CIS WUR Parts Number Question now help getting initial mixture settings
 

I have a 78 3.0 motor with CIS. Last weekend it wouldn't make any power or review. But the pressure gauge on the Fuel system and fuel pump test good with 70 psi valve closed. However with valve open I'm seeing less then 1.5 bar. Looks like I need a new WUR as all the WUR charts in the Bentley manual say I should have 2.5 bar plus for a 90 degree outside temp. I pull the WUR and look at the parts number and it is 0 438 140 089. This is not listed in Bentley as a possible WUR for an SC ( not sure why). Specialty Auto shows this as a 911 WUR from the 80's. Car ran and drove fine with this WUR for 5 years. Do I send in the WUR I have and have it rebuilt and throw it back on the car or should I go for a 0-438-140-045 or some other WUR? Am I worrying too much as it worked fine before?

Nick

Whatever you chose to do, do not send it to Specialty for repair, it's unlikely you'll get it back in working order, and just wait until you try and deal with the guy over that. Look up Brian Leask or Rarely8 on this board and get the 082 rebuilt and/or modified to be fully adjustable and it will work fine.

His Pelican handle is actually RarlyL8 - can't go wrong with either him or Leask (I've patronized both) . . .

The -089 WUR is correct for a 1978/9 Euro 911SC.
I have these in stock, can rebuild yours or do an exchange where you send your core after you are up and running. Shoot me an email if I can help.

The 089 suffix identifies your WUR as a WUR built for EURO SC's.

Off the top of my head I believe first used in the SC's EURO from January 81. So not original to your car.
This does not mean an issue or problem juste that it has been replaced before.

Here is a link to a post of mine with the relavant chart for your WUR.

Your WUR should have two vacuum connections. One on top to atmosphere.
One at the side for Vacuum.

Notice the testing procedure values of this WUR and the sentence that says Testin Vacuum 550mbar

http://forums.pelicanparts.com/porsche-911-technical-forum/678022-euro-sc-troubleshooting-over.html

How much does applying vacuum affect the reading?

it increases it with about 0,6 bar.

As I said I do not think it to be original to your car as teh Bosch production run of the 089 seems to start in January 81 but it is a correct WUR type for a Euro SC.
But I can be wrong as I do not have specific Porsche data only Bosh data.

Now car won't start
 

Got the new WUR installed yesterday and now the fuel pressures are within stock specs, so that seems good. But now the car will not start. I have two theories anythoughts on which I should pursue first?

1. I took the car to a shop because the idle was bad a while back. The adjusted the mixture with an analyzer and all was well. Could they have adjusted the mixture to compensate for a WUR going bad so the good WUR has moved the idle mixture so far off that the car won't run?

2. I installed a high torch started from Pelican. It only had one spade connector so I did not connect the cold start injector system thinking that this would cause hard starting not cold starting. Do I need to hook this up to get the car to start or is it a red herring

You need the cold start injector working.

What is your outside temparture and the bar reading of the WUR at dead cold vacuum to WUR disconnected?

The experience I have is that the CSV is great for preventing backfire when starting really cold but once at temperatures of 20 degrees celcius and up does not do much to improve starting.

Michel

2.4 bar outside temp 93

The CIS components are on an electrical daisy chain, if not plugged in none will work. CSInjector is on a thermo time switch and does not function when temps are that high.
Mixture may have been adjusted lean as an attempt to compensate for the off-spec WUR fuel pressures. If so you may need to manually pull the air meter plate and shoot some fuel to get it to fire and run long enough to adjust. If you don't have one, an AFR meter will be a tremendous help.

93 that is 34 celcius so the CSV is out (or perhaps active for only a second).
Also the thermo valve to the WUR will be open at that temp (or at most stay closed for at most a couple of seconds). So immediate Vac to the 089
2.4 at 34 celcius is in the ball park for the 089 (at the low side but OK).

So my guess from reading the above. Your first WUR was kinda FUBAR with a CCP (and perhaps WCP) that was likely too low thus giving more fuel ; the shop leaned it out by the mixture screw.
Now you have a functional WUR and the fuel delivery is lean from the get go.

This is the time to get an innovate LM 1 or 2.

Or turn the mixture screw 1 full turn clockwise. If it starts the above guess was right.

But you would need to reset CO again with the appropriate tools.

Michel

Just an update those who offered their advice. 4 turns of the idle mixture screw got the car to cough to life. When it did start it spat about a 1/2 cupof gas out of the tail pipe. Let the car warm up with a fast idle and slowly adjusted th idle screw and micture screw until I had a nice stable idle. I will put it on an analyzer later this week but as of now the car drives and idles well. Thanks for the help!

Nick

Did the new WUR fail? Outside temp is 26 C control pressure reads 3.0 bar no vacuum applied as I don't have a means to apply vacuum. Car was put away running fine now it will not start. Just cranks and cranks. Confirmed spark and CD are ok. I never had a chance to get it on an analyzer so it only ran and drove once with the new WUR. Went to drive the car today for the first time and no go managed to get it to run for a couple minutes with my foot flat on the floor. It smoked badly and backfired both through the exhaust and the intake. would not rev. 1000 RPMs foot to the floor. As soon as I took my foot off it dies. Thoughts?

Huge vacuum leak? Pop off valve not seated?

Doesn't appear to be a vacuum leak. Pop off looks good and all hoses are relatively new

Is there a known setting for the idle mixture screw that the car will run. IE turn all the way in one direction then back off x number of turns?

Not that I've seen. The last few pages of Needspace's thread about his '76 have numerous links to setting it up.
I'm on 2g in Montana on my phone so you'll have to look for it.

Can be a number of things.

A 089 WUR should post 2.5 bar at 26 degrees celcius. Given that you have 3 bar on the WUR means that the WUR will not let it run rich. Which is not a big worry at these outside temps.

I am unsure what you mean by 4 turns of the IDLE mixture screw in one of you earlier posts.

Do you mean 4 turns of the Idle screw (left of the throttle plate) or 4 turns of the mixture screw (allen type) on top of the FD an a pain to get to?

if the latter; 4 turns is a lot and I can imagine togheter with a cold cp from the WUR you are flooding the engine.

Smoke? White smoke that hurts the eyes? If so way too rich.

What would I do now? Try to warm up the WUR so that the pressure gets to warm control pressure. You can do that by jumping the Fuel Relay and turning the ignition on. The 12v will be applied to the WUR and the Fuel pump will be running. Do this for 5 minutes. Chech that battery is strong.

Give the idle screw 2 turns counterclockwise.

Start the car. If it starts throttle it to get it warmed up an burn off all excess fuel.

The following day you can start baselining.

The procedure for setting initial mixture is as follows (I do not recommend it, it is only for when everything is lost).

Pull out 1 injector. Put in jar. Jump the fp relay. Turn mixture screw until the injector starts to spray, then turn back 1/2 turn.

Initial setting for the Idle screw. 4 turns out from completly closed.

Nick, the fuel pressure is about right for the temperature. You mentioned previously that the mixture screw was turned 4 times to get the engine started. Does this mean 4 complete 360° revolutions? Typical adjustment is maybe 20° or less. You also mentioned a lot of gas came out the tailpipe when the engine started which is not typical.
To properly diagnose this an AFR gage is needed along with the fuel pressure gage. You can have proper fuel pressure and the AFR's be way off due to vac leaks or fuel leaking into the cylinders. What do the plugs look like?

4 turns of the mixture screw. Just kept making 1/4 turns until it fired. Then adjusted the air screw and the mixture until idle was and smooth. Drive the car for an hour no problems and put it away. Now it won't start. Just looking to get to a point where I should expect the car to start. It was 4 turns towards lean to get the car to fire the first time. Not sure if a gas analyzer will help at this point as the car will not run. I only manged to get it go for a few seconds where it was backfiring through the intake and billowing tons of white smoke. I did pull the plugs and one was black the rest looked clean. I apologize for typos doing this on my phone

4 turns to the lean? So counterclockwise on the mixture screw?

Again that is a lot but in the lean direction.

So assuming that timing is well and that Idle screw is about 4 turns out, I would disconnect the cold start valve at the ThermoTimeSwitch -just to make sure it is out of the equation- then I would give the mixture screw 1/4 turn clockwise and try to start it.

I would give 1/4 turn clockwise until it starts.

What you could also do is push up on the air sensor plate with the key to on. You will hear the injectors squeal. Do that for a second. Then start. If it catches but dies you can start to move 1/4 clockwise at a time.

Michel

Update:

Decided to go with the all is lost method. Pulled an injector and put it in a jar. set the idle screw 4 turns from fully closed and fired up the fuel pump. It took 4 turns towards lean to get fuel to stop flowing from the injector in the jar. 1/4 turn towards rich tried to start the car. Nothing. Pulled the injector again. placed it in the jar again and there was no fuel flowing from the injector even with the quarter turn. It took almost a full turn plus the quarter already done to make small stream of fuel from the injector in a jar more drip than a stream. put the injector back in a tried again. Engine coughed. kept doing small turns towards rich until car started and ran. Let the car idle for 10 minutes like that. Tapped the gas pedal. Car died and now won't start.

Thoughts on how to proceed from here? Just trying to get it to run well enough to get to the shop with an exhaust gas analyzer. Unless someone in the DC area has one I can borrow.

Nick

CIS troubleshooting.......
 

Nick,

You don't need a gas analyzer to make your engine start or come to life. A gas analyzer is used for tune-up and setting the CO level. Now that you had tinkered the mixture screw setting without verifying the absence of significant air/vacuum leaks, troubleshooting would be more difficult at this point.

After all the hundreds of posts about CIS troubleshooting, people still tinker the mixture screw setting in order to make the engine start or run. This is a NO NO!!! Adjusting the mixture screw is for fine tuning and setting the desired CO level in the exhaust (engine completely warmed up). The two (2) major factors for a change in AFR (air fuel ratio) are: fuel pressures and air supply. Both these could be checked and tested.

If I were in your shoes, I'll check for air/vacuum leaks. This simple test has been discussed in numerous posts and very effective in CIS troubleshooting. Then check your control fuel pressures (cold and warm). The tests suggested could be accomplished without running the engine. If you could verify the absence of a significant source of air/vacuum leak and having the correct cold control fuel pressure and proper ignition timing, I don't see why you can not make your engine start on the first turn of the ignition switch.

Tony

Tony

Thanks for your reply. I don't think you read through the whole thread. The car initially was not running well so I check the Fuel pressures and they were way off. I got a new WUR and the the fuel pressures are good. Before I check the fuel pressures I confirmed good spark and correct timing. All vac hoses are less than 2 years old and I tested their connections with some ether and no change in idle. Air box is in good shape and flapper is correctly seated.

The car stopped running after the new WUR was installed. I theorized that in order to get the car to run on a bad WUR adjustments had been made to the idle mixture to make the car run with incorrect fuel pressures. Now with correct fuel pressure the mixture is way off. I think it was way too rich as when I pulled the injector it was spraying like a garden hose.

In order to get the car running I need a point of reference rather than just slowly cranking the mixture and hoping for the best. Unless Iget some other suggestions I think I will pull the injector again adjust the mixture so there is no spray and then slow richen it up from there until the car fires up.

I have been following your thread, and as it might be plausible you are missing an obvious air leak I agree with your approach given the pickle you are in at this moment.

The German bosch manual states that when all is lost you need to pull an injector an turn the mixture screw until the injector just starts to spray. Then back off 1/2 turn.

What you also would like to check is that your Air throttle plate is riding high enough in the throat. The earlier models had a spring loaded stop that would sag (the recent SC had a stopper with a screw). As a result the throttle plate can sink deeper into the throat effectively closing off fuel delivery because the vacuum created by the engine is not strong enough to lift the throttle plate high enough.
This also causes hard starts.

Michel

Michel

thanks for all your help! I will check the throttle and see if the flapper looks like it is in its normal position. For the all is lost method When you said turn the screw back I read that was toward rich as that was back in the direction I had turned from. Does back mean toward rich or lean from after the spray has stopped?

Have you pulled all 6 injectors and measured for equal flow into seperate jars?
Maybe one or two need repair.
This thread helped me get my car running:

http://forums.pelicanparts.com/porsche-911-technical-forum/232089-cis-idle-speed-mixture-setting-without-analyzer.html

Ideally make it run rich, tune it lean until it won't run, richen it back up to the midpoint and then get an analyzer to fine tune it.
Running rich is not a horrible thing. (Our cars like it)
I basically tuned mine from rich where it was surging down to a point where it was driveable and had lots of power. Lots of short road tests, small adjustments.
I later bought an analyzer and when I checked the CO it was about 4%, tuned it down to about 3.5% (ROW car) and have been enjoying the ride ever since.

Be more specific......
 

Nick,

You need to give us numbers to be able to understand what parameters you have now. For example: Incorrect fuel pressures, way-off setting, correct fuel pressures, too rich, turn 4 turns.......these are adjectives and descriptions when used in a technical forum like this means nothing!!!!!! Fuel pressures are measurable in psi or bar. etc. Not being able to find air/vacuum leaks does not mean you don't have any. You need to test and confirm. Don't guess and you'll find the culprit.

Why would you make a '4-turn' adjustment on the mixture screw to make an engine start? You could drop your engine from a ten-storey building and the mixture screw would not change from its setting!!!!

Do you still have the old WUR? I don't think there's something wrong with your old WUR. The engine was running before maybe not optimal as you wanted but it was running. Now it won't even start.

Test your WUR (old and new) with the FP running and record the control fuel pressures versus different time intervals (0-5 min. max.). And confirm absence of a significant source of air/vacuum leak/s by doing a pressure test. Keep us posted.

Tony

You pull the injector and run the FP. The idea seems to be that you turn clockwise (rich) until the injector just starts to spray (spray/dribble)
When it does that you turn the mixture screw 1/2 turn counterclockwise (lean). At that point the injector should no longer spray/dribble.

This is supposed to be the setting where the car would start receiving enough fuel (but not the setting for the correct co, that you need to do when fully warmed up.

Ofcourse all this means everything else is in fine fettle.

It seems that this is the method used when the engine and fuel system has been overhauled.

Tony,

Again thank you for your reply but I think you should be more measured in your response. As I said before I don't think you have read the whole thread. Information From my first post:

Original WUR 90 degree outside system pressure 4.8 bar control pressure 1.5 bar. car ran like this but had a light throttle stumble that I had been chasing. After confirming timing and spark and finding no air leaks I moved on to checking the system pressures

Were I am now:


I did not bother checking warm control pressures as the cold was down ~1 bar. Pulled the part number off my WUR and got a rebuilt unit from Rarelyl8. System pressure with the new WUR appears to be correct. 78 degree ambient temps 2.5 bar initially and after about 10 min with the fuel pump running rises to about 2.9 bar. However with the new WUR the car does not run. I'm theorizing that the previous owner of this motor and CIS system was working around the bad WUR by adjusting the idle mixture. Motor is new to me so I have no idea really what happened before I put it in the 914.

Nick, just my 2c here:

- Are you sure there are no air leaks ? What about the underside of the airbox (where the runners connect), have you checked it ?
- When you say 4 turns of the mixture screw, you mean 4 complete revolutions ( 4 x 360º) or 4 clicks ? My mix screw has a notch everey few degrees, so 4 turns would be a lot of clicking... Just to really be sure we understand you.

4X360

I will have a poke around the airbox and runners and see if I can discover any leaks

Nick,

Do you have access to an innovate LM1 or 2?

Nice little tool.

I have trouble shot my CIS with this LM 1 and a pressure gauge.

On the basis of the AFM readings on the LM 1 I can make a lot of educated guesses.

Given that AF and co are interrelated it does away with the need for a gas analyzer (ok not really but its the closes thing we will get as amateurs).

Michel

Run the engine.......
 

Michel,

The engine has to run first before you could measure the AFR!!!!! I'm no CIS expert but I'm still looking for a CIS engine that I could not make to run. The parameters for running CIS engines is very simple and yet people make these requirements too complicated. Check your ignition (sparks & timing), fuel pressures, absence of air/vacuum leak/s, a fully charged battery and it would run.

I was away for 5 weeks on vacation and arrived home the other day. This morning, I went to the garage and started the the two (2) 911. One car started after the 2nd turn of the ignition, the other took 3 turns. Early this evening, both cars started on the first turn of the ignition switch. And same thing with the engine on my test stand. It started and idle as expected. There is really nothing difficult or magical in making these engines RUN!!!!! Keep or maintain the parameters within close range of the specs and they would run on demand. But how I do it? Test and confirm in case of doubt. Stay away from guess-work. Air/vacuum leak is the Achilles heel of Ketronic system.

Tony

Finally had a chance to work on the car. I pulled an injector and followed the method list earlier in this thread to etablish a baseline setting. car fire right up with a very fats idle ~5k. Gntle worked it back down to by riching up the mixture a 1.4 turn and turning the idle screw in 3.25 turns. Car now idles at 1K dead smooth. I have some rough running issues right at throttle tip in but other than that all seems well. I will get it on an exhaust analyser in the coming weeks.

Thanks to all who offered their advice.

Nick