Failed smog test

[Dopamine]

I failed in hydro carbons and CO.
HC
Test Max GP Meas
15mph 106 281 268
25mph 81 231 244

CO
Test Max GP Meas
15mph .70 2.20 5.69
25mph .57 2.07 6.04

co2
Test Meas
15mph 11.3
25mph 11.1

o2
Test Meas
15mph 0.0
25mph 0.0

no
Test Max GP Meas
15mph 762 1949 196
25mph 701 1749 182


I just purchased this car recently and I took it to a local test only station to get it tested. My car failed smog and tech said it might be the o2 sensor(s). Besides the o2 sensor(s) what are other possible causes? It has an aftermarket intake, aftermarket exhaust, and I'm not sure if the maf is a stock U.S. version; it says Fuji Electronic made in Japan.

Another thing I noticed is that my car backfires rarely when I'm not pressing the gas on the road. However a friend of mine says this is normal for Supras?

Anyways I'm about to take the 2nd retest sometime next week and I just want a few pointers on what I should do to hopefully pass the next try. Is there anything I should do in advance? Such as getting an oil change, new spark plugs, etc?

 

[3p141592654]

Need other gases to help. O2 CO2, post em up!

 

[Dopamine]

Sorry. Added those up now.

 

[3p141592654]

Car is running very rich (A/F 12.2:1).

Clearly not in closed loop fuel control. Could be a bunch of things.

I'd start with checking a few easy things like the thermostat and ECU coolant temp sensor. If the thermo is stuck open it will be in cold enrichment. Does your temp gauge read low all the time? With a bad ECU coolant temp sensor the ECU can get stuck in warm up mode as well.

The Supra was at the time Toyota's most expensive flagship car. Do you think it would be normal and acceptable for it to backfire? Tell your friend to stop being an idiot.

 

[jdub]

Check ECU codes.

The cold start injector could be mechanically stuck open as well.

 

[Dopamine]

Car is running very rich (A/F 12.2:1).

Clearly not in closed loop fuel control. Could be a bunch of things.

I'd start with checking a few easy things like the thermostat and ECU coolant temp sensor. If the thermo is stuck open it will be in cold enrichment. Does your temp gauge read low all the time? With a bad ECU coolant temp sensor the ECU can get stuck in warm up mode as well.

The Supra was at the time Toyota's most expensive flagship car. Do you think it would be normal and acceptable for it to backfire? Tell your friend to stop being an idiot.

I haven't paid much attention to my temperature gauge, but I do know that it goes towards the middle while warming up my car. Btw, how low are we talking about? Because at operating temperature, my car goes near the center, but it's not quite there. If anything, it's a bit more towards cold than hot I guess.

Also a bit off topic, if the speedo is not functioning, does it somehow make a squeaking noise? Not sure what's causing it, but whenever I drive my car there's some loud squeaking noise, and the speed of the sound increases as I go faster and decreases as I slow down.

I'm going to check out all those problems sometime today and hopefully find an answer as to why my car is running rich. Thanks for the the help 3p14 and jdub.

 

[7mgte1988]

Is this a Turbo or Non Turbo cuz usaully a larger exhust system may make u run richer but iam not sure how rich... And does it have cats??

 

[Dopamine]

Yes it has cats and is turbo (ct-26). So I found out today that I need o2 sensors, vss, my intake hose has a crack at the end which might be giving the maf sensor false readings, and one of the hoses around the egr was disconnected. Also my car was originally automatic and it was converted to a 5-speed manual so it still has the automatic ecu. It threw off some weird codes that is only valid on automatic transmissions lol. Finally, the maf sensor is the one from a Japanese engine.

So I might also have to change out the maf sensor for the smog test, but is it fine with the stock Japanese automatic ecu?

As for the thermostat, it seems to be working fine. The temperature seems to be reading fine. The top hose is warm and the bottom hose is cool. And I found that my spark plugs had a lot of carbon build up and I cleaned it off with a wire brush.

So what I'm going to do is change out the o2 sensors, vehicle speed sensor, maf sensor, intake hose, thermostat (just incase), spark plugs, and some other parts non related to smog.

 

[7mgte1988]

Iam surprised it works with the Auto ECU..Yea I think all the MAF sensor are FIJI or Fuji made including the LS400 are the same but yea if its the MAF malfunctioning your car would idle weird...Yea the o2 sensor might be the couse..hows your MPG??

 

[jdub]

Is this a Turbo or Non Turbo cuz usaully a larger exhust system may make u run richer but iam not sure how rich... And does it have cats??

Did a little fairy tell you this? Must have because it's complete BS.
This is the tech section..."I heard", "I think", "I'm not sure, "my mother's brother's cousin told me", etc are not acceptable here. If you are not 100% sure, DO NOT post in the Tech sections. This is your one and only warning.

BTW - It's an AFM, not a MAF. The one you have is stock, unless you are running a Lexus AFM...in that case the housing is bigger, but the electronics are the same.

Dope - your O2 sensor may need to be replaced, but it is not the cause of your problems. Also, the ECU coolant temp sensor is separate from the one that senses for the gauge.

 

[Dopamine]

Dope - your O2 sensor may need to be replaced, but it is not the cause of your problems. Also, the ECU coolant temp sensor is separate from the one that senses for the gauge.

That's what I'm afraid of. I don't think my car is running rich solely due to the o2 sensor.

I'm thinking I might as well do a coolant flush and change out water-pump, thermostat, o2 sensor, coolant temp sensor, cat, spark plugs, and possibly even change out my ecu. I mentioned before that my car uses an automatic transmission ecu, but my car is manual. Will an automatic ecu effect emissions somehow?

Also my accordian hose has a tiny crack at the end, so I have to replace that as well.

Another thing I noticed is that my engine bay is really, really hot. I mean I just drove my car for 10 minutes and it feels like there's a fire inside there. Are turbo Supras supposed to get this hot? I feel like a fire will erupt if I drive my car for over 30 minutes. So there might (or most likely) be something wrong with the cooling system in my car.

I won't be able to change out all the things I mentioned until Sept25 which is when I get my next check . For now I'm going to take it easy and barely drive my car anywhere.

Thanks for the help everyone and any additional tips on emissions and possible reasons as to why my car's engine bay is so hot is appreciated.

 

[Hmong_1G]

Any intake leak aka or boost leak after the AFM will cause misreadings. Is the BOV vented out? Jdub has the best answers so do as he stated. Also check your ignition timing and plugs. Colder plugs at idle or low rpm won't fire (burn) efficiently.

 

[3p141592654]

An air leak in the accordion tube will not cause it to run rich, nor a marginal cooling system. You guys need to think a little harder.

It is supposed to be running closed loop during the smog test cycle anyway. Is it?

Jdub suggested getting the codes. I already told you that a bad ECU temp sensor can cause this problem. What is the Vf reading on the ECU? Have you measured fuel pressure, checked for leaking injectors? Unless you come up with a plan and follow through this has got FAIL written all over it.

 

[Dopamine]

Already had the numbers ran and it was codes that are related to a automatic vehicle. Things like parking and other crap that doesn't relate to a manual car. Also, something about an egr, but that was because a hose wasn't connected on the egr. That's all the codes that were shown

Another thing I should mention is that I'm pretty ignorant when it comes to cars and some of the terms related. Such as what does VF mean? And does ecu temp sensor = coolant temp sensor? Or is it something directly with the ecu?

I already inspected the radiator hoses. The top is hot and the bottom is less hot. I also squeezed the upper radiator hose and let go to see if I can feel pressure, which I did. Next thing I'm going to do is check the resistance on various sensors such as cts and cold start injector.

As for replacing the parts, that will be done on sept 25. So this is probably my last update until sept 25 and I'll let you guys know if the problem was solved. Hopefully this will turn out to be informative for future people who also fail the smog test with similar results.

Thanks for the all the help!

 

[3p141592654]

There are no ECU codes related only to an automatic. I assume you have a code 51 which is most of the time due to a bad TPS idle switch and very rarely due to the A/C being on or the auto NSW failing. Since you can start the car, my guess is the NSW has been correctly bypassed and is not the cause of your code 51. Post up the codes you have.

Yes, the ECU coolant sensor is not the same as the temp gauge sensor. It has two wires going to it and is located on the water neck near the gauge sensor and a few others.

VF can be read with a voltmeter on the diagnostic block. After codes, it is the next thing to check when you have a mixture problem. Find more about it here...

http://www.supras.com/06/techcenter/display.php?QID=80

 

[Dopamine]

Here's the codes I got: 42, 43, 51, and 71.

I checked my throttle position sensor with my dmm and the resistance wasn't according to specs, so I'm pretty sure I have a bad a tps. I'm saying pretty sure because my dmm was acting weird for some reason.

And how do you check the cold start injector? I mean I can't even reach there (under the intake manifold) to measure the resistance on it.

Btw, what is "STA" signal?

 

[jdub]

42 - Speed sensor. It's in the speedo...is your speedo working?
43 - STA is the starter signal to the ECU. It's used to activate start parameters for the engine. Did someone do the starter relay "mod" on this engine?
51 - IDL signal for the TPS...tells the ECU when the TB is closed and activates idle control to the ISCV. Usually an adjustment problem.
71 - EGR temp sensor reading low. Indicates a problem with the EGR (usually blocked) or the EGR circuit (VSV or wiring).

it would be a good idea to reset codes by pulling the EFI fuse for 30 sec...this is in case some are old stored codes. Drive the car and pull codes again.

It is not possible to set timing accurately with a code 51 present.

For the CSI to cause a rich condition, it has to be mechanically stuck open. The CSI is only active when the starter is engaged. However, since you have a STA problem it's likely not to work at all.

 

[Dopamine]

Ok I finally found out why my car was running rich. The wires for the CTS was messed up and it was the same for my o2 sensor wires. However, I now have a new problem lol. But I'll make a new thread for it since it doesn't relate to this thread topic. Thanks and one problem was finally solved....