car running rich

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car running rich

Postby 819_ay » Wed Dec 18, 2013 12:18 am

hey everyone, i've done some research and can't find a solution to my problem, here are a quick description of the car
90 JDM GT4
3 inch exhaust, no cat
replaced air box with cone
mines ecu
APEXI avcr
WTA top mount IC(from an RC)
the rest is pretty much stock
DIY catch can( using compressor filter)

so here is my problem, she is running very rich(aem wideband), at idle the gauge is reading 11.3-12.3
i recently changed my transmission, and when i was done with that the she was idling at 1100-1200, with the afr good, then a couple months later (cold weather arrived) and she started to run rich with the numbers above. i don't have an O2 sensor,there was none when i bought the car 3 years ago, and all was good until recently, she drives good, no hesitation, no power loss, no abnormal back fires, no abnormal smoke , no smells, nothing...only running too rich, i was maybe thinking the afm is going bad, but then again i'm not sure...any help would be much appreciated

if there is any info i did not put here just ask
thanks
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Re: car running rich

Postby underscore » Wed Dec 18, 2013 3:37 pm

If you don't have an O2 sensor you need to put one in. Also take a look at the AEM sensor, it could be going bad and giving you false readings.
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Re: car running rich

Postby 819_ay » Wed Dec 18, 2013 10:41 pm

I tried putting one in when I bought the car and well honestly it changed absolutely nothing, I think the mines Ecu just cancels it... Because when I put the stock one back it drives like shit
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Re: car running rich

Postby alltracman78 » Thu Dec 19, 2013 10:26 pm

It might be the ECU you have, the programmers might have been more concerned with power than fuel economy.
Your ECU might be in open loop. No O2 signal or bad ECT sensor. Or the CSI may be leaking.
Or it might be programmed to stay in open loop.

The JDM ECUs use a single wire O2 sensor, but the US/Canada ones use a 4 wire w/heater.
If you stick one of the 4 wire ones into a JDM car the O2 sensor won't get hot enough so it won't work right.
Also, if your O2 wire is damaged up by the alternator [the harness gets flexed when ever work is done around there] it will cause the ECU to go into open loop if it doesn't get the O2 signal.

But whatever else, without an O2 sensor you won't have good fuel economy period.
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Re: car running rich

Postby underscore » Fri Dec 20, 2013 5:05 am

^ I think you nailed it, if they chose to remove the O2 sensor from the system it would need to be tuned very rich.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
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Re: car running rich

Postby 819_ay » Sun Dec 22, 2013 2:36 pm

Thanks for the help guys, but just until recently the the wideband would indicate at idle at 13.8-14.1 and now at idle it's about 11.8-12.1.... Why the sudden drop is what I'm looking for.. Like I said in my initial post the car runs still runs fine but I'm worried that if it's always rich it might end up causing unwanted problems
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Re: car running rich

Postby Tecker185 » Sun Dec 22, 2013 4:49 pm

You prolly have a vacuum/boost leak. I'd replace them all, they are cheap enough. Then check all your couplers for wear.
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Re: car running rich

Postby 819_ay » Sun Dec 22, 2013 9:19 pm

Thanks... I found a diagram for the hoses and try and check and replace the hoses when I can... Winter here sucks... Just got another 20cm of snow lol
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Re: car running rich

Postby underscore » Tue Dec 24, 2013 10:55 pm

Before you bother replacing all those hoses get a boost leak tester and pressurize the system with the engine off and listen for leaks.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
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Re: car running rich

Postby Rallly » Mon Aug 17, 2015 10:18 pm

underscore wrote:Before you bother replacing all those hoses get a boost leak tester and pressurize the system with the engine off and listen for leaks.



How do I do a boost leak test on my st185 Celica alltrac?
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Re: car running rich

Postby underscore » Mon Aug 17, 2015 10:24 pm

You buy or build a boost leak tester, which basically allows you to connect an air compressor to the pre-turbo intake piping (ideally before the MAF). You can then pressurize the system with the engine off and easily listen for/feel leaks. Be sure to have the throttle held as far open as possible to allow air to pressurize the intake manifold fully as well. When you do this be careful not to have the pressure regulator on your compressor set too high or too low, you want it just above the highest boost pressure you run. For example I never go above 16psi so I test for leaks with 20psi.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
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Re: car running rich

Postby Rallly » Tue Aug 18, 2015 1:51 am

underscore wrote:You buy or build a boost leak tester, which basically allows you to connect an air compressor to the pre-turbo intake piping (ideally before the MAF). You can then pressurize the system with the engine off and easily listen for/feel leaks. Be sure to have the throttle held as far open as possible to allow air to pressurize the intake manifold fully as well. When you do this be careful not to have the pressure regulator on your compressor set too high or too low, you want it just above the highest boost pressure you run. For example I never go above 16psi so I test for leaks with 20psi.



Where exactly do I connect the air compressor? Can I use a tire valve stem to input the air?
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Re: car running rich

Postby underscore » Tue Aug 18, 2015 6:01 pm

Connect the compressor to the tester, and the tester to the intake piping. Considering the volume of the intake system I think a tire would go flat pretty quickly.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
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Re: car running rich

Postby alltracman78 » Fri Aug 28, 2015 10:15 pm

I think he means a tire valve on the boost tester itself as the way to get air into the system.
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Re: car running rich

Postby Rallly » Fri Aug 28, 2015 10:37 pm

To do a boost leak test on my mkiv supra I place a tire valve stem on the intake, and block off the air filter with a can of stew. Applying air through the tire valve stem using my air comp and tire air tool.

How can I do this to Celica st185 properly?
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