ST185 swap fuel/air ratio, Getting black smoke from my exhaust Options

[ManpreetS512]

Hey 6GC Members,

I hope you all are doing well.

My name is Manu and I am new to this site, so I apologize if this has been discussed else where and I couldn't find it. If there is already a thread, please point me to it and i'll look it over.

I have a 97 Celica GT with a JDM ST185 swap with JDM ECU. The engine is stock with no modifications thus far. This car was given to me as it sat in a garage for 10 years without ever running. Needless to say, I've gone through a lot of different issues starting with replacing fuel lines, gas tank, fuel pump, cold start injector, etc. to get the motor to crank up again.

The car did not have an exhaust since the previous owner didn't purchase one and mainly wanted to get the swap to run. When we got the motor to crank (finally), it was running really rich. So I took it to a muffler shop and had them add a catback exhaust from the downpipe back with turbo muffler and all 2.5" piping.

Now the car has black smoke coming from the exhaust when it cranks up, so I am assuming that the engine is still getting too much fuel. So friends of mine recommended that I may need a ECU tune but in order to do that I would have to purchase an expensive standalone ECU and then take it to a certified shop and have them tune it.

Before going down that route I wanted to post here to see if anyone has seen similar issues with their swap or this engine in particular? I was also wondering if anyone here knows if the O2 sensor on the downpipe is needed for the ECU to function properly? I ask because when the car was at the muffler shop, I saw the O2 sensor on the downpipe and it was not only rusted but the wire connected to it had been snipped clean - so that O2 sensor in not connected to the wiring harness at all. I also get no check engine light which is odd.

I'm thinking that the O2 sensor on the downpipe does need connection to wiring harness and someone may have snipped it to get the car running before since it had no exhaust. I am not an expert by any means and am learning as I go.

Please let me know if anyone can provide any advice.

Thanks,


Manu

[NgoFcukinWay]

did you pull codes? Jump pins E1 and TE1 in the diagnostic box. Google Toyota OBD1 codes and it'll tell you exactly how to do it.

[ManpreetS512]

reconnect the o2 sensor first and go from there. You can also pair it up with a wideband sensor like an AEM, FJO, Innovative, etc to see what your readings are.

Would've been ideal to do a 3" exhaust piping to let the system breathe as much as possible.

NgoFcukinWay - I just re-read this and noticed that I may have confused everyone on the thread. The O2 sensor that I mentioned wasn't connected was a wide-band one. The one on the top of the downpipe (single wire) is connected to ECU. Do you have a recommendation on how to connect the wideband sensor on the bottom of the downpipe to a reader (and what reader)?

did you pull codes? Jump pins E1 and TE1 in the diagnostic box. Google Toyota OBD1 codes and it'll tell you exactly how to do it.

I have not pulled codes yet but this is something I feel like I can do pretty easily. I'll keep you posted on what I find with that. I didn't think about pulling any codes since I do not see a check engine light when I drive. So I thought maybe everything is 'fine' according to ECU.