April 2002

20th April, 2002

I know that its been a long time in coming, but here are a few pictures showing what I've done over the last two months. Most are self explanatory.

Dials close
                up.No one can complain that I'm not green!

                Sierra discs now look a tad smal!

The images that follow show the newly coated exhaust system (headers only). There was some patching done on the inside where the branches join the collector but you cannot see this in daily use. All in all a pleasing effect and a guaranteed talking point at all of those DROC meets.

Matt chrome headersLuverly welding

Worth the wait?

And finally, for the moment at least, a couple of pictures of the current state of play:-

                good Still a couple of
                months work :-(

On the
                ground at last!

So the car is now at the stage to start up and the big day was supposed to be the 6th April, 2002. All preparations were made and water and fuel added. The key was turned, the fuel pump primed but she no start.

A lengthy period of phaffing about resulted in no more than a flat battery. However I did mange to identify a small wiring fault which meant that whenever the handbrake was applied or the brake fluid low, there would be no spark! This was due to joining the White/Black tacho wire to the Black/White brake warning lamp wire! So I retired hurt until the next day.

The 7th April dawned and armed with new knowledge gained from the list I set about testing all of my recently modified EFI wiring. I was predominately concerned with not having defeated all of the electrical interlocks that prevent the ECU firing up the car in an unsafe situation. This being done and no errors found, it was back to head scratching. It then occurred to me that I might have timed the car up 180 degrees out. Although I'd set the static timing to 6 degrees BTDC, I didn't check to see if cylinder was on it's power stroke or exhaust stroke. So some deft plug lead swapping occurred and what do you know, my car, my Rush came to life.

Well there was of course short term relief but this was rapidly followed by a whole new set of problems. None the least, will a 1992 3900 cc Efi system really be able to be adjusted to run on a 1974 3500cc engine with a 10.35:1 compression ratio?

To answer the above I spent most of today, 20th April, tweaking the engine. Initially the engine was 'hunting' and would not stay running. However after several hours adjusting the timing, the idle setting, the mixture setting along with adjusting the 'end stop' of the throttle assembly, I've ended up with an engine that stays running and idles reasonably well. In order the really fine tune it, I need to:-

  • Adjust the throttle 'end-stop' more accurately. Ideally I need to adjust the throttle potentiometer first to give 325mV (290mV for flapper) at idle but the unit I have has no adjustment slots. I will measure the voltage that I'm currently getting with the throttle 'end stop' set as it is and if not too far away from the required 325mV I will adjust the 'end stop' to suit.

  • Attach the tacho wire to the tacho to get a reasonable chance of getting the idle RPM correct.

  • Adjust the idle speed screw (very subtle control this) the get the required 750 rpm.

  • Check and adjust the static timing to 6 degrees BTDC.

  • Do items 3 and 4 again.

  • Adjust the mixture to give between 0.5% and 1% CO exhaust emissions output.

  • That should be that.

To check the CO emissions I need to borrow the necessary meter. I hope my brother-in-law has one easily to hand.

Important point:- V8s don't half chuck out a lot of exhaust fumes. As I sit here some 4 hours later, I can still feel the effect on my throat and eyes. It doesn't take very long to fill up even a large workshop to a dangerous level of CO and other noxious gases, even with both garage doors open, cough cough splutter splutter!!

I was pleased that the radiator cooling fan came on and off during today's tests. Hopefully a sign that thing are fine in the cooling department.

Unfortunately, the same cant be said of the oil system. It would seem that I have too much pressure!! I know I know I should be grateful, but according to my gauge, its over 10 bar (140psi)!!! There are perhaps several possible reasons for this:-

  • My incorrectly wiring up of my oil pressure gauge earlier this month has somewhat stuffed it up and now won't work wired correctly. Unlikely.

  • Greengauges have sent me an inappropriate sender. Possible.

  • The sender is faulty. Perhaps.

  • The oil pump pressure bypass/relief valve is stuck. Maybe.

  • I've got my remote oil filter hoses the wrong way around. Possible. Unlikely to have such an effect.

  • A blockage somewhere. Maybe. There is oil circulating into all the right places as witnessed by removing a rocker cover and I also noticed a nice oily gear on the dizzy when I had it out today.

I can see that I'm gonna have to spend some time sorting this one out. I expect the oil pump will have to come off. Whilst I'm doing that I might have the sump off and check the oil pick-up for clogging. Additionally I might run the engine with some proprietary oil way cleaner in to perhaps improve oil flow. If anyone has any ideas on what this oil problem might be, please e-mail me.

Finally, I have noticed a strange phenomenon now that my Rush is breathing, there's a petrol thief in my workshop. I'm sure I had a gallon in the tank, but its suddenly all gone, can't possibly be the Rush......

30th April, 2002

Well, I've spent much time and fuel trying to get the engine to run smoothly at idle. I have tested all parts of the system according to the Haynes manual and can find nowt wrong. Yet the idle is less than stable. I am beginning to wonder if some of the missing items (Aircon, Fuel Vapour Purge Valve etc.) are confusing the ECU and affecting the fueling since all of the remaining items test OK.

Having spoken to an expert at work (his daily car is a Sierra Cosworth with an ex-Andy Rouse BTC engine) and he has given me some pointers as how best to set-up the idle by doing so with the air-bypass valve disconnected from the ECU. In fact reading the Haynes manual, it might be possible to do away with it completely since all it does is change the airflow into the engine to vary the idle when ancillaries such as aircon kick in.

The consensus at work seems to be that the fueling differences between a 3.5 and 3.9 are smaller than a gnat's nadger and given the free-er flowing exhaust system, a 3.9 fuel map ought to be better suited. In case none of this can be sorted by modifying what I've got, I have also made some enquiries about re-chipping my ECU. RPI have kindly offered to do this for £300. Well maybe that will have to be done, but only after every other avenue has been exhausted. Before that day comes, I will replace the spark plugs for new, replace all of the plug leads in case they are breaking down and have all of the injectors overhauled by Lucas. Occasionally the engine runs lumpy at speed and there is evidence from the exhaust on one bank that fuel is not being fully burned. Further investigation in this area required and lazy injectors/poor ignition leads are suspected.

Meantime, some success with the oil pressure problem. I don't have one! I'm afraid to admit that as with the rather odd non-spark wiring fault, I did the same with the oil pressure sender and oil pressure switch wiring. Essentially one wire is brown/white and the other is white/brown. I inadvertently joined them together at the point where the front loom joins the dash loom...DOH! That being sorted and the oil lamp goes on and off correctly and the pressure gauge reads approx. 1.5-2 bar. However the pressure sender is the old P6 one at the moment since I swapped it with the Greengauges one to 'fault find' and might not therefor be quite rightly matched to the gauge. Unfortunately I went to change it back for the Greengauges item but managed to split the adapter along its thread... DOH DOH! Still fortunately I was able to get the broken thread out of the oil pump housing.

I've still got problems with getting the tacho to work properly. The readings are all over the place. The root cause of this is the fact that the wiring colours on the tacho supplied doesn't match the colour code on the Greengauges site. A telephone call will be required. Additionally to try and sort this out I also added a capacitor to the coil to stop back emf spikes upsetting the instruments.

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