03 pontiac grand am ultra cruise

Ok I put a ultra cruise model #250-1316 on a 03 pontiac grand am w2.2 ecotec 4 cylinder.I  adjusted dip switches accordingly. The cruise works but whenever it needs to accelerate to maintain speed ie hit the gas a little for hills and such it surges. Kind of like its over compensating, it will hit the gas hard enough to over accelerate then it will let off making  it seem like its having a seizure. I called tech support to see if a dip switchs could be the problem but to be honest I think I knew more about it than he did. I have the car coming back in and I am trying to get some ideas before it gets here. Any ideas will be much appreciated.

You can check a few things. Make sure that the DIP switches are set for either Med (default) or Low sensitivity. Set the DIP switches for the engine set-up timer to 4 cylinder low. The VSS is 4,000 PPM. The DIP switches should also be set for a square wave. If you have to change any of the switches, you MUST unplug the electrical plug from the cruise unit, otherwise it won't take the new settings. The throttle cable for the cruise should be absolutely tight, but not so tight that the engine's idle speed increases. I assume that the vehicle is an automatic, so DO NOT hook up the blue tach wire. Cut it and tape it off if it is hooked up. Make sure that the cruise has a good ground connection to the chassis of the car. I guarantee if you do these things, the cruise will work perfect. The likely cause of your problem is incorrectly set DIP switches for Sensitivity and Engine/Set-Up Timer.sparky

Becareful about setting pin switches # 1-3 because if you overcompensate for the downshift when going up the hill ( extending the time on the throttle ) you could damage the servo on the CC. I had this happen with a customer a month back where he drives up this hill and the accelorator kicks in hard and all of a sudden in the middle of the hill the CC kicks out the accelorator. Setting the CC to compensate for a longer acceloration durationon a hill will cause servo burn out.Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

I test drove the car and the accelerator comes in going up hill but not aggresive it maintained speed well without any surging. Is there a tech source that says how to set the dip switches for most vehicles? I originally went with what the book said for this car and it was off considerably, causing the car to have seizures when going up a hill.

I actually called tech support as well about this problem and this is what they told me. The customer didn't want me to fool around witht he dip switches after he heard what it could do cause tech support said that they won't warranty the unit if it was set up to extend the accelorator while downshifting.Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

What it boils down to is there is no substitute for experience. Rostra won't deny warranty on any cruise unless they can actually prove the defect was caused by improper installation or other means. I am going to disagree with you Jeff on the matter of burning the CC out. As someone who has installed probably over 5,000 cruise controls, I rarely find a Rostra cruise control unit to go bad. I bet that in over 25 years of installing cruises, I have only seen about 20 units actually fail. Most of these were very old and well used units. Dip switches 1-3 are only for the cruises ability to notice a change in the VSS. The engine/set-up timer switches are designed for how fast the throttle is pulled back once it is told to by the cruise's logic circuits. Rostra techs (Thomas and Yates) are very good at what they do, but tend to very conservative when recommending solutions to problems. I have know them for many years and value their knowledge. Like ssomeone once said, "Good chef's don't follow recipes and good installers don't always follow manufacturers guidelines". The only way you can truly understand how to set DIP switches correctly to make the cruise smooth as silk is to fully understand all the variables that go into a cruise and how it relates to engine performance. If is installed or set up incorrectly, the cruise won't perform as it should and the customer will complain. Jeremy, I am glad you were able to resolve your problem. In future you will likely find that the best settings are for aa engine set-up timer that is the lowest for the correct size engine and mid sensitivity for 6 and 8 cylinder engines and low to extra for 4 cylinder ones.sparky

Well just to further explain what was happening is the cruise was not engaging soon enough for 2 reasons 1 the cable was not taught enough. Tach wire was also hooked up, gain settings were on high were install booklet was marked. I am no expert cruise installer, this was my 11th one. I can only go by what I've seen and by making these adjustments it works very well. I didn't notice the throttle holding on longer than normal. I hope it doesn't damage the cruise though, this guy was tough enough to deal with. I appreciate all the input, makes me realize how much I have to learn.