D-Jet troubleshooting Options

[saigon71]

Could use some ideas…

Background: Car sat idle in a garage for six years - 37K miles. Engine was free. 2.0 factory d-jet. I adjusted the valves, installed a new fuel filter, changed the oil & put some gas in it. It fired up but had a very high idle.

Since then, I have done the following:
-New plugs & wires
-New distributor cap, points & condenser (rotor was clean)
-New air filter
-New alternator & voltage regulator - tested good
-All new vacuum lines from AA
-New intake runner gaskets and manifold to head gaskets
-Tested all FI components except the brain. Replaced AAR and MPS with good used
ones, bench tested each before installation. MPS holds 20 in HG and electrical tests
were within limits. Replacement parts are compatible based on this site:
http://members.rennlist.com/pbanders/djetp...tm#troubleshoot
-Tested fuel pressure - dead on factory spec of 2.0 bar
-Dwell well within specs
-Set timing dead on at 27 degrees BTDC with distributor lines plugged and disty at
full advance
- TPS set according to the picture I found on this site
- New plenum to intake runner gasket
- New cold start valve gasket
- Tested PCV Valve
- Plenum inspected – no holes found
- Throttle body removed & thoroughly cleaned

At all ambient temps tested (50-70 degrees F), the car fires right up but stalls almost immediately…this happens twice. Tapping the throttle does not help. On the third start, the car stays running and idle varies between about 800-1200 RPM. After about 10 minutes, it settles in at about 950RPM or so. Besides this, the engine runs great, has plenty of power and pulls hard in all five gears. Is this as good as it gets or am I missing something. Thanks in advance.

Bob

[detoxcowboy]

How is it supposed to idle, anyway? (copied from the below link, not my car, I do not live in Pheanix and I can't spell)
I'm going to take you through a typical day of driving the car to work, going out for an errand, and driving home. What I describe below is how my car behaves, this is a real example.

Let's say it's spring and your garage temperature is about 60 degrees, and the car has been sitting overnight. This is a "cold" condition for the motor. If you're in the winter in New England and it's 0 degrees, this is called "cold-cold". We'll take the warmer case as our baseline for the scenario. Without pressing the accelerator (factory says to start the car with a wide-open throttle, I've personally never done that but sometime, I'll give it a try!), you turn the key, and the car starts. 99% of 914's in good condition will start up like a champ, but will need one or two light taps on the throttle to get the idle up after it drops a few seconds after starting. By the time you back out of the garage and stop to put the car in first, your idle should be about 1600 to 1800 rpm, as your auxiliary air regulator (AAR) is open and is providing air that bypasses the throttle plate, keeping the idle high to overcome internal friction while the engine warms up and the oil comes up to temperature.

By the time you get to the second or third stop light (about 5 to 10 minutes), the AAR is closed, and the idle drops to the spec setpoint, about 950 to 1000 rpm. You might note a slight instability of about 50 to 100 rpm, as the motor is still warming up and is probably a bit lean. As you approach the light and let off of the throttle, the engine speed should smoothly decrease to idle and slow as it approaches the idle level - not drop through it like a rock and bounce around. As you drive, on your 20 minute commute, the idle does not vary from the setpoint by more than 50 rpm any time you are sitting at a light. It gets smoother as the engine warms up, and by 10 to 15 minutes, the engine is fully warmed up and there is no change past this point in the way the idle behaves. You arrive at work and park the car. The air temperature is about 75 degrees (I live in Phoenix, that's how warm it is here in the spring in the morning...).

About an hour later, you need to make a 30 minute errand to go to the Post Office. You start the car, the idle comes to the setpoint or somewhat below, quickly. That's because the AAR is still hot and isn't open, and while the motor is warm, the heads have cooled considerably. Because the air-cooled D-Jetronic depends on head temp for setting the warm-up mixture, you're likely to have a bit of bogging and low idle for the first 5 minutes, until head temperatures come up. This is a well-known design issue with 914's, "warm start over-enrichment" is what we'll call it. There's not too much you can do about it. You may have to use an open throttle to get the car to start, as it's too rich and needs more air.

You go into the Post Office and it takes you less than 10 minutes to do your business. When you restart the car, it idles stably. That's because the head temp is still high and you have the correct mixture. Your car idles properly until you shut it off back at work.

It's now 5 pm and you're ready to go home. Let's also say this is early spring, and it's dark enough to use your headlights. When you start your car, it's very similar to the morning start. The AAR is active for 5 to 10 minutes, you have high idle, then it comes down. But your idle is now no more than 50 rpm lower than the setpoint, due to the power needed to drive the alternator to supply the headlights, so your idle is about 900 to 950 rpm. The car idles fine until you shut it off back home.

Idle Stability Trouble Shooting..

http://members.rennlist.com/pbanders/idle.htm

[saigon71]

How is it supposed to idle, anyway? (copied from the below link, not my car, I do not live in Pheanix and I can't spell)
I'm going to take you through a typical day of driving the car to work, going out for an errand, and driving home. What I describe below is how my car behaves, this is a real example.

Let's say it's spring and your garage temperature is about 60 degrees, and the car has been sitting overnight. This is a "cold" condition for the motor. If you're in the winter in New England and it's 0 degrees, this is called "cold-cold". We'll take the warmer case as our baseline for the scenario. Without pressing the accelerator (factory says to start the car with a wide-open throttle, I've personally never done that but sometime, I'll give it a try!), you turn the key, and the car starts. 99% of 914's in good condition will start up like a champ, but will need one or two light taps on the throttle to get the idle up after it drops a few seconds after starting. By the time you back out of the garage and stop to put the car in first, your idle should be about 1600 to 1800 rpm, as your auxiliary air regulator (AAR) is open and is providing air that bypasses the throttle plate, keeping the idle high to overcome internal friction while the engine warms up and the oil comes up to temperature.

By the time you get to the second or third stop light (about 5 to 10 minutes), the AAR is closed, and the idle drops to the spec setpoint, about 950 to 1000 rpm. You might note a slight instability of about 50 to 100 rpm, as the motor is still warming up and is probably a bit lean. As you approach the light and let off of the throttle, the engine speed should smoothly decrease to idle and slow as it approaches the idle level - not drop through it like a rock and bounce around. As you drive, on your 20 minute commute, the idle does not vary from the setpoint by more than 50 rpm any time you are sitting at a light. It gets smoother as the engine warms up, and by 10 to 15 minutes, the engine is fully warmed up and there is no change past this point in the way the idle behaves. You arrive at work and park the car. The air temperature is about 75 degrees (I live in Phoenix, that's how warm it is here in the spring in the morning...).

About an hour later, you need to make a 30 minute errand to go to the Post Office. You start the car, the idle comes to the setpoint or somewhat below, quickly. That's because the AAR is still hot and isn't open, and while the motor is warm, the heads have cooled considerably. Because the air-cooled D-Jetronic depends on head temp for setting the warm-up mixture, you're likely to have a bit of bogging and low idle for the first 5 minutes, until head temperatures come up. This is a well-known design issue with 914's, "warm start over-enrichment" is what we'll call it. There's not too much you can do about it. You may have to use an open throttle to get the car to start, as it's too rich and needs more air.

You go into the Post Office and it takes you less than 10 minutes to do your business. When you restart the car, it idles stably. That's because the head temp is still high and you have the correct mixture. Your car idles properly until you shut it off back at work.

It's now 5 pm and you're ready to go home. Let's also say this is early spring, and it's dark enough to use your headlights. When you start your car, it's very similar to the morning start. The AAR is active for 5 to 10 minutes, you have high idle, then it comes down. But your idle is now no more than 50 rpm lower than the setpoint, due to the power needed to drive the alternator to supply the headlights, so your idle is about 900 to 950 rpm. The car idles fine until you shut it off back home.

Idle Stability Trouble Shooting..

http://members.rennlist.com/pbanders/idle.htm

Went another two clicks on the ECU after bumping the fuel pressure to 30 PSI. Now two taps of the throttle after it initially fires seems to do the trick.

I still have to check a few more things but it looks like things I am getting there - from reading "99% of 914's in good condition will start up like a champ, but will need one or two light taps on the throttle to get the idle up after it drops a few seconds after starting." - it sounds like my system is functioning pretty well.

Thanks,
Bob