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Different Voltage Readings To ECU After 30min Disconect
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Handy Offline
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Exclamation Different Voltage Readings To ECU After 30min Disconect
Hello All, I have a 1990 Geo Metro XFI with a new rebuilt motor and new 0/2. It has a 1.0 liter motor with one single wire upstream 0/2. It is Fuel injected Throttle body. The EFIE is attached right next to the 0/2 and finding the wire was a snap as I rebuilt the motor and replaced the 0/2 myself. All Gaskets are new in the exhaust. All grounds on chassis are ground down and cleaned. I have installed the Basic EFIE as per instructions with solder and shrink wrap. The EFIE is in a new outdoor Electric Box with cover in the engine compartment close to the 0/2 line insulated and attached with velcro. I have a home built HHO Generator that puts out 1/2 liter per minute doing a water bottle displacement test. I have done a poor mans quality test and the stuff burns nice (Pops very Loud) ! It's using KOH for an electrolight and pulling about 10 to 15 amp depending on temp. All wire is Stranded 10 gauge with relay and fuses (except for the EFIE). All leaks have been checked with soap and water. After reading the check list page I added a small hose inside my air filter housing so that it goes directly into the throttle area. I have the EFIE now set at .250. I have gone through your page that talks about things to do and have checked and double checked and fixed some of the things that were mentioned. So this brings me to my question.

When I first installed the EFIE and I would test the output to the ECU with a good ground it would still give the ECU a lower value between .200 to .600. After going through the list I saw that I needed to disconnect the Battery and so today I did that for almost an hour. After hooking the battery up again I did a new test. I have a switch inside so that I can turn the HHO on or off and when I'm sitting in the seat it shows a reading of .200 to .750 with the EFIE & HHO ON, and that is pretty much where I wanted it. But the weird thing is that now when I turn off the EFIE & HHO the voltage goes down even to the negative as it cycles, with a high of about .400. My understanding was that the 0/2 chose the voltage, not the ECU. But it is clear that After the Reset of the ECU that it now thinks the normal voltage set is when I have the EFIE & HHO on instead of off. Can Anyone explain this to me? Mind you I'm not complaining but I guess I still need some schooling on this. Any help would be Great.

Thank you Handy
                   
Here are a few more Pictures.

Handy                    
(This post was last modified: 06-07-2011 12:33 PM by Handy.)
06-07-2011 12:10 PM
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mike Offline
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RE: Different Voltage Readings To ECU After 30min Disconect
I understood all of your post, except the most important part. Where exactly are you measuring where you saw the negative voltage?

The o2 sensors "choosed the voltage" as you say. It's actually a little chemical battery. It generates a voltage signal based on oxygen and hydrocarbon content in the exhaust. That value will always be between 0 and 1 volt ( when compared to it's ground wire ). Your measurements must be picking up some king of ground fluctuation because the o2 sensor doesn't put out negative voltage. Only positive voltage.

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06-07-2011 12:41 PM
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Handy Offline
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RE: Different Voltage Readings To ECU After 30min Disconect
(06-07-2011 12:41 PM)mike Wrote:  I understood all of your post, except the most important part. Where exactly are you measuring where you saw the negative voltage?

The o2 sensors "choosed the voltage" as you say. It's actually a little chemical battery. It generates a voltage signal based on oxygen and hydrocarbon content in the exhaust. That value will always be between 0 and 1 volt ( when compared to it's ground wire ). Your measurements must be picking up some king of ground fluctuation because the o2 sensor doesn't put out negative voltage. Only positive voltage.

My meter ground was attached to the ground on the battery and the positive was attached to the white output wire to the ECU. When I flipped the switch to turn off the HHO & EFIE the fluctuation dropped as it should but two times it showed a negative symbol on the low side as it was fluctuating between high and low. Does that make better sense? Let me know. Now my understanding is that it could just be my meter and that may be the case. Thank you for clearing up my misunderstanding on the o2 voltage. Now with that understanding should I not always be able to see the voltage difference going to the ECU that the EFIE is adding? So say I'm adding .250 with the EFIE, should I not see that same amount added to the output going to the ECU? Correct me if I'm wrong. It seems that it does not add as much as the EFIE is set at.

Handy
06-08-2011 03:20 PM
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koya1893 Offline
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RE: Different Voltage Readings To ECU After 30min Disconect
I would like to comment your system. You are playing with a bomb with a wet cell, since your engine is not all that big you can build a small efficient cell that produce enough for your car.

When you say adding mv, are you doing that with the rear sensor? Because that's the only sensor you would add to to fool the ECU. The front you start out by decreasing the signal. Also, you only see what you add or take away, you will not see the total voltage: 450+.250 = .700 You will not see that final number just what you dial in to increase or decrease.

One thing you might want to consider for the front, I know 350mv was suggested in the instruction. However, lately on several imports that's been too lean already and you will get a code PO133, which is "slow to response" on the front sensor. The only way I was able to stop that was start higher (385mv) which eleminated the CEL and gain was noticed.

You have a single wire you should be able to combat that easy. so don't read too much into it. Cut the wire route it to the EFIE as per instruction and set initial setting.

Make sure your HHO production is enough for you eng. Look into getting a dry cell also, you will be much happier and let pain.
06-09-2011 06:16 AM
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creepyjon Offline
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RE: Different Voltage Readings To ECU After 30min Disconect
geo metros had obd1 until 1994, bastard half obd1/2 in 1995 I had one of those lovely gems, and full obd 2 in 1996. His car is obd1 and has only one o2 sensor, and will have 2 digit codes that you can easily get with a paper clip in the diagnostic port under the dash. Why on earth can't every car be that easy to get codes out of!

Biggest problem is loss of hp, you have NONE to spare, and the alternator is a pathetic 55 amps at most. I upgraded my stero in the metro I used to have and my lights got dim at idle, that's only an extra few amps. The hho cell will drag down you alternator, on a normal car that's not an issue but on yours it can be one very quick. Hell if you turn the ac on a geo metro it doubles the 0-60 time! Wet cells aren't bad, they use more amps and make more heat. For the amount of gas you need I don't see an issue with a wet cell. Bottom line is something is hooked up wrong in your wiring, or your multimeter is not very accurate.
06-09-2011 08:01 AM
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Handy Offline
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Big Grin RE: Different Voltage Readings To ECU After 30min Disconect
I appreciate your input but please note that I only have one o2 as I stated above. Not worried about the wet cell as it does just fine and is protected from the heat. As I stated above it's putting out 1/2 liter per minute at 12 to 13 amps and works really well. Also everything has already been installed. I was just trying to understand if I would see that voltage if the o/2 wasn't giving a voltage or if it only showed up when the o/2 was running. I don't think that is (trying to read to much into it). I'm just trying to understand what I am dealing with and how it works. But again I thank you for your input and yes I know that a wet cell is not as efficient as a dry cell but at this point I cannot afford another cell so this will work for now.

HandyBig Grin
(06-09-2011 08:01 AM)creepyjon Wrote:  geo metros had obd1 until 1994, bastard half obd1/2 in 1995 I had one of those lovely gems, and full obd 2 in 1996. His car is obd1 and has only one o2 sensor, and will have 2 digit codes that you can easily get with a paper clip in the diagnostic port under the dash. Why on earth can't every car be that easy to get codes out of!

Biggest problem is loss of hp, you have NONE to spare, and the alternator is a pathetic 55 amps at most. I upgraded my stero in the metro I used to have and my lights got dim at idle, that's only an extra few amps. The hho cell will drag down you alternator, on a normal car that's not an issue but on yours it can be one very quick. Hell if you turn the ac on a geo metro it doubles the 0-60 time! Wet cells aren't bad, they use more amps and make more heat. For the amount of gas you need I don't see an issue with a wet cell. Bottom line is something is hooked up wrong in your wiring, or your multimeter is not very accurate.

Yep, you are very right about that. Good thing is I don't have A/C so the wet cell is the only major draw. As for something being hooked up wrong, can say without a doubt that everything is hooked up correctly. I do electronics for a living and I have gone through everything 3 times step by step to see if my dyslexia popped up somewhere. Darn Brain anywayConfused So I know it's right. The funny thing is that I can get a code if I go above .375 so I know it's putting out the voltage. I just was thinking that I would be able to see the voltage if I just ran the EFIE separate from the engine running. Apparently not. That's fine. No, the meter is working great. I can see the fluctuation between high and low on the o/2 when the engine is running and it shows me the voltage the EFIE is putting out with no problems. Like I said, I just was wondering if I would see that voltage from the EFIE on the white ECU line ( and the meter blk grounded to the batt) when the engine was not running and I had just run a jumper to the EFIE. Mostly to satisfy my curiosity really. Other than that it works great and I'm pretty happy with it. Maybe someday I will get the time to build me a dry cell. Till then the wet will have to do.

Thanks for the replyBig Grin
(06-09-2011 08:01 AM)creepyjon Wrote:  geo metros had obd1 until 1994, bastard half obd1/2 in 1995 I had one of those lovely gems, and full obd 2 in 1996. His car is obd1 and has only one o2 sensor, and will have 2 digit codes that you can easily get with a paper clip in the diagnostic port under the dash. Why on earth can't every car be that easy to get codes out of!

Biggest problem is loss of hp, you have NONE to spare, and the alternator is a pathetic 55 amps at most. I upgraded my stero in the metro I used to have and my lights got dim at idle, that's only an extra few amps. The hho cell will drag down you alternator, on a normal car that's not an issue but on yours it can be one very quick. Hell if you turn the ac on a geo metro it doubles the 0-60 time! Wet cells aren't bad, they use more amps and make more heat. For the amount of gas you need I don't see an issue with a wet cell. Bottom line is something is hooked up wrong in your wiring, or your multimeter is not very accurate.

Oh, and also creepyjon I'm sure that when I was getting those readings that the meter was not giving me a accurate measure and I'm sure thats where the reading got crazy. It's a cheap meter so I would suspect thats the case. But it does alright with everything else.

Thanks Laugh
(This post was last modified: 06-09-2011 08:30 AM by Handy.)
06-09-2011 08:01 AM
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Handy Offline
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Cool RE: Different Voltage Readings To ECU After 30min Disconect
Just wanted to let you know that this problem was solved and everything is working great. After I get a long trip in I will be posting the results.

Happy Hydrogen
HandyBig GrinLaugh
06-12-2011 04:51 PM
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