CIS advice needed...experts please help

[997at]

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.

[Alan L]

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

[boyt911sc]

Originally Posted by 997at

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.

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

[997at]

Originally Posted by boyt911sc

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

[997at]

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?

[boyt911sc]

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

Originally Posted by 997at

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?

[997at]

Originally Posted by boyt911sc

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.

[tirwin]

Originally Posted by 997at

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?

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.