Re: Please help with engine Idle speed when warm ok, when cold hunts and stalls.

["kevin_sar <k@xxxx>" <k@xxxx>]

I think you need to speak to Mark Bourne or David Howarth on this, 
when yo find the answer make sure you post the answer. 

Kevin 

--- In doc-uk@xxxxxxxxxxxxxxx, "nickandkathryntomlinson 
<nickandkathryntomlinson@xxxx>" <nickandkathryntomlinson@xxxx> wrote:
> To All Delorean Tech-heads.
> Please excuse me if you have heard of this problem before but I am 
> fairly new to the world of Delorean ownership.
> 
> I have a problem with the idle speed on my car (Automatic) when the 
> engine is cold. It also appears to run rich although this maybe 
> associated with this problem.
> I have just tuned the engine and have performed the following 
> changes/ tests.
> 
> Changed spark plugs (plug gaps set to 0.68-0.70mm)
> Checked throttle is fully closed (including checking the throttle 
rod)
> Checked microswitch engages correctly and is electrically OK.
> Checked Distributor timing and vacuum advance shut off solenoid.
> Checked Fuel Canister purge valve/ isolated carbon canister 
(removed 
> and plugged hoses)
> Changed Lambda/O2 sensor
> Checked Frequency valve `buzzez'
> Checked Supply voltage and earth return at Fuel Control Pressure 
> Regulator.
> Checked for 35 ohm resistance for Fuel Control Pressure Regulator 
> heater.
> Adjusted Fuel Distributor flap so frequency valve duty cycle 
> oscillates between 32 and 45 on a dwell meter. (Note I have re-
> plugged the adjustment hole when taken a reading).
> Check Idle Speed control valve for operation.
> Pins 1 and 2	approx 100 ohms
> Pins 2 and 3	approx 100 ohms
> Pins 1 and 3	approx 200 ohms
> With +12v on Pin 2, momentarily earthing Pins 1 and 3 in succession 
> successfully opens and closes the control valve.
> Checked continuity of cabling from the control valve back to the 
> plugs on the idle speed ecu.
> Checked thermistor resistance at idle speed ecu. Reads approx 1.8-2 
> Kohms with engine cold, approx 220-290 ohms engine warm.
> 
> When the engine is warm the engine idles pretty smooth, varies +/- 
50 
> RPM at approx.780 RPM.
> The engine speed does drop when the air conditioning/ heated rear 
> window and lights are put on.
> As a further test I have at the ecu end put a manual variable 
> potentiometer (resistor) that can vary the resistance between 0 and 
> 5k on the ecu to simulate the idle speed thermistor. I used short 
> cables to connect the other connectors to the ecu using standard 
> spade/ blade male female connectors.
> I presumed that changing this resistance would make the engine idle 
> speed raise and lower as it would change the duty cycle 
oscillations 
> on the idle speed valve but this has no effect.
> Am I right in thinking that my idle speed ecu is at fault?
> I've check the other connectors i.e. supply voltage, earth, idle 
> switch operation, connection back to coil, continuity to idle speed 
> valve, protection diodes etc.
> 
> My other test tonight when the engine is cold would be to use a 
> standard auxiliary air valve used on standard volvos to simulate 
the 
> extra air required for a cold engine. OK, I don't have the correct 
> valve so I've improvised (don't laugh) by using a 22mm plumbing 
> isolator valve in place of the idle speed valve (in effect a gate 
> valve). I tried this out on a warm engine and it raises/ lowers the 
> idle speed ok. (Can't imagine screwing this slowly down while in 
> traffic !!)
> 
> Can anyone advice anything else I can try before I buy a 
replacement 
> idle speed ecu?
> Can anyone let me know what the idle speed of their Delorean is at 
> cold and how long roughly it is high for? My car is an automatic.
> 
> When warm the engine drives really smooth and is a joy to drive, 
when 
> cold I have to use my left foot on the brake.
> 
> Thanks all in advance for any further help
> Nick Tomlinson ? DOC Member 241.
> 
> p.s. If anyone has a "spare" ECU I could try then i'd be v. 
grateful.
> If this is a common problem I could try and source and test a few 
> from a breakers yard. Apparrently the same ECU could come from a 
> Volvo 200 and 700 series with the PRV engine.