| Author | Message | ||
     Richard Treacy Grand Master Username: richard_treacy Post Number: 958 Registered: 4-2003 |
Further to Bill's comments of fuel accumulators, many owners have had starting difficulties with fuel injected SZ cars over the years. If yours is so, the following may be useful. This may complement Bill's post to some degree. Cold starting is helped by a cold start injector, controlled by the thermal/time switch. This little devil switches out the injector after 8 seconds' cranking or whenever the motor coolant is at over 35C. The thermal/time switch is very easily replaced, being located on the thermostat housing. It is also easily tested in-situ. If your car is more difficult to start than it should be when hot but the accumlator is fine, simply pull off the plug on the cold start injector and see if it is temporarily cured. If so, then the thermal/time switch has probably failed. Now that winter is passing, and after trying an improvement under all imaginable conditions since last July, I feel ready to share that improvement with other potentially frustrated owners. My motor (KE2 Jetronic) started instantly under all conditions (-25C included) except when cold on warm days over about 18C. On those warm days, it took a few seconds, sometimes as long as 5 painful seconds, as the thermal/time switch stays on for up to 8 seconds. Starting was followed by a puff of black smoke, proving mild flooding. Clearly the cold start injector tends to flood these motors in warm weather when the motor is not warmed up for the thermal/time switch to inhibit it. Experience has proven that the 8 second time-out on the standard Bosch switch is far too long for these large motors. As a permanent improvement, I have designed and fitted a very simple timer relay in the circuit using the standard Bosch relay type used throughout these cars. It is adjustable. I set mine to 1 ½ seconds, so the cold start injector switches out regardless of the thermal/time switch status after that interval. The longest it ever takes to start is 2 seconds now, and only in that worst case: warm day, cold motor. One great advantage is also that, should starting be difficult in cold weather, you simply try again. With the timer, the thermal/time switch will not time out: every time you turn the key when cold, you will have a squirt of fuel for 1 ½ seconds. Functionally this makes far more sense than the basic arrangement. In the basic arrangement, a failure to start due to inadequate fuel requires a wait of 5 minutes for the thermal/time switch to reset. In fact, the thermal/time switch is basically redundant now, but nice to have to guarantee instant hot starts. The wiring diagram is shown below. The relay is mounted on its socket (I mounted the timer components under the socket and encapsulated the socket base to form a timer module with a plug-in removable relay), and is mounted neatly next to the headlamp sequencing relay by the LH suspension tower. The two wires to the injector share an original loom, so it does not look in any way tacked on. I cut the + lead to the injector, and fitted a standard spade plug to one end and a spade socket to the other. In the unlikely event that the timer were to fail, you would simply unplug it and reconnect the injector direct via the new plug and socket. RT.  | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 525 Registered: 9-2004 |
Richard not wanting to put the dampers on your clever mod with the shorter timer etc, but could what you are doing be getting over another inherent fault within the the system. For instance the temperature.... to name just one? | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 959 Registered: 4-2003 |
What system fault is that Pat ? Global warming or natural Summer temperatures ? The fact is that the K Jetronic and KE-2 Jetronic cold start injectors are controlled by a simple electro-mechanical thermal/time switch optimised for low temperatures and small capacity German vehicles. In ambients between 15C and 35C, whilst the motors are never difficult to start, unnecessarily the cold start injector squirts in more fuel than is optimum when cold-starting a fuel injected Crewe motor working properly. This has been apparent since the cars were new and has not changed. Whilst the switch is standard and optimised mainly for small capacity motors, our largish V8s benefit usefully from the simple tweak I have noted. | ||
| James Feller Yet to post message Username: james_feller Post Number: 1 Registered: 10-2007 |
This is an interesting topic and one that has puzzled me for a bit of late on my 86/87 Spirit SCAZS0006GCH16504. On occasion and I mean 3 times if my memory services me right, my 86 EFI Spirit has had similar issues. Most times cold start is a breeze, a brief crank and it fires up no probs and not idling much higher than normal then settles down to the normal low V8 beat about 5 seconds later as Brake 1&2 lights extinguish. Then at other times again cold starting, it turns and fires and for about 3-6 second chugs, not stalling although I am sure if I blipped the throttle it would and has on one occasion I could not help myself, then it settles down nicely to the normal low beat.... could this be the cold start do you think...? I am not aware of black smoke from the exhausts on these occasions, but as I am sitting in the car I probably cannot see it, though I will check from now on. Although, I will tell you that I was slightly terrified 2 weeks or so ago. I was driving around with the low fuel light on so I pulled into a Shell service station and filled it up, I use only 98 octane. I got back in, started it up, pulled out and noticed it running very rich and missing, not back firing, just missing. I suspected is was flooding itself, it was puffing a bit of black smoke this time as I did notice it as I looked in the review mirror, not a huge amount but enough to notice the rear exhausts, which are normally clear and clean had sooted up when I got out and had a look. I stayed in the servo for a bit and let idle to see if it would right itself. After about 30 seconds sitting there I put it into D and as I accelerated out it cut out. Needless to say I was a bit concerned! I then cranked it again and it fired up and it drove away fine, full power back and not a puff of black smoke. I thought maybe dirty fuel or something but after reading the above I suspect more the cold start is being a bit of a bugger at times.... Interestingly enough it was not a hot day and it has not acted up again... for now... yes I am touching wood. On another note, the instruction manual says not to touch the accelerator on cold starting an EFI motor, and I don't but it does say to give the accelerator a bit of a depress when cranking a warm efi motor? why would you need to do this? I thought EFI controls fuel delivery 'electronically' ? I have tried starting the motor warm using a bit of accelerator depression and none at all. Indeed it does fire up much better with a bit of depression than not. anyway just another little malady to keep us all talking I suppose. Cheers James |
