Beezer
Member
- Messages
- 37
- Location
- South East England
Guys,
I have a Soarer v8 fitted with Rush headers. I decided to test my o2 sensors & they didn't appear to be working at all so I bought and fitted some new universal 1-wire units. After all, the original ones were over 150k miles old, so I figured it was time for replacement anyway. However, the new ones ALSO didn't appear to be working!! I checked & double checked that I was testing them properly but they still didn't appear to be putting out the voltages they were meant to!
I knew that the o2 sensors need to be hot to work but the car was up to full temperature. I decided to take the car for a quick thrash round the block to get it REALLY hot. When I got back, I quickly tested them again & this time they appeared to be working fine. However, as I stood there, the voltage tailed off to almost nothing as the car cooled.
After some research, I found some American modders who had similar issues on their cars after installing aftermarket headers. Apparently the o2 sensors were further away from the engine on a cooler part of the exhaust & hence didn't work properly. The solution, of course, is to use heated sensors instead. So, I ordered some universal 3-wire units & wired them in so that the heater circuits come on when the ignition was on.
To test their effectiveness, I connected my digital multimeter to the laptop & did a sample of the voltages whilst driving around the block (mixture of 30mph + brief 60mph section).
Without heaters:-
As you can see, without the heaters running, the o2 sensors barely ever even activated properly. I think that the ecu never even went into closed-loop mode. I think the o2 sensors just barely even registered what the ecu was doing in open-loop. Worse, as the sensors cooled, they registered weak mixture, so the ecu was injecting even more fuel - judging by the constant smell of fuel whilst in traffic.
With heaters:-
You can see here that the o2 sensors are working properly. The ecu is obviously running in closed loop mode. This reflects in the driving characteristics. The car feels MUCH more lively. Part throttle response is much better. Car is a joy to drive.
I've done this mod on friends car who also owns a 1991 Soarer with Rush headers + 1-wire o2 sensors. Here is what he has to say....
http://www.soarerworld.com/forum/showpost.php?p=239295&postcount=16
Of course, what I've found & done here is obvious really when you consider it. However, I've mentioned this here because people might not always think of checking this after they've fitted headers to their v8, especially if you've got 1-wire o2 sensors.
I have a Soarer v8 fitted with Rush headers. I decided to test my o2 sensors & they didn't appear to be working at all so I bought and fitted some new universal 1-wire units. After all, the original ones were over 150k miles old, so I figured it was time for replacement anyway. However, the new ones ALSO didn't appear to be working!! I checked & double checked that I was testing them properly but they still didn't appear to be putting out the voltages they were meant to!
I knew that the o2 sensors need to be hot to work but the car was up to full temperature. I decided to take the car for a quick thrash round the block to get it REALLY hot. When I got back, I quickly tested them again & this time they appeared to be working fine. However, as I stood there, the voltage tailed off to almost nothing as the car cooled.
After some research, I found some American modders who had similar issues on their cars after installing aftermarket headers. Apparently the o2 sensors were further away from the engine on a cooler part of the exhaust & hence didn't work properly. The solution, of course, is to use heated sensors instead. So, I ordered some universal 3-wire units & wired them in so that the heater circuits come on when the ignition was on.
To test their effectiveness, I connected my digital multimeter to the laptop & did a sample of the voltages whilst driving around the block (mixture of 30mph + brief 60mph section).
Without heaters:-
As you can see, without the heaters running, the o2 sensors barely ever even activated properly. I think that the ecu never even went into closed-loop mode. I think the o2 sensors just barely even registered what the ecu was doing in open-loop. Worse, as the sensors cooled, they registered weak mixture, so the ecu was injecting even more fuel - judging by the constant smell of fuel whilst in traffic.
With heaters:-
You can see here that the o2 sensors are working properly. The ecu is obviously running in closed loop mode. This reflects in the driving characteristics. The car feels MUCH more lively. Part throttle response is much better. Car is a joy to drive.
I've done this mod on friends car who also owns a 1991 Soarer with Rush headers + 1-wire o2 sensors. Here is what he has to say....
http://www.soarerworld.com/forum/showpost.php?p=239295&postcount=16
Of course, what I've found & done here is obvious really when you consider it. However, I've mentioned this here because people might not always think of checking this after they've fitted headers to their v8, especially if you've got 1-wire o2 sensors.