The silent killer of 930 power and fuel economy.

[RarlyL8]

This is from a customer's 930 I ran on the dyno today.
Very few 930s run as smooth and flawlessly as this one seemed to. As you can see from the graph, the AFRs are in the toilet. There is significant torque and fuel mileage being robbed from this otherwise perfectly running car.

So if you have an old 930 that runs well but has never had the WUR functions tested it is a worthy thing to do.

[Craig 930 RS]

Whose car?

[RarlyL8]

I should not identify the owner without permission. The car is an absolutely perfect low-mileage factory '87 slant nose 930. Painfully bone stock. Spec on this engine is 282HP so you can see he is giving up a few ponies due to the fueling issue.

[356-930]

Originally Posted by RarlyL8

This is from a customer's 930 I ran on the dyno today. . . .As you can see from the graph, the AFRs are in the toilet.

So if you have an old 930 that runs well but has never had the WUR functions tested it is a worthy thing to do.

Your customer could do himself and this forum through you, a favor. Have you install/tune Unwired's UTCIS-PT Digital Warm Up Regulator, dyno and post/compare performance difference.
BTW, your posts and shared knowledge have proven invaluable in my own pursuit of turbo power excellence. Many thanks.
Chris

[Rasta Monsta]

Yikes, that leaning out under boost will cost more than a few HP!

[9dreizig]

Originally Posted by Rasta Monsta

Yikes, that leaning out under boost will cost more than a few HP!

Don't you mean rich ?? Looks like it goes pig rich over 3500 rpm, unless I'm missing something ?

[Facey]

air/ fuel. larger value = less fuel (or more air) = lean
lower value = extra fuel (or less air) = rich.

easy to mix up though... there are IMO some better methods to display this information, one of them being the equivalence ratio of a system; which is defined as the ratio of the fuel-to-oxidizer ratio to the stoichiometric fuel-to-oxidizer ratio... meaning 1 is perfect, greater than 1 is rich, less than 1 is lean... neat and clean.

anways, is it really safe to run that lean?

[willtel]

I'm glad this came up. Any opinions on my graph? I'm assuming that big dip in the middle is bad news for power output.

[RarlyL8]

Yes, the AFRs on my graph go RICH at ~3500rpm which will rob power, reduce fuel mileage and wash the cylinders which reduces the life of the engine.

The reason for taking the car to the dyno in the first place was to have the AFRs checked before I did a few modifications. I expected to see rich but had to verify that it was not lean on top before any changes are made.

The owner's representative has been informed of the condition and it will be addressed after the modifications are complete. I have recommended making the WUR adjustable and then I'll tune it.

If you recall on previous posts I had a buddy who did everything on the planet to his 930. Multiple cam changes, multiple turbos, intercoolers, headers, you name it. Well he tried multiple WURs as well which included a digi-WUR to be offered by a popular tuner. He was not impressed. The digi-WUR performed no better than the adjustable WUR and added a level of complication. This may not be the case with the new stuff but I have no experience with it and will not risk harming this engine because of a computer glitch. I am looking forward to seeing how it goes with all the folks now installing and tuning these gadgets.

[964 T #304]

Brian, I have recently installed the UT digatal wur on my 92 turbo. I am totaly pleased with it and see no added complications that you speek of! I just last week loaded a map with the help of Frank on the advise S teve @ UT. I made some 3rd & 4th gear pulls on the highway with my lm1 monitering the afr all the way to 6800 rpm in each gear. I run a 1bar spring in a stock waste gate, cat and muffler delete, stock 92 turbo, 3 angle valve job, raceware case and head studs. Pretty much stock. My car reaches full bost in 3rd. or 4th. at around 3000 rpm . The afr went from around 14.5 to 15.0 flat in 5 th. gear at 2000 , just riding around, to 11.6 to 11.8 under full boost all the way to 6800 rpm. My car is a street car only and that is plenty good for what I need.

[JFairman]

That graph looks like the engine starts out with 14:1 AFR @ 2600rpm and gradually drops to as rich as the graph can display @ 4000rpm with 10:1 AFR and stays there until it reaches 5900rpm where the the power cuts out completely on the top graph, and immediately goes as lean as the lower graph can read, 18:1 AFR at the same time.

Looks more like the charge pressure overboost switch is turning off the fuel pumps at that point.

[RarlyL8]

The same thing happens when you take your foot off the gas at 5800rpm.
No need to go beyond 5800rpm with a stock engine as they make no more power and I would have the data needed. The AFRs actually went into the 9s as it is off-scale at 10 flat.

I look for great things with the digi-WUR now that they are on the open market and being tested. I am sure they will evolve to include more functions such as turning things on and off and ignition inputs, etc. I want to see longevity testing and testimonials of what happens when one fails before putting it on a car that doesn't belong to me.

[Craig 930 RS]

Agreed on the Digi WUR -

[turboteener]

Is a local car? Didn't know there were any other 930 in this area.

[gogomobil]

Originally Posted by 964 T #304

to 11.6 to 11.8 under full boost all the way to 6800 rpm. My car is a street car only and that is plenty good for what I need.

That is impressive.
Did you notice a powerincrease also?
I think I will go the UTCIS route too, very soon.

[964 T #304]

What I did notice as soon as I started car that the rich smell of unburnt fuel that was allways there with factory wur ( no mater where you set the idel CO @) was gone . I have deleated the aar valve a while back, and like Brian always said was no problem. you just needed to play with the throttle a bit till the factory wur started to heat up then it would idel fine. Now all of that is gone and it idles fine by just reaching in window and hitting key when it is cold. The idel co. is great. The car is chrisp @ ever rpm. And you can feel a greater linnear movement in the seat of your pants then before. I had an adj. wur with a msd rpm switch that I used a 4200 rpm pill in and it was a lot better than stock and could tune it to get Unough fuel on top end to keep afr @ around 12 flat @ 6000 rpm. With the Ut by being able to tune your engine @ every 250 rpm ,You IMO can not beat that without going the EFI route. Mabey some of you can do that with an adj. wur , but not the adv. person. With this you can.And yes you can feel the extra HP by having a flatter fuel curve. I have spent a lot more to get a lot less a lot of times as most of us have!

[RarlyL8]

Mabey some of you can do that with an adj. wur , but not the adv. person. With this you can.And yes you can feel the extra HP by having a flatter fuel curve. I have spent a lot more to get a lot less a lot of times as most of us have!

This is a very good statement. The adjustable WUR simply takes time and patients which may prevent some from achieving perfect results. The digi-WUR also takes time and patients, the difference being computer time vs fiddling with a mechanical device time. For some that is more in their comfort zone. The AFRs on my car are the same, mid to high 11s under boost, nothing lower than 11.5 on the curve. Fuel mileage is 21+

[Rasta Monsta]

Forgive what is probably a dumb question (to follow my dumb statement above), but is the WUR the only thing providing enrichment under boost, or do these cars have a WOT switch/lambda frequency valve as well?

I'm curious because, although I don't have a 930, I have a car covered in 930 parts!



Oh, and one more question. . .does anyone know if this company is planning to release a part that uses O2 sensor feedback? Seems that could be helpful.

[RarlyL8]

There is a thread specific to the digi-WUR recently brought back to the top.

Brett - there are about a half dozen 930s in the Hunstville/Decatur area that I am aware of. I am sure more are hidden away or owned by folks who do not frequent the boards and/or are not PCA members.

[tj930]

Originally Posted by willtel

I'm glad this came up. Any opinions on my graph? I'm assuming that big dip in the middle is bad news for power output.

Yep, seen exactly the same thing with my car and Dyno AFR - symptomatic of CIS ("mechanical-style fuel injection").

Ideally one would want to start of at 14.7 when off boost, slope down linearly to 12.0 when at full boost, and then be a flat horizontal line to the right the remainder of the rev range - this is the point of 'mapping' with EFi and UTCIS.

I hope to have a UTCIS device fitted very soon...