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]

So took the advice of checking the valve adjustments. Watched a couple videos and read some more on doing the adjustment, and decided they were all a bit tight, so loosened them up.

And it started right up.

https://youtube.com/shorts/HaebjvxBtD0?feature=share

and the idle vacuum is much better and the idle adjustment screw actually has some effect! Would never have thought it would be that sensitive to something like the valve adjustment!

Thanks for all the suggestions and seeing me through this! Time for (IMG:style_emoticons/default/driving.gif)

[Ron914]

So took the advice of checking the valve adjustments. Watched a couple videos and read some more on doing the adjustment, and decided they were all a bit tight, so loosened them up.

And it started right up.

https://youtube.com/shorts/HaebjvxBtD0?feature=share

and the idle vacuum is much better and the idle adjustment screw actually has some effect! Would never have thought it would be that sensitive to something like the valve adjustment!

Thanks for all the suggestions and seeing me through this! Time for (IMG:style_emoticons/default/driving.gif)

@Blue Lighting
Great job and this is very interesting to me ,as I said we are on similar journeys .
I appreciate the link and will look at it later.
My newly rebuilt motor probably has a couple of hundred miles now as I drive the car for testing only still until I figure out my source of a high idle ( I need to pass a California smog first) .
My brother-in-law told me my louder than what I think its normal exhaust noise may be a result of needing a valve adjustment . He said after that many miles now I should adjust the valves so you link will be welcomed because it's been 4-50 years since I have adjusted valves and that was on VW's .My motor initial break in after rebuild plus the miles I have added happened over a few years now.I brought the motor home from the rebuild shop in October 2022.
Now your comments lead me to believe my valve adjustment should be checked as I have this high idle issue and have struggled little to no effect from the idle adjustment screw.

[Blue Lightning]

Great job and this is very interesting to me ,as I said we are on similar journeys .
I appreciate the link and will look at it later.
My newly rebuilt motor probably has a couple of hundred miles now as I drive the car for testing only still until I figure out my source of a high idle ( I need to pass a California smog first) .
My brother-in-law told me my louder than what I think its normal exhaust noise may be a result of needing a valve adjustment . He said after that many miles now I should adjust the valves so you link will be welcomed because it's been 4-50 years since I have adjusted valves and that was on VW's .My motor initial break in after rebuild plus the miles I have added happened over a few years now.I brought the motor home from the rebuild shop in October 2022.
Now your comments lead me to believe my valve adjustment should be checked as I have this high idle issue and have struggled little to no effect from the idle adjustment screw.

I started with Ian Karr's video, which he does on a clean engine out of the car but you can see what you are trying to accomplish: https://www.youtube.com/watch?v=XdVIgtpSSJs

This is the method of doing it in the car that I actually used:
https://www.pelicanparts.com/techarticles/9...iKG3Q08SrethTSq

There are many variations on the adjustment theme. Make sure you have the following items:

• 0.006" feeler gauge
• 0.008" feeler gauge
• new valve cover gaskets (in case you wreck one removing the covers)

one tip/trick I read was to use a dime to turn and hold the adjuster screws. That and apparently I was an overachiever and adjusted mine to more than "just a bit of drag" on the feeler gauge (IMG:style_emoticons/default/smile.gif)

[Superhawk996]

I was an overachiever and adjusted mine to more than "just a bit of drag" on the feeler gauge (IMG:style_emoticons/default/smile.gif)

You got an excellent lesson from the school of hard knocks about assumptions.

Adjusting valves is definitely a skill and the “feel” can only be learned by doing it. No shame there. They don’t call them feeler gauges for nothing. (IMG:style_emoticons/default/lol-2.gif) If you hadn’t assumed the valve adjustment was OK early on, you would have been off to the races much sooner.

I was trained by USAF in troubleshooting. During tech school, they would set up test scenarios that would intentionally draw you into misleading assumptions.

Tests were timed. It would often take only seconds to verify an assumption. If you took the time, you would be on a correct path to find the root cause issue and pass the test.

If you didn’t, the assumption would draw you down various paths that were dead ends and you would run out of time and would fail.

I don’t post this to shame you but rather to encourage & challenge us all to think about what the assumptions are, and to verify them before we end up chasing our tails.

You did a great job of testing components and working it through methodically! (IMG:style_emoticons/default/smilie_pokal.gif)

[Ron914]

I was an overachiever and adjusted mine to more than "just a bit of drag" on the feeler gauge (IMG:style_emoticons/default/smile.gif)

You got an excellent lesson from the school of hard knocks about assumptions.

Adjusting valves is definitely a skill and the “feel” can only be learned by doing it. No shame there. They don’t call them feeler gauges for nothing. (IMG:style_emoticons/default/lol-2.gif) If you hadn’t assumed the valve adjustment was OK early on, you would have been off to the races much sooner.

I was trained by USAF in troubleshooting. During tech school, they would set up test scenarios that would intentionally draw you into misleading assumptions.

Tests were timed. It would often take only seconds to verify an assumption. If you took the time, you would be on a correct path to find the root cause issue and pass the test.

If you didn’t, the assumption would draw you down various paths that were dead ends and you would run out of time and would fail.

I don’t post this to shame you but rather to encourage & challenge us all to think about what the assumptions are, and to verify them before we end up chasing our tails.

You did a great job of testing components and working it through methodically! (IMG:style_emoticons/default/smilie_pokal.gif)

(IMG:style_emoticons/default/agree.gif)