Help - Djet running way too rich Options

[rjames]

I spent well over a year troubleshooting a similar issue. The car would run fine for a while, and then out of nowhere, go rich and then stall. Right before I figured out what it was, the amount of time it would run well before stalling decreased.

It turned out to be a bad ECU- the things that rarely fail supposedly. I think it was a heat issue. As the engine bay warmed up something in the ECU would fail and cause an overly rich condition. Figuring it out wasn't easy. I had two other ECUs that I used for testing and both caused the car to flood- including a NOS unit that had never been installed. A 3rd ECU I tried out of desperation fixed the issue, and have had no issues since installing it 2 years ago.

It's an easy thing to rule out if you have another known good ECU you can swap in for testing.

[JamesM]

Have you checked your CSV for leakage?

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You mentioned before that you had disconnected the injectors and were still getting fuel, the cold start injector is the only other source for fuel.

[Halfnelson]

Have you checked your CSV for leakage?

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You mentioned before that you had disconnected the injectors and were still getting fuel, the cold start injector is the only other source for fuel.

Thanks for the ideas - yes, we have bypassed the cold start injector.

[mgphoto]

Calibrating the MPS correctly requires being able to know what the AFR is at idle, part load and WOT.
It could be said that fully dialing it in requires an inductance meter, but it isn’t necessary to get the car running well.

Fix/replace faulty FI components, don’t just bypass them. They are there for a reason. For example, removing the decel valve will shorten the life of the MPS diaphragm.

No it won’t, going on ten years and 40k miles, deaccl valve is a stop gap pollution device pretty much ruins engine braking.

[emerygt350]

Yeah, check that cold start valve.

Any chance you can borrow another ECU? (another quick and easy check if it is available).

I have to suspect soemthing catastrophic with something like the csv. Even max rich by the ECU wouldn't cause what you are experiencing. I seriously doubt your brand new injectors are stuck open. as stated above... it's the only other thing bringing fuel. You could block the csv fuel line (super easy) and give it a go.


Not even sure the trigger points or malfunctioning 123dizzy could cause this either.

[Halfnelson]

Yeah, check that cold start valve.

Any chance you can borrow another ECU? (another quick and easy check if it is available).

I have to suspect soemthing catastrophic with something like the csv. Even max rich by the ECU wouldn't cause what you are experiencing. I seriously doubt your brand new injectors are stuck open. as stated above... it's the only other thing bringing fuel. You could block the csv fuel line (super easy) and give it a go.


Not even sure the trigger points or malfunctioning 123dizzy could cause this either.

The CSV should have been done - but I'll double check as that makes sense. Also, will try and borrow an ECU.

[mgphoto]

Pull one side of the fuel rail off while the engine is running, note the amount of spray, at idle it should be minimal, if the injectors are just open the ECU is at fault.

[emerygt350]

Pull one side of the fuel rail off while the engine is running, note the amount of spray, at idle it should be minimal, if the injectors are just open the ECU is at fault.

You mean the injectors right? Make sure you put them In coffee cans too. Double check that csv first since it is easy. Have you checked your fuel pressure recently? On the rails?

[JeffBowlsby]

Two other things to check:

TS2 - cyl head temp sensor. It can fail to dump enough fuel not allowing it to start, perhaps yours is intermittently failing.

MPS - check its ability to hold vacuum. Does it hold up to 18 inHG steady, or is there a vacuum leak? When the diaphragm fractures it fails rich. No vacuum or a rapid vacuum loss will be very rich.

[rjames]

Even max rich by the ECU wouldn't cause what you are experiencing

@emerygt350 Not true. What he is experiencing is exactly what the bad ECUs I had did, and all were the correct model for my car.

[emerygt350]

Even max rich by the ECU wouldn't cause what you are experiencing

@emerygt350 Not true. What he is experiencing is exactly what the bad ECUs I had did, and all were the correct model for my car.

Gas pouring out of the exhaust?

And speaking of that, make sure you are changing your oil.

[rjames]

Even max rich by the ECU wouldn't cause what you are experiencing

@emerygt350 Not true. What he is experiencing is exactly what the bad ECUs I had did, and all were the correct model for my car.

Gas pouring out of the exhaust?

And speaking of that, make sure you are changing your oil.

I didn't let it get that far, but it contaminated the oil bad enough pretty quickly.

[emerygt350]

I guess there is no reason it couldn't go outside of normal parameters if something fries in the ecu...

[Lockwodo]

Yeah, check that cold start valve.

Any chance you can borrow another ECU? (another quick and easy check if it is available).

I have to suspect soemthing catastrophic with something like the csv. Even max rich by the ECU wouldn't cause what you are experiencing. I seriously doubt your brand new injectors are stuck open. as stated above... it's the only other thing bringing fuel. You could block the csv fuel line (super easy) and give it a go.


Not even sure the trigger points or malfunctioning 123dizzy could cause this either.

The CSV should have been done - but I'll double check as that makes sense. Also, will try and borrow an ECU.

You mentioned checking the CSV "bypass" but I'm not seeing in this string if that was done. If the pressurized fuel line is still connected to the cold start valve and that valve is leaking, that could be the source of the fuel leak into the engine as others have pointed out. You could confirm by pulling the valve out of the manifold and pressurizing the fuel line.

[emerygt350]

Yeah, check that cold start valve.

Any chance you can borrow another ECU? (another quick and easy check if it is available).

I have to suspect soemthing catastrophic with something like the csv. Even max rich by the ECU wouldn't cause what you are experiencing. I seriously doubt your brand new injectors are stuck open. as stated above... it's the only other thing bringing fuel. You could block the csv fuel line (super easy) and give it a go.


Not even sure the trigger points or malfunctioning 123dizzy could cause this either.

The CSV should have been done - but I'll double check as that makes sense. Also, will try and borrow an ECU.

You mentioned checking the CSV "bypass" but I'm not seeing in this string if that was done. If the pressurized fuel line is still connected to the cold start valve and that valve is leaking, that could be the source of the fuel leak into the engine as others have pointed out. You could confirm by pulling the valve out of the manifold and pressurizing the fuel line.

And with the ignition on as well.

[914_teener]

Time Out.

There is a difference between testing and speculation.
Testing is methodical (there's a method) and speculation guessing albeit it MAYBE somewhat educated guessing.

FIRST IS TO Confirm the right parts to the engine. Has this been done?

Let the OP provide results.....I think there is a lot of speculation that throwing partsat the situation is testing and not confirming that a component or system is good. A system is component driven. You need the right components for a 1.7.
First off...is it in fact a 1.7? How do you know that it is? Let’s ASSUME your cam is the stock cam and not another grind. Has the engine ever been rebuilt to your knowledge? You can measure valve lift and degree the cam for duration to be sure.
Make sure all the mechanical systems are within spec. This includes valve function and piston compression specs FIRST. Any failure or out of spec situation here means that you haven't assured that the engine vacuum system mechanically is functional or functioning properly. If not, D-jet won't function properly if at all. You don't have to have the engine running to do this.
Air-Fuel -Spark
Vaccum
If you’ve checked your valves and compression and this is ok then the next thing to check is the actual system for vacuum leaks...everywhere the is vacuum. You mention that you did this, but a smoke test under vacuum is a very definitive test. Instead it reads like you just visually tested the components and not the intake system like the plenum and all the parts installed. This Do a smoke test to make sure there isn't a crack there or anywhere else. There are threads here on how to do it….safely.

As far as the MPS is concerned...I had an instance where the Diaphragm was cracked and only intermittently would leak which did the same thing...dumped fuel like crazy into the manifold and cylinder to the point where the fuel vapor coming out the exhaust like a white fog and gas dripping out of the tip.

So when you do a test on the MPS you should pull it to about 12 HG and test it for leak down overnight. Make SURE you test it for leak down and not just for a minute or two. Any leak down could mean it is only slightly cracked or it is leaking somewhere. You also did not mention if you testing it electrically. All of this procedure is listed on Brad (Paul) Anders website with addition of all the component testing for the D-jet system. We’ll assume you’ve done this and all the D-jet components test good.

Fuel:
It doesn’t appear that you have a fuel delivery issue except from your post, it appear you have a mismatched injectors….maybe. If you’ve had check for components for the 1.7 D-jet you probably would have picked this up already.
Testing for injectors is best left to hydraulic bench and electrical testing for pintel function and is best left to a house that specializes doing it. Its well worth the money and aggravation. Forget baby jars or coffee cans as a test. They will check mostly for flow rate…that it..not worth your time.
Fuel pressure test is essential and easy to do at the test point at the driver side fuel rail. Check also the fuel tank sock and return lines. and all fuel connections for safety, correct type and for cracks while your’re there. Make sure the fuel pressure is to spec and you don’t need the car running to do this.
Testing for a bad CSV is simple. Just bypass the fuel line for it. There is a gasket there…however youv’e done the smoke test already so don’t worry about it. You found no leaks…right?
Spark:

Again we’ll assume you have done a component checks and testing and if good the only check are for there installed function. These are mostly electrical connections such as the ground contacts and wires for the CHT, wires and contact to the head. The test for these are resistance to ground and if either the head thread is dirty and the ground lead to the ECU is not cracked or grounded properly the engine will not run. Period.
The CHT is a thermistor so it is resister to ground but it must ground to provide a signal to the ECU. The full test is to ground the lead and see if the engine will run. Again…if you have tested the harness you know either the CHT is bad or the ECU and if you tested the CHT and the ground points then it HAS to be the ECU. I hate the threads about bad CHT when very rarely do they actually fail.
As already mentioned the dizzy is a big issue, but you should have already confirmed that it is the right dizzy for that displacement and functions properly including the advance and retard vaccum can.

When I fist bought my 73 914 (now almost 20 years ago) I removed the entire top end including all the D-jet parts. I checked them all, cleaned them, and serviced and tested the injectors. I replaced everything that didn’t test or check to spec. It ran flawlessly. In that time I had three failures. The MPS, the ECU and then the dizzy. I replaced the dizzy with a 123 unit and it ran better than it ever did before.

If you do all of the above and mostly in that order your car will be well sorted and provide many years of enjoyment as it did for me. Sometimes I regret selling it but looking back now…years of fun and friends.

Good luck and wrenching.

[Halfnelson]

Finally got a chance to get to the 914 so can confirm...

Engine is original EB 1.7 unit.
ECU is a 0280000037
MPS is 0280100049

I did a vacuum test on the MPS and it is holding vacuum. Was tested up to 20inHg and left for an hour and was at 18inHg which I assume is OK?

One of the things I did notice was that the ECU as very loose. At some point the garage hadn't re-attached it properly and it was rubbing on the wiring loom which in turn was resting on the cooling shroud. It had rubbed through some off the outer protective sleeve but the wires appeared intact - however some had a weird brown discolouration on them... (Pic attached) perhaps like they had been getting hot? Anyone seen this before?

Cheers

Chris

[emerygt350]

Possibly but they look ok.