Hesitation when cold, is it normal?

[Tom_hd02]

I drove an early DeLorean a few days ago. Started right up, but I noticed some engine hesitation when I stepped on the gas pedal. The owner said that it is normal when the car is cold. I had to feather the gas pedal to get smooth acceleration. Is this normal?

[David T]

Yes. It can be minimized but not eliminated.

[Tom_hd02]

Thanks David.
I believe I found the answer in this thread:
http://dmctalk.org/showthread.php?10...tion-When-Cold

It could be an issue with Warm up Regulator (a.k.a. Control Pressure Regulator).

[Michael]

A slight hesitation for the first minute or less is normal. It should be only a slight hesitation and the car should be 100% drivable still. If it bogs down drastically or has to "warm up" before you drive then you may have an issue, possibly in the WUR. If the car takes longer than 1 or 2 minutes to warm up before it idles and drives correctly, I would be more skeptical of the fuel distributor than the WUR.(or even both!) You can test the resistance on the heating element in the WUR but I do not know if there is a way to test the WUR itself(if it were clogged, etc). You can check the screen to see if maybe a bunch of crud has impeded the fuel flow but I am not aware of any tests to the mechanical side ither than the heating element(maybe someone else can chime in).

Also check those vacuum lines on the backside of the rocker cover that connect to the WUR.

Check the o rings in the primary pressure regulator in on the fuel distributor. These are mostly associated with hot start issues but if they are really bad, they can affect cold start issues as well(plus it's very easy to check). Any deformity or slightest nicks in the rubber o-rings and you should replace them which is very cheap and easy (also make sure they have not hardened). PS, be careful when removing the nut that holds that plunger in place. It's spring loaded and could fly out.

Another thing to check is the plunger on the FD. The three screws hold it in place and you can check without removing any fuel lines. Gently lift the FD up and make sure the plunger falls freely down and does not stick. It's a machined fit and nothing holds it in place so don't let it cone conpletely out. It should move slowly but have absolutely no resistance when pushed back into the FD. If it is sticky or stuck then a new fuel distributor may be in order.