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]

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.

[ManpreetS512]

Thank you for the quick response.

I thought of changing the downpipe to a 3" but the current one is 2.5" cast iron and the muffler shop did not want to mess with it. They ensured me that 2.5" would be good enough for my setup but I agree with your statement that 3" would've been best for proper air flow.

Hopefully that is not the limiting factor here. I'll start with connecting the O2 sensor and see what happens.

Thanks again!

[slavie]

You have an OBD1 system and I don't know whether it has closed loop monitoring (the one where you rely on fuel trims off O2 sensor), but I'd save reconnect the upstream o2 sensor, the one in the DP before any catalytic converters.

2.5 exhaust is plenty for a stock engine. Definitely not an issue in your case.

Check fuel pressure to make sure the FPR is working. If the pressure is too high, it will be dumping too much fuel in. Also make sure the reference vacuum lines are connected to the FPR.
You may be dealing with leaky injectors if they sat with bad gas for 10 years. May be time to have them cleaned.

Finally, are you sure the smoke is black and not blue-ish as in burning oil?

[ManpreetS512]

You have an OBD1 system and I don't know whether it has closed loop monitoring (the one where you rely on fuel trims off O2 sensor), but I'd save reconnect the upstream o2 sensor, the one in the DP before any catalytic converters.

2.5 exhaust is plenty for a stock engine. Definitely not an issue in your case.

Check fuel pressure to make sure the FPR is working. If the pressure is too high, it will be dumping too much fuel in. Also make sure the reference vacuum lines are connected to the FPR.
You may be dealing with leaky injectors if they sat with bad gas for 10 years. May be time to have them cleaned.

Finally, are you sure the smoke is black and not blue-ish as in burning oil?

You are correct, it is OBD1 system. The O2 sensor before the CAT is connected. Also, the muffler shop was *slightly* mistaken. They did not test drive the car and told me that when they first installed the exhaust they saw a puff of black smoke but did not pay attention to if it was consistent or not. They then cranked it back up to park it. When I went to check the car myself, there was absolutely no black smoke at all. There was some blue-ish smoke if I hit the throttle but that could be because there is no cat. So I think the fuel problem is good.

The problem now is that the car has trouble going over 3000 rpm. It idles fine (around 1000 - 1100 rpm) and sometimes in first I can get it up to 4000 rpm but when I am drive it gives a slight shake around 3000 rpm and does not let me pass it. I did reset the ECU and when I did that, I think the cylinder flooded. I say this because it was cranking fine and once the ECU reset it would not crank anymore (battery was fine). The next day, it cranked and started up right away but still had the same problem (I think the extra fuel evaporated).

I was looking online and I found a few things that mentioned this issue could relate to timing. I don't have the proper tools to check the degree but I read that it should be at 10 degrees when the spark plugs ignite. It does sound like it is misfiring when I get it up to 3000 rpms though. One of the problems I have is there are no gauges for fuel pressure or air/fuel mix so it is hard to isolate where the issue is.

Does anyone have any suggestions for this or have ran into this issue?

[slavie]

Replace the spark plugs. Weak spark could be causing misfires and incomplete burn thus running rich. Setting the correct timing should be high on your list if you have reasons to believe it is incorrect.

Weak spark haunted me for several days once with a no-start on my ST185 motor. All plugs would light outside the cylinder but were too weak to ignite air-fuel mixture causing the engine to run on 1 cylinder (WOT needed to keep it from dying). $10 for new NGK copper plug set and the car starts as new.

[ManpreetS512]

Replace the spark plugs. Weak spark could be causing misfires and incomplete burn thus running rich. Setting the correct timing should be high on your list if you have reasons to believe it is incorrect.

Weak spark haunted me for several days once with a no-start on my ST185 motor. All plugs would light outside the cylinder but were too weak to ignite air-fuel mixture causing the engine to run on 1 cylinder (WOT needed to keep it from dying). $10 for new NGK copper plug set and the car starts as new.

I know my spark plugs are going bad, I just figured that replacing them alone wouldn’t solve the root cause so I waited to do so. I’ll go ahead and replace them. I bought the NGK iridium ones for like $30 a set. Not bad imo.

Do you know what gap you set on them when you installed?

The only thing that led me to believe that the timing may be off is my research when looking up this issue on various forums. I called the mechanic shop that resurrected this car yesterday and they assured me that my compression and timing was good before I put the exhaust on.

[slavie]

It's smaller than non-turbo cars, but don't remember exactly what it was off the top of my hat. 23 or 34 thou, something like that. Do yourself a favor though and search for factory manual for the GT4 - readily available online, has answers on how to put just about anything on these cars.

[bloodMoney]

I just replaced the plugs in my alltrac and gapped them at .028"

[ManpreetS512]

Thank you for the responses.

I replaced the spark plugs last night and still have the same issue. I test drove it again a few times and on the 3rd or 4th start up, the cylinder had flooded again as well.

My next item to troubleshoot is the vacuum system. I’m going to see if I can locate all of the vacuum lines and replace myself. I have the JDM ST185 and from what I read this version doesn’t have an EGR. Can anyone confirm this? I think the US all Trac gt4 does have it though which is confusing to me. I cannot seem to find a manual specially for the JDM version nor can I locate the EGR valve or lines on my set up. I also don’t see a map sensor or place to plug one in either.

If anyone here has experience with their vacuum system and can provide any input or pointers, please let me know. I’ll try and post a pic of my setup as well so you all can see what I’m working with.

[NgoFcukinWay]

Flooded with fuel? Maybe you have an injector or 2 that are stuck open.

[bloodMoney]

Mine is swapped with a JDM engine, and it is true that there is no EGR.

On the intake manifold, there will just be a large flat spot with nothing mounted to it. You can't miss it, it looks out of place. Not having it actually cleans up some of the vacuum lines, so there's less to worry about.

How do you know that the engine is flooded?

[ManpreetS512]

NgoFcukinWay - yes, it is flooded with fuel. I would suspect that if the fuel injectors were open then I’d have problems every time I try to crank. But the problem i have is once the car has been running and then I try to start it again. Also the car runs fine until 3000 rpms and that’s when it starts shuttering and doesn’t let me pass that threshold.

bloodMoney - Thank you for confirming no EGR with the JDM version. I’ll try and look today for the flat spot that you mentioned. Assuming the map sensor will be there? Or were you just mentioning the spot where the EGR is removed? I’m sure that the engine is flooded because the car cranks fine when it has been sitting for a while. Once I drive it and turn it off, it doesn’t start right away. Before replacing the spark plugs, I could also start the car by cranking and giving it fuel.

I still need to post some pics on here so you all can have a visual of what I’m working with. I’ll hopefully get that uploaded today or tomorrow.

[ManpreetS512]

Sorry for the delay in this but here are the pics I mentioned.

Note:
1.) The metal shield on my innercooler was intentionally taken off temporarily to make it easier for me to get to the spark plugs. I'll put back on once my performance issues are resolved.
2.) Yes, the battery is sitting on my motor mount with no support. I know this is no good but we had to re-situate the air intake when the radiator was put in for space. I would ideally like to move the battery to where the air intake is now and vice-versa but we had to custom rig what we have now and it was not easy to find the correct elbows that we needed for the intake to be moved to where I want.
3.) My engine bay needs some serious TLC and detailing - Please don't judge me.

I'm trying to figure out where all of the smaller vacuum lines are located so I can check them. I see the 2 main ones that come from the engine to the air intake - is this normal on your setups?

I also took out my ECU to see if there were any issues with it and it appears to be fine. Posted pics of that as well.

Shared Album: https://photos.app.goo.gl/AbCJcHxSuyrND7Zd6

[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.

[slavie]

Looking purty. You even retained the AC! You could re-locate the intake to the stock location like the ST205 has, but that ST185 AFM is going to be massively in the way of you doing that.

There isn't an easy way to hook up the wideband, as they require a controller that your stock ECU does not have. You'll need to take a look at the sensor you have to figure out PN or the manufacturer, and get their controller package.

However, given that you don't know the history of the sensor (they don't last forever) and the fact that it's probably older then dinosaur fart, your best bet is to junk it and get a whole new package. There are some new solutions on the market these days that integrate AFR and EBC (electronic boost control) and would make your life overall simpler.

[ManpreetS512]

Looking purty. You even retained the AC! You could re-locate the intake to the stock location like the ST205 has, but that ST185 AFM is going to be massively in the way of you doing that.

Thank you! Yes, AC works but I don't use it since the car sounds like it will die in idle with it on. During idle, RPMs will fluctuate (even with no AC) which I think is a separate issue but may be related. I am also worried that my AFM may be bad and unfortunately, I cannot even read the part number on it to see how much another one will cost

There isn't an easy way to hook up the wideband, as they require a controller that your stock ECU does not have. You'll need to take a look at the sensor you have to figure out PN or the manufacturer, and get their controller package.

However, given that you don't know the history of the sensor (they don't last forever) and the fact that it's probably older then dinosaur fart, your best bet is to junk it and get a whole new package. There are some new solutions on the market these days that integrate AFR and EBC (electronic boost control) and would make your life overall simpler.

This o2 sensor is clearly rusted over. I highly doubt it still works and it is older than dinosaur fart . Do you have a brand or certain system in mind. I wouldn't mind getting one if it wont break the bank.

[slavie]

Innovate SCG-1 is one I've been looking at myself. There are competing offers from other makers as well I'm sure, but Innovate guys seem to be near the top right now from what I've read.
https://www.innovatemotorsports.com/products/scg1.php

The thing also has an analog out to feed back to the stock computer in lieu of the stock O2 sensor, but I don't know how easy it is in practice to emulate an output the stock ECU will be happy with.
I know that there was also an offering from AEM at the time Gen2 3SGTE was in it's prime that was pre-programmed to feed the "correct" signal out to the stock ECU, but I doubt there is a solution that does that AND has EBC functionality.

[NgoFcukinWay]

that wideband may have been used to plug up a temporary hole or it was used at some point in its life. Not entirely necessary for your application at the moment unless you go standalone to delete the factory narrowband o2 sensor to run strictly off of the aftermarket wide band.

Do you have the factory o2 sensor in place? If you don't have one, wire one in. They're usually a 3-pin or a 4-pin connector depending on how the harness was done.

Also see if you can borrow another AFM and test that as well to see if it's faulty.

Occasionally, you'll get codes hiding even when the CEL isn't on.