engine shuts down

[RSR Motors]

Hi everyone,
I've been figuring out for a while what the problem is with a 965 whose engine turns off when the accelerator is released. The engine is going very well, but if you release your accelerator, it will fall off.
Petrol pumps, filter, pressure accumulator, Lambda sensor and WUR have already been replaced, everything has been checked for leaks.
Nothing helps

[Ken911]

soundls like the idle richness needs adjusted. you need to also hook up a set of cis gauges to make sure te pressures are correct.

[flightlead404]

Originally Posted by RSR Motors

Hi everyone,
I've been figuring out for a while what the problem is with a 965 whose engine turns off when the accelerator is released. The engine is going very well, but if you release your accelerator, it will fall off.
Petrol pumps, filter, pressure accumulator, Lambda sensor and WUR have already been replaced, everything has been checked for leaks.
Nothing helps

What, are you just randomly replacing components until the problem goes away?

Hope this is your car not a customers car.

What are the symptoms or indications that lead to you diagnosing these components as bad? That might help understand the issue.

[RSR Motors]

Originally Posted by flightlead404

What, are you just randomly replacing components until the problem goes away?

Hope this is your car not a customers car.

What are the symptoms or indications that lead to you diagnosing these components as bad? That might help understand the issue.

The car has been standing still for years and all these parts were broken. Pumps were blocked, lamda gave nothing and the WUR was also broken.

[RSR Motors]

Originally Posted by Ken911

soundls like the idle richness needs adjusted. you need to also hook up a set of cis gauges to make sure te pressures are correct.

The pressure on the system is ok

[Bucketlist]

Originally Posted by RSR Motors

The pressure on the system is ok

Just a little more info is needed to help you out.
Sounds like CIS so fuel control pressure readings would help. Cold, Warm control pressure and system pressure. Air fuel numbers. What is your idle speed? Have you adjusted the idle mixture? Was anything done to the fuel distributor after sitting for years?
Good luck!

[flightlead404]

Originally Posted by Hot Euro

Just a little more info is needed to help you out.
Sounds like CIS so fuel control pressure readings would help. Cold, Warm control pressure and system pressure. Air fuel numbers. What is your idle speed? Have you adjusted the idle mixture? Was anything done to the fuel distributor after sitting for years?
Good luck!

Second this request for information.

If you can't give AFR directly, but have a gastester type exhaust sniffer, giving us the %CO at idle with a warm engine at the tailpipe if no cat, or at the lambda sensor bung in front of the cat if there is one, would be a help.

[RSR Motors]

Originally Posted by flightlead404

Second this request for information.

If you can't give AFR directly, but have a gastester type exhaust sniffer, giving us the %CO at idle with a warm engine at the tailpipe if no cat, or at the lambda sensor bung in front of the cat if there is one, would be a help.

The engine starts immediately when the engine is cold.
Stationeir is at 950 rmp both cold and warm and continues to run nicely.
If you give gas cold or warm and when discharging the gas it falls silent.
When you drive the vehicle, he pulls the stones out of the ground.
The prints are in order both gold and warm because we have already checked them.
CO has not yet been tested because I do not see the point at present.
On the throttle is a potentio meter and this could not be correct and I am looking for everything to find these adjustment data but nothing found in the documents.
System pressure 7.1 bar
When the engine is warm, press 4.52 bar
The car has always ridden well until he has stood still for 9 months and then the problems started, what is the car was much washed off to remove the dust.

[T77911S]

I don't know what WUR you but 4.5 looks hi. BUT, it also depends in if the mixture had been adjusted with this CP setting.

from what I have experienced, mainly on my 77s, if it is too rich, when you let off the gas the RPM';s will either drop down too low then come back up or it will just stall.

on my 930 I have run it very rich but I have not had it do this.

one other rich indication is if the idle surges, let it idle for a while.

950 cold and warm is a bit of concern. could be the ICV is stuck, mixture could be off enough to keep it from idling up.

you can try removing the air cleaner, start it cold and lift up on the sensor plate (or push down) and see if the mixture change helps the idle,

[flightlead404]

Originally Posted by T77911S

I don't know what WUR you but 4.5 looks hi. BUT, it also depends in if the mixture had been adjusted with this CP setting.

which is exactly why an AFR/% CO number is important.

High CP means lean mixture

unchanging rpm setting hot/cold could indicate aux air valve non-functional as well

[T77911S]

Originally Posted by flightlead404

High CP means lean mixture

u

not necessarily. believe me, I have played with WCP's down to 3 and up to 4.5. I could always set my idle AFR the same. the engine also ran the same, could not really tell. about the only way I could tell is at what RPM the mixture would go lean for cruise.

you don't know if the mixture has been adjusted after the CP went hi. just covering bases.

[RarlyL8]

This could be an electronics issue associated with the Lambda or EZ69 system. Have you cleaned the throttle position sensor? Allowing the throttle to close (chop throttle) is typically a more rapid event than acceleration plus the system changes from open to closed loop.

[flightlead404]

Originally Posted by T77911S

not necessarily. believe me, I have played with WCP's down to 3 and up to 4.5. I could always set my idle AFR the same. the engine also ran the same, could not really tell. about the only way I could tell is at what RPM the mixture would go lean for cruise.

you don't know if the mixture has been adjusted after the CP went hi. just covering bases.

Sorry, you are correct. I misspoke. What I meant to say was that CP sets the limits to what the mixture can be adjusted to. Sort of.

The way it makes sense to me is that the shape of the cone and the movement of the arm in the fuel distributor sets the overall shape of the mixture curve so to speak and is not (easily) changeable. I think of the curve as relative mixture on the Y and MAP on the X.

The CP moves the starting point of the graph set by the fuel distributor to Y location, but doesn't change the shape of the curve. Maybe it has some effect on flattening or steepening the curve slightly, but that doesn't change the overall model.

Adjustable pressure regulators can change the min or max range for CP and therefore indirectly min or max mixture. The lambda valve in cars so equipped essentially does the same thing but dynamically. Only at idle in stock cars, or over the entire range via computer control in FrankenCIS cars with EGO enabled.

The WUR dynamically moves the curve down the Y axis based on temperature during warm up, without changing the shape of the curve, by heating the bimetallic strip and adjusting CP. This WCP vs CCP.

This curve is moved in some cars by the boost enrichment feature of the WUR, which effectively changes control pressure quickly at some point based on MAP, effectively jumping the graph up or down on the Y axis.

Finally the curve for individual cylinders can be moved up and down the Y axis relative to each other (but not changed in shape) with the adjustment screws on the top of the fuel distributor.

May not be technically 100% accurate, but helps me think about it.

[T77911S]

Originally Posted by flightlead404

The way it makes sense to me is that the shape of the cone and the movement of the arm in the fuel distributor sets the overall shape of the mixture curve so to speak and is not (easily) changeable. it.

I did not really understand the rest of what you said but from this I think you understand the purpose of the specs or range of CP settings per bosch. most do not.

I don't really see the change in cone shape on the 930 like I do on the 911 so I will use the 911 as a reference for how I understand it, and I think you do too.

the engine has idle mixture, cruise mixture and WOT mixture. the shape of the cone (and the CP setting) determines at what RPM these transitions take place.
in short, if you lower the CP, then adjust mixture back to spec, all those things happen at a lower RPM due to the fact that the sensor plate will be in a higher (lower for 930) position in the cone.

I could see these transitions move in RPM on my 930 (and 911) when I would change the CP. I don't really understand how on the 930 as the cone looks linear to me but the 911 I could actually see the transitional sections.

[Bucketlist]

"When the engine is warm, press 4.52 bar"
If this is your warm control pressure it may be too high causing a lean condition.
My engine has stalled twice. The first was after the weather changed (spring) and the engine was completely warm it died a few times. I found the wcp was too high and set it back to about 3.2 bar I think, which cured the problem.
The other time I had a vacuum leak at my bov which caused it to stall when I took my foot off the gas. Easy fix.

[mark houghton]

I echo what others have said: Mixture is the first place I would look. Your symptoms point to that. Very simple to even tune by ear in a pinch, though not very accurate. With your trusty mixture adjusting allen wrench, just push down through the adjustment hole in the fuel head until it lightly contacts the control arm, then increase pressure very slightly which will eventually deflect the arm and richen the mixture. (alternately, remove the air filter as already mentioned to get to the control arm). If the idle rpm drops and/or the engine dies, then you're base idle mixture setting is too rich. Conversely, if the rpm goes up then you are too lean. Just a very very rough initial diagnostic. You really do need to know what your exhaust emissions are doing to; Gastester or AFR meter.

Brian's point on the Lambda system possible malfunction is something to look at too. One simple test would be to unplug the O2 sensor, just to see if you get any change in idle speed. That won't diagnose the entire lambda operation, but will tell you it's "kinda" working or not. Me, I run without the lambda and just tune around it.

[RSR Motors]

Originally Posted by RarlyL8

This could be an electronics issue associated with the Lambda or EZ69 system. Have you cleaned the throttle position sensor? Allowing the throttle to close (chop throttle) is typically a more rapid event than acceleration plus the system changes from open to closed loop.

That's right, but how do you adjust it? We have now inscribed him that he will be nice on O ° when the gas valve is closed