726 running rich?

[ILM1010]

I am not a mechanic. When i start my Delorean, it idles...and then starts to hunt for idle..and goes high and then drops low enough to quit..so i restart it, and give it a little throttle until it is warmed up so to speak and then it runs good. Also when i am driving, im hearing a lot of back firing sputtering, etc...when i downshift. The motor sounds right, I have noticed when sitting at instersections that the car shakes while it idles...on and off. Up and Down, Up and down..the motor goes in idle. I recently had my accumulator changed out by a mechanic who is good, but is still guessing his way through issues with Deloreans. Any ideas on whats going on? As long as its not hurting the engine, then Im fine with it.

Thanks guys
Pete Voss
Minneapolis, MN

[David T]

I am not a mechanic. When i start my Delorean, it idles...and then starts to hunt for idle..and goes high and then drops low enough to quit..so i restart it, and give it a little throttle until it is warmed up so to speak and then it runs good. Also when i am driving, im hearing a lot of back firing sputtering, etc...when i downshift. The motor sounds right, I have noticed when sitting at instersections that the car shakes while it idles...on and off. Up and Down, Up and down..the motor goes in idle. I recently had my accumulator changed out by a mechanic who is good, but is still guessing his way through issues with Deloreans. Any ideas on whats going on? As long as its not hurting the engine, then Im fine with it.

Thanks guys
Pete Voss
Minneapolis, MN

With no history on the car I am guessing it is in need of a tune-up and possibly a warm-up regulator and numerous vacuum leaks.

[ILM1010]

I had a stage 2 put in it last year at DMCMW, this year it developed a hot start issue, so the accumulator was changed out, and since then...this has been happening

[Mark D]

Given your car's history then I'd start with Dave at DMCMW to help diagnose your issues. Chances are he'll be able to find the root cause of your issue since he's got experience with your particular car. I'd be recommending him anyway even if you hadn't already had work done at his shop. Often times he can talk you through a few things to check over the phone to at least narrow down the possibilities.

[David T]

Given your car's history then I'd start with Dave at DMCMW to help diagnose your issues. Chances are he'll be able to find the root cause of your issue since he's got experience with your particular car. I'd be recommending him anyway even if you hadn't already had work done at his shop. Often times he can talk you through a few things to check over the phone to at least narrow down the possibilities.

Start by looking for vacuum leaks and possibly the warm-up regulator.

[Rich]

First, there is nothing in your description of symptoms that points to running rich - or not. We can set that aside for now. Numbered your car's symptoms in bold here and commented below.


1. When i start my Delorean, it idles...and then starts to hunt for idle..and goes high and then drops low enough to quit..so i restart it, and give it a little throttle until it is warmed up so to speak and then it runs good. 2. Also when i am driving, im hearing a lot of back firing sputtering, etc...when i downshift. 3. The motor sounds right, I have noticed when sitting at instersections that the car shakes while it idles...on and off. Up and Down, Up and down..the motor goes in idle. 4. I recently had my accumulator changed out by a mechanic who is good, but is still guessing his way through issues with Deloreans. Any ideas on whats going on? 5. As long as its not hurting the engine, then I'm fine with it.

1. A bad idle condition during initial warm-up phase can be due to, among other things, a warm-up regulator that isn't working right (bad connections, burned out, etc.)
2. No idea about that nor whether it's related to other problems here. Hard to be sure what the symptom description is.
3. A widely-fluctuating idle after warm-up can be several things. Bad/dirty idle motor, bad connections to idle motor, vacuum leaks as David T mentions, maybe other causes
4. Replacing the accumulator would by itself not affect any of the engine symptoms on your list.
5. None of your problems will hurt the engine. But they might hurt other stuff:
- running very rough and almost quitting at idle will be rough on the motor mounts
- hunting idle speed can be bad on the auto transmission and drivetrain if you put it into gear at a moment when the engine happens to be running real fast
- and if you are having to restart the engine a lot as noted in #1 then of course you are putting unnecessary wear on the starter system and everything feeding that system

If you cannot get the car over to Dave's in Chicago then find a good foreign car shop in the Twin Cities who knows their way around the Bosch K-Jetronic system.