warm up regulator

[Tom Eberlin]

We are getting 10.5 to 11 ohms reading on the WUR for an 81 sc. It makes no difference if the WUR is electrically connected to the car or not? The car starts cold and now after a new fuel pump and replacing the gas that was in it it starts when it is warm. It was not starting warm before. Does that resistance reading mean it has failed.

[Vereeken]

Maybe; It depends on the type of WUR you have in front.

Last three digits stamped on the WUR casing.

In all respect 11 ohm is low. But at least you are not reading infinity, that would definately make it kaput.

[T77911S]

I think the lambda WUR are low, tony knows for sure.

post the number on the WUR

[Vereeken]

Thought they where 17ohm...anyway lets see what he brings to the table.

[gazzerr]

I think you are supposed to see 22 Ohms for a -090.

[Bob Kontak]

Originally Posted by gazzerr

I think you are supposed to see 22 Ohms for a -090.

At least. Tony did a study about five years ago and asked if I would send my resistance readings to him for my newish 090.

I remember about 26.

[boyt911sc]

Originally Posted by Bob Kontak

At least. Tony did a study about five years ago and asked if I would send my resistance readings to him for my newish 090.

I remember about 26.

Bob,

You are indeed correct my friend. A typical WUR-090 has 25 - 26 Ohms resistance at room temperature (68°-72°F). This is for '81-'83 SC US MY and for RoW or Euro cars would be WUR-089 which is totally different from -090. I am away from home and presently enjoying the cool breeze at Monterey, CA.

Tony

[Bob Kontak]

Originally Posted by boyt911sc

I am away from home and presently enjoying the cool breeze at Monterey, CA.

In case you don't know, there is some cool car stuff going down this weekend in the Monterey area.

Google Laguna Seca.

All the best to my long time Pelican mentor and friend!

[Vereeken]

089 is around 32 ohms at room temp.

[Steve F]

My 045 is 24.7/24.9 Ohms @ 75 degrees.

[RMG001]

Apparently mine is very low also. Fuel pressure still comes up. Rises to spec in 90 seconds. Obviously something is out of spec but if pressures come to spec (I should clarify that I am just below spec control pressure at 70degrees (withing a couple of pounds)
How does the low resistance affect the performance? Is it only on start-up or will it affect the entire system?
Hope I am not hijacking this thread, seems to be relevant to the entire discussion

[Bob Kontak]

Originally Posted by RMG001

Rises to spec in 90 seconds. Obviously something is out of spec but if pressures come to spec........

Just for a data point. Drove my 81 from Cleveland to Charlotte (8 hour drive) in January a few years back. The "warm up" connection was not attached correctly. It was 15F. Half way, filled up and 15mpg was my mileage. Reconnected and mileage went to mid 20's.

Downside I see is that it may take a little extra time to warm up if resistance is wimpy. No one ever states "It won't warm up if resistance is low". May be a smidgeon slower but I am just talking. The bar will bend with heat. In my case it was so cold, it did not bend from engine heat. Way rich.

[RMG001]

Originally Posted by Bob Kontak

Just for a data point. Drove my 81 from Cleveland to Charlotte (8 hour drive) in January a few years back. The "warm up" connection was not attached correctly. It was 15F. Half way, filled up and 15mpg was my mileage. Reconnected and mileage went to mid 20's.

Downside I see is that it may take a little extra time to warm up if resistance is wimpy. No one ever states "It won't warm up if resistance is low". May be a smidgeon slower but I am just talking. The bar will bend with heat. In my case it was so cold, it did not bend from engine heat. Way rich.

Thanks Bob, I obviously have an issue here and will address it, but for now it seems like I have bigger fish to fry.

[Vereeken]

Originally Posted by RMG001

Apparently mine is very low also. Fuel pressure still comes up. Rises to spec in 90 seconds. Obviously something is out of spec but if pressures come to spec (I should clarify that I am just below spec control pressure at 70degrees (withing a couple of pounds)
How does the low resistance affect the performance? Is it only on start-up or will it affect the entire system?
Hope I am not hijacking this thread, seems to be relevant to the entire discussion

A lower ohm reading equals slower leaning of the fuel ratio (or slower increase of the control pressure) during warm -up. It can also mean the maximum intended flex of the bi-metal is never reached during shorter trips. On longer trips the engine heat will help a bit.
If you are within a couple of pounds of spec you are actually quite off. The band wherin you operate is 0.4 bar I believe 6 PSI.
For perfect cold start/warm-up it is necessary to be within the band Porsche suggested.

[niner11]

I've got a WUR out of an 83SC and the ohms were in the same range when I just tested on the bench (10-12). As soon as I put it back in the car and pressurized the system it went to (22-25).
Never even started the car or plugged in 12v to the WUR. Interesting

[schoward]

I have a 090 in my 1981. After sitting in my warm basement for many days over Christmas, I tested the ohms and it came up consistently at 9.1. I was kind of bummed thinking it was bad, but then I read about some sort of two-stage element in these later ones where temperature comes into play.

Sure enough, put it in my cold garage for an hour or so and then it consistently read 26.1. I don't know if that's right but my car starts and runs pretty darn good cold, warm or in between so I didn't pursue it any further. Recent winter drives and warm up starting the car after a week or two dormant have been no issue in 20 degree temps.

Never got a definitive answer but seems to be OK as is. One forum member said normal...(?).

[Bob Kontak]

Originally Posted by schoward

but then I read about some sort of two-stage element in these later ones where temperature comes into play.

Interesting.

Drove mine on a frigid cold day and the WUR connector had come loose. I am talking 3F. Five hours from home. Gas mileage was for shiet at a consistent 65 mph Cleveland to Charlotte. Maybe 14 mpg with a stock setup. On the upside throttle response was superb.

All I am saying is that temp may come into play if engine heat can transfer to the bimetallic strip.

When I checked mine on a warm day communicating with Tony a few years back it was dead nuts 26 plus or minus a half ohm.

If I find the enthusiasm, I will check ohms tonight. It's about 45F now and the car is outside.

[gazzerr]

Yeah I seem to remember back when I was researching WURs that there's a thread in here somewhere that talks about the 2 stage element on 090's.

[schoward]

Bob my guess is you will still be at 26. I only saw the 9.1 reading after it sat in my toasty basement maybe 78° F for like two weeks. One hour or so back in a 40° garage over Christmas and it read 26.1 ohms again.

I think I read about this two stage thing on a Ferrari 400i forum.
This thread has some info. See second post from bottom
[url]http://forums.pelicanparts.com/porsche-911-technical-forum/693583-82-sc-wur-question.htm[url]

[boyt911sc]

Originally Posted by Vereeken

A lower ohm reading equals slower leaning of the fuel ratio (or slower increase of the control pressure) during warm -up. It can also mean the maximum intended flex of the bi-metal is never reached during shorter trips. On longer trips the engine heat will help a bit.
If you are within a couple of pounds of spec you are actually quite off. The band wherin you operate is 0.4 bar I believe 6 PSI.
For perfect cold start/warm-up it is necessary to be within the band Porsche suggested.

Michel,

A lower resistance reading would cause the opposite. A lower resistance WUR will lean much faster than a higher resistance WUR. V (voltage) = I (current) x R (resistance). Missed this post in August 2016 while I was on vacation with my family in Monterey and just wanted to correct this misinformation.

Two (2) critical factors for a good working WUR are heater resistance value and control fuel pressures (cold and warm). System fuel pressure is controlled by the FD.

Tony