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Tuning, AFR, Altitude and More Questions

Iím trying to get my car dialed in while not blowing it up after last yearís top end rebuild. I am having two issues:
First is that I canít seem to get consistent AFR readings and second is that it wonít build more than .6bar boost.

Car is setup as follows: 1985, black fuel head, stock 3LDZ turbo, stock waste gate, stock intercooler, stock heat exchangers, no emissions including no catalytic on what I believe is a Borla exhaust. Included in the pile of money I sent to Pelican, I replaced all vacuum lines, replaced injector blocks with stock due to cracks and erosion, rebuilt stock bypass valve, installed aftermarket PLX boost sensor on intermediate manifold (used port where decel valve used to live) and PLX wideband AFR gauge approximately 18Ē from end of tailpipe. I also have some kind of adjustable WUR - it was there when I bought it.
Black Euro Fuel head at 6.5 System Pressure (up from 5.9)
Cold Pressure: 2.1bar at 75 degrees
Warm Pressure: 3.4bar
Cold start: Idle AFR at 10.4 on start and rising to 14.7 on warm engine
Enrichment: Full boost of .6bar yields 10.3 - 10.8 AFR
Cruise: 70-75mph, slightly in boost, .05 - .1 bar, 14.2 - 14.5 AFR
Warm idle: 14.5AFR
Decel from cruise: 15 - 16 +AFR.
Correct me if Iím wrong, but these numbers seem okay. Where I get confounded is when I park for pretty much any length of time and the motor heat soaks, I start it back up and it idles rich again at +-12AFR and sometimes with an idle speed of 1200 RPM. As I drive it again, it seems to run a bit leaner with the idle AFR eventually running over 15 and the cruise AFR 14.5 - 14.8. Enrichment still runs into the 10ís and boost is remaining at .6bar.

Some of my thoughts:
Iíve checked and believe I have sufficiently tight intake and exhaust systems without any leaks.
My Ďadjustableí WUR has been very finicky. I can tap or back off the pin on top to get it to an exact warm measurement and when I test it again, the measurement is different. Maybe this is the culprit? Would a rich AFR on a hot engine cause the idle to run high? Iíve tested the AAV and it appears to work as its supposed to, but should I pinch this off to take it out of the equation?

I believe my timing is correct, but if the distributor wasnít advancing/retarding as it should, would this cause any of these problems?

Regarding the .6 boost issue. The waste gate is consistently gassing off at .6bar in every gear. I didnít have the PLX boost gauge prior to the rebuild but I thought I made closer to .8 per the stock gauge, which reads pretty much identical to the PLX gauge, just not nearly as instant. Would I be crazy to cap the waste gate to intercooler for testing purposes to see if I can carefully make .8 bar? Are there real performance gains to be had from .6 - .8bar?

One closing question. I live in Utah at 7,000í feet and frequently run this car between 4,500' and 8,000í and sometime up and over the Continental Divide at 10,000í. Iíve read somewhere about an altitude compensating WUR and was wondering if I should consider this or if it doesnít matter because I am theoretically running consistent air volume via boost? Come to think of it, the last question may only be true when running on boostÖhmm..

And a final piece of information regarding the PLX system; their Kiwi wifi system is pretty slick but not perfect. I show boost and AFR in one handy iPhone screen but it cuts off if you run bluetooth for music of phone calls in the background, which is annoying. I was hoping to have an all-in unit information and entertainment unit. I replaced an AEM-Xwifi unit because I wanted both gauges in one iPhone screen. The AEM unit would run the bluetooth in the background; they just didnít have a boost gauge to integrate into the system, which is more important to me than the entertainment. Let me know if anybody wants the AEM - Iíll make you a great deal on a unit that has been used less than 500 miles.

I appreciate any input from the experts and canít say enough good things about the Pelican community, esp this 930 board.

-Chip
Old 05-28-2014, 03:08 PM
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Crotchety Old Bastard
 
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Internet diagnostics is scetchy at best but I'll take a stab at it.
First off I don't trust gadgetty crap. Get good mechanical boost and AFR gages.
Test your waste gate cracking pressure with a mity vac. If it is sloppy put a boost controller on it and set at 0.8 bar or pony up for a TiAL.
Altitude does add a layer of complexity to the situation. An altitude compensating -160 WUR from a 3.3L 965 would be a nice addition.
It sounds like your WUR bi-metalic strip electronics are shot. One fail mode is that the engine will run extremely rich when started hot after sitting for a few minutes, such as at a gas station. It acts as if the engine is going through a cold start cycle, only it is warm. The condition clears up after a couple minutes. WCP can be all over the place as the bi-metalic strip is not behaving in a consistant manner. You can test the electronics with an ohm meter. If it is bad we can rebuild it.
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Old 05-28-2014, 05:46 PM
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Great feedback, Brian, but I have to say that I like my gadgety crap; its the same PLX sensors and modules as connect to their gauges; it just sends the info to my iPhone instead of a gauge.

I will test the waste gate in the manner you suggested tomorrow.

Your description of the failed bi-metallic strip is spot-on. I previously tested the strip at 26 Ohms - is that in spec? I'll also drop you a PM/email/phone call tomorrow to discuss the virtues of the -160 WUR.
Old 05-28-2014, 08:19 PM
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i must agree with brian on this one, gadgety crap is just that. first thought was you have over complicated something that does not need to be. after all, the only real mods you have done are the fuel head and muffler.
you said some things that i have questions about.
you said you are knocking the pin, which pin? the small one or the large one with the fuel lines?
i was really interested in your AFR's until you said your afr was eventually running over 15 and th ecruise was 14.5-14.8. if your cruise is 14.5-14.8, when are you at 15+?

70-75mph and you are in or at boost. that is not good. sounds like a serious air leak, which i why i was very interested in your AFR's and i was expecting to see more in the 15's+.
i dont know what this PLX wideband sensor you are using but i hope it is reliable. does not sound like but thats just what i suspect.

.6bar? not good. pull the waste gate and regulate air down to around 15-20 psi. find out about what psi it opens. also listen for air escaping the exhaust pipe. that is a sign the valve guide is bad. not sure how to do it with a mitty vac as brian suggested unless it produces air pressure.

control pressure is low. should be 3.65. another indication you have an air leak.

i would get better readings on AFr'S. steady cruise is what i am interested in. 2500rpm, 3k rpm, but steady, for a few miles.

check the throttle switch. in fact just remove it. mine was not letting the throttle close consistantly giving me different idle RPM's.

you can also bypass the speed relay and make the car more reliable but you need to install something with a rev limiter like an MSD.

again, get rid of all that other crap. you are not making gobs of HP where you need all that stuff. sell it and buy a bigger IC.

just for your info, i too put new stock injector blocks on my car. they have been a source of air leaks since i put them on. i am now waiting on aluminum ones. i have had a lot of the same sysmptoms you have had except my AFR's were leaner, 15.5-16.7. i was expceting soemthing like that from you. kind of why i doubt your equipment.
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Old 05-29-2014, 04:07 AM
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911S - Thanks for the input. I read your posts multiple times as your issues sound similar to mine, albeit slightly different.


Here is a picture of the WUR. The 'pin' is the allen head bolt on the left side of the picture with the nut underneath it. This picture was taken prior to build, so the vacuum hoses have been replaced. Tap the pin and pressure rises, back off the pin with the nut and pressure decreases. The issue I have had is consistency; I can set it today and tomorrow it will be different.

I am showing idle AFR over 15 after a hot-stop, even though my cruise was still in the high 14's. To clarify, on initial start of the day, the car warms up, idle AFR settles to 14.5, cruise to 14.2-14.5. Turn off the car at a gas station and re-start. At this hot re-start, idle AFR drops to 12-13 and slowly climbs to over 15. Cruise AFR also increases slightly to 14.5 - 14.8. In any case, I'll try to set closer to 3.65 warm and get more AFR numbers.

Car has a Permatune system, so no speed relay or throttle valve switch as far as I can tell. I think that equipment was either not there on the Euro '85, removed with cat prior to my purchase, or removed with the Permatune prior to my purchase. Thinking about this reminds me of how much I didn't know when I bought the car and how much I still need to learn..

Your comment on boost introduction is interesting. I wouldn't think it unusual to start touching into boost at 75 mph, level ground, 7,000' MSL, and 80 degrees, with the heat and altitude being factors. You have much denser air down there in MYR, I remember well from living in CHS. When do you see boost introduction at sea level in highway cruise mode?

Regarding the w/g, I need to check my tools and see if my Mightyvac does pressure too. I'll figure out how to test it one way or another.

About the gadgets..I see many guys on this forum running PLX Devices equipment to monitor AFR and boost. I'm confident I am getting good readings.

Thanks again for the input. Will report back after I get a chance to tinker over the weekend.
Old 05-29-2014, 07:15 AM
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i did not read all of your last post because, not to be mean, but all your tests dont mean anything because you have been changing the cold control pressure adjustment.

you need to raise that pin up, then check to see if you have any adjustments on the bottom of the WUR. warm it alll up, then check and set WCP with the adjustment on the bottom if there is one. i say this next part with great reservation, you can knock the big round plunger down to lower WCP, BUT!!! that will change boost pressure too. ONLY, ONLY do that as a last resort. i played with mine but i new i was going to send it off to have it modified.
set WCP to 3.6 and try to get things working from there. use the allen on the AFM to set idle mixture.

after WCP is set, the next day, set CCP.

then run your tests again.

yea, 7000, not sure what that would do as far as when boost would come in.
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Last edited by T77911S; 05-29-2014 at 09:08 AM..
Old 05-29-2014, 08:40 AM
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I'm going to guess that your WUR is only modified for cold control pressure adjustment. BL used different hardware for his mods, that one looks similar to what we used to do.
I did not address the presence of boost when cruising down the highway due to your altitude. I have no experience with it so cannot comment but to say my engine runs ~12inHG vacuum at 70mph on flat ground.
Specs for the -112 WUR are as follows:
> Pump Delivery Rate 1500ml / 30 seconds
> System Pressure 6.2-6.4 bar
> CCP 1.2-1.6 bar @ 20įC
> WCP 3.65 +/- 0.2 bar
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Old 05-29-2014, 05:01 PM
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I have used other monitoring systems, but not PLX, so I'm not sure what their calibration procedure is.

Make sure your gage is reading a perfect 0 with the engine off. No pressure, no vacumn. If it doesn't, it needs to be calibrated. If the gage is calibrated to sea level (about 1.0 bar absolute) and you're at 7000 ft (about 0.8 bar absolute) then 0.6 bar on the gage is 0.8 bar boost.
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Old 05-30-2014, 06:50 AM
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winrice you got me to thinking. i found the site. 7k ft has a pressure of 11.3psi vs 14.7 here at sea level. i have a mech RUF gauge and it reads 0 witht he engine off. i may be wrong on this but his may read -.2bar down from 0.

i dont think that is right when you say .6bar would =.8 bar of boost, if you are talking about when the turbo is actually making pressure. i say that because the boost gauge is measuring pressure inside the intake system. think of the intake as being sealed and the turbo os pressurizing it. duuuuh i just realized why he is only getting .6 bar thanks to you.

here at sea level i have 14.7 psi HELPING the spring close the waste gate. at 7k ft, he has .2bar LESS pressure (or only 11.3 psi) trying to close the wastegate. with .2bar less pressure keeping the WG closed, it is now opening at .6 bar instead of .8.

the exhaust gas also helps to open the WG but i dont know how much it would help.

Air Pressure and Altitude above Sea Level
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Old 05-30-2014, 08:46 AM
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here is something that is REALLY far fetched.
what if a WG is put together at sea level and the top part with the spring is sealed with no vent. would it still hold 14.7psi at 7000ft making it open at .8bar? then it is opened, now it has 11.3 psi on the top and it now opens at .6bar.

if you were to run a tube from earth to outer space, would it suck all the oxygen out?

its friday, im bored and getting ready to go home.
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Old 05-30-2014, 08:53 AM
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If the gage is calibrated to sea level, it will read a negative pressure at higher altitude, let' say for this example -0.2 bar. The waste gate is a dumb device with a set spring pressure. If it's set at 0.8 bar of boost that's 0.8 bar above the atmospheric pressure where it's located. One side of the waste diaphragm opens to the atmosphere.

So in the above example, IF the gage is calibrated at sea level that's 0.8 -0.2 = 0.6 on the gage.

I live at 6400 feet, and deal with this all the time.
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Old 05-30-2014, 08:56 AM
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Quote:
Originally Posted by T77911S View Post
here is something that is REALLY far fetched.
what if a WG is put together at sea level and the top part with the spring is sealed with no vent. would it still hold 14.7psi at 7000ft making it open at .8bar? then it is opened, now it has 11.3 psi on the top and it now opens at .6bar.

if you were to run a tube from earth to outer space, would it suck all the oxygen out?

its friday, im bored and getting ready to go home.
And once that sealed waste gate volume heats up from exhaust heat and expands it might be 20+ PSI then add spring pressure and it boosts to the moon...........LOL

Funny stuff!
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Old 05-30-2014, 08:59 AM
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Your warm up, cruise and idle afr's look normal if you have a k lambda CIS (oxygen sensor)
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Old 05-30-2014, 02:31 PM
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This is very enlightening. My understanding of turbocharging and waste gates at altitude was incorrect. What I now understand is that the waste gate opens at 1 Atmosphere + what the waste gate spring is set at. At 7,000', 1 Atmosphere = .797 bar per the chart. Add the altitude adjusted atmosphere of .8 to the .8 bar spring and you have 1.6bar. The waste gate sees this as max boost; which is indicated as .6 bar on the gauge. Well, that is good news then.

Maybe I need to take a ride to the 4,500' Salt Lake valley this weekend to see if I build more boost. Should be almost .7 down there. A boost controller would be a good thing for varying altitudes.

I still need to figure out the WUR issue. On the back of mine, I just have the disk without the hole and the adjustment. Thanks for pointing out my mistake on the CCP adjustment. I'm not going to mess with that pushing the plunger in and out - I have a message in for Brian to discuss altitude compensating WUR and/or rebuild of mine. As noted: still lots to learn...
Old 05-30-2014, 03:06 PM
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Quote:
Originally Posted by aerochip View Post
This is very enlightening. My understanding of turbocharging and waste gates at altitude was incorrect. What I now understand is that the waste gate opens at 1 Atmosphere + what the waste gate spring is set at. At 7,000', 1 Atmosphere = .797 bar per the chart. Add the altitude adjusted atmosphere of .8 to the .8 bar spring and you have 1.6bar. The waste gate sees this as max boost; which is indicated as .6 bar on the gauge.
You have to be careful because it depends on how the gage is calibrated.

0 at sea level it reads 0.6 bar
0 at 7000 ft it reads 0.8 bar

Assuming your numbers above.

My Zeitronix system calibrates to 0 everytime I turn the key on. Which is fine if I stay at one altitude. Not accurate if I travel down to Denver or up to the mountains without a restart.
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Old 05-30-2014, 04:29 PM
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i dont think you can just add .8 (spring) to .8 atmosphere and come up with 1.6bar. i think more goes into it than that. for one exhaust pressure has an effect too. you also have to be careful and not get psia and psig crossed.
also, i could be wrong. this jsut seems like a logical solution to why you are only getting .6bar of boost.
a good test would be to go to lower altitude.
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Old 06-02-2014, 01:46 AM
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Boost spring tension is determined based on the differential between exhaust flow pressure pushing to open the valve and backpressure pushing to keep it shut. In stock exhaust systems back pressure can be significant causing a slight increase in boost once the back pressure is reduced. I don't think that is the issue here, just a consideration.
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Old 06-02-2014, 03:39 AM
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What fuel head/wur adjustments would you make to compensate for the elevation change? My motor was built and tuned at sea level (Bay Area). At 7,000 ft my a/f's at wot seem to be the same as sea level, 11.5 wot. I recently had a full rebuild on the K27 and was checking the a/f's. I did crank up the boost knob slightly to get up to 1.1.
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Old 06-02-2014, 05:29 AM
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my boost is .9bar with the header/muffler i have. .8bar spring tial WG.
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Old 06-02-2014, 06:21 AM
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Quote:
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i dont think you can just add .8 (spring) to .8 atmosphere and come up with 1.6bar. i think more goes into it than that. for one exhaust pressure has an effect too. you also have to be careful and not get psia and psig crossed.
That's 1.6 bar absolute pressure, you have to subtract out the atmospheric pressure. If the gage is zeroed at atmospheric pressure of 0.8 then it reads 0.8.

As others have pointed out, depending upon back pressure, exhaust design, etc, a 0.8 spring might give you 0.8 bar boost, but it might be higher or lower. You really need to make sure your gage is calibrated to zero before determining your actual boost pressure.

If everything is constant, and no changes have been made to the exhaust system, and you have the system set for 0.8 bar of boost regardless of spring, controller, etc. It's pretty consistent that the boost is 0.8 bar above atmospheric pressure, if (a big if), the turbo has the reserve capacity. As you increase altitude with the same boost pressure your pressure ratio goes up.

I ran these tests at 5200 ft, 6400 ft, 8000 ft, 10,000 ft, resetting zero on my Zeitronix at each altitude and the results were consistent.

Like Gumba, to compensate for the altitude, I run more boost where I'm at. Guys at sea level run 1 bar, I run 1.15 bar without issues with my EVC-V controller.
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Last edited by WinRice; 06-02-2014 at 08:35 AM..
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