SOLVED !!!!!!!!! Re: [doc] Please help with engine Idle speed when warm ok, when cold hunts and stalls.

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

Hi Nick

When you took the ECU apart did you take any pictures of the PCB from 
the top or the bottom. If any one has an old one it may be worth 
reconing it so other members can try one that actually works. It 
could then save a lot of problems. 

Did you manage to work out the circuit diagram.

Thanks for letting everyone know how you fixed it 

Kevin

--- In doc-uk@xxxxxxxxxxxxxxx, Nick Tomlinson 
<nickandkathryntomlinson@xxxx> wrote:
> 
> I've sorted my idle speed problem out !!!!!!!!!! Bad news and good 
news. Bad news was that it required a new idle speed ecu. Are these a 
common failure? Seeing as though I needed a new one I decided to take 
the old one out and have a look inside (I did electronic engineering 
for my degree and I don't get out much ! ) The case is definately NOT 
designed to come apart easy so I had to cut it open. I did this 
underneath so if glued back together it would appear original when 
screwed back in place behind the drivers seat. I looked at the 
components inside and couldn't believe how basic it is, well, 
compared to new ones anyway. Good news, after some quick checks on 
the transistors and looking for dry joints on the circuit board I 
decided to see if you could still get the IC's (chips). I recognised 
3 out of the 5 straightaway (I said I don't get out much) and with 
some quick cross matching with the others I made a list. I also 
decided to get plug in sockets for the chips so I could change them 
quick in the future (no jokes here please about being made in Japan 
or substituting them for 1950's valves). Guess how much? Approx £3.50 
for the lot from Farnells. The question is, did it work? Answer YES 
IT DOES. I am now a happy bunny with a lovely running engine, well, 
apart from the rich mixture at startup. I think I'll strip down the 
warm-up regulator at the weekend for a look. I managed to borrow a 
digital pressure indicator from work so I will test all my fuelly 
bits this weekend (assuming I don't get called out) Wish me luck! 
btw, I bought enough chips to do 2 ecu's. If anyone wants me to have 
a go at repairing thiers then let me know. If this is a common 
failure then I may have some work on with the club ! If anyone wishes 
to do the same, i have supplied an excel spreadsheet with the order 
codes and prices from Farnells. Please note that a minimum order is 
probably required, I bought a new soldering iron at the same time.
> 
> 
> Nick.
> 
> "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.
> 
> 
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