big time idle problem after NEW TPS and cleaning IACV
03-10-2006, 04:35 PM
#1
big time idle problem after NEW TPS and cleaning IACV
I decided to knock both of these things out in one day. i was having a throttle problem originally and decided to get a new TPS.
well i installed it and obviously (i didnt know this before hand) the TPS has play for proper adjustment.
i saw the write up suggesting i use a voltage meter to determine the proper positioning. it says put one end on one of the pins with the car in the OFF position the check the ECU signal (which should be 5 volts i think) well anyway, i wasnt getting ANY THING FROM THE PIN, but when i poked it in to the HARNESS i got a 5.10.
okay so i know its getting a signal, but the rest of the write up doesnt work for me, it says to check the PINS (which get no signal), not the harness where the pins plug in to.
i dont understand how, when the car is in off position, the signal is supposed to change due to turning the TPS on the throttle body?
somebody please help me with this i need to be able ot drive m ycar, i tried and its just so messed up, wont even go above 1500 rpm.
well i installed it and obviously (i didnt know this before hand) the TPS has play for proper adjustment.
i saw the write up suggesting i use a voltage meter to determine the proper positioning. it says put one end on one of the pins with the car in the OFF position the check the ECU signal (which should be 5 volts i think) well anyway, i wasnt getting ANY THING FROM THE PIN, but when i poked it in to the HARNESS i got a 5.10.
okay so i know its getting a signal, but the rest of the write up doesnt work for me, it says to check the PINS (which get no signal), not the harness where the pins plug in to.
i dont understand how, when the car is in off position, the signal is supposed to change due to turning the TPS on the throttle body?
somebody please help me with this i need to be able ot drive m ycar, i tried and its just so messed up, wont even go above 1500 rpm.
03-10-2006, 05:38 PM
#3
car seems to be running fairly normal now, but the gas pedal is sticky and i didnt check the position on the TPS. i just adjusted the IACV to where it'd idle normal and everything else seems to be.
when checking the voltage i accidently grounded the POSITIVE and checked the harness with the NEGATIVE end, i heard a weird buzzing sound everytime i made teh connection from teh fuse box area i think, i hope i didnt mess anything up. resistance seemd to just continue decreasing after i did that and corrected myself...
also, earlier when running the TPS from "behind the throttle 't'" i kept hearing a clicking from the IACV.
i jsut want to make sure i didnt mess anything up , or hurt anything.
when checking the voltage i accidently grounded the POSITIVE and checked the harness with the NEGATIVE end, i heard a weird buzzing sound everytime i made teh connection from teh fuse box area i think, i hope i didnt mess anything up. resistance seemd to just continue decreasing after i did that and corrected myself...
also, earlier when running the TPS from "behind the throttle 't'" i kept hearing a clicking from the IACV.
i jsut want to make sure i didnt mess anything up , or hurt anything.
03-11-2006, 07:54 AM
#6
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Originally Posted by chillin014
I know, I'm having trouble using the voltmeter like that how to says cause there is only current from the harness not the pins.
Take a straight pin (like sewing needle) stick in the back of the plug into the power wire. Use the voltmeter to probe the needle sticking out of the plug. Grounding the other one obviously. Your looking to get the proper voltage at closed throttle and WOT. It's been a while since I did it and I don't have time to go get my haynes manual. But your looking for as close to 4 volts (IIRC) as possible at WOT while maintainig a correct idle.
I don't have time right now to give you all the info I want, but I know I have posted about his several times in some old threads when I did the PF throttle body install. Just search and it's all there. If you don't figure it out I can explain it better later
03-11-2006, 04:30 PM
#9
okay, so i backprobed and everything looked about correct. however it reads "OL" everytime i try to get a reading on it.
i ended up measuring in volts i think.
the car idles really high now like a little under 1500 RPM.
the IACV just doesnt make big enough of a difference to bring it down. I disconnected the TPS harness on the TPS. (the side further to the left of the car), and started th car to adjust the IACV. i didnt see a real difference. is it okay to unplug both harnesses?
i have been going by the Haynes manual, and it seems like everything is okay except for the high idle.
is it okay to take m ycar to the track with an idle like this , just incase i dont get it fixed before hand? i'll be going tomorrow afternoon.
i read something in another thread about the car having to relearn the parameters. i just dont know how long it takes, or if i need to reset the ecu or what.
also, when adjusting the TPS while the ignition was in the "on" position i heard a buzzing from the fuse box i think, anyone know what this means? it only happened if i turned it too far towards where the throttle was closed.
i ended up measuring in volts i think.
the car idles really high now like a little under 1500 RPM.
the IACV just doesnt make big enough of a difference to bring it down. I disconnected the TPS harness on the TPS. (the side further to the left of the car), and started th car to adjust the IACV. i didnt see a real difference. is it okay to unplug both harnesses?
i have been going by the Haynes manual, and it seems like everything is okay except for the high idle.
is it okay to take m ycar to the track with an idle like this , just incase i dont get it fixed before hand? i'll be going tomorrow afternoon.
i read something in another thread about the car having to relearn the parameters. i just dont know how long it takes, or if i need to reset the ecu or what.
also, when adjusting the TPS while the ignition was in the "on" position i heard a buzzing from the fuse box i think, anyone know what this means? it only happened if i turned it too far towards where the throttle was closed.
03-11-2006, 05:37 PM
#10
wow, the car really does learn its own parameters, that is amazing, the car seems fine now.
i think i felt the "choking for air" symptom at one point agian though...so i dont know what could be causing that, i'll keep an "eye" on it.
if the TPS is not positioned properly, how will i know? i think it is but im not positive.
i think i felt the "choking for air" symptom at one point agian though...so i dont know what could be causing that, i'll keep an "eye" on it.
if the TPS is not positioned properly, how will i know? i think it is but im not positive.
03-11-2006, 05:48 PM
#11
Originally Posted by chillin014
okay, so i backprobed and everything looked about correct. however it reads "OL" everytime i try to get a reading on it.
i ended up measuring in volts i think.
the car idles really high now like a little under 1500 RPM.
the IACV just doesnt make big enough of a difference to bring it down. I disconnected the TPS harness on the TPS. (the side further to the left of the car), and started th car to adjust the IACV. i didnt see a real difference. is it okay to unplug both harnesses?
i have been going by the Haynes manual, and it seems like everything is okay except for the high idle.
is it okay to take m ycar to the track with an idle like this , just incase i dont get it fixed before hand? i'll be going tomorrow afternoon.
i read something in another thread about the car having to relearn the parameters. i just dont know how long it takes, or if i need to reset the ecu or what.
also, when adjusting the TPS while the ignition was in the "on" position i heard a buzzing from the fuse box i think, anyone know what this means? it only happened if i turned it too far towards where the throttle was closed.
i ended up measuring in volts i think.
the car idles really high now like a little under 1500 RPM.
the IACV just doesnt make big enough of a difference to bring it down. I disconnected the TPS harness on the TPS. (the side further to the left of the car), and started th car to adjust the IACV. i didnt see a real difference. is it okay to unplug both harnesses?
i have been going by the Haynes manual, and it seems like everything is okay except for the high idle.
is it okay to take m ycar to the track with an idle like this , just incase i dont get it fixed before hand? i'll be going tomorrow afternoon.
i read something in another thread about the car having to relearn the parameters. i just dont know how long it takes, or if i need to reset the ecu or what.
also, when adjusting the TPS while the ignition was in the "on" position i heard a buzzing from the fuse box i think, anyone know what this means? it only happened if i turned it too far towards where the throttle was closed.
03-11-2006, 05:49 PM
#12
Originally Posted by chillin014
wow, the car really does learn its own parameters, that is amazing, the car seems fine now.
i think i felt the "choking for air" symptom at one point agian though...so i dont know what could be causing that, i'll keep an "eye" on it.
if the TPS is not positioned properly, how will i know? i think it is but im not positive.
i think i felt the "choking for air" symptom at one point agian though...so i dont know what could be causing that, i'll keep an "eye" on it.
if the TPS is not positioned properly, how will i know? i think it is but im not positive.
03-13-2006, 05:33 PM
#13
Originally Posted by nismology
No the car doesn't learn it's own operating parameters. If a sensor is off, the ECU doesn't just adjust it's way around the incorrect readings.
i will get back out there tomorrow and try to measure it in ohms. pin number 2 gives me a different reading than 3.
i am getting the studder at idle still, not as bad as usual though. for some reason the rpms seems higher than they should be now. and transmission is shifting different, which could just be a result of the TPS being weird. Like when cruising at 50 rpms will be above 2k and stay there. when i let off the throttle, the rpm needle does not drop like it used to. it stays in position, like the transmission is staying in gear? its got the feeling (At times) like it does when i would manually put it into first gear and drive it. its like alot more responsive, but then again i did clean the IACV and TB although this seems like a drastic change.
i dont know if i've mentioned that i have a front 02 sensor that needs replacing.
03-14-2006, 08:33 AM
#14
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it is very important to have the TPS in the correct voltage range. The ECU uses the TPS to adjus fuel and timing maps. If it is way off it could possibly cause major problems.
Are you sure your probing the correct sensor. Different year Maxima's have different set ups. Some just have a TPS and some have both a TPS and WOT sensor. The are usually attached to each other.
Your not doing this right.
Read this thread
http://forums.maxima.org/showthread....ht=TPS+voltage
Are you sure your probing the correct sensor. Different year Maxima's have different set ups. Some just have a TPS and some have both a TPS and WOT sensor. The are usually attached to each other.
Your not doing this right.
Read this thread
http://forums.maxima.org/showthread....ht=TPS+voltage
03-14-2006, 08:45 AM
#15
Originally Posted by I30tMikeD
it is very important to have the TPS in the correct voltage range. The ECU uses the TPS to adjus fuel and timing maps. If it is way off it could possibly cause major problems.
Are you sure your probing the correct sensor. Different year Maxima's have different set ups. Some just have a TPS and some have both a TPS and WOT sensor. The are usually attached to each other.
Your not doing this right.
Read this thread
http://forums.maxima.org/showthread....ht=TPS+voltage
Are you sure your probing the correct sensor. Different year Maxima's have different set ups. Some just have a TPS and some have both a TPS and WOT sensor. The are usually attached to each other.
Your not doing this right.
Read this thread
http://forums.maxima.org/showthread....ht=TPS+voltage
thank you. i hope it works. i was not putting both pins on the black and white wire at the same time, i was checking them individually the first time.
thank you.
03-14-2006, 09:01 AM
#16
Not sure what the problem is, however the ECU does adjust the IACV and even timing to get to the target idle RPM. If your TPS is off, it will cause the car to idle high/low and act funny especially on quick throttle changes. However, with some time the ECU via the IACV will compensate for a high/low TPS voltage to a point.
The FSM says every time you change the MAF, TPS, IACV, throttle body, or anything used to control idle, you must perform an Idle Air Volume Learning, which is something I think the dealer can only do with a Consult at least on 5th gens.. Basically, it clears all the ECU learned values at idle and quickly relearns the changes made by the new part. However, do to aging parts, the ECU is programmed to compensate for small changes over time. That is why it seems to get better as you drive. However, if your TPS is way off, I'm sure it will still cause driveability issues do to lost range/resolution. You need to adjust it within spec.
People that clean the throttle-body screw with the amount of idle bypass air through the IACV by cleaning out the junk or worse clog/damage the IACV with cleaner. Once you clean out all the buildup, assuming you didn't damage the IACV, your ECU must now decrease the duty cycle on the IACV since it doesn't need to allow as much bypass air around the throttle plate. The previously learned duty cycle the ECU has stored was slowly over time increased to compensate for blockage. Now that you've cleaned it, it must relearn.
Probably not 100% correct, but that's the jist of what I've come to understand from the FSM.
The FSM says every time you change the MAF, TPS, IACV, throttle body, or anything used to control idle, you must perform an Idle Air Volume Learning, which is something I think the dealer can only do with a Consult at least on 5th gens.. Basically, it clears all the ECU learned values at idle and quickly relearns the changes made by the new part. However, do to aging parts, the ECU is programmed to compensate for small changes over time. That is why it seems to get better as you drive. However, if your TPS is way off, I'm sure it will still cause driveability issues do to lost range/resolution. You need to adjust it within spec.
People that clean the throttle-body screw with the amount of idle bypass air through the IACV by cleaning out the junk or worse clog/damage the IACV with cleaner. Once you clean out all the buildup, assuming you didn't damage the IACV, your ECU must now decrease the duty cycle on the IACV since it doesn't need to allow as much bypass air around the throttle plate. The previously learned duty cycle the ECU has stored was slowly over time increased to compensate for blockage. Now that you've cleaned it, it must relearn.
Probably not 100% correct, but that's the jist of what I've come to understand from the FSM.
03-14-2006, 09:43 AM
#18
okay. i just went for a drive, and then came back to do the measurement. it wasn't off that much at all so i think i had it adjusted basically correctly, however i loosened the screws and readjusted it anyway.
i got .4 at closed and 4.02 at WOT.
if thats not good enough, then i just dont know what to do.
here's pictures just for sh*ts and giggles.
i did not adjust the TB screw like yall have said, although i have messed with the IACV screw. i read someting about a feeler gauge but i have not explored that either, do you think i should check that out?
i appreciate yalls help.
i got .4 at closed and 4.02 at WOT.
if thats not good enough, then i just dont know what to do.
here's pictures just for sh*ts and giggles.
i did not adjust the TB screw like yall have said, although i have messed with the IACV screw. i read someting about a feeler gauge but i have not explored that either, do you think i should check that out?
i appreciate yalls help.
03-18-2006, 10:04 AM
#21
still getting the hesitation at idle. so i guess it wasnt the TPS. i dont get the choking at WOT anymore, so i dont know waht i did that could have fixed that, maybe the tps was bad and something else is bad as well?
i checked with the voltmeter, the coilpacks, iacv, and MAF. the tests just dont seem accurate since the chilton manual usually says somethign generic like "it should be getting a reading" or "it should read inifinite resistance (for coilpacks).
i'm at the point where i'm about to just start replacing stuff. MAF is a pretty common thing to malfunction, right? i think i'll buy that next.
i checked with the voltmeter, the coilpacks, iacv, and MAF. the tests just dont seem accurate since the chilton manual usually says somethign generic like "it should be getting a reading" or "it should read inifinite resistance (for coilpacks).
i'm at the point where i'm about to just start replacing stuff. MAF is a pretty common thing to malfunction, right? i think i'll buy that next.
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