AFM spring tension vs output voltage
#16
Rennlist Member
Ok ok.. I know you guys are right
Started looking at WB02s. Um... seems you can buy separate sensors and gauges (at $200+ USD EACH) or kits which appear significantly cheaper (ex $250 USD for both gauge and sensor: https://www.aemelectronics.com/produ...uge#buy-direct )
I guess I'm asking what is a good yet relatively inexpensive setup? I'm looking for an analog gauge for a stock-like look. Odd: I can't seem to find a VDO stock-style afr gauge. Don't they make them?
Started looking at WB02s. Um... seems you can buy separate sensors and gauges (at $200+ USD EACH) or kits which appear significantly cheaper (ex $250 USD for both gauge and sensor: https://www.aemelectronics.com/produ...uge#buy-direct )
I guess I'm asking what is a good yet relatively inexpensive setup? I'm looking for an analog gauge for a stock-like look. Odd: I can't seem to find a VDO stock-style afr gauge. Don't they make them?
#17
Drifting
Thread Starter
I see your point re: gauge type. You're right: I could just hide it and I'd probably prefer that. I actually found one that transmits to the cell phone; maybe that's the best for me.
In the meantime, tell me more how to use my little 'scope to check for closed-loop
In the meantime, tell me more how to use my little 'scope to check for closed-loop
#18
Drifting
Thread Starter
Wait--I think I know: hook it up to the O2 sensor and see if it responds to changes in afr such as pulling a vac line or adding propane? Except I can't see how to back-probe that connector. I suppose I could take if from the DME end by back-probing through the (open) harness connector?
Is there an easier way or back-probing trick?
Is there an easier way or back-probing trick?
#19
Rennlist Member
Wait--I think I know: hook it up to the O2 sensor and see if it responds to changes in afr such as pulling a vac line or adding propane? Except I can't see how to back-probe that connector. I suppose I could take if from the DME end by back-probing through the (open) harness connector?
Is there an easier way or back-probing trick?
Is there an easier way or back-probing trick?
#20
Drifting
Thread Starter
"I'd probably tap the signal at the barrel connector..." - this is the part I'm stuck on! How do you tap into that connector without damaging it?
The rest I get. PS.. If I pull the connector and check pin voltage with a digital voltmeter, I get steady .9v at idle. Revving causes some changes then back to .9v.
I realize it's not ideal but... doesn't that pin's voltage indicate what the DME sees? Shouldn't it be around .45v --average--?
The rest I get. PS.. If I pull the connector and check pin voltage with a digital voltmeter, I get steady .9v at idle. Revving causes some changes then back to .9v.
I realize it's not ideal but... doesn't that pin's voltage indicate what the DME sees? Shouldn't it be around .45v --average--?
#21
Rennlist Member
If the jumper idea isn't clear, here's a picture I borrowed from a Pelican thread to give you the basic idea...
"I'd probably tap the signal at the barrel connector..." - this is the part I'm stuck on! How do you tap into that connector without damaging it?
The rest I get. PS.. If I pull the connector and check pin voltage with a digital voltmeter, I get steady .9v at idle. Revving causes some changes then back to .9v.
I realize it's not ideal but... doesn't that pin's voltage indicate what the DME sees? Shouldn't it be around .45v --average--?
The rest I get. PS.. If I pull the connector and check pin voltage with a digital voltmeter, I get steady .9v at idle. Revving causes some changes then back to .9v.
I realize it's not ideal but... doesn't that pin's voltage indicate what the DME sees? Shouldn't it be around .45v --average--?
#22
Drifting
Thread Starter
Got it! I'll be taking the signal with the connector disconnected but the signal pin hooked up with a jumper. I'm assuming the other two connections don't need to be connected--they are for the heater only then?
This should be easy... except I'll be viewing the scope under the hood, not while driving, which is fine with me as long as I can get enough info, perhaps while raising the rpm a bit to about 2500 or so. I read somewhere that is the speed for testiing.
I'm gonna make up a connector tomorrow!
This should be easy... except I'll be viewing the scope under the hood, not while driving, which is fine with me as long as I can get enough info, perhaps while raising the rpm a bit to about 2500 or so. I read somewhere that is the speed for testiing.
I'm gonna make up a connector tomorrow!
#23
Rennlist Member
I'd hook up all three wires. A cold O2 sensor is an inaccurate O2 sensor. Also, I'd take a co-pilot along and drive it on the road, with the scope on your lap. Reving it in the garage puts surprisingly little load on the motor -- barely more than idle really -- at least in terms of the 0-5v sweep of the AFM.
#24
Drifting
Thread Starter
Ok... but how do I get the wires into the passenger compartment from the engine bay? Perhaps laughable, but I don't see how with all the tight seals between engine & hood!
#25
Drifting
Thread Starter
#26
Three Wheelin'
If you are brave, you can pull out the massive rubber grommet for the DME wiring harness and run the wires through there. That is what I have been doing with the extra sensor and power wires for my VEMS ECU. If the installation becomes permanent, you can cut a slit in one side of the grommet and run the extra wires through there. Then make sure you lube up the grommet with silicone grease or similar to give yourself a fighting chance of getting it back in!
#27
Rennlist Member
For testing my various Wile E. Coyote projects, I have a long history of running wires out the engine bay at the base of the windshield and into the cabin through a cracked window. Easy-Peasy. The weather-stripping on top of the inner firewall is soft and covers a big gap, so running a wire or two over it and closing the hood fully isn't an issue at all.
#28
Drifting
Thread Starter
I made my own version of the testing wires. Wish I had the actual pins; the Molex .062 are only good for the holes (using the female .062--took me a while to figure that out). The .062 males are too small. The female doesn't fit on the O2 plug male pin. The next size up .093 are too big.
I mangled a few and ended up with having to use my last one backwards.. don't ask
I suppose the originals are some older metric sizes and not readily available at the local electronics store
I just have to wrap the ends with heat shrink. I would imagine I only have to take the signal off that one pin ie. the one wire I'll run into the passenger area? That is, I won't have to connect the 'scope ground anywhere, correct?
I also made a 9-volt adapter plug for the 'scope.... now to figure out where to place all that so I can view while driving. This is no simple setup..
I mangled a few and ended up with having to use my last one backwards.. don't ask
I suppose the originals are some older metric sizes and not readily available at the local electronics store
I just have to wrap the ends with heat shrink. I would imagine I only have to take the signal off that one pin ie. the one wire I'll run into the passenger area? That is, I won't have to connect the 'scope ground anywhere, correct?
I also made a 9-volt adapter plug for the 'scope.... now to figure out where to place all that so I can view while driving. This is no simple setup..
#29
Rennlist Member
Looks good enough -- you aren't wiring up a mars rover after all. The scope needs a ground signal to work, but any solid chassis ground should be good enough to see if it's dithering around its closed-loop point. Given the small voltages, slight resistances to ground can throw off the voltage reading a bit, but you aren't really looking to confirm specific voltages, just that it is bouncing above and below something in the neighborhood of .45v.
#30
Drifting
Thread Starter
I see... that's two wires running inside then, unless there's a good ground point near the front seat. Wait, maybe I should look under that seat....