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So, I bought this 91 ef si... perhaps.. 5months ago. Hoping I can make it run. It was overheating and had tags owed. I paid the tags, got a new radiator. It ran so I went to get it smogged only to find out it was state ref'd. GREAT... I took it to the state ref and it came out as a gross polluter, running rich. Black smoke (soot) comes out the exhaust. Ontop of that when I change gears from 2-> 3rd gear it bogs down and accelerates and black smoke shoots out. I checked the spark plugs and they were coated with carbon deposits real bad. It was throwing a code. 1 flash. Constant. It never stopped flashing so im assuming it was was the o2 sensor. I swapped it out with a ngk o2 sensor. The light hasn't came on again but still running rich. Same symptoms. Then these are the parts I have changed so far. Spark plugs, wires, cap and rotor, intake manifold and throttle body, tps sensor, map sensor + charcoal canister, fuel filter, fuel pressure regulator, I smoke tested it with no vacuum leaks, injectors, previous owner installed new exhaust and cat (gave me receipts), I adjusted the throttle cable, I tried my friends pm6 ecu, same outcome...
the next parts I'm going to swap out are the intake air temp sensor, fuel pump, and fuel damper. Thats the only things left to swap out.
the engine is a sohc zc 1.6L. Mpfi.
​​I've looked on the forums over and over, can't seem to find the answer to my problem..
compression test numbers
Cylinder 1- >160
Cylinder 2- >175
Cylinder 3->160-163
Cylinder 4->165
ignition timing is good as well.

 
Rep Power: 222

Compression looks a little low but not terrible. Not overheating any more?

 
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nah, it doesn't overheat at all.

 
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((Update))
the wires on the tps was flipped around and giving me 5v closed and. 05 wot
I flipped the wires and its reading .77 closed
​​​​​5vim thinking my multi meter isn't accurate.
now it doesn't bog or sputter anymore. But black smoke still comes out of the exhaust..
I tried to lower the volts from tps further but it wont let me..
Is there a way to get it to. 45 closed throttle??

 
Rep Power: 222

Aftermarket tps?

 
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Yea I don't know what the brand is. Should I buy a Denso one?
can you send me the link to an oem tps? I don't know which one it is..

 
Rep Power: 222

Denso would be the oe. I don't know if you can find it new still. Maybe you could find a complete throttle body on ebay?

 
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I have been messing around with the throttle body and I was supposed to be able to adjust the voltage range by adjusting the nut and screw on the bottom of the throttle body, the throttle cable but after I loosened everything up to reach the lowest setting of the closed throttle voltage reading. It actually went up from .68 to .88 ... I thought it was supposed to go down to .00?!?!

 
Rep Power: 222

You need a different tps, Honda's are very particular when it comes to electronics and sensors

 
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I ordered a new one, brand wve is says it supposed to be oem or better. I took off the throttle body and the throttle plate/butterfly is opened slightly. Wouldnt that be the reason why I can't reach the voltage down to .10? I do have an idl at 1.5 rpms how would I be able to adjust the plate to be completely closed? Or very slightly closed?

 
Rep Power: 222

Should be open slightly, tried cleaning the iac at all?

 
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Yes, I've cleaned the iac. Thats the first things I've done. I messed around with the throttle body and managed to get it closed. It seemed like it was stuck. I put everything back together and I was able to get the tps down to .47, I asked my lady to help me to fine tune the tps to be .48 CT and 4.50 ot but she accidentally ripped the wire from my multimeter. ( I will have to buy another one)
The smoke hasn't changed much but my car runs like a new car. The difference is time and day.
still don't know how to get rid of the black smoke tho.

 
Rep Power: 222

O2 sensor maybe?

 
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I have 3 o2 sensors at this point. I got 2 after markets and I have an ngk o2 sensor in the car right now
Imma try to pass the car smog this week and if its still a gross polluter I may just pay them to figure out whats wrong with it.

 
Rep Power: 222

Should be denso or ntk (which might be ngk?)

 
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You're correct, my car passed the pre-test smog today. So I made the appointment for the state referee. I'm assuming now that the car doesn't blow black smoke on 3rd gear like before, it passed smog since it only throws black smoke around 6-8k rpms and they only test from 15, 25 mph. 1-3 gears. I lucked out. I still don't know why it throws black smoke but I'm glad I'm finally going to pass smog now and be able to legally drive the car.
the car drives excellent despite a ghost draw which is next on the list of things to fix.
thanks for helping me out Collin.

 
Rep Power: 222

Glad it passed! Are you sure its black smoke and not blue?

 
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From what I've seen its black. Doesnt get any lighter shade than that. The same reason I didn't pass smog. Gross polluter

 
Rep Power: 222

Just wanted to make sure it wasn't oil, it would make sense at the high rpms

 
Rep Power: 366

potentially was turbo-ed and have bigger injectors, throwing out the fuel?