G'day All, the additional 86 K100RS in the shed is just about ready for rego. Changed HT leads and coils and now runs on all 4!!!!!. BUT it is difficult to start when cold. I suspect it is the temperature sensor stub, the heat sensor relay or the ECU. Can anyone of you learned members please enlighten me. Thanks in advance. Cheers Tom

The relay have nothing to do with this, it only starts the fan and warning lamp.

I would suspect the temp. sensor (or its connections), easy enough to check.

Measure the resistance between contact #10 and 13 at the injection ECU connector
(female side).
Count from the rear end, also the empty slots.
In the troubleshooting guide at the portal you find a table, resistance vs. temperature.

Thank you Inge, will do that and let you know the results. Cheers Tom

One thing I have found Tom is that some of the K100s don't like even a slight touch of open throttle at start up.
My grey K100 and a few others I have come across were like it to the extent that you remove your hand from the grip when starting cold, just push the button with your index finger and don't touch the grip and when it fires let it do what it wants to do, it may stop in which case hit it again, mostly it just idled and then after about 10 seconds it would accept a touch of throttle and all was good to go. But even the slightest touch of throttle made it very cantankerous and difficult to get going. I spent 2 years trying to make it easier to start but just gave up and accepted that it was to be.
Bosch do say don't touch the throttle but it usually doesn't make them cranky.
I have had 2 Ford cars with similar EFI and both would let you know if the throttle was pushed before starting by being a bit harder to start.

Thanks Rick, I have found it to be similar to your description. It will take about 4 hits on the starter without touching the throttle. After starting it splutters a bit but then settles into a good idle. Maybe it's a case of a grumpy old K in which case the K and I are very compatible. Cheers Tom

That was about what I had figured with mine, it was just grumpy like its owner.

G'day Tom , my K is also a reluctant starter in cold weather , I spoke to my mechs about it and the first thing they asked me is what octane fuel I use ( 98 ) , he suggested I try a tank of 91 to see if it made a difference , sure enough instant start in similar temps ( cold winter 1st thing in the morning ) , he explained the higher ratio's of octane improver's etc , this is just my experience in a similar situation , don't flame me !

John R

Thanks for that info John. Will try the lower octane fuel and see what happens. Will let you know. Cheers Tom

Hi Tom. Lean fuel mixture can give these symptoms. That could be caused by different things. Temp sensor as Inge sugested. Also look at the fuel system. Low fuel pressure caused by dickie pump or regulator, blocked filter or patially blocked or faulty injectors. If it's spluttering a little when she fires up sounds to me like its a little starved. How does it respond when you give it a fistfull? Does she hesitate? Also, how do your spark plugs look?

Cheers

G'day Nige,thanks for the input. Plugs are new but will take them out to check condition.Fuel filter is new and it will not rev up until well warmed up. It dies when trying to rev when cold - ie after start up.Will check the injectors next as well as heat sensor unit as suggested by Inge. Will report back soon. Cheers Tom

Re plugs... just looking for signs of lean/rich fuel. Will give you a bit of an idea about what's happening.
But from what you've described, my money is on exhuast valves. Could be a good idea to check the clearances to see what's happening there even if to just rule that out. I have the valve tools and a few spare shims. Will drop them in when I'm in Newcastle in a couple of weeks.
Cheers

When you first posted I didn't realize it wouldn,t rev till warm. I agree with Inge and that it is fairly symptomatic of the temp sensor going low resistance or short circuit. The poor old computer thinks it is already hot and wont supply fuel at the correct ratio till it warms up. If you do need a sensor give me a yell I probably have 5-6 round here.

easy to test that bit ,,,but hard to get at with right hand side lower fairing on tom

do as inge suggests first up

good luck mate.... hope that's it .

I have to use the 'choke' when cold and in winter. If I don't starting is not good, but when I use it I can get
a nice steady tickover. Once warmed a little all is well.

Plugs are NGK D8EA and always come out the right colour. Lots of debate about using NGK 7DEA but my buddy who is ex BMW always goes for no 8 and he knows the Ks well. [To quote: 'The only time I ever had to work inside a K engine was to repair crash damage, never had a failed engine']. He regarded use of the 'choke' as normal.

I haven't noticed a problem with pick up and after about a mile I can back off the 'choke'.

Not going to get technical with sensors and stuff but does the 'choke' lever increase the throttle opening slightly when used?
In other words, if you hold the choke lever on, does it keep the revs up a bit higher than tick over?
Easy adjustment if it doesn't.
They can be odd, too.
My '89 needed a short press of the starter and then another press before it would start. The '84 just gave a cough and started instantly. Even if it had been sitting in sub zero temperatures for a week!

Spot on Comberjohn, hence my 'choke' rather than merely choke. It simply applies a small amount of throttle opening and does not alter fuel/air ratios etc. My K has been sitting now for 6 weeks so a good time to try it.

One should also check for lower than spec compression. Low compression can cause this also.

Regards, Ibjman

G'day All, thank you for all the input. Got the wrong readings on pins 10 and 13 on the ECU. Changed over the heat unit sensor behind the radiator and got the right readings for pins 10 and 13. It now starts to fire first up but  still won't idle or rev happily until warm. Next step is to put 91 oct.fuel in it and check compression. Cheers Tom.

Expect it to require the "Choke" on the first step until you've driven at least a block or two. As discussed before the Choke is actually nothing more than a fast idle device....does not set mixture.
 You might run a bottle of chevron techron fuel injector cleaner through it.

Also.......I don't recall if you've tested the fuel pressure yet. 
Regards, Ibjman

Thanks Ibjman,  a fuel pressure test has not yet been done but is on the list. Have given up for the day - need a cold beer. Cheers Tom