Got it running.......and then..
 

Probably ran better than it has ever before in it's early 500mi life. Cleaned the plugs installed the correct head temp sensor all was groovy, stopped a couple of times to tweek the idle. But once again at or above 220 deg oil temp the idle dropped way low and it wanted to die and did. It was very hard to start (happened twice). It didn't smell rich like last time though. I couldn't keep it running long enough to try to readjust mix knob on ecu and idle screw on throttle body.
Maybye it's vapor locking?
Maybye I have an exhaust leak that makes it impossible to get to idle when hot?!
Maybye my motor is a bit outside the parameters of stock FI to compensate over full operating temperature(slightly larger displacement 2.1, webcam FI cam, 8.5to1 compression ratio, pp heads).
Let it cool down and tried again mix screw full counterclockwise...idle screw full out, makes no differance, tried slowly turning mix clockwise got worse..won't idle when driving and coming to a stop....runs fine as long as there is a load on it. I will try swapping MPS this weekend. May still be too rich I am going to remove ballast resistor and drive tommorow.

[This message has been edited by DF (edited 05-03-2001).]

this may help or be totally off base, but
my dimly remembered motorcycle (carb)experience says lean idle mixture. Don't know enough about D-Jet yet to suggest a fix, but does D-Jet enrich when cold, then lean it out when hot? With a bike, I think I used to set the approximate idle, then lean out the mixture till it stumbled a bit, then enrich it by a half turn or so (IIRC) then set the final idle.
The plugs should help tell you what's up.

D-jet does indeed richen the mixture when cold, and lean it out when warm. That is what the head temp sensor does.

In my own experience, the "idle bogs way down" syndrome is often a result of an overly-rich mixture, not overly-lean. But pulling the plugs will tell the tale. Black sooty deposits mean too rich, white or grey deposits mean too lean.

Can we assume that DF has read through Kjell's D-jet Guide ( http://www.914fan.net/djet.html )? And that he has checked the ignition system thoroughly and looked for vacuum leaks and so on?

--DD

DF, I agree with Dave, you have to pull the plugs when your car is bogging at idle, and check to see if they're sooty - if so, the car is rich.

Vapor lock is a possiblity, but your symptoms don't sound like that's what is happening. As Dave suggested, follow through Kjell's procedures for checking out the system, ESPECIALLY the part about checking the fuel pressure. If the D-Jet system has been renewed as you have previously described, and all the components are working properly, you should be pretty close to the correct mixture when you've got the ECU knob centered - unless you're fuel pressure is way off.

Keep at it. It only took me 15 years to get my system working properly http://www.pelicanparts.com/ultimate/smile.gif.

Brad Anders

ps: I strongly suggest that when you review Kjell's article that you DO NOT make any attempt to adjust the MPS as he describes. It is very likely to make things worse and leave you with a out-of-whack MPS.

DF, did you post your mechanical setup before? I wasn't aware that you were using the non-stock cam, 2.1L, 8.5:1 compression, and PP heads. Add it all up and I would think that the stock FI settings would have you running lean.

In addition to the other suggestions, I would also suggest that you get your hands on a A/F meter that installs into your car. Then you can directly see what the A/F ratio is when your bogging idle happens. That's how I debugged my FI system recently. CB Performance sells a unit that I think Dave has in his car.

Brad Anders

Same caveats as previous post, but if above line of reasoning makes sense, a quick test would be to eliminate the head temp effect from the circuit temporarily (ie create constantly rich, cold condition) and see if that improves matters. If so, then its probably too lean hot idle mixture.
To the point about patiently going through Kjell's excellent reference, Yup. It would probably save a lot of time 'chasing your tail'. (Don't ask me how long it took to learn this...) Djet is coming up for me too.

Dave

[This message has been edited by DDS (edited 05-05-2001).]

DF
Where is your fuel pump located? Possibly overheating the pump?