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Discussion Starter #1 (Edited)
So upstream O2 sensor seems to not be working properly and I also get a check engine light code saying that heater circuit short circuit, was wondering if I can go and pick up any wideband you UEGO O2 sensor and change the connector for the upstream sensor.

I found them on eBay about $70-$90 for an AEM wideband six wire just curious if I could use that and just change the connector?

The tip looks identical to what I have in my car.

Problem arose when the car would run really rich and fluctuate in big differences while idling and driving normally idling at 14.7 AFR drops down to 9.8 8F AFR...

Leading me to believe the O2 sensor is the issue.
@admin BUMP please
 

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So upstream O2 sensor seems to not be working properly and I also get a check engine light code saying that heater circuit short circuit, was wondering if I can go and pick up any wideband you UEGO O2 sensor and change the connector for the upstream sensor.

I found them on eBay about $70-$90 for an AEM wideband six wire just curious if I could use that and just change the connector?

The tip looks identical to what I have in my car.

Problem arose when the car would run really rich and fluctuate in big differences while idling and driving normally idling at 14.7 AFR drops down to 9.8 8F AFR...

Leading me to believe the O2 sensor is the issue.
If the question is, can you replace the factory wide-band air-fuel sensor with a aftermarket sensor, then it is quite likely it will not work properly. Even on a unmodified vehicle aftermarket sensors very frequently do not work properly due to different internal calibrations. If you are fighting a problem, the last thing you need is to introduce another one.

Just my opinion.
 

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Discussion Starter #3
Does my problem with richness seem like an O2 problem?
I've already tripled checked all vacuum hoses everywhere. Including the EGR valve it is not stuck open.

It's very odd cause the car sometime starts out at 14.7 right away at idle then just drops to 9.6 AFR right away running very rich.
 

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Does my problem with richness seem like an O2 problem?
I've already tripled checked all vacuum hoses everywhere. Including the EGR valve it is not stuck open.

It's very odd cause the car sometime starts out at 14.7 right away at idle then just drops to 9.6 AFR right away running very rich.
Do you want a guess? Because that's all I have without any data. If you have a fault code for the sensor heater then the heater may be faulty. (Duh.) If the sensor is not heated it will not work properly, especially when cold. If it goes dead it may give a false lean indication which leads to a rich mixture commanded when it may not need one. So, the guess is: Maybe.

This is another example of a problem that can be quickly analyzed with live data on a scan tool. Without it all you have are live guesses. Try disconnecting the air/fuel sensor completely and see what it does. It may default to fuel trimming off the rear or downstream sensor. If the mixture does not continue to jump around then there is your answer. You will set other codes but that is to be expected. If you have a piggy-back controller try disconnecting that to see what changes.
 

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Disclaimer: I am assuming that your car is otherwise stock, because you have not stated otherwise.

The stock front O2 sensor is a conventional narrow-band type. You can NOT simply replace that with a wide-band. If that is what someone has attempted to do in the past, there's your problem, go back to the conventional narrow-band front sensor. If the front O2 sensor is the standard one that came with the car ... you need a new one, simple as that.
 

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Disclaimer: I am assuming that your car is otherwise stock, because you have not stated otherwise.

The stock front O2 sensor is a conventional narrow-band type. You can NOT simply replace that with a wide-band. If that is what someone has attempted to do in the past, there's your problem, go back to the conventional narrow-band front sensor. If the front O2 sensor is the standard one that came with the car ... you need a new one, simple as that.
Not sure what your calling the front O2 sensor... In a smart the upstream O2 sensor, the one in the exhaust manifold is a wide band...
The one in the cat. is the downstream or narrow band O2 sensor...
 

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Really? For an engine with a 3 way catalyst that is not designed to operate in lean-burn mode, that is exceptionally odd.

Still, the point remains that the front O2 sensor has to be the correct one, and I wouldn't count on a generic aftermarket replacement being correct, especially if you have to change the electrical connectors in order to install it.
 

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Three ways are not designed for just lean burn apps... However, Mitsu is injecting a large mass of air into the exhaust side of the cylinder head during cold start ups also..
 

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Discussion Starter #9
Hi guys,

Okay okay here is my set up.

Yes it's turbo

SFR header.

Yes upstream is a wideband.

Wideband was blown with to much pressure. Being about 4" away from cylinder 3 and these sensors are sensitive to to much pressure.

I ended up replacing the upstream with a new OEM Bosch O2 sensor and my problems are gone no more 9.8AFR now I'm at 12.1 at cold first start ups and back up to 14.7 warmed up idling.

I've had this problem before when the upstream sensor was disconnect but in this case it wasn't the sensor just experienced way to much pressure.

I found a fault with SFR header being used on a Turbocharged engine.
The main issue here is using a NA header with the upstream and downstream bungs in there respective place sure it will work just fine for a NA smart engine but the problem lies with the upstream is much to close to cylinder #3 and the extra exhaust pressure cause of boost destroyed my sensor.

Hence why you always see these O2 sensors placed past the turbine exhaust exit not before it as SFR headers have it.

They should have developed a specific down pipe with a bung after the turbo to eliminate the O2 sensor being exposed to extra exhaust pressure.

I welded a bung to my down pipe and placed the new sensor there, then extended my factory upstream harness and connected the upstream there.
No way am I putting it back in the same location as SFR wants it, I'll just blow it out again.

"They say go turbo it'll be fun" 😬
Pain in the azz I tell you!!!
 

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What's your drive pressure ?? I've had o2 mounted in manifolds seeing over 30lbs of drive pressure with no issue? I can't see you ever herring close to that with your set up
 

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Discussion Starter #11
What's your drive pressure ?? I've had o2 mounted in manifolds seeing over 30lbs of drive pressure with no issue? I can't see you ever herring close to that with your set up

Wastegate opens at 12psi.

But just look at the other turbo cars out on the market they are all past the turbo not before it.
 

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Drive pressure is on the exhaust side not intake. It's helpful to see what the exhaust side of the turbo is seeing.
I'm guessing that if your getting 15psi on the intake side, the drive side should be the same at most. 15psi should not take out an O2.
 
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