[ruffyrder]

Recently purchased an '02 Deville DTS. So far, very happy with the car. One thing that did come up was the Crank Sensor and after lurking around here a little bit, that seems to be a common problem. SO, I had the dealership replace it as part of the purchase agreement. I had about 2 weeks to drive the car before they could get it in to replace it. Gas mileage seemed to average about 25-26 highway....not too bad.
Now that the sensor has been replaced, mileage has dropped to 19 to 21 average. I found a buddy with the Snap-on programmer and had him do the Crank position learn, assuming the dealership had not done, or forgotton to do it....didnt seem to help, mileage has remained low.
So, the question is, what else could have changed? Is there something else that needs to be done, changed, reprogrammed? Anything? Any help would be greatly appreciated!

 

[mcowden]

Recently purchased an '02 Deville DTS. So far, very happy with the car. One thing that did come up was the Crank Sensor and after lurking around here a little bit, that seems to be a common problem. SO, I had the dealership replace it as part of the purchase agreement. I had about 2 weeks to drive the car before they could get it in to replace it. Gas mileage seemed to average about 25-26 highway....not too bad.
Now that the sensor has been replaced, mileage has dropped to 19 to 21 average. I found a buddy with the Snap-on programmer and had him do the Crank position learn, assuming the dealership had not done, or forgotton to do it....didnt seem to help, mileage has remained low.
So, the question is, what else could have changed? Is there something else that needs to be done, changed, reprogrammed? Anything? Any help would be greatly appreciated!

Have you looked for any new codes yet? Does the car accelerate as well as it did before the sensors were replaced? Are you absolutely sure your driving style hasn't influenced the mileage? Gas mileage goes down a little bit in the winter, but probably not as much as you're seeing. That's a significant decrease.

 

[ruffyrder]

No new codes, thought to look at that too. Car seems to accelerate just like it did before, if not a little better.

Driving style hasn't changed. The milage I'm looking at is with the cruise set on the interstate. Even around town though, it at least seems worse. I am watching the instant mpg read-out on the dash. Accelerating from a stoplight I am seeing 4 or 5 instant mpg, where before it was 8 or 9.

Just puttering around town, I am seeing 14 or 15, before it was around 18 or 19.

Can the crank position learn be done inaccuratly? The scan tool said it was completed successfully.

 

[Ranger]

Have you checked for a leaky FPR? That would affect milage negatively.

 

[ruffyrder]

Also, another thought. I notice this right away after leaving the dealership. But of course, I picked it up afterhours and its 90 miles from my home. I just assumed the crank learn had not been done and would do it on my own time.

But now that its done, I think they may have done it anyway and the problem is associated with something else, or the crank learn not being done correctly. I did follow the Snap On instructions that I found online for doing the learn and the tool said it was successful...

 

[ruffyrder]

Have you checked for a leaky FPR? That would affect milage negatively.

Will check it out, but no smell of fuel and nothing leaking as far as I can tell.

Where is it located? I will take a look just to be sure...

 

[Ranger]

You most likely will not smell fuel as it will leak into the intake manifold. The FPR is a about the size of a 35mm film can and is located on the rear fuel rail. It has a vacuum hose attatched to the top. Just pull the vacuum hose while idling and look for fuel leaking. If there is any, it needs to be replaced.

 

[ruffyrder]

Nothing really for codes, no PCm codes, nothing in the history. Cleared them all anyway.

Also, pulled negative battery cable off the battery for an hour last night and let the PCM re-learn.

Check the FPR, doesnt appear to be anything leaking. Pulled the vaccum line and there is plenty of suction there.

Still having the same problem. Really crappy gas mileage....

Any more suggestions?