MAF Sensor
#21
01-25-2018 | 10:53 AM
I hooked up the Autocom and checked Fuel Trim. Both Banks Short term Fuel Trim is 0, Long tern is -6.2 on Bank 1 and -7.0 on Bank 2.
Fuel trim can be a valuable diagnostic tool - Eastern Manufacturing
Based on this article it is running rich during closed loop operation. 6.2 and 7% seem pretty high. I am going to try the disconnect battery and hold terminals together to reset the adaptive settings. I will see if it works. May or may not. There is a post from way back on this procedure. I have not been able to find a shop willing to just plug in and reset them for me here.
I am chickening out from touching the battery cables together. I am going to monitor the Trims and see if they trend either direction.
Fuel trim can be a valuable diagnostic tool - Eastern Manufacturing
Based on this article it is running rich during closed loop operation. 6.2 and 7% seem pretty high. I am going to try the disconnect battery and hold terminals together to reset the adaptive settings. I will see if it works. May or may not. There is a post from way back on this procedure. I have not been able to find a shop willing to just plug in and reset them for me here.
I am chickening out from touching the battery cables together. I am going to monitor the Trims and see if they trend either direction.
Rechecked my long term fuel trims, and they are now at -.8 and -1.6. Mass air 5.6
#22
01-25-2018 | 12:24 PM
Camel Trophy
Joined: Dec 2009
Posts: 3,790
Likes: 905
From: Charlotte
Static fuel trim readings are not relevant. By design fuel trim should fluctuate based on the closed-loop feedback from the O2s. A range of +5 to -5 is normal. Getting outside that range sporadically and for brief periods is no big deal. Mine usually bounce around between +3 and -3. When I've had O2s go bad the fuel trim goes to +20 and stays there. Not long after the SES light pays a visit.
Closely related, and an input to fuel trim, is O2 sensor voltage, which should bounce around above and below 0.45 volts. Prolonged readings of 0.0 or 1.0 volt means the sensor is shot or there's a wiring fault between the sensor and the ECM.
I have one page on my UltraGauge set up to monitor O2 sensor volts plus ST and LT fuel trims. I would expect a ScanGauge to be capable of doing the same. I like seeing the O2 volts and fuel trims bouncing around. Gives me peace of mind that all is well.
On a trip a couple years ago I notice the Bank 1 fuel trim was pegged at +20. (This was before I had the UG setup to monitor O2 volts.) I stopped at a parts store and picked up a new O2 and installed it in the motel parking lot the next morning. Seeing the fuel trim pegged at +20 told me there was a problem well before the SES light came on.
Closely related, and an input to fuel trim, is O2 sensor voltage, which should bounce around above and below 0.45 volts. Prolonged readings of 0.0 or 1.0 volt means the sensor is shot or there's a wiring fault between the sensor and the ECM.
I have one page on my UltraGauge set up to monitor O2 sensor volts plus ST and LT fuel trims. I would expect a ScanGauge to be capable of doing the same. I like seeing the O2 volts and fuel trims bouncing around. Gives me peace of mind that all is well.
On a trip a couple years ago I notice the Bank 1 fuel trim was pegged at +20. (This was before I had the UG setup to monitor O2 volts.) I stopped at a parts store and picked up a new O2 and installed it in the motel parking lot the next morning. Seeing the fuel trim pegged at +20 told me there was a problem well before the SES light came on.
The following users liked this post:
Jeff Blake (03-27-2018)
#23
01-25-2018 | 01:21 PM
Static fuel trim readings are not relevant. By design fuel trim should fluctuate based on the closed-loop feedback from the O2s. A range of +5 to -5 is normal. Getting outside that range sporadically and for brief periods is no big deal. Mine usually bounce around between +3 and -3. When I've had O2s go bad the fuel trim goes to +20 and stays there. Not long after the SES light pays a visit.
Closely related, and an input to fuel trim, is O2 sensor voltage, which should bounce around above and below 0.45 volts. Prolonged readings of 0.0 or 1.0 volt means the sensor is shot or there's a wiring fault between the sensor and the ECM.
I have one page on my UltraGauge set up to monitor O2 sensor volts plus ST and LT fuel trims. I would expect a ScanGauge to be capable of doing the same. I like seeing the O2 volts and fuel trims bouncing around. Gives me peace of mind that all is well.
On a trip a couple years ago I notice the Bank 1 fuel trim was pegged at +20. (This was before I had the UG setup to monitor O2 volts.) I stopped at a parts store and picked up a new O2 and installed it in the motel parking lot the next morning. Seeing the fuel trim pegged at +20 told me there was a problem well before the SES light came on.
Closely related, and an input to fuel trim, is O2 sensor voltage, which should bounce around above and below 0.45 volts. Prolonged readings of 0.0 or 1.0 volt means the sensor is shot or there's a wiring fault between the sensor and the ECM.
I have one page on my UltraGauge set up to monitor O2 sensor volts plus ST and LT fuel trims. I would expect a ScanGauge to be capable of doing the same. I like seeing the O2 volts and fuel trims bouncing around. Gives me peace of mind that all is well.
On a trip a couple years ago I notice the Bank 1 fuel trim was pegged at +20. (This was before I had the UG setup to monitor O2 volts.) I stopped at a parts store and picked up a new O2 and installed it in the motel parking lot the next morning. Seeing the fuel trim pegged at +20 told me there was a problem well before the SES light came on.
Good to know! My scangauge doesn’t do those, may have to switch. My O2 sensors were .445
#24
03-27-2018 | 07:17 PM
So I put in a new MAF today. It has apparently solved a rough starting issue I have been having.
I ordered 4 times to get the correct MAF sensor. Make sure you get the # off of your current MAF and use that to search. I got a too small one every time searching by vehicle. I got lucky and Amazon had a return for $52. So no complaints.
I will report back on MPG.
I ordered 4 times to get the correct MAF sensor. Make sure you get the # off of your current MAF and use that to search. I got a too small one every time searching by vehicle. I got lucky and Amazon had a return for $52. So no complaints.
I will report back on MPG.
#25
03-27-2018 | 09:34 PM
Pro Wrench
Joined: May 2016
Posts: 1,617
Likes: 184
From: Lake Tahoe
All the MAF does it send a reading of grams per second right? So if the reading is outside the norm, then that calls for replacement? No ifs, buts or elses.
IIRC, my ultragauge shows 6.2 at idle. What are y'alls numbers, and under load? Does anyone know what the "correct" numbers are? My MAF is original, and I'd like to verify it's running optimally. It's one of the few sensors I haven't replaced (cam and crank sensor are the only other originals I can think of).
Thanks for the tip on adding Fuel trims to the UG. I only have coolant temp on mine haha... never got around to configuring it.
IIRC, my ultragauge shows 6.2 at idle. What are y'alls numbers, and under load? Does anyone know what the "correct" numbers are? My MAF is original, and I'd like to verify it's running optimally. It's one of the few sensors I haven't replaced (cam and crank sensor are the only other originals I can think of).
Thanks for the tip on adding Fuel trims to the UG. I only have coolant temp on mine haha... never got around to configuring it.
Last edited by Jeff Blake; 03-27-2018 at 09:41 PM.
#26
03-28-2018 | 07:16 AM
So I put in a new MAF today. It has apparently solved a rough starting issue I have been having.
I ordered 4 times to get the correct MAF sensor. Make sure you get the # off of your current MAF and use that to search. I got a too small one every time searching by vehicle. I got lucky and Amazon had a return for $52. So no complaints.
I will report back on MPG.
I ordered 4 times to get the correct MAF sensor. Make sure you get the # off of your current MAF and use that to search. I got a too small one every time searching by vehicle. I got lucky and Amazon had a return for $52. So no complaints.
I will report back on MPG.
#27
03-28-2018 | 07:20 AM
Yeah online Vendors seem to have issues with 4.0/4,6L MAF's. They seem to always send MAF's with the 4.0L housing vs the 4.6L housing. I personally just remove the darn MAF itself and install it into the housing I need to as the actual sensor itself is the exact same. I then install them into the MAF housing with some phillips head SS screws vs the security bit screws they come with. The housings are the only part that is different between 4.0/4.6L engines.
#28
03-28-2018 | 09:12 AM
Sometimes the security bit screws are easy & sometimes they’ll fight ya, but yep the actual MAF sensor is the exact same. I grabbed a good amount of spares at junk yards throughout the years for like 5.00 (bare sensor). I’ve only bought one so far used from a junk yard that was INOP. I quickly was able to test it & return it and swap it out for another one.
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CollieRover (03-28-2018)
#29
03-28-2018 | 10:17 AM
Rock Crawling
Joined: Dec 2017
Posts: 306
Likes: 53
From: Charlotte, North Carolina
So I put in a new MAF today. It has apparently solved a rough starting issue I have been having.
I ordered 4 times to get the correct MAF sensor. Make sure you get the # off of your current MAF and use that to search. I got a too small one every time searching by vehicle. I got lucky and Amazon had a return for $52. So no complaints.
I will report back on MPG.
I ordered 4 times to get the correct MAF sensor. Make sure you get the # off of your current MAF and use that to search. I got a too small one every time searching by vehicle. I got lucky and Amazon had a return for $52. So no complaints.
I will report back on MPG.
#30
03-28-2018 | 10:29 AM
