Okay, so a bit of background.
Late last year, my car ('74 2.0 with Mark De Bernardi's 2056 hardware kit) suffered a betrayal from one of the old Bosch injectors, resulting in a fire which, while happily small and caught quickly, ruined the engine wiring looms, MPS, and battery. I figured repairs would be pretty straightforward - and they were. Got parts frome eBay, and new looms from Jeff Bowlsby, took the car to the shop of the painter who did the original restoration bodywork on it, and dropped, cleaned, and rewired the engine while he fixed the decklid and rollbar up. Threw the engine back in, got it running, tuned it to perfection, and went to reassemble the car.
Now this is the point where everything started going very wrong. We put the decklid in place and went to install the trunklid, and the trunk hinges both sheared at the bolt. I replaced the bolts, and we noticed the sheet metal flex mounts for the hinges were both nearly undone at the welds as well, so the painter offered to weld them up, which I agreed to. We disconnected the battery just in case, welded them up, and assembled the car. I got in to drive it away, and the car would not start. Engine turns over, kicks into life, then dies.
And this is all I've gotten it to do since, and I am out of ideas. EVERYTHING checks out and is working, to the point where I'm not sure how it's physically possible that this thing isn't running.
So far, I have verified:
- There is good fuel pressure (32-33psi at prime, 33-35psi during cranking and running)
- All 4 injectors (matching, new SMP FJ6 units) are firing
- There is spark, and it is timed correctly
- The point dwell is optimal (about 47 degrees)
- There is strong compression (around 140-155# in all cylinders)
- The valves are all actuating, and have correct lash
- All electrical and pneumatic connections are secure
And I have tried:
- Draining the tank and using fresh fuel (what was in it was several months old)
- Swapping coils from the stock-alike to an MFD Blaster 2 with appropriate ballast in case the coil was failing to charge up at running speeds
- Swapping the ECU out between a NOS replacement and the original which seems to be free of damage
- Setting fuel pressure all the way up and all the way down as far as the Bosch regulator allows
- Clamping off the cold-start injector
- Starting the engine while hooked up to a battery charger
- Unplugging the TPS
Not a thing so far has produced the slightest change of behavior. The closest I've gotten to having it run is, with WOT, holding the starter keeps the engine "running" at about 800rpm, with constant combustion, but no pickup of rpms or power, which is still pushing me towards either spark or fuel mixture.
What has me completely aghast, though, is that this thing was running perfectly and not a thing has changed. I'm beginning to think it's just angry at me.
What the heck am I missing?
It sounds like you're not getting past the cold start cycle.
So did you get a new MPS and calibrate after the old one burned and was destroyed or did we miss something.
I usually dont jopi nthese discussoin, but here goes:
1. What MPS part number do you have and does it hold steady vacuum?
2. Known good original MPS or recent rebuild?
3. Fuel pressure is too high, should be about 28-30psi if I recall correctly. Check the factory specs.
4. Trigger points verified to function?
5. Fuel injector grounds connected to ground?
Yes - I should have specified better - I did replace the MPS. The old one was pretty much destroyed.
The new one is a -043 P/N that has been re-manufactured by Rich Bontempi. It holds vacuum and the impedance is in the right area.
The fuel pressure is boosted to match the more aggressive cam and slightly increased displacement (although I based my calculations on a 32psi stock spec and the Bosch injectors). I'll redo the calculations for the new injectors and readjust it more precisely when the thing runs again.
Trigger points are working, as the injectors are pulsing (I've squirted fuel into a jar out of all 4 with the engine cranking). Is there a good way to tell if they're consistent? It's crossed my mind that they might be intermittent or sticky.
The injectors ground to the stud at the back at the back of the block, right? I'll double check continuity when I get a chance to be sure of them, but that ground is secure.
MPS needs to be calibrated to your engine.
Cylinder head temp sensor?
My car was down for three months and I "thought" I had spark. Under compression spark plugs do funny things. Replaced the coil and car has run fantastic ever since. Just an idea.
All the best,
gg
why up the fuel pressure for a big cam …..never heard of that but my skills are with later systems but still don't see it working.
"Not a thing so far has produced the slightest change of behavior. The closest I've gotten to having it run is, with WOT, holding the starter keeps the engine "running" at about 800rpm, with constant combustion, but no pickup of rpms or power, which is still pushing me towards either spark or fuel mixture."
I guess this is with the key in the "engine start" position, does it die when you release the key? I would try taking the ignition lock ou of the equation, bridge the fuel pump to run on the relay board and then just use a remote starter switch directly on the starter motor.
Gearbox earth strap in place?
The CHT is a good call. I will check it out and make sure it's got the right resistance.
I'll also check the plugs for signs of rich/lean running.
I don't think it's ignition switch related as the engine does run with the key released, just only for a few seconds. It actually starts and catches quite quickly.
Data point: my intermittent start, start then dies, random dies.
http://www.914world.com/bbs2/index.php?showtopic=291477&hl=
Spoiler alert: bad MPS diaphragm. It held vacuum.
Guys, You can’t set the MPS if the motor won’t run!
I suggest checking to make certain the engine/trans are securely grounded. Check for presence and cleanliness of the ground strap between the rear of the trans and body. Because the car was repainted due to the engine fire, also check (1) battery negative cable connection to body is sparkling clean; (2) all the wires going to the grounding point behind terminal/relay board in left (driver) side of engine compartment are clean and paint free.
The CHT should read somewhere around 2500 Ohm resistance cold and then go down to below 100 when hot.
You could trick the ECU by substituting a 2500 Ohm resistor between the lead where the cht plugs in and ground. That would mimic a cold situation to the ECU. it should work to at least start the engine. But if left in place it would be too rich to drive around after warmed up.
Okay, checked the CHT and plugs. The CHT measures about 3600 Ohms at a cold engine temperature of about 50F, and dropped to about 3300 after several attempted starts. Plugs were wet.
I pulled the fuel pump relay, and tried it with starter fluid, and the engine started and idled for about a minute.
I think I have a culprit. Anyone have recommendations on where I can get a decent replacement that isn't made by Urö? This is the second time one of their electrical components has failed in short order.
914 Rubber, one of their new ones. Or take an old one out of your
headlight motor up front.
I use Bleysengs 2056 settings for my before fire up
MPS setting.
I have a car coming in next month for component
verification and testing. New rebuilt MPS and no idle.
Previous work was done by one of the areas oldest air
cooled techs.
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