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tops911's Avatar
 
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air fuel ratios all over

I have a question for the brain trust here. I just put in a wide band O2 sensor and an AFR gauge, from "In Your Face Gauges"; the one that replaced the stock boost gauge, I love the gauge.
I seems to me that the AFRs are all over the place and not consistent.
When I first start the car it's in the 10s (sometimes sub 10s) and will stay in the 10s until I shut it off and then when restarting it- it reads in the 12s or 13s. It spends most of it's time in the 10s to 12s though. This is driving non boosted. I have had limited time on boost, well I have had a couple 100 mph plus trips on the Autobahn where on boost it was in the 10s or so. The driving on Post at a whopping 20 mph (idle) the AFR seems to change after every time i start the car; starting at the 10s, shut off and re-start and it goes up to 12s or 13s, and then after another re-start it did see 14s today for the first time ever. But with the revs at about 2000 rpm or so it drops into the 10 to 12 range.
I know it's running pig rich; but I'm wondering if this is normal or is it looking like time to replace the WUR.
Thanks Frank

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1982 930, K-27, BL adj. WUR, Rarlyl8 Headers and Hooligan muffler, MSD 6, 22 and 30mm torsion bars, poly bronze bushings 30mm raised spindles and custom valved Bilstein shocks (by Elephant Racing), monoballs front and rear (by Rennline), Alton 17" Fuchs, Fred Cook fuse panel
Old 09-30-2011, 10:02 AM
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Not familiar with the IYFG setup but check your ground connections and the sensor calibration.

10 to 12 non_boosted is way too rich. 10 on start up is normal for a moment.
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Old 09-30-2011, 11:20 AM
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Frank has the sensor been calibrated? I know that when I used am lm2, I had to calibrate it before I got accurate numbers. Also with it being that rich at idle I am surprised that the idle is not "hunting."
Old 09-30-2011, 11:21 AM
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The paperwork says it does not need calibrated (it is a PLX Devices set up). I'll read the instructions again but there was nothing that I remember about calibrating. i know it's rich; when i first got it running again I got about 100 miles to 3/4s of a tank of gas. It was so bad I was looking for fuel leaks....The mileage has since gotten better as I drove it more. The car had been in a non-running status since May.
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1982 930, K-27, BL adj. WUR, Rarlyl8 Headers and Hooligan muffler, MSD 6, 22 and 30mm torsion bars, poly bronze bushings 30mm raised spindles and custom valved Bilstein shocks (by Elephant Racing), monoballs front and rear (by Rennline), Alton 17" Fuchs, Fred Cook fuse panel
Old 09-30-2011, 11:37 AM
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The sensor should be a heated 5 wire type? I suspect it may not be heating up properly and giving false readings. My innovate kit takes 30 sseconds to complete the warm up cycle before it gives a reading.
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, full bay intercooler, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.95 bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 09-30-2011, 12:10 PM
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All wideband AFR gauges I've seen are just 0-5 volt DC voltmeters with AFR numbers screened on the bezel.

Take the PLX wideband controller and sell it or throw it in the trash where it belongs. They are junk made for the ricer crowd that has no clue anyway.

Buy an innnovate wideband controller and use that. They are by far the most accurate and you have O2 sensor calibration and free air AFR calibration which are both stored in onboard flash memory and should be recalibrated periodically as the sensor ages or a new one installed to maintain accuracy + or - .1 AFR.
Old 09-30-2011, 01:14 PM
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Definitely too rich. You should see 10's at cold startup, but within just a couple of minutes you'll see the AFR's rise to high 13's low 14's (depending on various things). 10 - 12 normal running non-boosted is too rich.
In addition to the advice on calibrating, heater not working consistently, etc. please tell us where you have the sensor mounted. And if you're running with stock CIS, then suggest turning the mixture screw out (counterclockwise) just a little bit to lean her out. That should help your idle AFR's, but to a much lesser extent your AFR's when running down the road.

Start there (with a small adjusment and checking all connections) before assuming the WUR is shot.

One more thought, and this is something that has plagued me all summer. My AFR's would suddenly go pig rich 10-11) with a full warmed up car but only afer hitting around 2500 rpms and beyond. And only after the car had been driven for at least 20 miles, followed by a few miles of city driving. I had some other symptoms that made me look at my charge voltage and guess what...my voltage regulator was puting out up to 18 volts but only after the engine got really warm and caused the voltage regulator to crap out....and when it did that, my AFR's on the gauge would drop like a rock. So, too much voltage to the AFR electronic circuits for me is causing erroneous readings. Could you perhaps be having an inconsistent voltage issue? Just a thought, my issue may be unique to me only.
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Old 09-30-2011, 01:25 PM
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Quote:
Originally Posted by mark houghton View Post
One more thought, and this is something that has plagued me all summer. My AFR's would suddenly go pig rich 10-11) with a full warmed up car but only afer hitting around 2500 rpms and beyond. And only after the car had been driven for at least 20 miles, followed by a few miles of city driving. I had some other symptoms that made me look at my charge voltage and guess what...my voltage regulator was puting out up to 18 volts but only after the engine got really warm and caused the voltage regulator to crap out....and when it did that, my AFR's on the gauge would drop like a rock. So, too much voltage to the AFR electronic circuits for me is causing erroneous readings. Could you perhaps be having an inconsistent voltage issue? Just a thought, my issue may be unique to me only.
Was it erroneous readings or was 18V to the fuel pumps causing the issue? I guess it doesn't really matter since you figured it out... but at 18V, I bet those bad boys were spinning pretty freaking fast!
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Old 09-30-2011, 03:03 PM
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Mr. Turtle,

Good point! But, if the pumps were just screaming like bats outa hell, then one would think that the system pressure would be higher than it should be, and the AFR's would likely go high (more fuel pressure would mean more resistance to the fuel arm/metering plate, which would restrict/reduce how much it can move in response to throttle position - thus feeding less gas to the injectors).

But I can tell you this, that when my volt meter says the regulator is on the fritz (again, only after the dude gets hot enough to flake out), my AC fan definitely kicks up a notch. Gotta fix this before it fries something. Got another month or so before it's time to retire her for the winter, so WTF...gotta enjoy while I can.
Oh...that's right...you Floridians don't know the meaining of winter. I hate you.....
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 09-30-2011, 07:10 PM
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We fix them during the summer so we can drive them in the winter. After the heat and after the rainy season. Good stuff baby...
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Old 09-30-2011, 07:39 PM
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Winter = snow, that white stuff that falls from the sky when temperatures fall to points that wipe out the citrus groves.
I have fond memories of driving my '73 Targa cross-country during a move from SE Idaho to Chicago in mid January. Absolutely the stupidest thing I've ever done. Blizzards, icey roads, no weight in the front end. White knunckle all the way for what ended up taking 5 days.

Oh well, those of us that have to deal with the less favorable seasons just learn to savor the moments we have.
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 09-30-2011, 07:48 PM
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Mark H. and DSP, nice hijack...
Frank, welcome to the AFR knowledge base. It is amazing what you learn about your engine when you install a wideband AFR system in your car. I have the same unit as you have and I was fortunate to discover steady 14.5 AFR at idle and dipping to 12 under full boost. In your 1982 car you can find a long stretch and hold the RPM at 3500 (in any gear) under moderate load and measure your mid AFRs. Adjust the fuel mixture until that reading is 14.7 or nearly so. If it then runs poorly at idle, when cold, or under full boost, you have other issues that need to be resolved depending on the reading.

Despite what Mr. Fairman says, these are quality made units and not junk. His description shows that he has no idea of what he is talking about. Anyone familiar with the PLX system would know that "AFR numbers screened on the bezel" would never come close to what we see on our PLX digital displays. Unless someone has done a side-by-side comparison between PLX and innovate, I doubt they can claim higher accuracy "by far" as he has done here. He should also know the PLX is +/- .1 on the wideband Bosch LSU 4.2 sensor and self-calibrates at each power-up sequence based on the heater voltage sent to the O2 sensor. Relating the clueless factor of a buyer to the quality of a product is a new marketing metric that I'm sure Innovate and PLX would like to know about, or is Mr. Fairman just calling you and I clueless ricers?
Mark
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Old 09-30-2011, 07:52 PM
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I have not idea if the PLX is any good.....I am sure it is. The Innovate is OK, but very complicated.

The best AFR instrument I have used is the Daytona Sensors WGeO IV . You calibrate it manually once in a while. I can't imagine auto calibrate. It takes 12 hours for the exhaust to purge, so how can you auto calibrate each time your turn it on? If you turn it on 2 hours after running, you are going to get inaccurate readings.

You really need to capture the data for AFR vs RPM and boost to know what is going on. The Daytona keeps 2 hours of data that is easily downloaded and studied. The complete unit is a little over $400.00.....and it is available from out hosts.
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Old 09-30-2011, 09:17 PM
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Thanks for all the help. The CIS is stock and the sensor is after the turbo, about 4 inches from the turbo and as close to the muffler as I could get the bung welded. I also installed the Innovate heat sink making sure that the hole was pointed in the right direction.
I've only been able to put about 250 miles on the car since I've gotten it to run. There was a point where when accelerating quickly and hitting boost fast the car would fall off on power, like a miss or loading on fuel, I did not have the gauge in yet when that happened. But if I took it up to max boost slowly it would not do that. After driving for a while it has not done it since. So I'm thinking maybe the WUR may be going out or it was just "dirt in the fuel" and it needed run to clean thing out. I think the car just need driven some more, however that gets hard as I'm leaving for training this afternoon, for a month. I've done a couple of trips on the Autobahn as 100 mph plus and the AFRs were in the rich range. I was mostly watching the boosted AFRs and they were in the 10 to 11s. I have never seen anything in the 14s at a steady speed. I have the fuel pressure readings somewhere from when I was trying to get the car running I need to look them up as well to see what that may be doing to the AFRs.
I need to look into data logging I'm sure that PLX has it, but that is in the future....
This is a new car to me and my first turbo, so I'm learning about this car.
Thanks Frank
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1982 930, K-27, BL adj. WUR, Rarlyl8 Headers and Hooligan muffler, MSD 6, 22 and 30mm torsion bars, poly bronze bushings 30mm raised spindles and custom valved Bilstein shocks (by Elephant Racing), monoballs front and rear (by Rennline), Alton 17" Fuchs, Fred Cook fuse panel
Old 10-01-2011, 12:41 AM
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Frank,

Congrats on the IYF gauge. I've had one for over 3-yrs and have loved the constant/reliable feedback it gives me!

It sounds like the sensor is in the right place, now I would look at your Fuel Pressures, mainly:

1. System Pressure
2. Initial [Cold] Control Pressure
3. Warmed-Up Control Pressure
4. Under Boost Control Pressure

You'll need a set of CIS gauges to do this. There are many threads with pictures on how to setup the gauges. Like you, this was my fore' [sp] into the realm of turbos and higher-than-normal maintenance cars. This forum has been invaluable!

I would have to strongly agree with Mark [Lucittm] on this one - - you've got a great product!

One suggestion: look at the actual electrical connection [the plug] on the WUR. Maybe it's intermittent [got a bad connection]? Thus causing intermittent voltage to the WUR... Just a thought... Good luck and keep us posted!
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Old 10-01-2011, 05:43 AM
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I thought I'd give an update on all that was happening. I got the WUR rebuilt (I have not tried to do any further adjustments to the WUR), I found a fuel leak at the fuel distributor (I feel lucky on that one; lucky the car did not burn up!!!) I also had too small of fuse on the AFR gauge hook up (I blame that on old eyes; borrowed the wife's reading glasses to ensure I had the correct fuse) and the gauge and AFRs are pretty good and consistent now.
I'll be enjoying the car for the next coulpe of months before I deploy, again.... (4th deployment since 2005)
Oh and I'm going to put on a new RarlyL8 Hooligan muffler this week; hopefully the muffler gets here before Friday. I'm taking a trip to Garmisch and would love to have the muffler on for the trip ;o)
Thanks to all for the help!!
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1982 930, K-27, BL adj. WUR, Rarlyl8 Headers and Hooligan muffler, MSD 6, 22 and 30mm torsion bars, poly bronze bushings 30mm raised spindles and custom valved Bilstein shocks (by Elephant Racing), monoballs front and rear (by Rennline), Alton 17" Fuchs, Fred Cook fuse panel
Old 04-17-2012, 12:08 AM
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Good for you. It was the WUR and fuel leak not the fuse as it's only there to prevent failures not cause them. Have fun on Garmisch trip.
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Old 04-17-2012, 12:27 AM
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Oh and one other issue was the power to the WUR not getting to the WUR. The car had "black" relays for the fuel pumps and I bought new "red" relays to replace the "incorrect" black relays. I don't know if the red relays are bad or what but there was no power to the WUR with the red relays in place, once I removed the red relays and replaced them with the old black relays there was power to the WUR and the WUR warmed up correctly things were a whole lot better ;o) I'm getting a lot better mileage now and better AFRs too.
Again thanks to all for the help, Frank
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1982 930, K-27, BL adj. WUR, Rarlyl8 Headers and Hooligan muffler, MSD 6, 22 and 30mm torsion bars, poly bronze bushings 30mm raised spindles and custom valved Bilstein shocks (by Elephant Racing), monoballs front and rear (by Rennline), Alton 17" Fuchs, Fred Cook fuse panel
Old 04-17-2012, 12:28 AM
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If no power to the WUR it would stay in cold pressure forewer (if not heatsoak) which is rich so for sure it will show in better milage with power to WUR. I bet you had also high idle because of AAV not getting power as well.
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Old 04-17-2012, 02:15 AM
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I got my muffler this morning, already have it installed, sounds GREAT!!

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1982 930, K-27, BL adj. WUR, Rarlyl8 Headers and Hooligan muffler, MSD 6, 22 and 30mm torsion bars, poly bronze bushings 30mm raised spindles and custom valved Bilstein shocks (by Elephant Racing), monoballs front and rear (by Rennline), Alton 17" Fuchs, Fred Cook fuse panel
Old 04-17-2012, 11:05 AM
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