Calling On The FI Experts, Stumped Again Options

[Mblizzard]

Been trying to sort my newly installed FI system. I have checked out the components as best I can but I can't seem to resolve my problems.

2.0 L 73 D-jet

So here's the issue. At idle the engine surges. Remove the TPS wires it is reduced but still present. Remove the wires on the plenum temp sensor the surging is gone.

Next when trying to set the timing it goes well with the vac off. When I hook the vac up to the dizzy the timing advances 20 degrees and the idle shoots up.

Any suggestions?

[Cap'n Krusty]

Hi, Mike. The timing: Sounds like you have the vacuum hoses reversed. The larger diameter hose goes to both larger diameter ports, one on the throttle body, one on the distributor vacuum can (on the vac can, it's the one on the "back side, just above the plug for the trigger points). '74 FI doesn't have a TB port for the advance, IIRC. A hunting at idle is generally, when all else is correct, a mixture problem. In the past I've seen cars that never ran right with the plenum temp sensor connected. Taking the lazy man's way out, we left it unplugged ...... Before doing that, try adjusting the idle mixture with the knob on the top of the ECU. Set it in the middle and experiment with various settings from there. Once you have the timing issue fixed, you might want to take a look at PB Anders D-jet pages on his website. Keep us posted!

The Cap'n

[DRPHIL914]

Hi, Mike. The timing: Sounds like you have the vacuum hoses reversed. The larger diameter hose goes to both larger diameter ports, one on the throttle body, one on the distributor vacuum can (on the vac can, it's the one on the "back side, just above the plug for the trigger points). '74 FI doesn't have a TB port for the advance, IIRC. A hunting at idle is generally, when all else is correct, a mixture problem. In the past I've seen cars that never ran right with the plenum temp sensor connected. Taking the lazy man's way out, we left it unplugged ...... Before doing that, try adjusting the idle mixture with the knob on the top of the ECU. Set it in the middle and experiment with various settings from there. Once you have the timing issue fixed, you might want to take a look at PB Anders D-jet pages on his website. Keep us posted!

The Cap'n

(IMG:style_emoticons/default/agree.gif) , what he said -
If vac hoses are correct, idle will slow slightly upon hooking them up. Then as you accelerate and the vac increases the advance increases so it sounds lime this is backwards right now. And surge is a mixture issue too lean. As captn says you should be able to increase your idle richness with ecu knob. Go 2 clicks, let it adjust for a minute or 2. If I'd does not effect the idle at all doing this, then your TPS is not set right . You can get rid of the surge by speading up the idle with idle adjust screw on the t.b.but this is not permanent solution.
If all this fails to get idle to balance, for me it was the MPS set too lean. It had been calibrated per factor spec but just was not right. Once readjusted u was able to dial it in.
Let us know how it plays out today. Might be good to have a spare MPS to compare to.
Good luck,