Can MAF tuning cause slow O2 switching
01-09-2009, 08:35 AM
#1
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Can MAF tuning cause slow O2 switching I recently had a problem with getting SES lights for insufficient O2 switching. I didn't have the problem while dialing in my VE table or any other changes till I started dialing in the MAF. Now my O2's are extreamly LAZY, they switch maybe once every 2 seconds. Is this even possible or are my O2's shot?
Should I throw the MAF table back to stock and see if SES's or just replace the O2's?
Should I throw the MAF table back to stock and see if SES's or just replace the O2's?
01-09-2009, 09:30 AM
#3
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I recently had a problem with getting SES lights for insufficient O2 switching. I didn't have the problem while dialing in my VE table or any other changes till I started dialing in the MAF. Now my O2's are extreamly LAZY, they switch maybe once every 2 seconds. Is this even possible or are my O2's shot?
Should I throw the MAF table back to stock and see if SES's or just replace the O2's?
Should I throw the MAF table back to stock and see if SES's or just replace the O2's?
I assume that you have a LS? in this 87. What year? What PCM? What OS?
Even with this lack of info I will make a few assumptions and give you a general answer.
How old are the O2's? If more than a few years, more than 50,000 miles, or just from a transplanted car then change them. The older they are the slower they are. Left untouched in a car they can easily last 100,000 miles, but any changes or modifications then they will likely fail.
I also assume that you used a WB to dial in the VE. If so then you can now properly scale the MAF.
Good luck
01-09-2009, 10:09 AM
#4
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Thread Starter
It's a 2002 WS6 TA with a custom OS for HP Tuners for RTT so no issues there. O2's are getting up there in age. I put long tubes in about 1 year ago and the car has about 40k miles on the O2's. Yes I have a LC-1 that I used to dial in the VE fueling tables.
My AF ratio now will stay constantly in the 14.4 - 14.8 range now instead of switching. I started the thread because I found it odd that the sensors just stopped switching instead of progressively getting slower. The only change I made was getting the MAF adjusted. I am using the STFT to dial in the MAF using a guide I got from EC Tune on the HP Tuners forum. Now I'm concerned that my MAF table is screwed since the O2's may be dead.
I'm going to try to set the MAF back to stock and see if it kicks the O2's back into normal switching or not.
My AF ratio now will stay constantly in the 14.4 - 14.8 range now instead of switching. I started the thread because I found it odd that the sensors just stopped switching instead of progressively getting slower. The only change I made was getting the MAF adjusted. I am using the STFT to dial in the MAF using a guide I got from EC Tune on the HP Tuners forum. Now I'm concerned that my MAF table is screwed since the O2's may be dead.
I'm going to try to set the MAF back to stock and see if it kicks the O2's back into normal switching or not.
01-09-2009, 11:29 AM
#5
Long tubes position the O2 further downstream from where the ECM thinks they are. So there is now an increased time from when the ECM thinks the O2 should respond to the corrections, and when it actually senses the fuel mixture correction. This delay is a cause for concern for the ECM, it then thinks your O2s are old and throws a code. You could alter the O2 transport delay table to remedy this, but I have had little success with it. I just use new sensors with long tubes, sometimes Bosch 13111 work other times they do not. If all else fails, just turn off the code. This will occur on both SD and MAF setups, so it is not your MAF table calibration causing it.
