Some Bucking at Low-end...then pulls like a mule, Trying to get all the bugs out--I need your help Options

[computers4kids]

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

[computers4kids]

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!
I will go back and recheck all my engine grounds...but I did take special care when I put the harness back on the motor to pay attention to clean grounds...especially the ground FI cluster
- check your relayboard. make sure you don't have any cracks on the underside causing sporadic cutoffs.
Will check, but this board worked great with my Ljet...although different pathways are being used now with the Djet.- 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.
I sure wish I had taken the time to use an ohm meter on my harness when the motor was out...appearance wise...it looks pretty good...there was one FI connector that I had to add a new FI end from a parts harness. I need to go back and check from the ECU connection harness and check continuity on all FI injector plugs for both white wires.

you won't believe how much smoother my engine ran after i rebuild the main wire harness and got a new relay board!
(IMG:style_emoticons/default/bye1.gif) 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.
My motor's original head sensor was bad and my spare motor's sensor was setup to work with a 037MPS and had the 270ohm resistor setup that Atlanta sells everyone (1973 setup), even though it was a 75 motor. The PO accicentally switched the heads on my 76 motor and the sensor is actually on #1 cyclinder, which runs approx. 30 degrees cooler. I'm not sure what this is doing to the fuel mixture. I would think it would richen the mixture a tad at warm running, but since I added the early stainless exhaust that probably negated the enrichment (compared to stock 76 exhaust). I really need to get a hold of a air fuel gauge with an exhaust pipe probe...they are outrageously expensive.
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.

I'm in the process of finding a new oem set at a decent price...I thought I read somewhere bouncing trigger points could cause bucking

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

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 (IMG:style_emoticons/default/blowup.gif)

timing dwell--my problems lie here.

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!