Tickover

[Choosing a name is hard]

If you’re going down the road at 20 miles an hour and you take your foot off the throttle completely what happens does the car slowdown or does it carry on at that speed?

 

[Steven Smith]

If you’re going down the road at 20 miles an hour and you take your foot off the throttle completely what happens does the car slowdown or does it carry on at that speed?

Will let you know tomorrow.
Was the car up to temperature or was the engine cold ?

 

[Choosing a name is hard]

When it is warm

 

[Steven Smith]

If you’re going down the road at 20 miles an hour and you take your foot off the throttle completely what happens does the car slowdown or does it carry on at that speed?

Yes, car sits at 20.

 

[teamzr1]

If you’re going down the road at 20 miles an hour and you take your foot off the throttle completely what happens does the car slowdown or does it carry on at that speed?

Have to factor in if the road was level or not
What gear tranny was in and ratio of rear diff
and how long did it take for speed to drop

At some point mass of vehicle and getting off the gas pedal that mass would carry speed for a bit
Try tests in other tranny gears and see what difference in time it takes for the mass of the car to cause reduction of MPH

 

[Choosing a name is hard]

I should have also said if I sit at the lights with my foot on the break and without touching the throttle I let the brake off the car will up to about 20 miles an hour The tick over is at 1000 RPM and I think that might be a little high It’s not really a problem other than if you’re following along something slow your pretty much living on the brakes

 

[Chuffer]

I should have also said if I sit at the lights with my foot on the break and without touching the throttle I let the brake off the car will up to about 20 miles an hour The tick over is at 1000 RPM and I think that might be a little high It’s not really a problem other than if you’re following along something slow your pretty much living on the brakes

1000rpm sounds a bit high . I don`t have any experience of C4`s but all the cars I own or have owned in the past generally tick over at about 750 / 800 rpm max be they carburetor fed or fuel injected with ECU`s etc .

 

[Mr. Cricket]

1000rpm sounds a bit high . I don`t have any experience of C4`s but all the cars I own or have owned in the past generally tick over at about 750 / 800 rpm max be they carburetor fed or fuel injected with ECU`s etc .

It's the rare one-off self-driving Corvette Chuffers

But yes OP, idle seems to be the cause of that

 

[teamzr1]

You did not state what year your C4 is
but as an example, I selected a 1988 C4 as the GM tune in the ECM (engine controller)
As coolant raises, the ECM targets/commands what the RPMs for idle to be via the IAC solenoid
by a step motor that goes inward and outward against the TPS CAM of butterfly

You might want to make sure that IAC is dirty and sticking or the linkage from gas pedal to throttlebody
or needs adjustment and check the wiring connector for it is clean and plugged in firmly

Also, dirty fuel injectors or carb jets can effect the AFR that effects RPMs
also any air leaks at low RPMs



As RPMs increase, so does the commanded timing
As you see higher RPMs force than higher timing for idle (I highlight 400 to 1000 RPMs)
.

 

[Chuffer]

It's the rare one-off self-driving Corvette Chuffers

But yes OP, idle seems to be the cause of that

A self driving Corvette !!! What will they think of next ? Surely not an EV one ?

 

[CaptainK]

My Corvette is self driving - I drive it my self

 

[Chuffer]

My Corvette is self driving - I drive it my self

My Corvette has a voice activated driver assist system ... it`s the wife nagging in my right ear !!!

 

[CaptainK]

My Corvette has a voice activated driver assist system ... it`s the wife nagging in my right ear !!!

Thankfully mine deactivates when the Corvette's engine is running - I can't hear anything else except side pipes