For years I've wondered why the cruise control takes what feels like forever for the system to actually engage and take over maintaining a set speed. When I get to my desired speed and press the SET button, I have to keep my foot on the pedal for at least 25-30 seconds before I can feel the system taking over. If I press SET and remove my foot immediately, the car slows down a good 5 MPH or more before taking over and sloowwwwwwwly getting back up to the speed where I set it.

Other cars I have driven, cruise activation is INSTANT. Now in most cars I figured this was attributed to the drive-by-wire systems. 2010 Ford Fusion, our 2014 Mazda CX-5 and other newer vehicles and so on. Press the button, remove foot and it holds speed immediately.

However since I purchased my 2000 Miata this summer, I noticed that car also has INSTANT cruise actuation. Now on that car, the cruise uses a vacuum line from the engine, in addition to the cable controlling the throttle. The Integra only has a cable to the throttle pedal, no vacuum line. Could that be why it takes so much longer to engage, as opposed to a system using engine vacuum? I would have thought than an electronic system would be better, but in this case perhaps not.

 

Cable styled - cruise systems (both vacuum and electronically actuated) have some degree of lag built into the system, since neither of them know exactly where the throttle pedal is. In vacuum systems, the slack take-up is a lot faster because the vacuum force produced at cruising speeds is a lot higher. In electronically controlled cruise systems, a take-up motor must wind up and remove slack from the cruise control throttle cable. If the vacuum is weak (vacuum systems), or if the motor is weak (stepper motor systems), then a lag in system engagement will result. Likewise, in both systems, if the cable is not properly adjusted or is sticking, a lag will also develop. I have seen both conditions arise.

Diagnosing the system can be difficult since it is mostly mechanical in nature (even if it is electronically controlled). I would start by doing a free-pull test on the cruise control cable to see if it binds up. In an electronic system, if the cable is free to move, it is either out of adjustment, or the stepper motor cannot produce the torque required to move the cable fast enough. Typically you can feel this by having cruise on going down a steep hill where the vehicle will overspeed because the throttle will not close fast enough, or uphill where the vehicle will underspeed, not opening fast enough, but still function only slower. Most vacuum systems will behave the same way if the vacuum system has low vacuum due to a leak. In both cases, I have found bad motors, and leaking vacuum tanks as the root-cause.

Drive-by-wire throttles have near zero lag, because the inputs are from the accelerator pedal position sensors and current vehicle speed controlled via serial data by the ECM. This isn't much different from motor or vacuum systems, but the method of control (PWM of the vacuum solenoid on vacuum systems and PWM control of the stepper motor system on motor-driven systems) is slightly different. In drive-by-wire systems, the throttle is both input and output.

So in short: Laggy cruise control is likely caused by a mechanical issue that prevents fast feedback (cable stuck, low vacuum, weak motor). In a drive-by-wire system, you will see a DTC set if the system cannot maintain speed.

 

Mine does the 5 mph dip you experience, but it picks up speed reasonably well otherwise. It wasn't any worse than the cruise control system that was on my 80s VW lol.

My 2000 civic ex on the other hand, won't maintain speed when it is set. I gave up trying to figure out as I just use it for city driving

 

That sounds wrong. EG with cruise is instant response. Can feel it take the throttle pedal in less than a second. Same cruise module as the DC. Sounds like you have a failing cruise motor or bad cables.

 

hmm never thought about checking the cable or the motor in the cruise unit. Yeah I'll check that out. Haven't really noticed any problems up and down hills while actually cruising along the highway in 5th gear. It's only that first initial Set command that takes forever.

 

I know this is a few years old but did you figure out how to fix your cruise control? My 1994 Civic coupe is doing the same thing. My 1994 Civic sedan cruise control works fine.

 

not really. I looked inside the CC's motor control unit, and while it looked like the cable could be set to take out some slack, it was actually adjusted per the Helms factory service manual. So I didn't change it. I just live with it.

 

Patrick, I came across this thread while searching for a YouTube video I had previously found that had the solution to this, if you haven't already done it by now (TLDR: you do want to adjust that cable).

The video is by Kanjo Brothers and he explains the reason for the delay (too much free play in the cable inside the under-hood cruise control module) and the solution (loosen the two jamb nuts, slide the threaded sleeve outward to remove slack in the cable and then retighten the jamb nuts).

My delay was just like yours. I adjusted the threaded sleeve outward, moving the nuts down about 1/3 of the total remaining threaded length and it cut the delay in half, to about 2 seconds and a 2-3 mph drop. After a couple weeks, I adjusted the sleeve outward more, with the nuts down around the area of the fair-sized gap in the threads, to where I was almost afraid I adjusted them down too far, but they still grabbed. My cruise control activation is now all but instant, maybe a one second delay, and negligible mph drop. I'm a happy camper. This is the only video or other source that I found that definitively addresses this problem. Here's the link:

 

I'm gonna try this. Thanks! A shop had recommended a brand new VSS to address the cruise control issue.

 

thanks dude! Oddly enough, after I had my engine out last winter and put it all back together, my CC does seem to take over faster than before, for whatever reason. I didn’t change or even touch the cable in the actuator, while it was sitting up on the windshield for like 5 months. Who knows.

 

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