01 Taurus - No Acceleration - Tansmission? Speed Sensor? Please Help

[klnaco]

I have an 01 SEL with the DOHC engine. This past week I noticed that the engine as not nearly as 'responsive' as usual. When stepping on the gas the acceleration seemed sluggish and the transmission shifting seemed slower than normal.

Today, after the car had been driven about 20 minutes it began acting worse. As you step on the gas the RPM's would increase but the shifting was very slow. After a while it would actually decrease in speed and have a difficult time getting and staying over 30 MPH.

Transmission fluid level is not low.

Does this sound like a transmission issue or possibly a speed regulator? Does anyone have any suggestions on what I can check?

Thanks for your help.

Ken

[shorod]

Any check engine light or O/D light illumination on the instrument cluster? Sounds like something should be screwy enough that the PCM would recognize it. You may want to check for powertrain codes by stopping by your local auto parts store and asking if they read codes at no charge.

-Rod

[klnaco]

No "service engine soon" lights being displayed. Could there be codes without any indicator on the dash?

[shorod]

There could be pending codes, or the CIDS/PIDS may point you to a misfire or emissions leak that wouldn't show up as a diagnostic code or check engine light. I'm not sure the scan tools at most of the "free" places will have access to those though.

-Rod

[klnaco]

Thanks Rod, I'll try getting it too the auto parts place run the diagnostic.

It's odd because it doesn't feel like the transmission is shifting rough, just not when it's supposed to. I had an older Taurus wagon which had a failed Transmission and this doesn't feel like that one did. Also, I'm not sure why a failing transmission would cause the car to decelerate. I've read some posts about the VSS but I can't say that the speedometer isn't functioning correctly and there are no visible codes.

Any thoughts on what I could possibly check would be appreciated.

[shorod]

There is an input shaft speed sensor and an output shaft speed sensor, maybe even in intermediate shaft speed sensor. These speed sensors are used by the computer to determine when the shift, when to engage the torque converter, if the torque converter clutch is slipping, etc. If one or more of these speed sensors are bad, they would cause the shift points to change without impacting operation of the speedometer. But, you won't have an indication to if this is the issue or not without having the codes, and you'll probably need transmission codes. The free scan from the auto parts stores won't be able to read transmission codes, but for free it's worth a shot.

-Rod

[klnaco]

Here's an update.

I attempted to drive the car to a local auto parts place but didn't make it a mile before turning around. The engine was cool and it immediately was reacting as it did when I drove it last (not getting above 30 MPH, not shifting). so no chance to pull codes.

When I returned home and had the vehicle in park, I watched the engine at idle and it was ~ 800 rpm. When I attempted to step on the accelerator,the engine RPM's would only raise to ~ 2100 RPM's despite how much gas it was given. To me this seems to rule out any vehicle speed sensors.

Is it possible this could be related to some blockage in the exhaust system; say a failed catalytic converter which might cause too much back pressure?

[shorod]

[quote=klnaco]When I returned home and had the vehicle in park, I watched the engine at idle and it was ~ 800 rpm. When I attempted to step on the accelerator,the engine RPM's would only raise to ~ 2100 RPM's despite how much gas it was given. To me this seems to rule out any vehicle speed sensors.[quote]

Not necessarily. Your car has an overrev limiter to prevent you from revving the engine with the car in Park or Neutral. Typically the limiter would be around 3000 rpms, but not being present to witness what your did, I wouldn't say this is abnormal. Did it rev to 2100 rpm fine, but started to misfire at the point where it would rev no higher? If so, that sounds like the limiter. If it struggled to get to 2100 or so rpm, then you are probably correct in assuming the problem is not related to a speed sensor.

-Rod

[klnaco]

I tried this again while the car was cold. Started it up and the engine had not problem going beyond 3k RPM's in both Park and neutral. Then tried driving it again and the same sluggish performance. It seems like when I let off the accelerator, the car shifts and then it will slowly build up in speed. When I let of the accelerator again it shifts again. This time I was able to get it up to 40 MPH, but slowly and sluggishly.

When I returned to the driveway I put it in park and tried to rev the engine again and it wouldn't get past 2100 rpm's again. This was true in neutral as well.

[shorod]

Any chance you have access to a scan tool with datastream capabilities? I think you could learn a lot by monitoring the O2 sensors, MAF sensor, TPS sensor, VSS, Coolant Temperature Sensor, Intake Air Temperature sensor, and probably a few others while driving the car when it's acting up.

-Rod

[mitchkev]

I have a contour doing the same thing, I believe it is going to be a dirty MAF sensor. I am working on this as we speak. If you figure out please let me know

[klnaco]

A not so good update:

I managed to get this into 2 auto parts places and had them try to pull codes and neither of them were able to (came back "pass").

I then dropped it off at a local shop and they just called and explained that they believe at least 1 catalytic converter has gone bad. They also said that typically when they've seen this happen before many times an upstream cat goes bad and parts of it can dislodge and affect the downstream cats. They quoted me $2500 to replace 3 cats. They also said there were stripped bolts in the manifold and this too would need work/replacing.

While under the car they said they noticed a transmission leak near the bell housing, which they said the Taurus is notorious for. Essentially they said this transmission is going to fail in the not to distant future. They also noticed an oil leak from a cylinder block.

Bottom line, essentially they warned me that the car may not be worth repairing.

This is now the 2nd Taurus I've owned and the 2nd Taurus that has had significant problems shortly after turning 100k miles. I don't think I'll be buying another one of these...EVER.

I'd appreciate any feedback anyone may have (pro or against) what the shop told me.

[klnaco]

I finally got the car home painfully driving 10 mph. While the car was running I tapped on each cat and was able to hear some 'rattling' in the rear cat. I was able to drop the cat and empty out the loose cat material that had broken down. I also it blew out the (shop vac) and reinstalled the cat. It's driving OK again although I realize this is temporary. At least now I can trade it in without getting totally screwed.

Hope this helps.