Optimizing Engine Operation, How good can it get? Options

[ctc911ctc]

Overview

'74 2.0L, 20K miles, stored since '84, first run Oct 2018. 100% stock D-Jet engine with new hoses, fuel system, etc. Spec compression on all 4. Dwell set, timing set.

Engine runs good, strong - chasing idle problems (see my post 'idle weirdness').

My question is; how good can I get this engine to idle? Can this engine run smooth at 800-900 RPM with very little engine vibration? Can the engine run rock steady at 800 rpm without minor surges? Currently this engine is shaking at idle, not violently but you can feel it in the cab.

Does anyone have a high quality audio example of this engine running when new? Or to absolute factory spec? (yea, I know many of you believe that this is not a good method of reference, but hearing what one SHOULD sound like is helpful).

I look forward to coming into this group of like minded 914-crazy (me being the most crazy) group of awesome people each day.

Many thanks in advance

CTC911CTC

[914_teener]

Overview

'74 2.0L, 20K miles, stored since '84, first run Oct 2018. 100% stock D-Jet engine with new hoses, fuel system, etc. Spec compression on all 4. Dwell set, timing set.

Engine runs good, strong - chasing idle problems (see my post 'idle weirdness').

My question is; how good can I get this engine to idle? Can this engine run smooth at 800-900 RPM with very little engine vibration? Can the engine run rock steady at 800 rpm without minor surges? Currently this engine is shaking at idle, not violently but you can feel it in the cab.

Does anyone have a high quality audio example of this engine running when new? Or to absolute factory spec? (yea, I know many of you believe that this is not a good method of reference, but hearing what one SHOULD sound like is helpful).

I look forward to coming into this group of like minded 914-crazy (me being the most crazy) group of awesome people each day.

Many thanks in advance

CTC911CTC

You could be suffering misfires at the injectors due to a crack harness as Andy suggests.

After replacing and going through everything on my d-jet system including a new harness and finally the 123 distributor, it idled dead nuts to spec and steady an pulled strong up to the redline, and was right on the money after I check the AFM with a wideband.

I say this from experience FWIW. Unless you like programming and major fiddling yourself or can afford to pay for aftermarket injection for a stock motor, stick with the D-jet. The Bosch engineers knew what they were doing, and if they could have done it better they would have. Anybody who has done it will tell you that...anyone else who hasn't either likes fiddling or hasn't ever serviced FI or worked on it. My opinion and only mine.

If I could have found a good original dizzy I would have done that but I coudln't.

Good luck there are still a lot of good folks here....the ones who are still with us.

[thelogo]

Overview

'74 2.0L, 20K miles, stored since '84, first run Oct 2018. 100% stock D-Jet engine with new hoses, fuel system, etc. Spec compression on all 4. Dwell set, timing set.

Engine runs good, strong - chasing idle problems (see my post 'idle weirdness').

My question is; how good can I get this engine to idle? Can this engine run smooth at 800-900 RPM with very little engine vibration? Can the engine run rock steady at 800 rpm without minor surges? Currently this engine is shaking at idle, not violently but you can feel it in the cab.

Does anyone have a high quality audio example of this engine running when new? Or to absolute factory spec? (yea, I know many of you believe that this is not a good method of reference, but hearing what one SHOULD sound like is helpful).

I look forward to coming into this group of like minded 914-crazy (me being the most crazy) group of awesome people each day.

Many thanks in advance

CTC911CTC

You could be suffering misfires at the injectors due to a crack harness as Andy suggests.

After replacing and going through everything on my d-jet system including a new harness and finally the 123 distributor, it idled dead nuts to spec and steady an pulled strong up to the redline, and was right on the money after I check the AFM with a wideband.

I say this from experience FWIW. Unless you like programming and major fiddling yourself or can afford to pay for aftermarket injection for a stock motor, stick with the D-jet. The Bosch engineers knew what they were doing, and if they could have done it better they would have. Anybody who has done it will tell you that...anyone else who hasn't either likes fiddling or hasn't never serviced FI. My opinion and only mine.

If I could have found a good original dizzy I would have done that but I coudln't.

Good luck there are still a lot of good folks here....the ones who are still with us.

(IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif)


The bosch engineers did it way too good
When your design outlasts the parts required to build and maintain the system several decades over

You are pretty bad ass.

Niceest retro fit 914 f.i i ever saw was a bosch system off a rabbit .... Looked alomost factory .


But with virtually no parts /components available for djet
In theory you could 3d print a new mps ?

But in 1975 did they sell them (mps) or 5th injector
at flaps ?





And if modern fuel injection is so expensive.

Would carbs and a carb cam be cheaper
(Engine out anybody )