Hi I have a fairly serious just got back from a 15 hour drive, I had the cruise control set at 100 kph, as I was exiting the highway I pressed the brake pedal to slow down and the engine started accelerating I looked down and the cruise control light had gone off but the engine kept fighting against me, after about 6 or 7 seconds just before I was about to reach for the key it returned to idle.

everything on the truck is standard apart from my dp tuner, I was in the 60hp tow setting.

One other problem I have been seeing since I put the tuner in is that often when I am driving, if I come to a stop, just as I stop the engine will sometimes idle up to 1000 then back down, and sometimes will idle too low then bounce back up slightly above normal idle then settle.

Has anyone heard of this as I am now a little nervous to use the cruise.

 

K what year, model and engine size are we working with here?

 

The DP makes me think you have a 7.3 PSD? If the idle started acting up when you installed the DP, i'd suspect something related to the tuner being loose or a loose wire. Have you had the recall done on your rig yet (wiring harness on master cylinder)?

 

When the brakes didn't deactivate the cruise, did you try the "OFF" button on the steering wheel?

 

This was my thinking too. This is the first I recall reading about an issue with the DP, and it's by far the most popular tuner for the 99-03 7.3 here.

Give us some more specifics and we'll help you get to the bottom of this. If it's a problem with the DP, they will exchange it or do whatever it takes to make it right. They often monitor and chime in down in the 7.3 section.

 

Thanks for the info, I'm still pretty new to tuners

 

Ok its a 2002 F-250 7.3 PSD

I didnt have time to try the cruise off button it was all over before i thought of that, but I do know that the green cruide light went off, it was the first thing I looked at.

I checked today to see if I could have hit the gas and the brake at the same time as I was a bit tired, but I cant see how I could the pedals have quite a big gap between them. And the whole funky idle thing just gets me wondering.

Thanks for helping guys

 

If the light went out, then the cruise control turned off when the brakes were applied. That isn't what caused the issue, unless the cruise control is not releasing the throttle after deactivation.

Still, the "slow to return to idle" after adding the DP tune would point towards that being the problem. Did the manual say anything about the tuner having a "Toyota" setting?

 

wasn't this part of that Cruise Control recall?

 

There have been quite a few on here, myself included, that have done the "foot on the gas and brake at the same time" thing, so it is in fact possible, I think it depends on the type of clodhoppers you have on, and for me it seems like it is more the side of the foot that catches the gas pedal, not the bottom.

 

The diesel cruise control setup is different then the gasser version. Our throttle is fly by wire, so there's no movement of the pedal when cruise is on. The PCM simply tell the truck to go x speed and it does. You can still push the pedal down and get more speed out of it though.

 

"Toyota setting"

 

My throttle is also fly-by-wire.

 

Have you had the Cruise Switch recall done?

 

Almost the first thing I would do is check the cruise control deactivation switch.

I had a 2004 with the "new" switch, which failed and had to be replaced just outside of the warranty period.

Normally, the failure mode is stuck on "off" (safe) but it is possible for it to be stuck "on".

Coincidentally, when you buy a new master cylinder (as I am about to) from Ford, it includes both the sensor for fluid level and the cruise control deactivation switch.

That tells me that it is a "stealth" recall on the new switch.