I need your help...I've got my transplanted djet 2ltr (76 de-smogged motor) in and running...and driving. I'm trying to get the motor running good but I'm having a problem with low rpms.

If I try to slowly accelerate the motor seems to "buck," hestitate until the motor reaches about 3,000 rpm then it's smooth sailing. However, if I put my foot into the pedal harder and run through the gears it pulls hard and strong like a mule....awesome.
Below are some things I've done:

• valves adjusted while engine was cold .006 and .008(exhaust)
• Installed new petronix ignition
• Set timing at 27 degrees at 3500 rpm
• Completly removed and cleaned throttle body and blew out all the ports with carb cleaner
• Cleaned throttle position contacts (excellent condition) and adjusted idle and full throttle contacts using an ohm meter
• all injectors were serviced
• fuel pressure set and steady via gauge at 28lbs
• New plugs, rotor, cap...wires appear to be in good condition
• installed a rebuilt 043 MPS (Bleyseng)
• Checked for vaccum leaks
• Engine runs at 325-350 on CHT gauge
• New cylinder head temperature sensor
• New air cleaner

Things I haven't done

• adjusted the ECU....as I understand it...this is only an idle adjustment mixture....although the motor smells maybe a tad rich at idle
• Have not played with the trigger points (stock bosch dizzy)

At this point I don't want to just start throwing money at parts. From what I've read, the trigger points can cause bucking and too rich running. When I saw Pelican wanted $175 for them...I didn't want to roll the dice????

The only other symptom worth mentioning, is when I first start the motor when it is cold, the idle hunts quite a bit....like 1000 rpm...not to sure what that is all about. I did install a oem thermostat and the air flaps are working correctly. After it warms up the idle is fairly steady but a bit rough.

Sorry for the long story....I need some ideas

things you forgot to check:

- check your grounds. then check them again. clean them suckers. make sure the connectors on the engine ground cluster are a snug fit!

- check your relayboard. make sure you don't have any cracks on the underside causing sporadic cutoffs.

- electrical wires. look for broken insulation and brittle wires. dust off your multimeter, grab the haynes manual, and check ALL wires & connectors!
i had to salvage three (3) D-Jet harnesses to make just one good one. some wires were cracked *inside* the heavy plastic shielding. impossible to see from the outside.


you won't believe how much smoother my engine ran after i rebuild the main wire harness and got a new relay board!
Andy

do you have your original temp sensor? measure its resistance (while cold) and compare with the new one. there is apparently more than 1 part # with different specs. when I replaced mine the resistance of the new was alot less and this caused bucking on accel especially when cold. I compensated with a 500 ohm resistor, but this is not really the proper solution if the right part can still be obtained.

worn trigger pts wont cause rich running. the two times I've had them go (after 310k miles) it would go from good running to 2 cyl to 'walk home' in short order. No amt of fiddling will bring them back. If you're going to keep the car and keep djet, you need a spare set. Even at 175. think how much you're saving in insurance, gas, and registration.

another source of bucking is if your throttle switch is dead. you can check this by turning ign on (don't start engine). open the throttle valve on the engine and listen for the clicking sound of the injectors. this only takes a moment - dont leave your ign on or you can fry your pertronix. good luck

timing dwell--my problems lie here.

I did check the throttle switch with an ohm meter when I adjusted the idle and wide open throttle...but I need to check for the 20 clicks...easy enough...I'll unplug the petronix leads from the coil to be safe....been there...done that



Yeah...I wanted to eliminate dwell out of the equation so I had added the petronix (no points)...but timing could be part of it....got to go back and check and recheck.

Thanks guys...keep the ideas coming!

My car was doing exactly what yours was until I replaced the relay board. It was working fine one day, and then the next it would buck unless at 3000rpm.


It's an easy thing to check if you can borrow a known good one.

My '76 2.0 did the same- almost 20 years ago. I called George at AA, and he asked if I had a ballast resistor in series with the TS2. I originally had one, which I had removed since I couldn't find any reference for it. He told me to put it back in. I did, and it ran great and with no problems through '02 when I pulled it for its rebuild.

Yes, I KNOW the ballast resistor isn't supposed to be in on a '76, but it worked.

Good luck!

Well, I do have the 270 ohm resistor still from my spare 2ltr....which happened to be a 75. Worth a try at least...not sure what my stock 043 MPS will think about that...thanks

Hmmm...I'll have to see what I can dig-up to test this idea...even though it worked great with my L-Jet...there are a few circuits that are now being used that never have been used in the last 35 years.

It's too bad there are no active 914 enthusiasts in my area...there's nothing like another set of eyes...besides it's part of the ritual...you know...3 or 4 guys sitting around a 914 brainstorming and

Latest update...
I threw in a 270 ohm resistor in series with my head temp sensor and it made a world of difference on cold startup....no hunting idle...fast idle then settled right down as it warmed up (aux valve closing).

The resistor also improved my low end bucking quite a bit even after the car warmed-up...I guess this is telling me I was running my FI too lean??

Next, I want to get a air/fuel ration gauge and connect a variable pot to the head sensor and adjust for smoothest running at 2500 rpm (as suggested by Kjell Nelin article) or until CO is between 1.5-2.0%.

Checked the throttle position switch and I'm getting exactly 20 clicks...and tried unplugging it and running without it...amazing how well the car still will run...just a bit more sluggish....anyway, it appears to be OK so I plugged it back in.

I also advanced the timing a few more degrees which smoothed things out as well.

Overall, I think I'm on the right track. I don't want to play with the ECU idle knob until I know by CO levels are correct via the head sensor.

I'm getting closer and closer...