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Old 04-24-16, 08:02 PM   #1
dabrown
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I bought a 95 SC300 project a year ago, just gotten it started this weekend. Only ran it for a few seconds at a time as it was having troubles getting started, not sure if because of o2. Also had no water pump pulley to run drive belt so there's that. Was very difficult to start with battery on charger but once it started it sounded really good minus exhaust leak.


I bought a pulley on ebay should be here later in the week so I can diagnose other issues further without worries of overheating.


Exhaust mani was custom made by previous owner while the car was down, its a mess but all I had, few welds at ports broke when tightening manifold down. Going to JB weld for time being. Found mani with cat and all at junkyard but they wouldn't sell it because it had a cat.


Main question is the harness only seems to have 2x 1 wire o2 sensors. Is that right? I thought upstream would be 4 wire. Could I run the car without them to work on other things or will the car not run without them?
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Old 04-25-16, 04:54 AM   #2
RXRodger
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This question should probably move to maintenance section. Why do you think its an O2 sensor? What does check engine codes tell you? There are no "upstream" O2 sensors, only one for cylinders 1-3 and the other one is 4-6 and they are only 2 wire since they are non heated for the 93 meodel. Your car is OBD1 so no pre and post O2 sensors. And the cat you mention is a precat so they should sell it to you.

Edit: Sorry, I read your post as being a 93 so scratch what I say about the O2 sensors.

Last edited by RXRodger; 04-25-16 at 07:07 PM. Reason: wrong model
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Old 04-25-16, 10:27 AM   #3
dabrown
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I should have stated in the first post, the car was in peiecea when I bought it a year ago. With parts in boxes, over the past year things went missing and have been going to junk as I figure out what's missing.

In this boxes were 2x one wire o2. One harness connector is at the loom next to distributor, it is one wire and connects to the previously mentioned o2. Another one is in the wiring that goes to the coil. Also 1 wire that fits the o2.

I'll go to the junkyard today after work and see if they will sell the Mani then. I figured they wouldn't since they say no sell of cats under any circumstances.

As it is the custom made Mani doesn't have holes for o2, I was going to drill holes and temp them in until I found a stock manifold.
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Old 04-25-16, 11:49 AM   #4
gerrb
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I will assume your 1995 SC300 is a federal edition meaning not a California edition since O2 sensors in 1995 will differ . Cali spec'ed SC300 in 1995 have 3 heated O2 sensors (3 or 4 wires)

Yours being a federal edition ... Two of your O2 sensors will be more likely one wire as you said and its body is its negative or 2 wires.. .signal and negative . You will also have a SUB O2 sensor down there under the car which is a heated O2 sensor so it will have 3 or 4 wires depending on your engine harness ...

Last edited by gerrb; 04-25-16 at 01:44 PM.
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Old 04-25-16, 04:46 PM   #5
dabrown
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Haven't seen any wires for a 4 wire o2, but also no wires for speed sensor so guessing I am missing a sub harness.

Wen to the junk yard after work and they refused to sell me the manifold, told them it was pre-cat and said it didn't matter. I won't be going there again, no other "u pull it" yards have any sc300s though. Was thinking of just jb welding the broken welds, drilling holes in the mani and putting a bolt on the inside. Either that or but a cheap header on eBay.

No $120 headers on eBay specifically for the sc300, but there is for the na supra that has the same 2 bolt flange at the rear. Any idea if this work? Or at least close enough a exhaust shop could easily/cheaply connect the two?


I am just trying to get the car running correctly so I can sell it, was a bad buy in the first place. Going to look for a cleaner sc in the future.

Last edited by dabrown; 04-25-16 at 04:57 PM.
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