I'll take any help I can get on this one. I had issues with the car bucking/ low power when driving, even to the point where power just goes away and lucky to get it home. Alot of popping from the exhaust like it is running lean.
I replaced my points with a compufire module which improved the starting but still have issues off idle.
Fuel pressure = 29 psi on the rail.
Timing is set at 27 deg. BTDC.

While troubleshooting, I noticed the info from Pbanders site about throttle switch calibration. I calibrated the switch and cleaned the contacts with alcohol and a pencil eraser on two different tps's.
I connected the tps and checked resistance at the ECU connectoer per the table on his site.
Between 9 and gnd - 10 indications on continuity
Between 20 and gnd - 10 indications on continuity
Between 17 and gnd - 0 ohms closed throttle, infinite open throttle

these all check out. I even checked the harness for all 4 wires back to the ECU and it is good.

When I key-on, I dont hear the 20 injector clicks I expectwhen I move throttle from closed to full open.
I even used two different ECU's one from a '73 2.0L and one from a '72, neither seemed to work.

This one has me stumped. Do I need to rotate the engine to get on a trigger contact or something?

BTW I have a '73 1.7
Thanks Don

The tps is independent of distributor rotor/trigger position. With key on, you should hear injector clicks as you open throttle. One time my tps stopped working and I found the cause to be bad ground connection on the engine case. Another time, the tps stopped working and I never did find the cause. I just drove it that way for years. It willl still drive well, just accel is off a little.

As a quickie pot shot, it might be worth taking off the relay plate and cleaning connections, especially the fuel pump fuse. Also, try swapping the FI relay for one of you headlight relays. Good luck.

Good Idea, I will re check my ground connections and clean the relay board, carefully of course.

Thanks for the input.

Another thing to consider is measuring the tps functionality at the ECU harness. That way any faults in the harness or grounds will show up.

OK, I checked voltage with key-on at the tps connecter.

pin 9 to gnd alternated from 0-4volts as the throttle was opened.
pin 20 to gnd alternated from 0-3.5volts as throttle was opened.
pin 12/47 was 0 volts as expected since it is gnd to the ECU. (It also measured 0.3 ohms to the neg. battery terminal with key-off.)
pin 17 was 0 volts throttle closed and 4.9 volts with throttle open.

anyone know if these sound good?
I checked it with both ECUs again and still no clicking.

I then check the voltage on the relay board terminal "I" to make sure correct voltage is getting to the ECU and it measured 12.2 volts

I got impatient and started the car, it fired up and ran at 500 rpm, once warm it idled fine ( i probably need to check the AAR is opening). Anyway once warm, i opened the throttle and up to 3500rpm it went, sounded good, then started misfiring and backfiring with a big puff of black smoke out the exhaust. Sounds like it is running lean. fuel pressure is still spot on at 29psi , but i will take another look for kinks in the fuel line.

One other thing I noticed is at idle, i was playing with the plug wire on the dizzy and it seemed to cause it to miss out. wiggleing each wire would cause it to miss a little. Could this cause backfiring?

Thanks for the input so far. time for a beer and some reflection java script:emoticon(':beer1:', 'smid_12')

Dumb question here, but I'm going to ask it. Has anyone measured the resistance of their spark plug wires? I measure 2kohms on cyl 1, 1k on cyl 2 and 4 and 1.5k on cyl 3.

Does this sound right???

brp986s - Thanks for the input on the relay board, that is what fixed the issue with the tps not clicking the injectors. I pulled everything off the relay board, cleaned the connections with steel wool then sprayed them with CRC contact cleaner. I put it all back together and with key-on it clicks the injectors like a champ. Never thought I would be so excited to hear injectors click.

I re-checked spark and it is strong on all 4 wires.

AAR is opening as it is sucking strong when cold.



The car runs like crap now and I noticed my fuel pressure bouncing around from 28-30 psi. I thought one of my fuel lines was kinking so i removed it and put a longer one on with the fuel filter. I then drained the tank and made sure I have clean fuel going through the system.

Its backfiring when off idle. Sounds like the backfiring is coming from the intake and not the exhaust now.

I will re-check the fuel pump is getting 12v solid when running.
The issue definitely appears to be fuel delivery though.
Anyway, any other input is welcomed,
Thanks again,
Don

Compression = ?

Also:
Do you have a spare injector trigger?
Does the pressure sensor hold vacuum?
What are head sensor resistance values, hot and cold?
Unlikely, but easy to check - put ammeter in ine with head sensor. Current will vary with temp as the engine warms, but I had one of those become intermittant. An open circuit will stop the engine.

I checked compression about a year ago 120 psi +/-4 on each cylinder.

Are you talking about trigger contacts in the distributor?

Pressure sensor holds 15 in-hg vacuum for about 2 minutes, its rebuit.

CHT reading cold is 2kohms, I need to check it when its hot.
I did find out that the engine does not like it to be unplugged.

I was able to get it to idle better with the idle adjustment screw opened a bit further. The longer it ran, the better so i took it for a spin through the neighborhood. It ran OK in 1st gear at about 3000rpm through 2 cul de sacs, then when going around a carner I got on it and it started putting like no power.


I will try to recheck the current and resistance on the CHT.

Either my CHT is too low when hot or I have residual rust particles in my injectors

I thought it my be a kinked line at the fuel tank but i replaced the tank two yrs ago and had it out on the road at WOT with no problem.

Fuel pump voltage measured 12.3 - 12.5 while running the car.

Thanks for the input, I will look back into it and let you know.

Idle vacuum=?

Yes, I'm referring to the trigger in the distributor. But, if the engine starts and you can get it up to 3k rpm then the trigger is working.

Are you saying that it reproducibly:

a. starts and
b. runs on all 4 and
c. has good power cold, but loses power as it warms or
d. low power cold, no power warm?

sorry for the late reply, I missed the email notification in my inbox.

Meanwhile, since I though it was a fuel restriction, I thought I would take the opportunity to relocate the fuel pump to the front of the car to resolve any vapor lock issues and check for kinks. During the process I found my return line was kinked. i completed the project and the engine ran much better when cold, but still a little off.
I have new spark plugs on order and they should be here Friday.

I'll need to measure the vacuum at idle, good idea.

The issue relates mostly to "c" had good power cold but loses power as it warms up.

again sorry for the late reply, thanks for the help,
Don

With backfiring out the exhaust with balck smoke, sounds like you may have sticking injectors. Was the car sitting for a while that could cause this?
Tom