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Hey everyone, I've had my 930 about 3 weeks now and it runs like a champ when its running, but on start up it is rough and sometimes dies, unless i give it gas and hold the RPMs for a minute or two, it also sometimes just dies if I pull up to a stop. What should I check/adjust?
Not sure if it matters but the car was in Chicago and now its down here in Houston, not sure if the elevation or cold/hot weather would matter or not.
Without doing a full in service on the K-jetronic system to answer your questions;
- False Air - yes, vacuum leak (in) or pressure leak (out). Air that is not metered or not metered correctly.
- The WUR (Warm up Regulator) is a misnaming issue - it controls mixture at all operating temperatures, not just warm-up.
- The Cold Start Valve is an enrichment device on the back left of the fuel distribution head which acts like a 'choke' by dumping more fuel in at start up. It has a thermo time switch controller.
- The WUR is only adjustable if you have an adjustable WUR and even then it cannot be done real-time. It needs to be adjusted and re-tested. I doubt you have one of these. The stock ones are not adjustable and need to be replaced if that is the culprit (see below on AFR).
- If its a CA spec engine it also has a AAV (Aux Air Valve) that is thermo timed, and like the AAR (Aux Air Regulator) adds additional fresh air at startup to boost idle speed when cold and to burn more fuel at startup (less emissions in the CA case). The AAV is termo-timed and the AAR is timed by an expanding internal metal diode which, when the car starts and 12v is applied it heats up and closes a crescent moon shaped opening inside - it is visible if you look into it. This is why 930's have a high initial idle then it drops to normal after about a minute.
- Lastly - check your normal idle. It could just be too low and thus it stalls at times. Clue - if you find yourself over compensating for low idle with this method and are 'maxed out on the idle adjustment' them you probably have another issue.
Based purely on your symptoms where it dies occasionally even after running for a while - when was the last tune-up? Spark plugs, cap, rotor, wires? In your shoes I would be focusing on the possibility of an air leak first, then these other controlling devices one at a time. If you can get a good AFR reading then do that and see if you are running rich or lean (particularly when this happens). I installed an AFR gauge in mine to monitor mixture all the time. Its probably your best measure of where to look next - for anything performance or stability related.
Please post what you discover for the benefit of the group.
I don’t want to hijack this thread, but does the ‘82 turbo also have a WUR? A buddy of mine just bought one and had to hold the accelerator all the way down to restart a hot engine (per my advice, since it was turning over fine, but not catching).
I don’t want to hijack this thread, but does the ‘82 turbo also have a WUR? A buddy of mine just bought one and had to hold the accelerator all the way down to restart a hot engine (per my advice, since it was turning over fine, but not catching).
Yes, all 930 have a WUR (exept efi conversions)
Given the symptoms, I would first check whether the pressure accumulator is OK; the holding pressure is also measured at the WUR.
The next check point is whether the injection valves are dripping (then the cylinders run full of fuel after switching off) and the thermo time switch (must keep off the cold start valve while engine is hot).
Yes, all 930 have a WUR (exept efi conversions)
Given the symptoms, I would first check whether the pressure accumulator is OK; the holding pressure is also measured at the WUR.
The next check point is whether the injection valves are dripping (then the cylinders run full of fuel after switching off) and the thermo time switch (must keep off the cold start valve while engine is hot).
Fritz
Thanks. Will let him know. His car is a ROW car, like a lot of 930s from this era.
Our car when I first start (Cold start only) likes to sit for like 30 seconds before moving or it seems to want to stall. I just assume she's temperamental because she's 45 years old lol
Without doing a full in service on the K-jetronic system to answer your questions;
- False Air - yes, vacuum leak (in) or pressure leak (out). Air that is not metered or not metered correctly.
- The WUR (Warm up Regulator) is a misnaming issue - it controls mixture at all operating temperatures, not just warm-up.
- The Cold Start Valve is an enrichment device on the back left of the fuel distribution head which acts like a 'choke' by dumping more fuel in at start up. It has a thermo time switch controller.
- The WUR is only adjustable if you have an adjustable WUR and even then it cannot be done real-time. It needs to be adjusted and re-tested. I doubt you have one of these. The stock ones are not adjustable and need to be replaced if that is the culprit (see below on AFR).
- If its a CA spec engine it also has a AAV (Aux Air Valve) that is thermo timed, and like the AAR (Aux Air Regulator) adds additional fresh air at startup to boost idle speed when cold and to burn more fuel at startup (less emissions in the CA case). The AAV is termo-timed and the AAR is timed by an expanding internal metal diode which, when the car starts and 12v is applied it heats up and closes a crescent moon shaped opening inside - it is visible if you look into it. This is why 930's have a high initial idle then it drops to normal after about a minute.
- Lastly - check your normal idle. It could just be too low and thus it stalls at times. Clue - if you find yourself over compensating for low idle with this method and are 'maxed out on the idle adjustment' them you probably have another issue.
Based purely on your symptoms where it dies occasionally even after running for a while - when was the last tune-up? Spark plugs, cap, rotor, wires? In your shoes I would be focusing on the possibility of an air leak first, then these other controlling devices one at a time. If you can get a good AFR reading then do that and see if you are running rich or lean (particularly when this happens). I installed an AFR gauge in mine to monitor mixture all the time. Its probably your best measure of where to look next - for anything performance or stability related.
Please post what you discover for the benefit of the group.
So the car just had a major service, top end, new hoses, etc. I was told from the dealer it was 100% tuned. The service was done in Chicago in the fall and I purchased the car in March and shipped it to Texas. It has no problem starting it just immediately wants to drop the idle to under 500 and half the time dies. If I give it gas and hold the RPMs between 1-2k for a few minutes it drives fine, while driving it sometimes dies if I'm coming up on a stop and depress the clutch and start braking, the RPMs dip down below 1000 and about 10% of the time it will die, if I'm still rolling I will let the clutch out and it will start back up. Definitely feels like like something with managing the idle at start or coming down from higher RPMs. My plan this weekend is to check the AFR with a fellow 930 owner who knows more than I and has a gauge/sensor/setup. The car is all original with only 25k miles.
I will report back when I know more. Hopefully its just an adjustment to the idle since the car is now at lower elevation.
As far as I understand the descriptions, after the first cold start problems it runs mostly (90%) at a stable idle and correct idle speed. If this is the case, no what kind ever idle adjustment will solve the problem. And the height correction is done by the effect of the ambient pressure on a membrane in the WUR, there is nothing to adjust.
As far as I understand the descriptions, after the first cold start problems it runs mostly (90%) at a stable idle and correct idle speed. If this is the case, no what kind ever idle adjustment will solve the problem. And the height correction is done by the effect of the ambient pressure on a membrane in the WUR, there is nothing to adjust.
Fritz
If it is controlled by the WUR, "nothing to adjust" does that mean my WUR is possibly bad? If so how do I check it?
If it is controlled by the WUR, "nothing to adjust" does that mean my WUR is possibly bad? If so how do I check it?
The WUR is the central component for mixture formation across all operating ranges, therefore it should be within the specification. The system and control pressure has to be checked cold and warm.
For this you need a pressure gauge with adapters and ideally a vacuum pump. In addition, the technical documents with the data about the vehicle.
The WUR is the central component for mixture formation across all operating ranges, therefore it should be within the specification. The system and control pressure has to be checked cold and warm.
For this you need a pressure gauge with adapters and ideally a vacuum pump. In addition, the technical documents with the data about the vehicle.
Fritz
Do you have recommended tool kits and where I would find the literature? I have a ton of tools but I don't have a pressure gauges or vacuum pump. Can obviously just hit up Summit Racing or something, but if there is an ideal kit for these vehicles happy to know.
The WUR is the central component for mixture formation across all operating ranges, therefore it should be within the specification. The system and control pressure has to be checked cold and warm.
For this you need a pressure gauge with adapters and ideally a vacuum pump. In addition, the technical documents with the data about the vehicle.
Fritz
Is the pressure gauge for fuel pressure? Is the vacuum pump, to determine if there is an air leak?
04-15-2024, 01:22 PM
Rough Start up 88 930
