CIS advice needed...experts please help
 

Hi Guys. Having some CIS troubles and could really use advice from the experts (Tony, et. al.)
I have a 1982 SC and just finished a refresh of my CIS. Took it all off and did an inspection/replacement of the components. I replaced quite a few items with brand new stuff including the air box, injector seat, injectors, all gaskets, runner boots, air boot, etc. Put it all back together and got the car started. The car will start with a turn of the key, but the cold start is not correct. The idle rpm does not go high on start up. The car starts out at about 600 rpm and slowly builds up to a perfect 900 rpm once the car is warm after about 5 mins. It runs beautifully once warm, no popping, no surging, and pulls like a freight train through to redline.
My WUR testing shows cold and warm pressures that are within spec (although the warm control pressure is on the upper limit of 3.8 bar for my 090 WUR). The WUR resistance is low at about 9 ohms which has it going to full warm control pressure in about 90 seconds.
When the engine was out I tested each component on the bench including the CSV, AAV, AAR and Decel Valve. The AAR closes nicely in 5 mins and the Decel Valve opens at about 25 in Hg. The AAV closed at about 5 in Hg, but would not hold closed as it had a small leak that slowly bled down to 0 in about 10 seconds. I put it back in thinking that this small a leak is okay since the engine is constantly pulling vacuum at idle and should not let much air in. I suspect that unmetered air is getting in somewhere as I have almost no rpm drop when pulling the oil cap off.
I just finished performing a positive pressure smoke test (cigar method by blowing in through the number one injector port) and didn't see any leaks.
If my AAV or Decel valve was leaking a bit, then I'm thinking that the air is still metered as it pulls from the boot between the AFM and the throttle body.
Any thoughts on where to go next? Is my thinking all off? Do I have leak somewhere I just haven't found yet?
Advice much appreciated as I want to approach this in a methodical way.

Ash

good job so far.
I don't know the resistance of 090, some are low though. i will let tony answer that one.

my first thought as I was reading is the mixture Is not correct.
questions,
how did you set the mixture?
have you checked the duty cycle of the freq valve?
what about the engine temp sensor/wiring?

one test you can do is to remove the power connector to the WUR. start it cold and lift up on the sensor plate and see if the RPMs come up. this will richen the mixture as a test.

One cheater trick is to plug the retard hose to the dist vacuum pod with a golf tee.

It advances your timing a wee bit on startup and can impact idle favorably in that first minute or two.

It's not the solution but a band-aid that makes up for some of the fatigue of older CIS parts. Assuming that's all the problem is.

Ohms are 26-ish on the 090.

Now that you mention it nine ohms seems to be where a lot of people ohm their 090's out to. I have talked to Tony (while back) and we were in agreement that it's 26. However, I don't know if they made different types of heating elements.

We may have just compared two with the same resistance? I think he did a study of multiple inputs on the 090 so stay tuned for his input.

Thanks for the suggestion. I think I'll do that next as a test.
I set the mixture per the Bentley which was to set the mixture screw so that the injectors just start misting and then back a half turn. I did subsequently mess around with the idle screw and mixture some more after this so its entirely possible that it needs to be revisited.

I've never checked the duty cycle. I'm not even sure how to do it so maybe that's something I look into next as well.
Engine temp sensor - what impact would this have? I'm just not familiar with how it impacts idle conditions.

Here is my input:

An AAV that does not hold Vac can be ok, but if it bleeds in under 10 secs that is not good. Yes the vac is replenished with a running engine but I am sure this will give issues under normal operation.
But this will not cause your low rpm. My advice would be to block or to replace.

WURS and pressures is for Tony.

But I have made one fatal flaw in the past. The AAR has to be aligned with the WUR type.

So for example if you have a 82+ EURO Porsche SC you need a 089 WUR with a 209 AAR. I can make it work with a 200, 226 and 201 but never as intended.

So check your combo and ask Tony for the correct Combo. So a 090 wur would go together with a XXX AAR.

The size and design and speed of closure of the hole is made for your engine characteristic.

I once was ignorant of that fact but no more.

ANd yes it is a pain to find the correct AAR but maybe less in the US.

Michel

Plug the retard hose for fun and humor this old man. It's the hose closest to the fan.

I think that is a very poor - hit/miss way to set the idle mix. Bit of a crap shoot. It is very sensitive to adjustments. A 1/4 turn is a big adjustment.
First, check all the other advices to eliminate other possible faults. Then, lastly revisit the idle mix/speed. Warm engine, tweek the idle screw one way until it just starts to change engine note. Take note of allen key position - eg 2 o'clock. Now turn it opposite direction, until engine just changes note. Take note of allen key position, then set to mid point. That will get you very close to where it needs to be - at that point, it is not the cause of any issue. Then see if idle speed needs adjusting. If it needs a decent tweek, you may need to repeat idle mix again.
Alan

CIS troubleshooting...........
 

Ash,

You need a fuel pressure gauge to do a meaningful diagnostic for any fuel injection system (Ketronic, motronic, etc.). Measure your cold and warm control fuel pressures versus time, record your system and residual pressure too. Save these data. They maybe not the optimum values but you have at least a data base to compare or to look back.

Test and confirm that you don’t have unmetered air going into the system. The worse you could do at this point is tinker the mixture setting. This setting is very stable and robust but people have the tendency to adjust this setting. You could drop your engine from a 10-storey building and that setting will not move or change a bit. Once you altered it, you lose the factory calibration for the said AFM (air flow meter). This was the reason the access to fuel mixture screw was originally plugged and sealed from the factory.

Your WUR-090’s heater resistance should read between 25~26 Ohms when engine is cold. When you have 10 Ohms reading with the engine cold, it would still start and run. But you will always have an erratic cold idle. This one problem you have to address sooner or later.

If you are not getting a noticeable engine RPM drop when you removed the oil fill cap with a fully warmed up engine, you have a serious vacuum leak some where in the system. Not being able to locate a vacuum leak does not mean you don’t have any. It is there some where waiting to be discovered.

The AAV should close and hold vacuum. They hardly go bad. But if you need one, I have box of AAV. Take note of the vacuum reading on the gauge. A good unit should hold the pressure for a long long time.

http://forums.pelicanparts.com/uploa...1522109501.jpg

Keep us posted. Thanks.

Tony

Hi Tony, thanks for the info. Below IS MY WUR testing data:
Resistance 8 ohms at 21 deg C.
System Pressure 4.8 Bar 17 deg C.
Cold control pressure. 2.1 bar at 17 deg C.
Warm control pressure 3.8 bar at 17 deg C.
Warm up time 1 min. 15 secs.
Residual pressures are very solid.

I think I need to do a more comprehensive leak test. I'll pick up a decent smoke machine and do a partial engine drop so I can see things a little better and also get the boot off the throttle so I can get a glove on top of it. As you know, the 82 SC with an engine sound pad has zero room to do this stuff with the engine all the way up.

I'll check back in when I've completed a thorough vacuum leak test. Let me know if you think this is the correct next step.

Thanks,
Ash

he does not have a very accurate mixture setting.
check the DC of the FV

I mention the temp sensor only as an outside option, if the computer thinks the engine is already warm even though it is cold it could be too lean when cold

I detected a leak in my cis system and found an improperly seated injector. I sprayed chem cleaner at each component as the engine idled and when I gave the culprit injector a shot there was a slight drop in rpm right away. Not very scientific but hey, it worked for me!

Hi Tony,

Just wanted to keep you posted on what I've been doing. I just received my Stinger Smoke Products smoke machine today and over this weekend I will do a partial drop, take the air boot off and test downstream of the throttle plate. I had previously dome a "cigar test" but of course this is not that great of a method. The cigar wasn't bad though! I will post the results of the smoke test.

I thought I would check that my AAR is working correctly so I popped off the exit line and checked it out with a mirror. Opening was good when cold. I then jumped the fuel pump relay and turned the ignition on to test warm operation. The valve closed completely within 7-8 minutes.

I know for a fact that my AAV does. not hold pressure that well, so I will PM you for details on how to get a perfect working one.

Thanks,
Ash

You also need to check the type of opening you have in your AAR.
It can be a half circle, a quarter moon a half circle with a square notch.

Each car comes with a combination of WUR type and AAR type.

you do not want to know how long I struggled with cold idle just as a result of an incorrect but perfectly functioning AAR.

You need the last 3 digits on your AAR and next ask Tony which AAR type you need for your WUR assuming that your WUR is correct for you car.

Okay, thanks. I'll check in with Tony on this.
If I recall correctly the shape on mine is a half circle and my WUR is an 090.

Quick update. Got the smoke machine in and did some testing. Found a pretty significant leak on the line connecting the vent from my WUR to the throttle body. I never thought about it before, but this is effectively unmetered air to the top of the throttle body above the butterfly...might explain why my oil cap removal doesn't cause a drop in rpm?
Also found a small leak that appears to come from the connection between the throttle body and the air box. I had previously installed the new air box with a fresh o ring for this connection and tightened the 4 throttle body bolts pretty darn tight. The o ring is the only seal there is between these two. I'm thinking I will remove the throttle body, put in another new o ring and try again. Anyone else had a leak here before? You wouldn't be able to see it with the soap bubble test but the smoke wafts up from down in that region.
I also was able to see small amounts of smoke from the throttle bypass screw. It must make its way past the threads. I even closed the screw completely and still got a faint waft every now and then.
There was absolutely nothing I could see from the boots, injectors, intakes runners etc.
The smoke machine is great by the way.

Not unusual to get a minor leakage around the throttle body. But when it gets to the point that is all you have, things should be pretty right. Check the butterfly spindle leakage is not too bad.
Alan

Conventional wisdom here seems to be that single digit resistance means your WUR is bad, burnt or blown.
That is wrong for the 090 WUR.

I learnt this recently myself by digging thru the archives that the 090 WUR has a temperature dependent resistance.
Here's a quote from Jim Williams (CIS primer site author)

At ambient temperatures below about 50˚F, the switch is open so that the applied + 12 volts "sees" 27 ohms.
at ambient temperatures above 50˚F, the + 12 volt input "sees" about 10 ohms

Your 090 WUR resistance of 9 ohms is not low. I wager the ambient temp was higher than 50F that day.


Where are you located ? Some here might wanna borrow it :)

Thanks pmax. Good to know.
My ambient temp the day of the test was 71 deg. C so it makes sense then.

I'm in Orinda in the East Bay. Happy to lend the smoke machine to any fellow Pelicans who'd like to use it.

Very frustrating. Fired the car back up yesterday and didn't really see any change to the behavior from before. Rpm still does not rise at cold start but instead starts at about 800, drops over a few minutes to 600, and then rises to 950 as the car warms up. It takes about as long to get to 950 as it takes the AAR to close (~7 min) and is dead on at set point once engine temp is at or above 180 deg. If I drive the car once warmed up it runs beautifully, pulls strong, no hesitation, full power all through red line, stable idle.
I also took note of a couple of other things. If I take the oil cap off I get a 50-100 rpm drop (you can definitely hear the change in engine note but it's not a massive drop). Also, if I disconnect the O2 sensor the engine speeds up about 100rpm as if the mixture just got richer.
I feel like I need a new plan of action to solve this. I'm determined to get the car running like it should.
Thoughts appreciated.

you have lambda gear on an 82 SC? I have an 83 RoW and no lambda. Just checking. I have no experience with lambda, but it does from several thousand kms away, sound like the warm up mix is a bit rich.
Alan

Ash,

If you are getting 9~10 Ohms reading @ 71°F ambient temp., your WUR-090 is out of spec and will always have an erratic cold idle. Anyone suggesting this was good and OK do not understand CIS very well. Aside from your WUR, you have other issues you have to address to get your CIS engine to run as it should.

Tony

Hi Tony,

I sent you a PM.

Thanks,
Ash

Okay guys...continuing to troubleshoot. I've ordered a dwell meter so I can check out the whole Lambda system later this week.
Tonight decided to check out the WUR a little more. At room temp (70 C) resistance was 10 ohms. I put it in the freezer for a few minutes. Came out cold and it tested to 26 ohms. I then measured every few minutes as it sat out and warmed up. I wasn't measuring the temps, but at a certain point the resistance switched almost instantly from 26 ohms to 10 ohms.
Can anyone confirm if this is normal behavior?

I was also thinking about the fact that on startup (CA mornings are not that cold) my WUR reaches warm control pressure in about 75 seconds, yet the AAR takes at least 5-7 minutes to close. Wouldn't this mean that I would be lean during almost my entire 5-7 minute warmup? Maybe that's a large part of the reason that I don't get a high idle on startup?

CIS components troubleshooting........
 

Ash,

Based from your information you have posted both your WUR and AAR are out off spec. A good and well calibrated WUR-090 should have 25~26 Ohms heater resistance value @room temperature and normally takes more than 75 sec. to reach WCP. The AAR is lethargic and usually closes between 3~4 mins. What is the ID number for the AAR?

What problem/s are you having now? Keep us posted. Thanks.

Tony

Hi Tony,

The issue I'm having right now is that at cold startup the engine will fire up with just a key turn but it starts out at lower rpm (~600) and slowly builds up to 900 rpm over the course of about 7-8 minutes. Once at operating temp the engine runs really well.

I'll get the AAR ID later today and get back to you on that.

I assume you meant 70°F, not C.

That is consistent with what Jim Williams has stated in the past. I think Tony disagrees.

It could be that what Jim found is a common failure mode for the WUR. By that I mean if you tested a significant sample of WURs from running cars you might find that many of them exhibit the same behavior. That doesn’t necessarily mean they would have operated that way new from the factory.

The calibration of the WUR is tricky. It seems that fall/winter operation is usually different from spring/summer.

A reason that CIS can be frustrating is something you pointed out. There is an implied expectation that these independent components operate and are coordinated. The cold start process is designed to enrichen the mixture. To do that the WUR starts with a lower fuel pressure and then gradually increases the fuel pressure. This is going from rich to lean. The AAR is operating independently of the WUR but they are related.

Do you have a way to measure AFR? If you do, then you could measure AFR during the warm-up process and know whether you were lean or not.