Non Running Engine Good Compression and Ignition Spark Present Noid Light Test no Signal

[bill]

Bill - you do know about Mario at VSR in Bedford NH, I assume ? Probably the best E9 shop in the East.
Can you "back probe" the MAP output and drive while watching the output voltage on the VOM> I do not know however what the expected voltages would be.
And you have swapped out the ECU I am sure. I wonder if these ECU's develop component failure - caps, transistors etc which may be manifest as intermittent operation.

Dana

Dana: half of the fun of owning my '74 for 20+ years is being able to work on it myself (the other half is driving/looking at it.) Have heard many good things about Mario but I'm not ready to hand it over. I am 99% sure my problem is with the TPS. Despite easy adjustments, the severe bucking problem persists. I have two MAPs and two ECUs, the bucking still happens...except when the TPS is disconnected. The TPS has a new PCB (5 years) and the traces shouldn't be worn or shorting, so I'm baffled for now. I will fiddle some more with the TPS.

BTW, the MAP (which you may know is a variable solenoid) provides engine vacuum data to the ECU in millihenries, not volts, unfortunately...

 

[neon]

autobooks_manual_160

autobooks_manual_160

e9coupe.com

Bill, Sfdon and fellow coupers, my update - the engine rotating test of the trigger points showed approx 135 degrees of points closed ( zero resistance between pin 12 and 21 or 22) and the same pattern 180 degrees away indicating that the trigger points are appropriately making contact. I tried back probing wires 3 and 4 (with the ECU attached ) and cranking the engine . I did see a mild voltage "deflection" to about 10 to 20 millivolts with engine turnover. I am wondering if this is the injector signal with the VOM not having time to reach the full signal voltage. I do not have an oscilloscope. On the other hand, the noid light test remains with the light dark on engine turnover. I have not tried the dwell meter on 3,4,5,6 but this would just give the timing characteristics not the strength of the signal. Do I need an oscilloscope to determine the voltage signal coming (or not) from 3,4,5,6 ?

Don - how best to contact you to borrow an ECU ?

Thanks
Dana

 

[sfdon]

pm sent

 

[neon]

pm sent

SfDon - Did try the throttle opening test while listening for the crickets Some clicking was present Then listened with the screwdriver w handle to ear and driver end on injector body while turning throttle. This was tough to interpret but it seemed that injectors 1 and 5 definitely were clicking Other injectors I doubt were firing though maybe 3 was. Also I need to investigate a "crimped" wire though I have at this point checked most of the grounds, but not all.
So I wonder if the above may be consistent with bad trigger points vs bad ECU drivers. Will carry on.
Great to discuss w you !

Dana
CT

 

[Ohmess]

Dana - I would divert your energies to checking all the grounds at this point. A ground would be a simple fix, and none of the other fixes will work if you have ground problems.

 

[sfdon]

I’m sending you a new set of trigger points and a ecu today.
To be clear- they are not for sale! These are the shops diagnostics equipment.

Let us know how it works out.

 

[neon]

Dana - I would divert your energies to checking all the grounds at this point. A ground would be a simple fix, and none of the other fixes will work if you have ground problems.

Chris - appreciate that, am soldiering on, I must have checked grounds on most 3 times but I am very interested in injectors 3 and 4 which are more difficult to access and may have a wire that is "crimped" that is hard flexed and maybe damaged, though no evidence as yet. Will be redoing grounds and continuity testing on the whole system this week. Meanwhile will test another ECU also.

Best
Dana

 

[neon]

I’m sending you a new set of trigger points and a ecu today.
To be clear- they are not for sale! These are the shops diagnostics equipment.

Let us know how it works out.

Sfdon - many, many thanks. All understood. Will report back prob next wk.

Enjoy the holiday and all the best to you

Dana, Hartford, CT

 

[sfdon]

sent you a MPS also

 

[neon]

Awesome, will put them all to good use, looking forward

DJ

 

[bill]

I’m sending you a new set of trigger points and a ecu today.
To be clear- they are not for sale! These are the shops diagnostics equipment.

Let us know how it works out.

Dana: my fingerprints are all over the points and ECU. I don't know what I would have done without SF Don.

 

[bill]

To Ohmess' point, I think I will re-do the FI grounds also-- although they are factory crimped and soldered. One never knows after 50+ years. The good thing with D-jet is the grounds are all at one point on the engine (except the fuel pump) so it won't be a big deal.

 

[neon]

Sfdon, Bill, Ohmess, and coupers

To Ohmess' point, I think I will re-do the FI grounds also-- although they are factory crimped and soldered. One never knows after 50+ years. The good thing with D-jet is the grounds are all at one point on the engine (except the fuel pump) so it won't be a big deal.

Bill,

Grounds all OK. Looks like trigger points were worn, did start with a replacement but now rough idle, checking plugs, poss replace , points attempt timing check

Onward !!

Regards
Dana

- Replacing Trigger points resulted in a start, with very rough idle, The metal cam followers on my tigger points were completely worn. Possible not running on all cylinders. I will check ignition points, attempt a timing check. I am wondering if there is a fuel injection "tuning" that was based on worn tigger points and now is incorrect for non worn trigger points. However the ECU I think should handle this ?
I was able to start with just the trigger point exchange, running my ECU and my MPS. I will try switching out the MPS to yours today as well.

Progress !!

 

[sfdon]

Likely 3 injectors were not working and 3 were stuck on.
Your plugs are likely fuel fouled now.
Go to Oreilly and buy TWELVE new plugs.
Get the NGK plugs.

 

[sfdon]

under compression in the bore a fuel fouled plug is no good

 

[sfdon]

You likely need fresh trigger points- I should have a rebuilt set ready soon.

 

[neon]

Sf
Most excellent, will report back ....

Dana

 

[bill]

Dana: progress, the ECU is working! Now the unbearable wait for SF Don’s points…

 

[neon]

Sf
Most excellent, will report back ....

Dana

Sf
Most excellent, will report back ....

Dana

SFdon and coupe gang - plugs replaced, point gap checked and reset. New trigger points in place. Only very intermittent start or no start. I think injectors not firing in sufficient numbers based on hearing only limited clicks when twisting the throttle w key on. I wonder if the signal path from ECU to injectors is out (wires, harness) though I did the continuity test early on a few wks ago. It def seems like a fuel prob. I suppose I should replace points ( today should be in at NAPA), try to check static timing, switch out my ECU for don's loaner, and recheck wires 3 thru 6 ( ecu to injector signal path) One strange theory comes to mind: a long time ago, before my ownership, there was a massive fuel system clog originating in the tank, I wonder if remnants have clogged the fuel filter, resulting in a relative loss of fuel. I could conceivably measure a good pressure in the fuel circuit, a static measurement - which I have - 2.05 bar - but still fuel starved in operation, a dynamic situation. Overthinking ?


Dana and Astrid in CT

 

[sfdon]

i have a set of inspected and calibrated trigger points arriving next week- good for 20,000 more miles. LMK if you need them. I will need you send me your core worn out one. (and my new test mule one too)