Troubleshooting help 1.7 FI, Updated: I almost have defeated the D Jet Demons! Options

[Robarabian]

Thank you to the collective here, I learned alot. As of yesterday, the car starts, idles higher when cold, settles after the AAR opens. The throttle is responsive. The MPS works, the throttle position switch was re-set and the timing is spot on at 27 degrees and the 123 ignition is working well and playing along with its new friends. . No pops, no backfires.

I took a smart suggestion and did swap out the 71 non adjustable brain box for a 73 1.7 brain box with the knob. That particular setup (thank you @MM1 ) had a very intact wiring harness so I swapped mine for it. Having the knob certainly helps it run smoother.

The last item to deal with is the air intake temperature sensor. It is unplugged right now and runs great. When I plug it in, the idle suffers and it hunts and hunts. So I have ordered a replacement and hope that will solve it. Everything else has been checked and / or replaced / upgraded so I'll cross my fingers there.

The best troubleshooting process was to disconnect everything except the MPS and plug the holes to determine if there was a vacuum leak somewhere, and then plug things in 1 at a time. As I did that, I located the likely faulty sensor.


Again, thank you to everyone who chimed in, your collective ideas kept me from ripping the FI off of it. I know how much better the car will be in stock FI form--in both MPG and value. This literally gets me to now assemble the interior and install the front windshield. Hopefully Hi-Hi Silver will be at a local 914 World Event soon.

Robert
__________________________________
I am trying to button up what I call "Hi Ho Silver" a 71 I bought during Covid.

Motor is rebuilt by me and cam break in went well, 8-10 months ago. How time flies. I had an oil leak, so I pulled the motor today and located it, resealed it and put the drivetrain back in.

Car now has a 1,2,3 ignition for FI cars. It has only one nipple for vacuum, so the hose from the top of the throttle body is connected to the nipple on the distributor, the bottom vacuum port on the throttle body is capped off. The timing has not been further adjusted, as it wont run long enough without throttle to do that. (I only have 2 hands).

Turn the key, fuel pump kicks on, and the car will start pretty easily with the key turn. It will light, then die within a few seconds. Fuel pressure is at 30 PSI based on the inline gauge.

I can start it and with throttle, keep it running. My best description is that with 0-1/4 throttle won't keep it running, I have to sort of put my foot in it. When it warmed up a bit, it sort of idled, but lobed up and down, to the point it wanted to stall but would catch itself at the last second, and lobe up again. I think this is my best symptom....

The MPS is stock, and holds vacuum and also checked out on the meter.

I've looked at every vacuum line and things are plugged. The car is not driving as of yet in the build process, I am trying to stabilize it so I can work toward a drive down the street.


Any FI info would be helpful. I really want to keep it as stock as possible. I will check all the valves again tomorrow and make sure they are in spec.

Thoughts on where to troubleshoot?

Thank you in advance.

[emerygt350]

My first suspicion is your timing. My second is you are only running on two cylinders. Did you double check your trigger point wires from the dizzy? Is it Bluetooth or switchable? In either case disconnect that vacuum from the distributor for the moment and plug it on the throttle body. I am not sure if Bluetooth does anything special with that (I don't think so) but you won't be needing vacuum advance or retard till later. Do you know which port on the TB is ported and which is manifold?


Double check those plug wires too....

[ConeDodger]

Vacuum

[ConeDodger]

A must be right factor for all efi

[Robarabian]

I will plug both ports and try. It is running on all 4 for sure (123 has no trigger points it is solid state) and you can hear all 4. It is running basically balanced when it starts and under throttle.

I think I have a vacuum issue as listed below as well.

I agree, the timing is still set in the static timing area, but it should still run and idle so that I can adjust the timing without providing any throttle.

Good question on which is ported and manifold I'll have to re-check there.

Thank you!

My first suspicion is your timing. My second is you are only running on two cylinders. Did you double check your trigger point wires from the dizzy? Is it Bluetooth or switchable? In either case disconnect that vacuum from the distributor for the moment and plug it on the throttle body. I am not sure if Bluetooth does anything special with that (I don't think so) but you won't be needing vacuum advance or retard till later. Do you know which port on the TB is ported and which is manifold?


Double check those plug wires too....

[Robarabian]

Yes. But... I researched here quite a bit and there's alot of talk about the cyl head temp sensor... but most of it talks about the resistor on the 2.0, there is nothing on the 1.7. I do have a replacement from Pelican that was for my car, but no resistor. The car didn't have one when I bought it (non running from original owner). Before I tore it all down, it did start and idle without a resistor, but likely had the original temp sensor that had a pretty frayed wire, so I replaced it during the rebuild.

Do you know if all that data for the 2.0 73-up applies to the 1.7?

Vacuum

[r_towle]

you need one vacuum line connected to run and idle perfectly, that is the MPS line.
Remove and plug 100% of the other lines, including distributor, AAR, etc etc...all of them.

Does it start and idle?
If still not, re-inspect the plenum to intake runner hoses...and inspect and remove, clean, replace all injectors to ensure all rubber o-rings are properly seated...

Gaskets from intake runners to head?
Valves properly loose and all seated ?

So, all air going into motor is going in the way the engine was designed...no other way into the motor.

The car (for real) needs power to the distributor and one vacuum line to the MPS to start and idle as designed.

You can unplug the CHT to get car to start and idle.

Heat expands things...so while it won't idle when cold..it kind of idles when warm...because the air leak is less now due to expansion of things.

Go find ALL the air leaks...5 little ones add up to one big ass air leak.

Go find all the ground wires for the EFI...they are on a top case bolt underneath the plenum...all clean, and seated?

If all else checks out...suspect the 50 year old EFI engine bay wiring harness...they make cars behave in all sorts of odd ways.

Rich

[Superhawk996]

Yes. But... I researched here quite a bit and there's alot of talk about the cyl head temp sensor... but most of it talks about the resistor on the 2.0, there is nothing on the 1.7. I do have a replacement from Pelican that was for my car, but no resistor. The car didn't have one when I bought it (non running from original owner). Before I tore it all down, it did start and idle without a resistor, but likely had the original temp sensor that had a pretty frayed wire, so I replaced it during the rebuild.

Do you know if all that data for the 2.0 73-up applies to the 1.7?

No resistor on the 1.7L

[emerygt350]

A must be right factor for all efi

Not for d jet. Just causes the engine to rev...

[emerygt350]

The 123 has a digital replacement for the trigger points, I was wondering if you hooked it up correctly.

[emerygt350]

This is not a vacuum leak. This is d jet.

[Robarabian]

Thank you and other, I will poke around a bit more for sure.

Yes, the valves are good, I started there today and #3 was out of spec. I started it again and got it warm. Moved the Dizzy a bit and it idled, but lobes alot. Switched out to another MPS and it improved slightly, but still not right, getting some backfiring through the intake... I believe Timing related there.

ill keep looking for vacuum leaks and see where that leads...

you need one vacuum line connected to run and idle perfectly, that is the MPS line.
Remove and plug 100% of the other lines, including distributor, AAR, etc etc...all of them.

Does it start and idle?
If still not, re-inspect the plenum to intake runner hoses...and inspect and remove, clean, replace all injectors to ensure all rubber o-rings are properly seated...

Gaskets from intake runners to head?
Valves properly loose and all seated ?

So, all air going into motor is going in the way the engine was designed...no other way into the motor.

The car (for real) needs power to the distributor and one vacuum line to the MPS to start and idle as designed.

You can unplug the CHT to get car to start and idle.

Heat expands things...so while it won't idle when cold..it kind of idles when warm...because the air leak is less now due to expansion of things.

Go find ALL the air leaks...5 little ones add up to one big ass air leak.

Go find all the ground wires for the EFI...they are on a top case bolt underneath the plenum...all clean, and seated?

If all else checks out...suspect the 50 year old EFI engine bay wiring harness...they make cars behave in all sorts of odd ways.

Rich

[914_teener]

Questions:

Does the ECU part number match the matrix on the Anders site? Is it the correct one?

What 123 did you put on? Switched or Blue tooth?

From the sounds of it, you have a fuel system problem or vaccum leak somewhere.

Check ALL electrical ground connections as has been suggested.


I you want help I'm in CA in August for the first couple of weeks.

[Ishley]

Make sure your fuel pressure is good. Running the engine up could be bringing the voltage / power up… and it could be dropping at lower rpm. Do you have a fuel pressure gauge?

[emerygt350]

All of those symptoms point to timing. Loping engine makes me think you are short a cylinder or 2.

[914_teener]

All of those symptoms point to timing. Loping engine makes me think you are short a cylinder or 2.

Disagree...they don't all point to timing.

[emerygt350]

It ran before with his equipment. The 123 is the new addition.

I would start with double checking spark plug order, then pulling wires to see the effect on idle (now that it is kind of idling)..

[Robarabian]

I suspect my MPS is faulty. All the vacuum lines are good, absent spraying some carb cleaner on the throttle body while it runs (new gasket to seal by the way) that is my current variable.

I pulled it yesterday and with the LCR 55 meter started measuring. It is out of spec. So I will start there and see if I can get someone (Jeff B or Chris F) to assist in a bench reset. IT holds vacuum, and reads right at zero vacuum, but once I add vacuum, it is way off.

If I cant sort it this way, I may ask you for help when you are in the So Cal area, but let's see how I do. I like to try to solve these things.

As to it running before the rebuild, yes it did, and it had pertronix in it, so the 123 bluetooth is a major upgrade. I have not messed with the stock settings in the 123 software so the curve is how they set it. Maybe there is something I need to tell it that it is looking for?

Again, thank you to everyone for chiming in, I couldn't work on stock FI without all of your knowledge.

All of those symptoms point to timing. Loping engine makes me think you are short a cylinder or 2.

Disagree...they don't all point to timing.

[FlacaProductions]

This is interesting.
I had a similar situation with my 2.0 after a 123 install.
Before the 123, it ran "fine" (stock distributor with a Pertronix)
After, it wouldn't even start.
Turned out the MPS was the culprit as swapping in a different one allowed it to start right up.
Check to make sure you have the correct MPS for your engine. Mine was the "wrong" one and had been rebuilt which may/may not have contributed. My money is on the MPS.

[emerygt350]

And don't put any faith in comparing those conductance measures. Ohm check? Yes. Conductance no...