Archived Surging throttle, then no throttle response

[Lhotka]

I recently (800 miles ago) had the lift pump replaced under warranty. Two days ago the truck was in for the crank case breather bottle relocate. The truck is not running right since I picked it up from the shop. The throttle began to surge up and down between 1700 and 1900 rpms. Then the throttle response ceased altogether and engine would not respond when I placed the pedal to the floor. The engine would only idle and the check engine light illuminated. I turned the truck off for a couple of minutes then restarted it with throttle response, but continued surging and hesitation. Limped the truck home.



Any suggestions?

 

[Gary - K7GLD]

IF you're talking about the full-blown breather relocate - that is quite involved, and according to instructions I have seen, involves substantial work around the VP44 and TPS - wonder if something in that area got screwed up in the process - especially the TPS, since when the VP44 goes, it usually dies completely - no idle...



There IS a rather quick and easy TPS re-calibreation procedure that can be done right from the driver's seat in only a few seconds - maybe someone can pop in here with the details...

 

[Alan Reagan]

The TPS or APPS calibration in this case requires you to disconnect the batteries for about 30 minutes. Reconnect and turn the key to on (DO NOT START). Slowly depress the accelerator to the floor and then slowly release completely. Turn the key off. Then start the truck.



I am more concerning that with the surging the problem is in the Camshaft Position Sensor (CPS). It's possible that the connector to the CPS was pulled during the breather bottle relo. That will cause surging and lack of response.



Not sure on your year but I believe you can retrieve the codes by:



Turn key on, then off, then on, then off, then on. Don't start. On the third ON, the odometer will display the fault code. Let us know what that is. It would have been set when the check engine light came on.

 

[Lhotka]

TPS related

Sounds like it might be TPS related. I am getting p 1693 and P 0500 codes.

 

[sag2]

Do you even have any grades steep enough to get the oil to leak out the breather? In my experience you have to have a VERY steep grade for any oil loss. Hope you didn't get it done for nothing and caused another problem as a result. Good luck.

 

[Alan Reagan]

P0500 is No VSS Signal. Vehicle Speed Sensor. Located on the rear axle. With the 1693 code you may have a dirty wiring harness connection causing this problem. Is the speedo working allright?

 

[JR2]

This is not related to your problem but I get the P0500 code all the time in the winter, its from the use of a high idler. I don't know if you have one or not (I know the Fairbanks dealer sells them and that if I lived in FBX I would have one) but what happens is the ECM sees high rpm for a while and no vech speed. It then assumes that the VSS is bad. The VSS error is probably not your problem. It sounds like a TPS problem. Remember some codes do not show on the odometer.





JR2

 

[Lhotka]

Thank You

A defective APPS was the culprit and replaced by the dealer under the engine/drivetrain warranty. They claim the problem APPS was not related (I'm skeptical) to the breather bottle relocate. Interesting... because I had no prior engines problems before the breather bottle TSB..... and the truck ran like crap shortly after leaving the dealer lot.



Thanks for your assistance.

 

[Alan Reagan]

Thanks for letting us know what the problem was.