2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

AFR Problems

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Old Mar 15, 2005 | 06:49 PM
  #1  
gotrotors?'s Avatar
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AFR Problems

I just got off the dyno today, and i guess im doing 13.2 afr across the board. I have s4 turbo II with stock everything (maybe a realtek) Im running s5 turbo, and im not sure about the fuel pump. I KNOW i have an n/a air flow meter (somebody put it there, not me)


Could the airflow meter be the problem? at 10 psi, afr is 13.2:1
if i drop to 6 psi, its 13.2:1

Need to get more fuel in there.

thanks in advance

Last edited by gotrotors?; Mar 15, 2005 at 06:53 PM.
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Old Mar 15, 2005 | 06:51 PM
  #2  
gotrotors?'s Avatar
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Oh crap, i forgot, 2 1/2 inch exhaust with no cats or silencers.
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Old Mar 16, 2005 | 12:18 AM
  #3  
YearsOfDecay's Avatar
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Jeezuz..... If you don't have a Walbro Fuel Pump... get one... that will help.

As for the AF meter... I'm stabbing here 'cause i didn't know it would even work on a TII.. BUT, since the N/A's don't flow as much air as a TII... it follows that the N/A AFM would be calibrated to a lower flow rate and may likely be maxing out at a lower signal than a TII would, thus, the ECU thinks its getting less air than it actually is and is lowering the fuel... So it would be the next logical step to put the proper AFM in there and see if it fixes the problem..

At least you know that you need more fuel....!!! Keep your boost back until you get this problem solved... ESPECIALLY if you are running the TMIC...
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Old Mar 16, 2005 | 08:29 AM
  #4  
gotrotors?'s Avatar
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Yah. I just wanted second opinions pretty much. Im getting a walbro 255, and hopefully turbo afm.


That is all what i suspected. Ive been running my motor like this for quite awhile. I run it HARD too. I have a ground problem right now as well...so that could also be causing my injectors to run incorrectly. Im running 5 lb of boost now. The funny thing tho is that i got the same afr at 5 psi as i got at 10. Wierd?


s5 turbo as well, so i know im not running it out of its efficiency range.


Just outa curiosity. Is the 550 pretty much the biggest injector my stock ecu can control? I want to run bigger on the safe side. Ill just get a fmu if i cant control any bigger.


thanx alot ppl
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Old Mar 16, 2005 | 10:42 AM
  #5  
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From: FORT WORTH, TEXAS,USA
I'd go buy a wideband OR go to another shop for a second opinion. A you shouldn't need a Waldo.

You might check the input voltage to your fuel puimp at full boost. It should be over 12v when at full throttle. If not, then do the fuel pump rewire.

That afr being the same at five psi and the same at ten psi should be a redflag to go to another shop or buy your own wideband.
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Old Mar 16, 2005 | 11:18 AM
  #6  
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The N/a AFM will cause a richer condition on a TII.

I don't think its your problem. Its likely your exhaust mods.
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