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.