Understood, but what could be causing the injectors to do this?

All good on the relay board, as I said, pending the outcome of my discussion with Bill, I'll know what course of action to take.

Thanks
Pete

OK, this was a very good resource to evaluating the inputs to the ECU, thanks Dave -

http://www.type2.com/library/fuel/Bosch_L-Jetronic_FI_Manual/

What I have been able to determine follows
All inputs to ECU checked out within prescribed limits, with the exception of an inconsistent reading from the Air Flow sensor. All diagnostic combinations with pin 6 at the ECU plug gave inconsistent readings, checked the wires for continuity, all proved sattis. The Throttle position sensor gives me an out of limits reading until almost full throttle has been reached and then very abruptly drops to 0 resistance at full throttle, is this normal? Should it be so abrupt, or is it meant to be a more gradual transition?

My airflow sensor has 6 pins, no number scheme found on the plug or elsewhere, for this connection, so I established which of those six are routed directly to the ECU when I checked for continuity between the Air Flow sensor plug and ECU plug (known numbers), got the order - looking from behind, from left to right
pins 1 & 2 on Air Flow sensor - unknown
3 on Air Flow sensor = 6 on ECU
4 on Air Flow sensor = 9 on ECU
5 on Air Flow sensor = 8 on ECU
6 on Air Flow sensor = 7 on ECU.

Pins 6 through 9 are the four pins referenced in all Air Flow sensor diagnostics. So I performed the same tests at the Air Flow sensor, that the diagnostic calls for at the ECU plug, came down to No. 3 pin on the Air Flow sensor (6 on the ECU plug) causing an intermittent out of limits reading. Aha! I say, hoping that this could be the problem after all! Could someone correlate this into something that I can work with? From what I gather this may be Temperature sensor 1?!

Should this prove to be the problem, It means the previous Air Flow sensor had the same problem though (same symptoms) how likely is this? We have replaced the CHT sensor (Temperature sensor 2), which could have been giving the initial problem?!

Anyways, I'll discuss this matter with Bill tomorrow and see where it takes us.

Thanks
Pete

The throttle position switch should show continuity at idle position between terminal #2 and #18 at the ECU plug, and continuity again at or near full throttle between terminal #3 and #18. It is an on-off at these two positions, off in between.
As to your air flow meter question, your #1 & #2 terminal is #36 & #39 that power the fuel pump thru the double relay. Terminal #6 to #9 should test 200-400 ohms, #7 to #9 should test 120-200 ohms continuity.
Just a thought, have you tried changing out the distributor cap? They sometimes look O.K. but cause irratic spark timing at the plugs.
Good hunting!

Correction #7 to #9 should be #7 to #8, sorry

Hello,

Yep! The distributor cap, rotor, leads, condensor, points and spark plugs have all been replaced with new, yet the problem persists!

In the Bosch manual for Air Flow sensor diagnosis at the ECU I got the following parameters;
Location--------------------Desired resistance specs
--6 & 9---------------------------200 - 400 Ohms
--6 & 8---------------------------130 - 260 Ohms
--8 & 9----------------------------70 - 140 Ohms
--6 & 7----------------------------40 - 300 Ohms
--7 & 8---------------------------100 - 500 Ohms

All of which that refer to terminal 6 are giving me inconsistent readings, intermittently in a matter of 5 minutes from testing, the readings vary between close to correct, incorrect to infinite resistance!

Very odd! But I think it is safe to say that things are not as they should be!

The other items, such as injector feedback, etc. all checks out very close to the required specs.

On Monday I'll have a look at the throttle position sensor again, I can't work on anything at home as I have no significant tools, and the throttle body will have to come off again.

Thanks for the input, at least now I know what the other two pins are for on the Air Flow sensor ;)

Any Helicopter Instructor jobs available in Hawaii? :)

Cheers
Pete

From the sound of it, #6 has problems. From the wiring diagram, it is common to everything in the AFM (Air Flow Meter). At the moment, I would suspect a problem with the wire from the ECU to the AFM, or possibly a problem with the parts of the ECU that hook up to that track.

I am not at all sure what would cause the extra injector openings. Best guess would be something funny in the ignition circuit (you running points? A points-replacement gizmo? An MSD unit?), as the points signal is used for injector opening.

--DD

Dave,

Yeah, it is No. 6 that is not entirely kosher!

I have already eliminated the wires as a problem area by performing continuity tests...

The ignition system is stock, we replaced the points with an OEM equivalent.

I'll know more tomorrow!

Thanks
Pete

The erratic spark has been tracked to a faulty coil, however it now skips an injection event from time to time, on every second ignition event... it never rains, I tell you!

I suspect the other troubles originate from a variety of sources (including the injection/ignition trigger fault), the airflow meter is unserviceable and then there are probably still some other small things that are adding up to contribute to this fiasco.

Furthermore I suspect we probably got similar symptoms from various independent malfunctions... the CHT has been replaced, but the old one was US. This could have affected the trial when we substituted air flow sensors... Further to this I have nothing new to add!

Shes causing me a slow painful death!

Thanks
Pete

Wohoooo! Problem resolved.

It was the air flow meter after all... along with some other small issues, she's finally running fine!

Problem now, I am leaving the contiguous US! Finally the car is running and I was offered a job far away! I must have had a total of three days of pleasure from her thus far!

Anyone interested in buying, let men know! I can tell you exactly what's been done and what's still wrong.

Pete