Cruise Control Surging/ Pulsing When At Cruising Speed

[silversmith]

I'm needing some help with a crusie control issue that has developed recently. Ford focus mark 2 2.0 tdci. It surges or pulses as if the brakes are being pulsed while at the cruisng speed I set. A bit like driving through lines of treacle. It only happens when trying to maintain the cruising speed. not on throttling up or down using the steering wheel controls. Ive had it into to the ford dealer who are perplexed. It's not showing up any error codes. However i have had the EGR replaced and the fuel filter changed in pursuit of the problem but it's still there. Does cruise control apply any braking if you run over the set cruising speed? say going down a steep hill is it applying braking I'm asking my self? Where are the sensors for the cruise control? where does it get its info from for mainting a constant speed?

Any help you can give me would be appreciated.

[Steve27]

Hi Allan

Regarding your question on cruise control and your brakes the answer is no the system does not apply brakes to slow you down should your speed increase. only on the latest models does the system slow you down to your set speed.

Regarding your surges I can't think of anything sorry.

[silversmith]

Still no joy on this. No faults were detected after a lengthy computer interrogation. Driving me crazy now.!

[InKontrol]

If I'll be honest if the dealership started throwing parts at it like the EGR and fuel filter then I'd use a different dealership.

Have you tried to maintain the same speed without the cruise control? Have you also set the cruise control to different speeds, e.g. 40, 50, 60, 70 and does it do it at all these speeds or just a certain speed?

Sent from my iPhone using Ford OC

[silversmith]

If I'll be honest if the dealership started throwing parts at it like the EGR and fuel filter then I'd use a different dealership.

Have you tried to maintain the same speed without the cruise control? Have you also set the cruise control to different speeds, e.g. 40, 50, 60, 70 and does it do it at all these speeds or just a certain speed?

Sent from my iPhone using Ford OC

Yes all is fine when maintaining a speed without the cruise control active. It accelerates and decelerates fine too using the steering wheel controls when it is active it just has trouble when it s at the set cruising speed what ever i set it at.

[silversmith]

If I try a swap out of parts, probably from a breaker - which ones will i need? ECU (CPM) presumably, what about the instrument cluster - is that involved with cruise control? Pedal sensors, steering wheel controls? I'm also assuming I'll need to take it it to a ford dealer for programming. Thank you.

[InKontrol]

I wouldn't throw any more parts at it but rather go back to the dealership, and then ask one of the guys to come out with you with the IDS connected. They should be able to read the values in real time while the car is moving, which touch wood would indicate why the car is surging. It's possible that one of the sensors measuring the speed of the vehicle is acting up, and therefore fooling the car in to thinking it's traveling slower than it actually is.

Just my two cents but considering that it only happens when cruise control is active leads me to believe there's an electronic control issue somewhere.

I dislike dealerships that throw parts at a car without thinking through the logic first. Was it Arnold Clark Dumfries by any chance?

[silversmith]

I wouldn't throw any more parts at it but rather go back to the dealership, and then ask one of the guys to come out with you with the IDS connected. They should be able to read the values in real time while the car is moving, which touch wood would indicate why the car is surging. It's possible that one of the sensors measuring the speed of the vehicle is acting up, and therefore fooling the car in to thinking it's traveling slower than it actually is.

Just my two cents but considering that it only happens when cruise control is active leads me to believe there's an electronic control issue somewhere.

I dislike dealerships that throw parts at a car without thinking through the logic first. Was it Arnold Clark Dumfries by any chance?

No it wasn't them - though I know what you mean. lol Thanks for your input though - I'm with you, I thought the problem was electronic and I dont want to throw more parts at it. Its good to get a second opinion.

[jeebowhite]

I must admit, if the fuel filter hasnt been changed yet, that would be the first thing I would change, as for the EGR, I would just blank it.

Total cost so far would be about £30, and both would do wonders for the car :p

[Hameee]

I know this is a old topic, however Ive been searching the web for weeks and this post is the only I can find that is the exact same conditions as mine, did you ever find a fix to the cruise control pulsating?