Warm up regulator on 82 911SC

[trojwl]

I am getting ready to troubleshoot the WUR. The car runs a little rough until the engine is thoroughly warmed up. Once warm the car runs perfectly. I have read many tech articles on the WUR and throughly understand its function (32 years experience in instrumentation and controls at a major power plant).

I've narrowed it down to the WUR (after studying entire system) as, once everything is hot, it runs absolutely perfectly. Therefore I don't envision any problems with system fuel pressure which tells me that doesn't need to be fooled with. My problem is definitely heat-related.

The ohm reading on the WUR element is 36.7 - which does not sound excessive to me. My next step is to check volts to the element.

My question is this. My WUR is different from the one in the manual. In addition to normal ports, mine also has a vacuum fitting and adjusting screw. My experience tell me that the vacuum line gives an "engine load" signal which causes the WUR to decrease control pressure to the fuel distributor which thus opens the slots allowing more fuel to injectors.

I'm assuming the screw on top is a way of "zeroing" the diaphragm.

Is this an improvement that occurred late in the model year?

Any insight would be appreciated.

Warren

[boyt911sc]

Warren,

The WUR you have as you mentioned previously is different from the original unit recommended by the manufacturer. Not only it is different in spec but a different type (vacuum assisted). This will be a piece of cake for you to improvise base from your long work experience in instrumentation. The recommeneded WUR for your car is 0-438-140-090 (USA) or -089 (RoW) non-vac assisted.

The adjustment screw you have on your WUR was introduced by a DIY guy some years ago to compensate for the cold deflection of the bi-metallic spring inside the WUR. This is a non-factory or Bosch improvement. If you could achieve to make this WUR deliver the cold and warm control pressures needed for your engine this WUR would be fine. But I doubt it. Good luck and keep us posted.

Tony

[Gogar]

Does your car have a Lambda computer and oxygen sensor?

I thought the .089 ROW WUR had a vacuum fitting, but I'm not positive.

+1 the adjustment screw (depending on how someone 'created it') can help you adjust your cold control pressure. Search "adjustable wur" and you'll find some threads about it.

It's probably tapped into a fat 'pin'. making the pin go down in the body of the WUR lowers cold control pressure, making it move up raises it.

This tech article is good too:

http://www.pelicanparts.com/techarticles/911_warmup_reg/911_warmup_reg.htm

[don gilbert]

warren, i would put the fuel gages on it just to see what your cold and warm press. are, one is prob. out of spec. I am not fam. with wur #'s as paul, but you you can possibly make this one work, since you have and adjustment screw added. are you sure that is not an atmospheric vent, as some later wur have?

[pete3799]

I'd like a better discription of "runs a little ruff" before laying blame on the WUR.
Does your cold start result in a fluctuating idle (surging)?
Could this be a simple mixture adjustment or am i missing something?

[boyt911sc]

Originally Posted by Gogar

Does your car have a Lambda computer and oxygen sensor?

I thought the .089 ROW WUR had a vacuum fitting, but I'm not positive.+1 the adjustment screw (depending on how someone 'created it') can help you adjust your cold control pressure. Search "adjustable wur" and you'll find some threads about it.

It's probably tapped into a fat 'pin'. making the pin go down in the body of the WUR lowers cold control pressure, making it move up raises it.

This tech article is good too:

Pelican Technical Article: 911 Warm-Up Regulator Adjustability

gogar,

You are indeed correct about the WUR-089. The words 'non-vacuum assisted' should have been typed right after -090 instead. It presented a totally different meaning. Thanks for catching the blunder.

Tony

[j911brick]

Right - I hope your not trying this without a CIS fuel pressure gauge, Total deflection between hot and cold on the bi-metal strip is only a couple thousands of an inch, so it has to be pretty spot on.

[trojwl]

I don't suspect cold start valve. Car starts fine and that is only time CSV comes into play.
The car idles somewhat smoothly at idle from cold start on. It stumbles a little on moderate to hard acceleration. It will then gradually get a little worse for about twenty minutes or so minutes of driving. Then miraculously the problem will fade away. I can tell from experience that this is a fuel delivery problem just by the way it stumbles. After everything is heat-soaked, the cars runs perfectly under all conditions. Definitely a heat-related issue.

My thought is that the WUR element is not prematurely heating the bi-metalic spring correctly and that it takes the warming up of the entire WUR body to get spring warm enough to deflect and thus decrease flow to injectors. I'm thinking the stumbling might actually be an overly-rich condition. The engine, now getting hotter and hotter requires less and less enrichment. However, the leaning does not happen until WUR is same temp as engine. When spring does finally sufficiently displace, the hot engine gets its non-enriched fuel delivery and is now very content.

I have a calibration set. I am waiting on a metal tubing piece (from distributor to WUR) from our sponser. Part of this line was somehow converted to plastic. When I get control pressures (cold and hot) I will likely re-enter forum for more discussion.

I will get everything factory-correct eventually.

One problem I have is that, since some joker decided to "modify" it, it probably won't be a suitable core. Rebuilders I talk to really want that core.

Anyone got an "090" (vacuum assist) WUR body lying around?

Thanks to all,
Warren

[trojwl]

I have attached pic of WUR. You can see rubber control pressure line (replacement due any day now).
Actually, the screw looks like it was installed correctly. I will get my new pressure testing rig out (a very nice one that I purchased from our sponser I may add) after tubing piece arrives.
If the stars are all in alignment, I can get this one into specs.

Happy New Years Guys,

Warren

[ossiblue]

Originally Posted by trojwl

One problem I have is that, since some joker decided to "modify" it, it probably won't be a suitable core. Rebuilders I talk to really want that core.


Thanks to all,
Warren

If the modification is to the pin of the cold contol pressure adjusting arm, as mentioned by Tony, it should not affect your unit's value as a "core" to a rebuilder. Also, if that is in fact the modification made, there are many other very experienced "jokers" right here on the forum.

[trojwl]

I probably should not have referred to whoever modified WUR as a "joker".

I've read in more than one article of a lot of Porsche guys doing this mod.

We'll see...

[Gogar]

My line from the FD to the WUR is also half metal, half rubber. Do you think that is not correct or something?

Also, is that rubber tubing over the breather, or what?

(PS, I'm one of those jokers and never happier.)


If someone wants a core, send them what you have, and don't start a conversation about the screw.

[trojwl]

OssieBlue, please note I submitted my apology for term "joker" before reading your post.

Having said that I just realize a simple way to prove my theory.

Start the car cold, drive it about ten minutes (before WUR becomes heat-soaked), and then put an adjustable tubing clamp on rubber part of control pressure line. This should max out control pressure in fuel distributor resulting in non-enriched fuel delivery.

I'll let you know.

[boyt911sc]

Warren,

After seeing the picture of the WUR, you might be able to adjust the control pressure for your car. What's the number on the body? Don't buy the WUR unless you really need one after doing the test & adjustments. Well, in case you would need one, I have some extra units for you. Keep us posted.

Tony

[ossiblue]

Originally Posted by trojwl

OssieBlue, please note I submitted my apology for term "joker" before reading your post.

Having said that I just realize a simple way to prove my theory.

Start the car cold, drive it about ten minutes (before WUR becomes heat-soaked), and then put an adjustable tubing clamp on rubber part of control pressure line. This should max out control pressure in fuel distributor resulting in non-enriched fuel delivery.

I'll let you know.

No problems here--that's the purpose of the "smilies" and yes, by the time I posted, you had apologized. All we really care about is getting your car to run properly.

[psalt]

Any insight would be appreciated.

Warren

Do you know that Porsche installed a band aid cold acceleration enrichment system on your MY to eliminate the symptom you are describing ? My advice would be to diagnose the system through the test port to determine if it is working properly (15% throttle switch, 75% duty cycle, 2 secs, below 35C). Chanting the mantra "It's the WUR" is strickly for the Koolaide Drinkers and should be avoided until the pressures are known to be out of the ranges.

[trojwl]

Paul, I have to confess I don't know what MY is and the other stuff makes even less sense to me.
Could you please elaborate?
Remember, mine is a 1982 911.


Thanks,
Warren

[j911brick]

Originally Posted by psalt

chanting the mantra "it's the wur" is strickly for the koolaide drinkers and should be avoided until the pressures are known to be out of the ranges.

+1

[psalt]

Paul, I have to confess I don't know what MY is and the other stuff makes even less sense to me.
Could you please elaborate?
Remember, mine is a 1982 911.


Warren

MY is model year, as in 1982. Your car's engine has the second version of CIS lambda. The first version in MY 1980 had a different calibration and several drivability issues, which were addressed in the later versions with band aid solutions until the EFI system arrived. If you think that your car has a cold acceleration problem and you are unaware that your engine has a separate cold acceleration control unit, my advice would be to take it to someone who understands the system or start studying until you understand the two dozen circuits of the control units. CIS lambda is very different than the basic system, corrects pressures are not "good enough" for good running. However, the system can be diagnosed with a dwell meter by someone who understands what they are doing. Swapping parts or altering pressures are a dead end until you know that all the system's functions are working as designed. My experience is most of the cold running issues on CIS lambda SC's have nothing to do with the WUR.

[Gogar]

Paul,

Is is safe to say, though, that with a Pressure test gauge and the knowledge of what your correct pressures should be for your CIS system, you can immediately (include or rule out) the WUR as a problem?

I do agree that without testing pressures there's not really a way you could say 'it's the WUR."

I made my WUR adjustable because I could tell that someone 'knocked my pin' in the past, and I was suffering from cold control pressure that was too low.