Good News with DJet - Almost there!, Making progress... Options

[customstarr]

I want to start by thanking everyone for the input & assistance - I still be totally fuched if it wasn't for this web site, and the people that are dedicated to the 914. Anders site on the DJET system is an unbelievable resource. The 914 community has to be one of the strongrest and most knowledgable of any that I've been associated with in my years of the car hobby.

Finally got to the bottom of my rich running D-Jet issues - saved the best for last I guess. Timing and trigger points - that's what made the difference. Trigger points were dirty & timing slighlty retarded (like me I guess.) In the quest to solve this, I replaced and/or checked everything.

Here's where I'm at: Car is running good overall. It wants to die if I don't stay on the gas during the first 10 seconds of a cold start. After that, it runs stable with a low idle (500-600 RPM) - but it doesn't stall. I suspect a lean condition based on the info I've read. The idle improves as the engine warms, ultimately stabilizing at about 1K.

Since this is an early system (early 71) it does not have the enrichment knob on the ECU, and it has a 4-Pin TPS. I can't find any info on how to test/adjust the 4-pin TPS.

Wondering how I can verify ECU is recogizing idle from TPS (no method to adjust), and how to richen the idle? Toon has a 1972 FI system available- I'm wondering if I should switch to that to gain control over these things, or if there's a way to do it on mine. I haven't found that answer anywhere.

[Demick]

Pretty much impossible for the AAR to cycle open and closed like you describe. More likely, when the AAR is open, it does cause a slightly lean condition which causes the cycling. When you plug it, that lean condition goes away, which stabilizes the idle, but also causes very low idle since you've plugged the bypass.

I'd still remove the AAR and check for full operation (goes from fully open when cold to fully closed within 10 minutes or so with 12V applied). Once that is confirmed to be working properly - or fixed if it has not been working properly, and if the fluctuating idle persists, then try to richen the mixture at idle.

Have you checked your fuel pressure?

Demick

[customstarr]

Pretty much impossible for the AAR to cycle open and closed like you describe. More likely, when the AAR is open, it does cause a slightly lean condition which causes the cycling. When you plug it, that lean condition goes away, which stabilizes the idle, but also causes very low idle since you've plugged the bypass.

I'd still remove the AAR and check for full operation (goes from fully open when cold to fully closed within 10 minutes or so with 12V applied). Once that is confirmed to be working properly - or fixed if it has not been working properly, and if the fluctuating idle persists, then try to richen the mixture at idle.

Have you checked your fuel pressure?

Demick

A little more investigation: After cold start, idle fluctuates with AAR connected - with it disconnected the idle is stable but low. At full operating temp, idle is low regardless of AAR status (connected/unconnected). Idle bleed screw has little to no effect on idle speed. Car runs great and it doesn't stall at a stop, but idle is very low (500 RPM).

Maybe it's also worth noting that even when the AAR line is unplugged from the intake boot (with the hole in the boot left wide open), the idle does not change (maybe lowers very slightly).

I checked the fuel pressure a while back (30 PSI), but I have to admit, it was with an el-cheapo Harbor Freight guage that felt like it was about ready to fall apart.