My car still idles like pure crap. Very inconsistent - high to low surging, super low, rich... you name it, this car's idle is ALL OVER THE PLACE. It's never the same condition. The car runs like a raped ape and goes good, but the idle sux complete ass. I used to be able to get some idle adjustment at the TB screw (I don't have the ECM screw), but today I set the fuel pressure correctly (was at 42 PSI) and now I have no control over the idle mix/speed. Maybe someone in the past tried to cover the problem by cranking up the fuel pressure. I'm not seeing the super rich condition now, but like I said... no control.

I've been through everything: replaced/fixed wiring, new ignition system, battery, cables, checked all the standard fare + what I've listed below, etc. This is getting ridiculous.


What I've replaced thus far:

1. Ignition: Coil, Cap, Rotor, Points, Condenser, Plugs, Wires (all Bosch except plugs).
2. Fuel/D-Jet: TS1, Fuel Filter, Vacuum Lines.

What I've checked, adjusted to spec, or tested to be good:

1. Ignition: Points, Timing, Trigger Points.
2. Fuel/D-Jet: MPS, TS2, Fuel Pressure Reg, Cold Start Valve, Aux Air Reg, Injectors, Fuel Lines, Fuel Pump, Throttle Body, Throttle Switch.
3. Engine: Timing, Compression, Valves.

There is a 3 way rubber "Y" underneath the intake box that I had to replace on my dads car several years ago. That alone was causing all of his erratic idleing.It cannot be seen with the intake bolted on. Looking at the engine from the fan housing end, it is to the right of center and just behind the fan housing. I"ll see if I can get to his engine to take a pic of it.

Nope I can't get to the engine for all of the sh*t I have piled up. Maybe somebody else will know what I am talking about.

Did you replace the injector seals? Mine was idling up and down after it warmed up until I replaced the seals.

Scotty- does this help? 74 D-jet w/ air filter removed-

[quote name='Johny Blackstain' date='Jun 19 2007, 04:50 PM' post='913326']
--><div class='quotetop'>QUOTE(scotty b @ Jun 19 2007, 08:28 PM) </div><div class='quotemain'><!--quotec-->
Nope I can't get to the engine for all of the sh*t I have piled up. Maybe somebody else will know what I am talking about.
[/quote]
Scotty- does this help? 74 D-jet w/ air filter removed-



[/quote]

Kionda. It's right there under the #1 runner where the 3 hoses seem to intersect. All I remember is there is also a small steel body with 2 ports down there also that the "Y" connects in with. See the green hoses from the intake boot and the air filter? That is the metal part and the rubber piece is there as well. Somebody will know it

Check your plenum to runner tubes for leakage. Pull your plenum off and shine a light inside it and look for the light to come through from the outside. These things can be sneaky but it sounds like a vacuum leak and EFI hates vacuum leaks.

Scotty- D-jet changed over the years... my charcoal canister is mounted on the backside of the rear trunk wall, inside the engine bay. Here's another top shot-

If this hasn't been resolved by Saturday I'll dig my way to the engine and get a pick of the piece. I need to get rid of some sh.....parts

My car is plumbed exactly like the diagram. Intake boot to Aux Air Valve, Air filter to Oil Breather, Throttle body to distributor x 2, Intake to MPS, and AIr Cleaner to Canister. I'm not aware of any "Y" connectors, or any additional hoses. This is a 1971 D-Jet just for clarification.

I'll look for more vac leaks, but I'm not aware of any at the intake.

Have you tried the "propane vacuum leak finding method"? Some of the guys in here advocate it. you take a small propane torch and turn it on (not lit) and probe around with it while the teener is running. Then the vacuum leak will suck it in and change speed (higher?lower, I think I heard both).

That's a great idea, but the idle is so unstable and erratic that it would be hard to note any change in idle speed.

I had this problem with my 1.8 litre - I was told by Martin Christensen at All German Auto that a part (a valve) was no longer available that would get the idle back into whack. My car would not idle until it got real warm, and sometimes not even then. You could call Martin or Auto Atlanta - This is a well known problem, or that is what I was led to believe. 760-739-4626 or http://www.allgermanauto.com/index.php

Good Luck...

Thanks for the info. Not aware of a valve, but i'll look into it.

I had leaks in my intake plenum. This can also cause Idle problems. TS2, is this the CHT (cylinder head temperature sensor). The CHT is on the head near cylinder 3. Did you check this?. If not, a pot can be substituted as a testing device. Should be a low value when warm. 100 to 200 ohms IIRC. There is a difference in these between 73 and 74. Maybe it is intermittent or loose. Also make sure that the engine ground connection is good. There are also ground connectors on the top of the motor. Make sure all is clean and tight.

Lots of luck

nope ...

your car (71) is prone to lean idle (high low idle) as the control unit is not adjustible in the early cars (no knob) and with old injectors and vacuum leaks (make sure that the aux air valve is closing by removing the hose to the u shaped intake boot and making sure that it is not sucking vacuum) When this is verified you can then as the car hi low idles spray carb cleaner around all of the fittings to see if the idle changes. If to no avail, and you have carefully checked everything you said (including proper routing of all of the vacuum lines and ascertained that the vacuum advance/retard is working properly, and remember that AUX AIR VALVE to make sure it is closing when the engine is hot) for the hell of it, install an inline 270 ohm resistor with the head temp sensor to richen the idle mixture and see what happens.

Thanks for the input George, I could really use some help with this - I'm seriously about reading to chalk this up as a loss.

I wish the car had a lean condition causing the poor idle, but that's not the case. This car runs so rich it will gag you. It is however, very unstable idle wise. Recently I checked and adjusted the Fuel Pressure - it was at 42 PSI and I set it to 30 PSI. I expected the car to run better, and that wasn't the case. Suddenly, I lost control over idle adjustment via the TB screw - it always worked in the past, but once I corrected the fuel pressure, the screw stopped having ANY effect on idle (accept for choking it off when screw all the way in).

I've adjusted valves, set timing, new ignition system, you name it...

I was thinking a leaky Cold Start Valve, but I bypassed that with no improvement. I guess it's hard to tell through, because my 3rd set of plugs are fouled - that's not helping my cause now.

I noticed nothing mentioned about your return line in this thread. Have you checked the fuel return? Does your 71 D-jet have a fuel return like my 74 ? If it's clogged that could be the source of your irratic idle? Don't give up on her yet & good luck!

You may also have a bad electrical connection to the ECU. Wires get old and crack. Dirt also plays havoc on connections. Make sure the connector on the ECU hac clean connections. Also make sure that there is a connection from the CHT (near cyl #3) to the ECU. This connection could be broken.

Don't give up! There is an answer and you will find it.

I'm ready to give up on this D-Jet system - pretty much at the point where I'm ready to switch to carbs.

I've done most every thing that has been suggested here at 914 World + studied Banders site constantly.

The car runs so rich - it's fuching ridiculous. I've got a guage hooked up and I never exceed 30 PSI - so I know it's not a kinked fuel line or the such. I've got brand new ground straps that are super clean + all the injector grouns are good & clean. I bypassed the Cold Start Valve (fuel line wise), checked the TS2 and replaced TS1. My running voltage at the BATT is 13.6 volts. Correct injectors, MPS tested and works fine. The ignition is ALL new and valves have been recently set.

The only thing that I can think that I haven't checked are the trigger points. Could they make the car run retardedly rich? The plumes of smoke will straight up gag you!

I'm not sure but why not check? Since you've gone over and/or replaced everything else what else could be left? Valves adjusted & not sticking, all new ignition, right PSI on the fuel, timing set, good voltage, injectors firing, no vacume leaks, etc... Go ahead & check them but they're a bitch & you know where they sit down below inside the dist. Just a thought- check your grounds... inadequate ground can shoot a lot of unburned fuel out the tail pipe.

All new grounds & engine grounds for FI are clean & tight.

Here's another, more expensive thought... did the battery ever corrode onto the ECU?

Scotty,

I know exactly what you're talking about. A white semi-Y shaped connector. The connecting hoses fall off easily with age, hich is why I'm changing mine. ANY air or vacuum leak screws the Djet system up. That's why every 5-7 years you should change every hose - vacuum AND hp fuel (low pressure seems to last longer). Sorry, my 914's UP right now, or I'd lift the prts & pic them. This "Y" piece has no clamps, so it can easilly cause lekage problems. And that means the idle can "hunt", like so many other hoses.

Guys, these hoses are readily available (non- high pressure fuel hoses) and they aren't all that expensive. We're talking about "vintage" cars these days - change 'em.

[quote name='Pat Garvey' date='Jun 21 2007, 06:37 PM' post='914393']
--><div class='quotetop'>QUOTE(scotty b @ Jun 19 2007, 06:28 PM) </div><div class='quotemain'><!--quotec-->
Nope I can't get to the engine for all of the sh*t I have piled up. Maybe somebody else will know what I am talking about.
[/quote]
Scotty,

I know exactly what you're talking about. A white semi-Y shaped connector. The connecting hoses fall off easily with age, hich is why I'm changing mine. ANY air or vacuum leak screws the Djet system up. That's why every 5-7 years you should change every hose - vacuum AND hp fuel (low pressure seems to last longer). Sorry, my 914's UP right now, or I'd lift the prts & pic them. This "Y" piece has no clamps, so it can easilly cause lekage problems. And that means the idle can "hunt", like so many other hoses.

Guys, these hoses are readily available (non- high pressure fuel hoses) and they aren't all that expensive. We're talking about "vintage" cars these days - change 'em.
[/quote]

All of my lines are good or new. I don't believe that the early DJet cars (mine's a 71) have this Y connector. Vac leak would mean lean - I could use my exhaust as a return fuel line it's so rich.