More 1.7 D-Jet issues, Please help before I remove it!! Options

[BK911]

One reason I bought this car was because it still had the fuel injection. But now I am getting so frustrated trying to get it to run well, I am considering swapping the FI for carbs. Please help before I switch to carbs!

She runs well cold and hot, but not in-between. She will stall and is very difficult to restart. In fact, I have pushed her out of traffic on several occasions after she stalled at a red light. I wait a couple of minutes and she fires right back up.

I have a gunson and have set the CO to 2.5 at idle and 2500 rpm. And again, she runs well once hot. The AAR works. I swapped out the CHT even though the old one tested fine. I am thinking it’s the cold start valve. I disconnected the wire to the CSV last night and reset the CO to 2.5. I went for a ride, came home and shut off the car. Let the gunson calibrate then rechecked the CO. Very lean and wouldn’t run worth a crap. I am thinking I have a leaky CSV. It was leaking when I set the CO and stopped leaking when the car heated up? Can I remove it? How do you plug it? If I just remove the gas lines to it, will it leak air?

Is 2.5 a good number for the CO at idle and 2500 rpm?

I’d appreciate any help. Please help me keep this car original!!

[jimkelly]

i have one laying around - it is yours free - don't know if it works though - i should have a thermotime switch too i can send.

16 cold start valve, 1.7 022 906 171 A

18 thermo switch 1970-73 1.7 311 906 161 A

see this list
http://www.autoatlanta.com/model/914catalog/914fuel1.html

jim

[toon1]

It's possible the CSV is leaking BUT unless it's in real bad shape, they usually don't.

In Florida you can go without it, they should only activate when it's real cold

How are all the other components in the system?

When was the last time a your fuel filter was replaced?

[BK911]

Thanks guys.

I bought the car about a year ago. It had been sitting for a couple of years and had rust in the tank. I por-15'd it, replaced all the fuel lines and filter, and put all the injectors in an ultra sonic cleaner. It ran awesome up until recently.

The MPS holds a vacuum. It leaks a little, but it doesn't drop like a rock. The AAV opens and closes.

At an AX this weekend I couldn't get the car to start after it had been sitting for about an hour. When she would turn over, I had to keep the pedal to the floor to keep her at idle. I pulled the plugs and they were BLACK! Cleaned them off and was able to do my runs. Pulled the plugs when i got home and they were fine.

So something is causing her to run really rich sometimes, usually when warm. The only thing I can think of is the CSV. I think I am going to plug the fuel lines to the CSV and see what happens.

Thanks for the offer Jim. I may take you up on it. Let me play around this weekend and I will let you know.

[tdgray]

The MPS holds a vacuum. It leaks a little, but it doesn't drop like a rock. The AAV opens and closes.

Whoa there Hobbes... you just jumped right over that.

Quantify that statement... not dropping like a rock is not adequate. Needs to hold certain vac for certain amount of time. Look up Brad Anders site to get specs and to familiarize yourself with the inner workings of D jet before you make a rash decision.

Report Back !

[swl]

just a couple of thoughts.

if the problem went away when you disconnected the wires then it would suggest that the thermoswitch might be the culprit rather than the CSV itself. One of the wires that go to the CSV routes back under the air cleaner to the base of the plenum where the thermoswitch lives. The jovb of that switch is to ground the cct when the temp goes below a certain temp. Down in florida you probably never get cold enough for that switch to close. So if you got out an ohm meter and checked between ground and that wire you should see an open cct. If it is closed (0 ohms) you have found the problem.

Don't plug the gas hose - you have to join them together to get gas over to the drivers side fuel rail.

If I were going to get rid of CSV I would just use the CSV itself as a plug and use a piece of innertube as a gasket.

[BK911]

When a vacuum is applied to the MPS the gauge drops real slow, but it does drop. So it does not pass the test as per Mr. Anders site, but it's been consistant since I have owned the car.

[tdgray]

When a vacuum is applied to the MPS the gauge drops real slow, but it does drop. So it does not pass the test as per Mr. Anders site, but it's been consistant since I have owned the car.

As I fount out when I was going through this very frustrating issue of getting the D jet working right... you have to start with a KNOWN - GOOD MPS or you are just playing guessing games.

I know Geoff used to rebuild these but not sure if he still does... club name is Bleyseng. He did mine.

Maybe he will chime in.

[914Sixer]

Check for bad wiring in the harness. Check the continuity from end to end. You may have what we used to call a high joint. Wire sheath gets warm and flows pulling the broken part into. When the sheath cools it will flow back to let the wires touch. It is all under the sheath where you can not see it. Look for knots or limp places in the sheath.

[Bleyseng]

When a vacuum is applied to the MPS the gauge drops real slow, but it does drop. So it does not pass the test as per Mr. Anders site, but it's been consistant since I have owned the car.

How slow? If its a drop over 5 minutes from 15hg to say 5hg, you're ok as the engine vacuum will overcome this drop. If its a drop in a minute then its giving you false mixture settings.

[BK911]

I bypassed the CSV and plugged the connections. No difference. I pulled and bench tested the MPS. The vacuum dropped from 20mm to 12mm in about 5 minutes. This has been consistant since I have had the car, so I am leaning towards something else. I just don't know what! I tested the resistance across the terminals of the MPS and they were pretty close to what is listed in Mr. Anders references.

After I bypassed the CSV, I set the CO to 2.5 at idle and 2500 rpm. Took it out for a spin and it drove like crap. I remeasured the CO and it was very lean, like around 0. I have no idea what to check next. It seems I can't hold a consistant mixture.

Is 2.5 the magic number?

I'm not giving up yet, but I am close.

Back to the garage.

[brp986s]

engine vacuum, warm @ idle = ?

fuel pressure at various speeds = ?

ign timing - correct advance ? Steady, or jumping all around?

fwiw, mine just started acting up today. have to keep it at 2000rpm at stop lights or it'll stall. Yay. Nice of it to wait until the coldest day of the year for it to happen.

[dfwteenerpr]

how are you adjusting the mixture? if you're just turning the knob on the top of the ECU, that's only for idle mixture, with the throttle position sensor closed . If you're turning the screw inside the MPS ( drilled it out) then you're affecting the whole range.

[jimkelly]

if it is truely only a mid-range temp related problem - it has got to be the TS1 or head temp sensor giving the ecu and bad reading?

what color are your fuel injectors - they should be yellow for 1.7.

does it really run fine after it is warmed up??

jim

[SirAndy]

i had similar problems with my 1.7L D-Jet motor. i rebuild the FI engine harness and peeled back all the hard plastic shielding just to discover that some of the wires were brittle and broken inside!

it took 4 used harnesses to make one good one. put that in and the car ran like a champ ...
(IMG:style_emoticons/default/bye1.gif) Andy

[bd1308]

if the MPS was leaking, wouldnt it think that the throttle was open more (less manifold vac) and then run on the 'more-rich' side?


throttle plate closed, high manifold vac--mps 'seeing' high vac

throttle plate closed, leaking mps, false lower 'input' reading -- mps seeing lower vac, runs richer

I'd check the trigger points in the distributor, in my experiences, THIS is what made ME stall out several--no many times at stop lights. VERY VERY hard to restart. Found one trigger point contact connected by ONE (yes ONE) strand of braided copper wire.