I have a relatively stock '75 2.0 FI minus the emissions stuff. Car has worked fine. Just did 750 mile round trip to Okteenerfest. Haven't changed anything since.
Now, car starts up same as always and runs fine for about 10 minutes. Once things are starting to get warmed up, the engine starts to hesitate getting quickly worse until it loses power and dies. Engine then turns over fine but does not fire / start. Wait about 10 minutes, car starts right up and drives fine again....until is get warmer and it hesitates then dies again.

What components would cause a problem like this ? and
How would I go about testing them to verify.

thanks,

Ken.

I hate to immediately go to my favorite usual suspect, but....failing CHT? Normally when it's totally failed you may not be able to get the car to start or it will stall very soon after starting and then not start again until the engine cools. Failure, failing, or intermittent failure can be caused by a bad sensor or an open or poor connection between sensor and ECU. Anytime there's an open, nearly open, or sometimes open circuit between the sensor and the ECU you're going to get an overly rich mixture that will cause a warm or hot engine to die. Check the connections, the sensor, and the whole wire on the harness back to ECU.

More info at this link: http://members.rennlist.com/pbanders/djetp...tm#troubleshoot

Scroll down in the table on that page to read about the Cylinder Head Temperature sensor troubleshooting.

Also -- totally unrelated -- verify dwell and that your timing didn't change for some reason and get way too retarded.

If both of those check out, on to something else...

A lot of times I don't respond to these requests, not because there's anything wrong with the question, it's just that given what's posted, I don't know enough to answer. We've talked about this before, but when you have problems like this, you have to go through a generalized checkout before you can say where the problem is coming from.

I learned this when I lived in Sunnyvale from my mechanic, Bob Grigsby. He told me that when a customer came in with a problem and a theory about what was causing it, he would write down what the problem was and listen attentively to the owner's theory, then pretty much completely ignore it. He then had a multi-step procedure he went through on every car that probably took him only an hour or so.

I'm guessing here as to what he'd do: He'd check the egine mechanical condition (compression), if it ran, he'd check the manifold vacuum. If it was noisy, he'd check the valve clearance. Check for intake and exhaust obstruction. Check the charging system and battery. Check the ignition system. Check fuel pressure and delivery. Etc., etc. Perform basic carburetor or fuel injection system tests.

Once he was done with this procedure, if the problem was still present, then he'd do more detailed testing on the systems he thought were most likely the cause. But, he told me that in at least 90% of the cases, the problem was gone.

We've talked about it a lot, there needs to be a sticky here with a set of procedures for the basic "doesn't run right" problem. It would be better to direct people there than to continuously post the same procedure, or different procedures, or just guess.

Thank you for the great information. Will let you know how it turns out.

I'm hoping we can put a procedure together so that you have something logical to follow that will help you figure out the problem quickly. In short of that (will take a while for it to be done), there are a number of checkout procedures you can find with Google.

In general, I'd check things in the order I suggested:

1. Mechanical (compression, vacuum, valve clearance, etc.)
2. Intake and Exhaust (blockages, exhaust leaks, vacuum leaks, hoses, etc.)
3. Charging and Battery (battery charge, load test, alternator, regulator, grounds)
4. Ignition (timing, dwell, spark energy, components condition, etc.)
5. Fuel Supply(pressure, volume, leaks, filter condition, etc.)
6. Fuel Delivery (Injection/Carbs) (components, wiring, condition, tests, etc.)

There's probably more I missed, but this would be a good start.

Hi,
Volker made a checklist for D-Jet-cars.
You can jump directly from this PDF document to explanations.

There are some (few) test points that do not apply to the 914, such as the ignition timing-advance in 2 directions or the trigger-points three and four.

You can download the checklist here: https://oldtimer.tips/images/cars/jetronic/Checklist-EN.pdf

I agree with Brad - doing the full-check is very useful.

The D-Jetronic is quite fault-tolerant, often only several errors together lead to big problems.
Me and many others had to learn that...

Regards
Norbert

Edit: Despite I recommend a full review, I would like to mention the following possible errors that occur quite often:
1. Bad connection to the temperature sensor (or defect)
2. Pollution in the fuel system, lack of fuel pressure
3. Defective ignition coil, which fails on heating up
4. Trigger contacts at the wear limit

First, I'd like to publicly thank Norbert for sending me one of the adjustment tools he invented for checking and adjusting the D-Jetronic trigger contact points, a very useful device. Thanks!

Thanks for posting the link to Volker's D-Jetronic troubleshooting list. Unfortunately, in many cases when there is a problem with a car that uses D-Jetronic, people jump to believing it is the cause of the problem, before completing more basic checks first. I'm hoping to come up with more detailed procedures to help in this area. I'm also going to be doing a "quick and dirty" set of tests that assure basic operation of all the systems but don't go into details, and also a set of tests that should be done at regular intervals (say, every 10K miles) and recorded, which will give a long-term picture of engine condition and wear. Hope to have these in a first draft form later this coming week.