MAF Unplugged = Car runs better PART 3? HELP!
07-15-09, 07:55 PM
#16
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Check the negitive battery cable for corrosion, The corrosion travels down the cable and you dont even see it because its under the insulation The SC are very sensitive to ground, Fixed my problem. Go to Wallmat and buy a negative cable. Its a 15" 4 Gauge cable its about $8.00. I bought a spare just in case. Its the cheapest fix. Follow the cable down until you see a bolt tieing down the Negative cable to Chassis Ground. Remove the bolt install the cable there & then to the battery. Let the other cable hang to the side and see if this solves the issue
Last edited by qmanlexus2; 07-15-09 at 07:58 PM.
07-15-09, 07:55 PM
#17
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hey phoenix go buy some crc maf sensor cleaner and spray down your sensor AND look down into the hole your sensor came from. you should see something like a camera lens looking at you. SPRAY THAT TOO. but be careful and be sure to let it dry, im talkin bout maybe leave it overnight if you dont have anywhere to go. then pull out ur ecu fuse for 5 mins or disconnect ur
negative battery cable. report back this solved my problem like literally 3 hours ago.
negative battery cable. report back this solved my problem like literally 3 hours ago.
Just wanted to mention that before someone tried this and messed up their maf.
Matt, good luck. My fingers are crossed on the exhaust.
-David
07-15-09, 09:35 PM
#19
While I wait to make some test pipes... Think about it.
Car is GOOD when its cold.. when it warms up it runs like poo. Disconnect the MAF and the car is fine when its warm.
So what makes the car run like crap when its warm but is no present when the MAF is disconnected?
Battery is in the trunk with a 0/1 gauge wire strapped to the chasis. I think its OK.
Car is GOOD when its cold.. when it warms up it runs like poo. Disconnect the MAF and the car is fine when its warm.
So what makes the car run like crap when its warm but is no present when the MAF is disconnected?
Check the negitive battery cable for corrosion, The corrosion travels down the cable and you dont even see it because its under the insulation The SC are very sensitive to ground, Fixed my problem. Go to Wallmat and buy a negative cable. Its a 15" 4 Gauge cable its about $8.00. I bought a spare just in case. Its the cheapest fix. Follow the cable down until you see a bolt tieing down the Negative cable to Chassis Ground. Remove the bolt install the cable there & then to the battery. Let the other cable hang to the side and see if this solves the issue
07-16-09, 08:34 AM
#20
Unplugging the MAF will probably put the computer in "Safe Mode." If the car runs better in "Safe Mode" than in "Normal Mode," then something is preventing the correct sensor feedback from generating the proper driveability results.
My Tercel has a clogged cat or a faulty rear O2 sensor as I am throwing P0420. When I talked with KC95SC400 about this (he is a Toyota Tech), he told me to pull the first O2 sensor (easy to do on the 1.5L 4cyl) to put the car into "Safe Mode." He said, if the car runs better without the first O2 sensor, then it is almost certainly a clogged cat. If the car does not run better, then it is almost certainly a bad sensor. Extending this analysis to your car that runs better with the MAF unplugged, it sounds like a clogged cat or two may indeed be the problem.
That being said, you may be the luckiest guy on the forum because I am pulling my headers and cats this weekend, and I will not be using the cats once I have my long tube headers installed. I am fairly certain that they are not clogged (76k miles...dealer serviced 14 times...no CEL until R154 swap 2k miles ago). If you are interested, we could work out a deal via PM.
07-16-09, 09:36 AM
#21
If it's not the maf sensor and not the ecu then it has to be in the wireing between the 2. The maf sensor sends a 5V or 12V reference to the ecu so it knows how much fuel you need. If the wire to the ecu is frayed spliced has cuts or corrosion the signal will be off. Tell me ur year and engine and I'll give you a wireing diagram so you can jump the signal wire and ground.
07-16-09, 12:07 PM
#23
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I had a discussion about this with another member. For the 92-95 SC's that had karman MAF's, DO NOT!!! spray the maf cleaner on them. This cleaner is only intended on hotwire mafs. (96+) It may make things worse! I suggest getting a can of dust-off and use that instead.
Just wanted to mention that before someone tried this and messed up their maf.
Matt, good luck. My fingers are crossed on the exhaust.
-David
Just wanted to mention that before someone tried this and messed up their maf.
Matt, good luck. My fingers are crossed on the exhaust.
-David
Ooops already did that
07-17-09, 04:28 PM
#24
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Okay I have an update here-
I hate noticed smthg, today the weather was nice here, the air wasn't as hot as usual. The car was running extraordinarily amazingly great! then after 20 mins of driving, I pushed the gas pedal all the way down, and the engine starting reving, the trans was getting ready to shift down, then I felt a cutoff and back to normal bogging bugging annoying SC slow acceleration
amazing - does that sound familiar to anyone?
I hate noticed smthg, today the weather was nice here, the air wasn't as hot as usual. The car was running extraordinarily amazingly great! then after 20 mins of driving, I pushed the gas pedal all the way down, and the engine starting reving, the trans was getting ready to shift down, then I felt a cutoff and back to normal bogging bugging annoying SC slow acceleration
amazing - does that sound familiar to anyone?
07-17-09, 06:55 PM
#25
I had a discussion about this with another member. For the 92-95 SC's that had karman MAF's, DO NOT!!! spray the maf cleaner on them. This cleaner is only intended on hotwire mafs. (96+) It may make things worse! I suggest getting a can of dust-off and use that instead.
Just wanted to mention that before someone tried this and messed up their maf.
Matt, good luck. My fingers are crossed on the exhaust.
-David
Just wanted to mention that before someone tried this and messed up their maf.
Matt, good luck. My fingers are crossed on the exhaust.
-David
Okay I take that back. The crc spray did fuc*k up my vortex maf sensor. Now when I idle it will stall and I get check engine light but normally if I rev it high to 4k rpm fast that will fix it. My cars still drivable and I'm glad as he'll that my hesitations gone but I still gotta look into a new maf sensor. Hey phenix would u happen to have any spare mafs for my 93 sc3
07-17-09, 09:02 PM
#26
Clogged cats can trigger the CEL. The rear O2 sensors are there mainly to measure catalyst efficiency. If the efficiency of the catalyst drops below a certain value, the O2 sensor reading will trigger the CEL.
Unplugging the MAF will probably put the computer in "Safe Mode." If the car runs better in "Safe Mode" than in "Normal Mode," then something is preventing the correct sensor feedback from generating the proper driveability results.
My Tercel has a clogged cat or a faulty rear O2 sensor as I am throwing P0420. When I talked with KC95SC400 about this (he is a Toyota Tech), he told me to pull the first O2 sensor (easy to do on the 1.5L 4cyl) to put the car into "Safe Mode." He said, if the car runs better without the first O2 sensor, then it is almost certainly a clogged cat. If the car does not run better, then it is almost certainly a bad sensor. Extending this analysis to your car that runs better with the MAF unplugged, it sounds like a clogged cat or two may indeed be the problem.
Unplugging the MAF will probably put the computer in "Safe Mode." If the car runs better in "Safe Mode" than in "Normal Mode," then something is preventing the correct sensor feedback from generating the proper driveability results.
My Tercel has a clogged cat or a faulty rear O2 sensor as I am throwing P0420. When I talked with KC95SC400 about this (he is a Toyota Tech), he told me to pull the first O2 sensor (easy to do on the 1.5L 4cyl) to put the car into "Safe Mode." He said, if the car runs better without the first O2 sensor, then it is almost certainly a clogged cat. If the car does not run better, then it is almost certainly a bad sensor. Extending this analysis to your car that runs better with the MAF unplugged, it sounds like a clogged cat or two may indeed be the problem.
If it's not the maf sensor and not the ecu then it has to be in the wireing between the 2. The maf sensor sends a 5V or 12V reference to the ecu so it knows how much fuel you need. If the wire to the ecu is frayed spliced has cuts or corrosion the signal will be off. Tell me ur year and engine and I'll give you a wireing diagram so you can jump the signal wire and ground.
The car has an UNmodified harness... NO corrosion or anything... its clean as a whistle.
07-24-09, 12:03 AM
#29
heres the diagram for your model/year, i traced out the signal wire in red and the ground wire blue. grab an electronic t pin to backprobe the brown wire on the MAF sensor connector and use gator clips or 18 gauge wire to connect it to a ground(anywhere metal not covered with paint). if that doesnt work backprobe the yellow/green wire to port 66 in the ECU. i believe your ecu is located by the passenger side footwell. Pull back carpet and remove big plastic black cover held on with 10mm bolts. only backprobe one wire at a time, if you were to use 2 t pins at once theyd most likely touch short out and then you get the magic white smoke. try the ground first as its more likely and easier
let me know if you need help or if it works
let me know if you need help or if it works
Last edited by topdog849; 07-24-09 at 12:18 AM.