yourself.