Need your help with AFR on 2nd gen 3sgte swap Options

[team_omega]

94 celica gt with 2nd gen 3sgte swap. Everything is stock with AEM EMS. Harness done by Dr.Tweak. The AFR would read 14-15 from cold start but when it starts to warm up it would gradually move to 16-17. Is this normal? Here is a short video of it. Any clues or suggestions would help Thanks in advance

http://www.youtube.com/watch?v=Bic419UjtsE

[garin]

my second gen does this too

[team_omega]

my second gen does this too

Is it normal or is it not supose to do that?

[garin]

im not sure my car smells rich... but i still get 20mpg.

[lagos]

No its not normal.

Two main things that will cause this are:
1. You have a pretty big Vac leak.
2. You have an exhaust leak/crack or you are running open downpipe.

If both of those check out, then you need to take a look at your mechanical timing as well as your ignition timing.
Its also possible that there is something setup incorrectly with your AEM. Also assuming that you don't have some huge aftermarket cams installed.

This post has been edited by lagos: Apr 19, 2013 - 8:15 PM

[team_omega]

Thanks lagos I will check on that sometime this week as the car is just stored in the garage as of now.

[garin]

my problem is not vacuum. it reads 18-22 inhg at idle.

[lagos]

my problem is not vacuum. it reads 18-22 inhg at idle.

Then work your way down the list I posted and check your exhaust and mechanical timing.
But whenever I have a vac leak, even a small one, I first notice it as a lean reading on the wideband.

I was just dealing with this issue last week. At idle I was very lean, while at cruising it was fine and my vac readings were about 18inhg. Poking around the engine bay I first found that a small vac cap that I was using on my AC Idle up valve had blown off. I fixed that, and now my car was idling at about 16 afr. Then I did some more investigating and found that my downpipe is starting to develop a small crack right next to the factory o2 sensor. I wrapped the crack in some exhaust heat wrap and put a clamp around it. Now im back to a 14.7 idle. So in my case, it was two issues that caused it.

You also have to remember that on a 2nd gen 3sgte, a "vac leak" means any air leak past the AFM. So the problem could also be cause by a leak in your intake piping.

This post has been edited by lagos: Apr 20, 2013 - 11:38 AM

[garin]

my problem is not vacuum. it reads 18-22 inhg at idle.

Then work your way down the list I posted and check your exhaust and mechanical timing.
But whenever I have a vac leak, even a small one, I first notice it as a lean reading on the wideband.

I was just dealing with this issue last week. At idle I was very lean, while at cruising it was fine and my vac readings were about 18inhg. Poking around the engine bay I first found that a small vac cap that I was using on my AC Idle up valve had blown off. I fixed that, and now my car was idling at about 16 afr. Then I did some more investigating and found that my downpipe is starting to develop a small crack right next to the factory o2 sensor. I wrapped the crack in some exhaust heat wrap and put a clamp around it. Now im back to a 14.7 idle. So in my case, it was two issues that caused it.

You also have to remember that on a 2nd gen 3sgte, a "vac leak" means any air leak past the AFM. So the problem could also be cause by a leak in your intake piping.

yes good advice