95twinturbo

I'm installing a wideband Innovate LC-2 into my 1995 993 (OBD-I). I wired the narrowband emulator signal brown wire to pin 28 of the Bosch ECU (WSM wiring diagram calls it "oxygen sensor signal"). Does anybody know what I should do --if anything-- with pin 10 (WSM "oxygen sensor ground")? In the factory configuration, pin 10 is wired to the narrowband sensor ground wire, but LC-2 doesn't have such a wire. Innovate installation instructions are very vague. Thanks for the advice.

pp000830

A little background as to why?

95twinturbo

I installed the LC-2 because I need a more accurate AFR indication. Narrowband read sucks when AFR moves away from 14.7. Plus my ECU sensor heater circuit is fried and I don't want to pay $900 to have the unit overhauled.

pp000830

Since the entire purpose of the sensor it keep the mixture at 14.7 to 1 and once the exhaust gasses heat the existing sensors they light-off and give useful;data to the ECU even if the heater circuit is dead why make the change?

Am I missing something here?

Some other thoughts:
The heater circuit can be very squirrely as if any of the oxygen sensor heating elements are out of specification or one of the plugs or sockets are dirty it can appear that the ECU heater control is bad.
If you are using Durametric it is a known issue that it gives bad information on the status of the oxygen sensors, a problem Durametric is working on.

My only reason for asking is that it seems that adding complexity to a system to solve a basic problem where the fix is not street legal as it is a tampering with the OE emissions system may not be the way to go.
Hope this helps,
Andy

4X4SCHE

The LC2 manual states:

"Note: The LC-2’s ground should share the same grounding source as the device to which you are feeding the analog outputs, the easiest wait to accomplish this is to run an aux ground wire from the ground point of the LC-2 to the ground or signal ground of the device you are interfacing with."

trophy

You will find that any aircooled 911 only operates at 14.7:1 or Lambda 1 when at cruise and that's about it, even idle is a little richer. Aircooled engines run much richer that watercooled as it uses fuel to help cooling. You will find that at WOT these engines will be close to 13:0 or lower, I know for my engine, power is made WOT at 12.8:1 (Dyno Verified and tuned)

I don't have a 88 pin wiring diagram handy, you want to find the ground input there, otherwise you can use the ground lug on the body that is located close to the ecu, make sure you don't use a ground that is used by the ignition modules.

95twinturbo

pp00830 this doesn't really help. The following is outside the scope of my original post which asked a wiring question, but to be clear, engine at operating temp and idling (e.g. traffic light) the exhaust gasses are not sufficient to keep the sensor within its operating temperature, so the sensor heater doesn't just come on at engine startup, it is cycled as needed by the ECU. The ECU was inspected by shop that specializes in ECU repairs and they confirmed it's a problem with the ECU. The unit has not thrown a fault code: it's OBD-1 and does not have any fault codes for bad sensor heater as evidenced by the WSM DME diagnosis section.

95twinturbo

4x4SCHE I read the manual too. There is a big difference between the "device ground" (that would be the ECU ground) and the ECU "sensor ground". I'm not about to connect the sensor ground to the LC-2 ground (black wire) until I confirm with Innovate or somebody on this forum who's installed the LC-2 on an OBD-I 993 can confirm. FYI the 964 Motronic (and probably predecessors) has no sensor ground pin so not an issue there. Mine does.

trophy

Sorry, I miss read your initial post, for some reason I assumed you were installing this onto a 993TT.

I had installed the LC-2 with my original ecu, connected the ground to pin 10 of the 55pin ECU.

95twinturbo

Steven thanks for the feedback, sounds like your 993 and mine share the same ECU. I was able to get through to Innovate this morning and tech said if LC-2 is working when connected to battery negative, leave pin 10 alone, it's a reference voltage designed to feed a clean ground free of interference to the sensor nothing else. So far it looks like my LC-2 install is working well with just the brown wire going to pin 28 so he said to leave well enough alone.

trophy

That's perfect. I chose the ground from the ECU because I knew it would be clean. Keeping it away from any potential interference from the ignition is the most important.

I learned alot when I installed the LC-2 and the subsequent install of an aftermarket ECU in the car regarding sensor grounding.... It is possibly the most critical area when it comes to electrical connections.

95twinturbo

As an update, the Innovate sensor has been installed in my 993 for a couple of months now and I'm very happy with how it emulates the narrowband signal to the ECU. I added an Innovate AFR gauge wired to the sensor wideband output and the read is much more useful compared to the prior "all-or-none" read when I was reading off narrowband sensor..

zelrik911

Good update - I am thinking of doing this myself on my OBD-1 993 motor.
I presume you used a Bosch WB Oxy sensor; can you recall which model it was? I note the Innovate doco states:

"The LC-2 is multi sensor compatible with the Bosch LSU 4.2 and 4.9 sensors."
Was yours one of these?

95twinturbo

I'm using the LSU 4.9 sensor.

Lorenfb

It's unfortunate that you went thru all that effort, when your DME ECU could have been repaired for about 1/3 the cost of the estimate you received.
Furthermore, you are aware that from a functional standpoint, that the O2 input on the '95 Bosch ECU just utilizes input voltages greater or less
than .50 volts to control the mixture, i.e. there's no benefit from using a wide band O2 sensor.