I'm using a Wideband to tune, so it gives me a real time air fuel ratio, it tells me how many parts air to one part fuel. When I apply vacuum, the mix richens 2-3 parts. It goes from 13 parts air without vacuum to as low as 10 parts air when vacuum is applied. I understand about how vacuum works, so I guess I don't understand how this unit will help me. I need fuel at higher rpms and under load, this wur gives me my most fuel at idle.
Maybe it's in my tuning technique. Should I NOT have the vacuum hooked up when I'm setting my mixture? Currently I'm unplugging my o2 and setting the mix.
tuned correctly at idle and as the vacuum drops during throttle opening the mixture richens.
i just need an explanation of how this works with a wur that does the opposite. i'm thinking that the wur will "richen" up the idle, so you set it with an "artificial" mix, a mix that's tricked by the wur. then when you come out of vacuum, the o2/frequency valve does the work to add extra fuel? by having more fuel at idle from the wur, your leaving enough adjustment in the frequency valve to fuel it up top? i'm killing myself here to wrap my head around this.....
on my cis turbo car the vaucm/boost signal hose was hooked to the big port on the side now think about this vacum at idle good a/f off idle (zero vacum) richens up (reduces control pressure) only as far as the thing is set for. now if tou include boost it actually pushed the diaphram and reduces control pressure even more to richen under boost ........less control pressure=more system pressure....just add vacume to the large port and it will lean at idle and richen up to its limit at wot
I pulled 20 inches of vacuum on the bigger port, didn't change the a/f ratio at all. I'm itching to pull this thing apart to see if there is a way to reverse how it changes pressure. It's not worth anything to me the way it's working right now, got nothing to loose. Gonna do some more research on how they work before.
my issue is that I'm leaning out under load. In the driveway, I can set the mixture and rev the engine fine. It I'll hold it at 4k and my a/r will stay around 12-13:1. But once I get it on the road I can't get into the throttle without it jumping up to 16-17:1.
Last edited by mr sarcastic; 07-01-2012 at 10:20 PM.
I pulled 20 inches of vacuum on the bigger port, didn't change the a/f ratio at all.
I know that some of these things have two ports for vacuum signals. It is some kind of "deceleration" function which I never bothered to look into just how it operates (I think boost systems use them and I know Audi has is on old turbo CIS setups). So what you did was going to be a suggestion from me on applying vacuum to the larger port. I think you had no response because you did not heat the bi-metal strip inside. It will stay on cold control pressure until the strip releases pressure on the spring inside. Try it again after applying 12v to the regulator for a few minutes to warm it up.
Originally Posted by mr sarcastic
. . . my issue is that I'm leaning out under load. In the driveway, I can set the mixture and rev the engine fine. It I'll hold it at 4k and my a/r will stay around 12-13:1. But once I get it on the road I can't get into the throttle without it jumping up to 16-17:1.
This is strange and I have no answer or suggestion as of yet for this kind of action. I have noticed in looking back a little you have a Lambda system. You do understand that no matter what you do for enrichment the Lambda control will always try to return the mixture to 14.7:1 up until it's maxed out. Have you altered the Lambda system or removed it or anything?
i have not removed the lambda system. my wideband o2 sensor has an analog output which i use as the factory lambda sensor. its pretty common for people to do this when they use a wideband on their cis setup. i figure keeping the lambda setup would help me richen up when i'm running lean. i'm thinking it works correctly, because it will correct my a/f ratio while i tune it in the driveway. as it idles its staying between 12.5-13:1, when i rev on it it spikes to 16-17:1 but immediately comes back down to 13:1 and stays there. i assume its the lambda system correcting the mixture, but its maxing out once i need lots of fuel under load.
i'm going to pull my wur and take a good look at it. i think the larger port, which is meant for atmospheric will work, but i have a sneaky feeling its clogged or has a plug in it. i found a cut away of a wur like mine on google and it shows the diaphragm in the middle of the 2 ports. pulling vacuum from the bottom port would pull the diaphragm down, enriching the mix. pulling vacuum from the top will pull it up, leaning it out. i want that, tune it at idle with the wur making the mix lean, once i come out of vacuum it'll richen.
i also found that my wur has a set screw on the bottom side of the unit, used to adjust its operation. i was pscyhed to see that, but i'm not gonna touch it yet.
I didn't get around to putting together a pressure gauge, my father in-law is on the hunt for the right fittings. But I did take apart the wur and cleaned it out. It was a little cruddy, nothing crazy. There was a huge spring on the backside of the vacuum disphram. It looks like its meant to max it out at lean, and when vacuum was applied to the bottom nipple it enrichens. I removed that spring, there's a smaller spring on the top side that keeps it rich, but now when I apply vacuum to the top port it leans it out.
So, at idle I set the mix to 11:1, kinda rich but I expect to have that if I want to be good in the higher rpm's. It's still lean at 1/2 or 3/4 throttle under load, around 15:1. But, as soon as I open the throttle completely it drops down to 12-13:1, and it pulls hard. I haven't revved it past 5k, but the a/f stayed steady all the way there. It feels real strong all the way from 1500-5000k with the gas mashed. My next thought is to get after that set scrrew at the bottom of the wur. I'm gonna back it off a touch so it starts to enrichen a little earlier. Hopefully that'll fix my mid throttle leaning issue.... I dont see myself highway driving the way its tuned right now.
So I got the car registered and inspected, fixed a few leaks, tuned it a bit more... Got it close to where I want it, still a little lean past 5500. So out of curiosity I hooked up a rpm switch I had kicking around to the fifth injector. Set it at 4000k, and reved it in the garage to test it. It's way too much fuel, pretty much chokes it out. It sputters and bog's down.... It might be different once under load, but probably not gonna be worth it. I put a toggle switch on it so I can tum it off and on to see the difference.