Okay, picked up this Teg a while back in trade and trying to get it smogged here in Williamson County (1 of 7 in the state that requires emissions). Was told it was a stock 91 LS, but after some looking, find out the motor/tranny is from an 89.

Found that the O2 plugs from the 91 harness were just dangling with nowhere to go. Picked up an OBD0 exhaust mani so that I could run the O2 in the stock location. Just this morning, I got to thinking about the ECU (prior to swapping manifolds), went to check and found that it's still the PR4 from the 91 LS.

My question, will the OBD1 ECU see the OBD0 O2 Sensor and will it actually work; or will the OBD1 ECU see it as running rich since the O2 location is closer to the head? Funny thing is, I have no check light, wondering if they pulled the bulb from the cluster.

 

Nobody?

It looks like they swapped the harness for the 89 motor though, as the connector/wiring for the O2 sensor is there. Will the OBD1 ECU make proper adjustments for the single wire O2 considering the position on the exhaust? If it sees it at all?

 

91 is still obd0... so why are you using an obd1 ecu?? 92 - 95 is obd1
88- 91 is obd0... there should only be one o2 sensor running to the header on obd0 engines.

and as far as the CEL goes.. when you start your car does the CEL light up upon start? just like the oil light and battery light and seat belt light? they should all light up when you turn the ignition then they will all shut off once the car starts..

 

No, that's what I'm saying, no check lights even with the absence of an O2. That's what make me wonder if they pulled the bulb from the cluster.

I guess you're right on the 91 being OBD0, thing that threw me off, the exhaust has the 02 sensor positioned rear of the motor on top of the B-pipe... like in OBD1 variants. Just doesn't make a lot of sense that I have a motor from an 89, an ecu and exhaust from a 92-95, and a body from 91. Why they wouldn't just keep the exhaust and ECU that were in the 91 and move them to the 89 long block is beyond me!

 

maybe they needed a header for some reason and grabbed on off a dc teg or something and threw it on...who knows. people that dont REALLY know what they are doing will do anything to make something work. i guess go outside to the car and turn the key all the way to on without starting it and see if the CEL comes on with the rest of the lights. if it doesnt...then there just might be a bulb missing. so then take out the cluster and find out if its blown or missing lol. then get back to me! haha

 

I guess.

But my question is, will the OBD1 PR4 ECU read the OBD0 single-wire O2 sensor correctly?

 

why would you have an obd1 ecu??? the teg is obd0 and the obd0 plugs wont plug into the obd1 computer without a jumper/conversion harness..

 

He has to keep every thing obd1 or higher bc he does emissions testing. I know in cali there is a **** load of rules reguarding emissions, so I'm going to assume he can't keep everything obd0. The only way I see him solving his problem if he convert to obd1, which of course would require underdash wiring

 

best bet would be to keep it obd0...sell..and grab something obd1 ha

 

Force trip a code (unplug a sensor) to check if your check engine light is still functioning.

 

Here's the problem I'm running into, have to get it smogged so I can register and sell this heap. I'll try to force the check light and see what I get.