FYI here is my WUR setting from Brian in 2015. Nothing has changed since this other than my upgraded K27 turbo last month. However I think the previous owner tuned it to be rich back in early 2000’s when he was racing.


http://forums.pelicanparts.com/uploa...1525130953.jpg

My Cold Pressure seems to be 1.4 bar at 60 degrees. Much lower then what is on Brian's WUR spec sheet. Can that change on its own?

Warm Pressure is 3.75 bar

My Enrichment Pressure seems to not change when I add .9 bar of pressure. It only drops to 3.7

Ok I think my mityvac isn't working right. The pressure didn't drop, then sometimes it would go down to 3.2 from 3.7.

I tried changing my full throttle enrichment a little and raising my warm pressure by 1/4 turn. I'll drive it tomorrow and see how the AFRs look.

To confirm, raising the warm or cold pressure will richen the mixture, lowering the pressures will lean it out?

No , other way around. A higher WUR pressure makes it harder for the airplate to move so the fuel metering piston does not dispense as much fuel for a given airflow = leaner.
Alan

You need to tweek it with the WUR gauge fitted - so you can see how much adjustment you have. To still be in spec you could go to 3.8 bar WP - which is negligible increase. But if you are seeing AFrs in 12s now at top end - that is about right. need to concentrate on the boost dump pressure and the transition point (Leask switch).
Alan

I took the car for a rip this morning, and AFR were at about 15-14 at idle cold, and going down the road at speed limit i'm leaner at 15 even a quick dip into 16, but when I get into boost it goes up to 9-10 then back down to 12 at close to WOT.

So to get things a little better I think I need to try the following:

1 - lower my Cold Pressure a touch - to enrichen my idle.
2 - lower my Full Throttle Enrichment Pressure. - I added some last night by drawing out the plate on the bottom of the WUR, set at 3 bar, I may have gone a touch too far.

OK, so the idle mixture is the aluminum post sticking up between the fuel distributor and the air plate. As seen in the link below? I'll check this tonight when home from work.

911 CIS Primer - Testing: Mixtures

Yes the long pin by the air plate housing.
But do this last. Your cold idle is too lean also.
You need to measure cold pressure from your CIS gauge - pull the plug on the WUR first and pumps on. Take note of the ambient temp approx.
Not sure if you understand this yet. If you raise the WUR pressures you lean the mixture. If you are just hitting 12 AFR at top end that is OK but you can probably go bit higher - tweek Boost WUR pressure by say 0.1-0.2 bar. That should take your boost dump pressure to around 3.2 bar? You have a Leask WUR - so this is adjustable . I have not seen one - but I think you have some adjustment screws on the base of the WUR for this. That will raise your top end AFR in to the 12s. The next challenge is to eliminate the dump into the 9/10s. The only way to do this is delay the boost dump transition - via a Leask rpm switch - set to around 4500 rpm and adjust rpm range from there. So you are close, and your WUR is already set close.
Post cold pressure - that will assist with cold idle sorting. But it looks like you can richen your idle anyway - you have lean cold and hot. Insert 3mm allen key in adjuster plunger (engine running)
, depress until feel it bottom out, and turn clockwise, then release and see AFR. 1/4 turn is a big adjustment.
Regards
Alan

Thanks Alan, as tested last night. CIS Pressure gauge hooked up, pumps running, WUR unplugged, trickle charger running.

Cold Pressure 1.4 bar at 60 degrees.

Warm Pressure is 3.75 bar (WUR plugged in)

I'll richen or lower pressure of my cold and warm pressures a little.

Your CP is slightly below spec - about 0.3 bar. (rich) But your cold idle is lean. So you should probably tweek your idle mix to a richer setting - try progressive small adjustments - preferably when engine warm. You should be able to note a happy spot where idle is even and rpms pick up by 1-200. Mine idles best around 12 -12.5. Others nearer 14.
It is the boost dump pressure you need to raise a bit - that is the Leask adjustable bit. From memory you dropped from 3.75 to 3.0 bar . That dump is a bit excessive. Raise the dump pressure by 0.2-.03 bar - around 3.3. That will have the effect of raising your top end AFR also - low to mid 12s?. Then you need the Leask delay switch. Your WUR is already close to where it needs to be - minor tweek. The main issue is the boost transition - which is the universal problem with this system - the boost dump is at 3-3500 rpm. You don't need all this fuel until after mid 4000 rpm and onwards. But they had no other way of moderating it pre electronic fuel management days. Enter Leask switch.
Cruise AFR at 15 is not unusual, but this may come down slightly with idle mix adjust.
Regards
Alan

Well I dicked it up. I changed my Warm Pressure .2 points and now my AFR in top end goes into 9 and has no power whatsoever ever. Gonna bring it back to where it was.

I also checked for any vacuum leaks and didn't seem to find any.

Something not right. Changed WP or boost pressure dump? Either way, raising it by 0.2 cannot make it run pig rich. Will be more lean. Changed WP from 3.75 to 3.95 or Boost pressure from 3.0 to 3.2? The latter should make it as good as you can go with out Leask switch.
Alan

I changed my Warm Pressure to 3.7 to 3.9 earlier tonight and after it was super rich. So I put it back down to 3.8. Also pulled the full throttle enchment out as far as it will go to be leaner. I was only about 1/16" out from where I left it last night. I'll drive it again tomorrow and see what happens.

My Boost pressure is about 3.4. I didn't do anything with it. The mityvac was acting weird. I would add .9 bar of Pressure but the gauge would hardly move maybe 1/2 a point. So I'd release the pressure and add .9 bar pressure again and it would jump down .4 points.

You got some weird s..t going on there. Things should be more consistent. Whatever the inconsistency is may have given you the weird AFR last time. But raising your WP 0.2 bar will have the effect of raising the dump pressure 0.2 also. But you still have a 0.7 bar drop - which is more than spec (manual asks for 0.5). So trying to even the dump AFRs out a bit, the better option is probably to keep the WP around the upper end of range (approx 3.7-3.8) and raise the dump pressure until you have about 0.5 drop. Then see where that gets you - that takes you into the spec range for both. But to get rid of the 9/10s on boost onset, the only way thru that is a Leask sw. You want to repeat these CIS pressure readings until you get something stable, or figure out where the instability is coming from. It will reflect itself in your AFRs also.
Regards
Alan

OK, so I took the car to work this morning and things are better at WOT it goes into as low as 10 but back to 11.5-12 so I don't think i'll mess with it much more than I have.

Maybe I can change my boost enrichment threshold. So if I understand the instructions properly, I should raise the threshold, which would mean I need to tighten the 3 screws in the bottom of the WUR.

If I adjust my idle mixture to make it leaner, does it make AFRs leaner higher in the rpm range too?

I went at lunch and was able to reach the WUR while it was plugged in, I turned the screw about 1/12 of a full rotation to raise pressure, so not very much, hopefully closer to what I had yesterday, I hope that make the drive home a little better for the AFR's.

ECU location
 

sorry Puddy, I put this in the wrong post... Duh..

Changing the idle AFR won't affect the WOT AFR - that adjustment is too small.
When you depress the idle adjust there is a hex head at the bottom that needs to engage , then turn the screw. You should be able to feel the hex head engage - it will engage at around the point you feel the airplate depress and AFRS change. I have heard of the very rare one where this contact point is stripped. In which case you will have no idle adjust - another issue. Have another try and see if the head will engage while loaded against the airplate pressure.
You are not adjusting the boost threshold - only a Leask sw can do that. What you are adjusting with the Leask adjustment on the WUR is the dump pressure. You need to narrow the gap between the WP and boost dump. That will help the big AFR drop at transition and lift your AFR slightly beyond 12. Sounds like you are just hitting 12. You can go a bit higher (I run 1 bar at 12.5). But as Brian said earlier - between 12.5-12 should be the aim.
Alan

Thanks Alan, for adjusting the idle mixture, it seems like my biggest problem is getting an allen key that I can get inside of it as I only have about 2" clearance between the plunger and the underside of my engine compartment. Maybe i'll have to cut one down.

No, a regular one has plenty clearance. Just insert the short end, not the long end. You will have at least 1-2"" clearance.
Alan

You have bags of room.
Alanhttp://forums.pelicanparts.com/uploa...1525289579.jpg

Ok just realized the Mityvac isn't helping set dump pressure. I used my air compressor set at 13 psi and I see the pressure setting is around 2 bar. Gonna raise it a couple points and see what happens. Maybe 2.5 bar?

Progress. Your dump pressure needs to come up to around 3.2 bar - if your WP is around 3.7.
You previously measured it at 3.0 bar?
Alan

Success!
 

So my enrichment pressure was set at 2 bar so I raised it to 3.4 with Warm Pressure at 3.8. Took it for a good rip and the AFRs were so much better! At idle thru WOT. At WOT they were as low as 11.5. Nice satisfying pull thru mid range and top end!

I realized the other day when I thought I was checking my enrichment pressures using the mityvac, I was using it wrong and not getting proper readings. The air compressor worked perfectly tonight. I'm so happy! The last couple days have been so stressful with a track event coming up this weekend. I was so nervous I'd screw something up and be screwed out of my track weekend! I'm celebrating with a Lagavulin and not touching a thing more til after the weekend.

I'm curious to try 3.2 enrichment pressure but maybe next week.

Cheers

Nice! Way to stick with it. It’s pretty cool that Alan can help you with this from half way around the world.
Gotta love the inter webs.

Yes it is cool and I really appreciate Alan's help along with others who've chimed in.

Now do I leave it be or try to improve upon it some more...

You are close. Butt, your car will love you more if you can tweek a bit more out of it.
The best improvement you can do tho is get a Leask sw (a few hundred $s). This will even that dump out even further.
Hard to know exactly where to tweek it now - you are close. But if you can get that 11.5 into 12s , all the better. Your dump pressure is now 3.4, 0.4 below WP. About where it should be. You could tweek it up to 3.5, but that is about as far as you would normally go. Each car/engine is a bit different tho. It is really a matter of getting the AFRs in the right range - by whatever adjustment works. Going to 3.2 dump pressure will push your AFrs lower - wrong way.
Maybe track it for the weekend and see how it settles down. But if you want to tweek it further after that, you would be pushing the WP and or the dump pressure UP by another 0.1 or 0.2. Maybe raise WP by 0.1 and dump by 0.2.
Glad you finally can see the improvement. Now treat yourself to a Leask switch. You deserve it now for perseverance.
Regards
Alan

I find my track AFRs go a bit leaner than beating down the road. Put it down to heat of battle.
So you have a comfortable safe margin to play with, without having to worry about having to adjust anything at the track. Drive like you stole it and after the w/end you will have a sense of where you need to go with it. you are in the ball park.
Alan

Thanks Again Alan, I can't find much info on the Leask RPM switch, i'd like some details about how it's installed before I consider it. If i'm spending another few hundred maybe I should get a FrankenCIS and a Megasquirt, and sell my WUR. Sounds like a project for next winter tho...

A small solenoid switch that plumbs in to the vac/boost line between the TB and WUR. Then wires run to a MSD rpm unit. This has a power and earth lead, 2 wires to the switch and one to the tach wire.
I can take a pic in a few days.nVery simple and effective. The switch mounts below the FD, the MSD box by your CDI.
Regards
Alan

So one more thing, if I want to correct a slightly rich spot mid range should I drop my Warm Pressure from 3.8 to 3.7, leave my enrichment pressure at 3.4?

I'm going to see who it goes at the track tomorrow and will attempt a tweek Sat night if needed.

Here is mine. Can’t seem to get an Allen key into it. Does mine look stock or modified? I’ve noticed my car is not as easy to start anymore. It used to fire with the flick of the key, now I have to crank it and apply some gas pedal. Maybe a idle mixture adjustment would help?
http://forums.pelicanparts.com/uploa...1525435747.jpg

If you changed the cold control pressure it may now be too lean to start properly. The cold pressure is a spec setting, set it to the low end of spec then adjust the idle mixture back where the engine runs best.

.

HI Brian, I didn't change my cold pressure, it was sitting at 1.4 when I first checked it, and I haven't touched it. Should I bump it up to 1.8 and see if it helps cold starting?

Also I plan to check residual pressure, so if I understand correctly i'll just turn my fuel pumps off after setting my CP and let it sit for about 1/2 hr, periodically checking pressure and noting the amount it drops?

So the track was fun today! Car pulled great, better than the old turbo. Has much better pull thru mid range and top end. But I think I need to tweet a little more which I'll do next week.

You prob need to remove the air filter to free the idle mix screw. It is probably jamming and not fully down. Your cold press is at low end of spec (rich end). No need to adjust. Idle mix is too lean.
The only way to tune out mid range fuel dump is Leask sw.
Alan

Hey Alan, I see in the picture your fuel head is silver, I assume stock, where mine is the euro black version which flows more, would that give mine the ability to be tuned richer than yours?

It is the version aluminum which has more flow and not the black. For some more of flow by staying with this system is to replace injectors by those of turbo3.6.

And mine is modded to 007 to flow more.
But you are not running out of fuel. You have plenty - according to your AFrs. It is all in the WUR tuning. But you cannot eliminate that mid range dump without Leask switch. It is a design limitation of the CIS system.
Alan

Thanks Alan, i'm just wrestling with thoughts about, why spend another $300+ on something I may remove in a few months if I do Franken CIS digital WUR. I think the car runs pretty good as is. But in mean time i'll tweek the pressure a touch more and see if I can get an improvement. Going hard thru the gears from a stop seems great, but from a roll it seems to bog or hesitate a little.