Troubleshooting help 1.7 FI, Updated: I almost have defeated the D Jet Demons! |
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Troubleshooting help 1.7 FI, Updated: I almost have defeated the D Jet Demons! |
Robarabian |
Jul 13 2024, 08:52 PM
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#1
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914 A Roo Group: Members Posts: 622 Joined: 11-February 19 From: Simi Valley, Kalifornia Member No.: 22,865 Region Association: Southern California |
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. |
r_towle |
Jul 14 2024, 11:05 AM
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#2
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Custom Member Group: Members Posts: 24,623 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
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 |
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