Cold Start Issue 914-4, Admitting I'm stuck and asking for help Options

[Blue Lightning]

Car: 1976 2.0, FI

Background: bought in November last year. I am least the 4th owner. Drove a couple times, then plugged up the fuel filter (? no fuel pressure when the fuel pump was running, but see note below on replacing the fuel pressure regulator), so spent a couple months with the gas tank out and replacing the fuel lines, pump (and yes, filter). Read a lot in the meantime, so corrected vacuum line issues (vac advance was connected, replaced all the lines that didn't already look new, added hose clamps). But where the car started and ran well last year, I can't get it to happily start any longer. While cranking, it will skip and catch. After a few minutes of cranking (and skipping and catching) it will finally start and run fine for a few minutes but only idle around 1000 rpm (until the AAR warms up the rest of the way?), then dies. Starter fluid has no effect, so guessing it is running rich? Pulling the air hose off the cold start injector while running causes the idle to increase to maybe 1400 rpm (but with hunting, as you might expect with that big leak). There are a lot of threads on what to look for when the engine is running lean, but few on it running rich.

Some things I have checked:
- AAR works (https://youtu.be/YmO1ZCLDB7g)
- Compression is good (130-140 psi cold)
- Replaced the MPS last weekend with new one from autoatlanta, after finding the previous one would not hold a vacuum
- Replaced fuel pressure regulator after finding it bad (yes, I've been told these never go bad, but this one would not hold any pressure). Fuel pressure set to ~29 psi.
- Timing is good (~27 degrees at 3500 rpm with vac retard disconnected)
- Vac retard mechanism is working (checked with vacuum pump)
- Spark on all 4 cylinders (checked by timing light)
- Smoke tested the intake...only leaks now are the bearings on the throttle plate
- CHT reads 2k at cold, ~250ohms at warm/hot (at splice connector)
- Plugs look okay (see attached)
- Fuel injectors are all spitting fuel (checked into bottles...all about the same) and have new seals
- idle adjust screw has some control, but I cannot get the idle above 1000 rpm with it
- valves adjusted back in December (my first time, but the car runs so I assume I didn't do too bad of a job?)

I'm at a loss of what to try next. (IMG:style_emoticons/default/hissyfit.gif) I'd like to consider myself fairly good with cars (we have a 1966 Mustang, as well as a Mazda RX-8 that I have kept running for >20 years), but I'm about ready to throw in the towel and have the 914 towed to someone smarter than me!

Thoughts?

[Blue Lightning]

Still no bueno. Added a jumper cable between the battery negative terminal and the engine, plugged off the cold-start injector fuel line, and plugged the vacuum lines on the decell valve. None of this seems to have made a change.

Video of run at https://www.youtube.com/watch?v=9xbr0VjFFkE
~1:20 adjusted the idle air bleed screw. At the end, it is backed out so far it is almost falling out of the throttle body, but I get the idle up to 1400 RPM.
~2:10 checked fuel pressure (30 psi)
~2:15 couple shots of starting fluid, which almost kill engine
~4:20 rev up to ~4k RPM
~6:30 starts to die (AAR fully closed at this point?)
~7:45 added the PO's air filter, which make things worse

Note that I cranked the engine for a minute or two before starting the recording, then pulled a spark plug (which looked the same as the previous pictures...no obvious fuel or oil fouling).

[ctc911ctc]

I watched the video:

1. Once it starts it runs good
2. Takes too long to start - Spark or Fuel?
3. Seat Buzzer - HHHHhhhhmmmmmmmmmmmm
4. Ignition Switch at the key?

Here is my experience - I had a 1.7 that would run fine and then not start, I was 20, and it drove me crazy - turned out the ignition switch was intermittent - know problem. Every 914 I have owned since I change the ignition switch - FIRST THING

I would:

1. Eliminate the seat belt buzzer and all of that circuitry - many guides as to how this is done
2. As you are cranking - check the ignition switch circuit at the junction box (Yellow wire?) for 12ish volts. If this is solid 12v while you have the long cranking, I have no idea, however, if you are long cranking and have no 12v - the switch behind the key is fried

Question: how many of us on this thread have experienced this before???? (IMG:style_emoticons/default/dry.gif)


Oh, as to the plenum leaks - fix them - this will be a constant cause of uncertainty - the entire DJet system is an open-loop control system based on differential vacuum between the high vacuum (plenum) and low vacuum (air cleaner area) system - The Djet system does not handle control variations in vacuum very well, fix the vacuum and the control equation is at least no longer a variable.

Still no bueno. Added a jumper cable between the battery negative terminal and the engine, plugged off the cold-start injector fuel line, and plugged the vacuum lines on the decell valve. None of this seems to have made a change.

Video of run at https://www.youtube.com/watch?v=9xbr0VjFFkE
~1:20 adjusted the idle air bleed screw. At the end, it is backed out so far it is almost falling out of the throttle body, but I get the idle up to 1400 RPM.
~2:10 checked fuel pressure (30 psi)
~2:15 couple shots of starting fluid, which almost kill engine
~4:20 rev up to ~4k RPM
~6:30 starts to die (AAR fully closed at this point?)
~7:45 added the PO's air filter, which make things worse

Note that I cranked the engine for a minute or two before starting the recording, then pulled a spark plug (which looked the same as the previous pictures...no obvious fuel or oil fouling).

[Blue Lightning]

I watched the video:

1. Once it starts it runs good
2. Takes too long to start - Spark or Fuel?
3. Seat Buzzer - HHHHhhhhmmmmmmmmmmmm
4. Ignition Switch at the key?

Here is my experience - I had a 1.7 that would run fine and then not start, I was 20, and it drove me crazy - turned out the ignition switch was intermittant - know problem.

I would:

1. Eliminate the seat belt buzzer and all of that circuitry - many guides as to how this is done
2. As you are cranking - check the ignition switch circuit at the junction box (Yellow wire?) for 12ish volts. If this is solid 12v while you have the long cranking, I have no idea, however, if you are long cranking and have no 12v - the switch behind the key is fried

Question: how many of us on this thread have experienced this before???? (IMG:style_emoticons/default/dry.gif)


Oh, as to the plenum leaks - fix them - this will be a constant cause of uncertainty - the entire DJet system is an open-loop control system based on differential vacuum between the high vacuum (plenum) and low vacuum (air cleaner area) system - The Djet system does not handle control variations in vacuum very well, fix the vacuum and the control equation is at least no longer a variable.

Still no bueno. Added a jumper cable between the battery negative terminal and the engine, plugged off the cold-start injector fuel line, and plugged the vacuum lines on the decell valve. None of this seems to have made a change.

Video of run at https://www.youtube.com/watch?v=9xbr0VjFFkE
~1:20 adjusted the idle air bleed screw. At the end, it is backed out so far it is almost falling out of the throttle body, but I get the idle up to 1400 RPM.
~2:10 checked fuel pressure (30 psi)
~2:15 couple shots of starting fluid, which almost kill engine
~4:20 rev up to ~4k RPM
~6:30 starts to die (AAR fully closed at this point?)
~7:45 added the PO's air filter, which make things worse

Note that I cranked the engine for a minute or two before starting the recording, then pulled a spark plug (which looked the same as the previous pictures...no obvious fuel or oil fouling).

The safety relay has been removed and the heavy yellow wires connected permanently. The seatbelt buzzer is the only part left. This was all done by one of the PO's, and the car was running with this so am reluctant to touch it at this time.

I have thought about replacing the ignition switch, but haven't found anything that doesn't work that it controls. The car does start, and even try to start while cranking early.