New 76 2.0L is cutting out and wants to quit after 5 minutes

[loser_cruiser]

reply to Raygreenwood:
The car is new to us. When we got it we replaced the plugs, points, rotor, cap, wires, checked dwell and timing. At .016 cap on the point yielded a dwell of 58. The Dwell range is 44 to 50 with a upper limit of 58. The car runs alot smoother with the new tune up. The car runs good for about 5 min or when it gets warm then I believe it is loading up, (Fuel injection kicking in). Plugs black, wants to die, have to rev the car to keep it gooding amd make it back to the barn.
~I have checked pressure, but not volume. I have ordered a new CHT, but I will pull the CHT and heat test it and check it with a VOM.
~I have removed the ground straps under car, under FI relay board and at battery, wired brushed, CRC electrical sprayed and replaced. Also have cleaned fuse box connections and FI relay boad.
~Have not done a resistance check on the parts, but I will and get back to you on results.
~Will Test MPS, I believe vacuum leaks have been corrected but Have order new FI seals. Have not checked FI volumes either.
~ Cars is a CA smog, EGR pump has been remove and EGR check valve left hanging there.
~ Different exhuast, so O2 sensor hanging in the wind, Is this a problem or do I need this feedback for the FI system????
~ Trigger points cleaned and working well.
I have some work to do, but I thought you may need more information. I appreciate your input, and will get back with you on the results.

[raygreenwood]

O2 sensor? On D-jet? Track the wires back and see where this goes. D-jet did not use an 02 sensor. Perhaps there are some other parts of this is not the original engine.

You are obviously running too rich. As the CHT heats up, it actually is supposed to lean you out. On many cars, the ambient air temperature sensor is unesscessary unless the baseline fuel mixture is already to the lean side...or ambient temps are very warm. I would say that about 60% of all D-jet that I see leaves teh ambient air temp sensor unplugged for better running. It generally signifies a need for a slight tweek to the MPS...but just disconnect it for now as it runs the entire system between 5 and 10% richer.

The ground wires I spoke of are in the fuel injection harness....though you did well to check all of your chassis ground cables. These wires ar under the air distributor on the case centerline.

Dwell angle...while important to keepng proper point gap....is not the timing. You need to check that you are about 7.5-12 degrees BTDC on ignition tming , with an upper end advance range at 3500 rpm of no more than 32 degrees. Check the vacuum advance unit for leakage.

If you yourself have not replaced any of the seals mentioned above....they are consdiered to be leaking 100% of the time.

Also, when you replace the injector seals....use seals from a CIS injected car like an 80 model rabbit/golf. They seal better and are cheaper. When you have the injectors out, check them for leakage at the tip. Also check the resistance with a VOM. They should be 3.2 ohms.

The fuel injection triger points must not only be clean...they should be de-tarnished. Drag a slip of brown paper sack through the triggers repeatedly to polish them. The resistance on these units is critical.
A resistance of between 1.0 ohms and .7 ohms is acceptable.....the lower the better. But....the difference between each contact set should be less than .2 ohms. For examples....a reading of 1.0 and 1.0 left to right..while on the high side...is perfectly acceptable. A reading of .7 and .7 would be ideal. A reading of .7 and 1.0 is not great. If you get that typoe of reading...clean them again, check the contacts in the plug and re-test. Ray

[loser_cruiser]

Reply to RayGreenwood:
The O2 sensor is located center rear and plugged into the orignal exhaust system. I believe it was part of the EGR system. I mention it to see if you knew if it was part of a FI feedback loop.
I have ordered new FI seals from PP, will these do the job?

Thanks for the reply, I will followup on the following:
~ ground wires you noted.
~ check Vacuum advance
~ new Vacuum and FI lines.
~ Polish the FI points and resistance check.
My list is growing but I really appreciate the help!!!

[raygreenwood]

As far as I know, D-jet has no input/output for an 02 sensor. I just don't know why they would have had an 02 sensor.... unless...as you speculate....it was part of the triggering for the EGR. I would have thought that they would have used a vacuum switch or a simple ingle pole switch on the TB. Others may know.

Most of the seal I mentioned...will not come in a seal pack. Porsche dealers can easily get you the runner boot seals and the TB seal. The injector seals will come from any parts store that sells European car parts. Do not use the stock seals. They suck and are expensive.
The intake manifold gaskets either come in gaslet sets, or the dealer may carry them seperatly. Same with the oil breather gasket. Also...all hoses must be clamped and no cracks.

One of the first things you must do is check the MPS. There are four contacts on the plug receptacle. The inner pair read about 33 ohms...the outers about 96 ohms. You can use a hand vacuum pump or a clean piece of line and your mouth. You must put a slight suction on the MpS...then hold it. If it leaks at all....you have either a bad seal on the body or a cracked diaphram. Ray

[Bleyseng]

Yep, first thing to do is pull a vacuum on the MPS. Pump it up to 15hg and it should hold that for 5 minutes without bleeding down. If it bleed down to zero in short order then the MPS's diaphram is cracked or broken.
Order a new MPS or find one of Ebay. Do not use the rebuilts from AA or others as they are either crap or calibrated for a 1.7l Djet car.


Geoff

[EricN]

The wires and sensor at the rear of the car are probably the CAT high temp warning sensor. Wires run up to a relay in the trunk.

[Bleyseng]

Good call, mine was all gone by the time I got my 76. Some of the CAT stuff was still laying around in the trunk but chopped.

[LOSER_cruiser]

-Not much time to put into the car this week but please stay with me.
found the fuel injection ground wires under air filter supports.
~ cleaned the connections and it has good continuity to the battery ground.
~ polished the injector points again, did not check the resistively of the parts yet(left a good VOM at work).
Received the CHT last week and FI seals.
Is their any good way to remove the CHT without removing the tin and intakes?
Working on some stripped exhaust stud

[Bleyseng]

I use a deep socket with a 3/8 extension that I grind off one corner so the wire can be pulled thru the corner.
Use a dab or dielectric grease to hold the washer on the CHT so you can install it without it falling into the engine.

[LOSER_cruiser]

That makes sense.
Thanks for the tip, grinding beats a drill anytime!
I'll let you know how it turns out.

[914Mothership]

I checked the MPS - Good, Pulled out CHT(thanks for the Socket tip, still not easy with the EGR equipment in the way), did not check it, but put the CHT in that I ordered and start up and actually ran for 35 minutes. Drove to the Gas station for it first fillup. Thanks for all the help.
Can't wait until tomorrow for some more driving!!!

[raygreenwood]

Its worth it to put a little anti-sieze compound on the CHT...to keep it from siezing up in the head. Ray