Re: [DML] idle revisited

[Louie Golden <louie@xxxx>]

Of course I remember my last DeLorean ran on a manual idle speed circuit Bill. The car actually ran much better that way. I am going to go and buy some vacuum caps and cap off the idle speed motor and see if my idle problem goes away when the idle speed motor is non-functional. However the idle speed motor does buzz with the ignition on, so I think it's OK. I can try running a manual idle circuit for a while, but don't want to keep the car that way permanently. The more things I change from stock on the car, the less someone down the road who works on the car will understand how it operates. Idon't plan on ever selling the car, but I may have someone else work on iteventually, and I'm also not going to be around permanently either. Someone will inherit the car one day. I try to look to the future with these cars...

I've been told before that the DeLorean O2 sensor does nothing until about 300 degrees. Why then is it so common for people to diagnose a car that hunts at idle to have a defective O2 sensor? Or is it only when the car hunts when *WARM* that the O2 sensor is bad? So would a vacuum leak cause huntingwhen cold, and high idle when warm then?

Just to reiterate my car's behavior, when the engine is VERY cold (when it has been sitting overnight), it does hunt for about a minute, then the idlesmoothes out to about 800 rpms and stays that way for several minutes until the engine gets warmer. Then something changes the idle speed- the car jumps from idling perfectly at 800 rpms to idling at 1500 rpms. It's literally like the flipping a switch. If I go out and drive the car after this, theidle will get stuck at about 2000 rpms now. The idle speed has progressively gotten higher since I've owned the car. These symptoms don't sound like a vacuum leak to me... it sounds like something electronic... though I could be wrong. I'm certain the car has had the intake manifold off in the last5-10 years. It was serviced through DeLorean Motor center until the late '90s until the car came to the east coast. The car has probably $10k-$15k inreciepts from DeLorean Motor Center for work done between '95 & '98. DeLorean Motor Center put on a new water pump in '98 I believe, so that pretty much means the top half of the engine was off as recently as that, and couldhave been off again up to 2 years ago by a mechanically savvy former ownerwho was an avid DML member (Rob Starling).

Just as another reference point the car idles extremely richly when the caris very cold (ie- sitting over night). That's why I tried putting on an ECU from Bill's parts engine. The car runs so richly that it puffs out unburned fuel. After the car has been running about 3 minutes I'd say this problem goes away. This roughly coincides with the car's hunting as well. After the car has been running about 5 minutes the high idle begins. I don't *think* the car has any vacuum leaks, though I will try and find some now per everyones suggestions. I know that some of the vacuum lines are showing theirage however, as Bill and I replaced a few while putting in a new CPR the other day.

Regarding the idle speed ECU- I don't have another car to pull parts from. I have a few random parts that I pulled off my old DeLorean which was wrecked earlier this year, but that was before I wrecked the car. The car is notin my posession, and the parts I have from it are completely random. Do you guys think a vendor would let me return an ECU if I bought one, and it didn't fix my idle problem? I just have a huge problem spending so much for this part.

Louie Golden
VIN 5252
NC Plates "88 MPH"

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