Mass Air Flow issue - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Torrid · 11-04-2007, 05:01 PM

1996 240SX. I kept getting the code for Mass Air Flow, forget the exact code. Anyway, went ahead and replaced the MAF and while the car starts better and idles better, it doesn't feel exactly like it did before I was getting this code. I finally got smart and grabbed the multimeter and checked out the connections. The one thing I read was that pin 2 in the harness for the maf was to read 5 ohms. I'm reading 3.8 ohms across this. Should I be worried or does it take time for the car to adjust to a new MAF? I know when it comes to speakers, when impedance is rated at 4 ohms, a speaker is going to read 3.2 because of the frequency at which the meter puts out, so I take it 3.8 acceptable and all I need to do is drive the vehicle more and let it sort itself out?

Torrid · 11-06-2007, 06:32 PM

Ok, I drove the car a while and the code went away, but now I'm kicking a few other codes. IAT, easy fix, I'll slap a new one in as soon as I can. The second one is the Idle Air Control Valve Control Circuit. I've seen this on this site when I did a search and it appears that my first course of action will be cleaning the throttle body. The most confusing one for me right now is the Vehicle Speed Sensor malfunction code. I was told by a few places that the main issue on these cars is a bad pin-out on a failing gauge control module, which I had replaced two years ago and the code just came back this week. I don't believe it is the sensor itself or a bad connection as the speedometer never fluctuates and it is accurate at all times. There are a number of speed zones here that have the digital readout on the side of the road and the speedometer is always reading at 1 mph fast, which I know is common.

First question, would a dirty throttle body cause the car to die when starting? I know it can make it idle low, so I'll try that first as I said.

Second question, is there another issue I should know about with the VSS's on these cars, or am I having an unusual issue?

s13rookie · 11-06-2007, 10:13 PM

the idle air control problem wont be fixed by cleaning the throttle body. The iacv can be cleaned on its own though. There is an adjustment screw on it, you may want to start there. Ihad a badly out of adjustment one when i got my car and it would die as i coasted to a red light. Cleaning the TB couldnt hurt though.

Did you check the resistance of the tps?

Torrid · 11-07-2007, 07:01 PM

Quote:

Originally Posted by s13rookie

the idle air control problem wont be fixed by cleaning the throttle body. The iacv can be cleaned on its own though. There is an adjustment screw on it, you may want to start there. Ihad a badly out of adjustment one when i got my car and it would die as i coasted to a red light. Cleaning the TB couldnt hurt though.

Did you check the resistance of the tps?

No, I haven't checked it yet, I didn't think anything of it as I wasn't getting that code. Is the IACV close to the throttle body? I want to make sure I'm getting at the right thing as I'm trying to fix the problem instead of throwing parts at it. I'll try cleaning it and then adjusting it from there as necessary.

Jung918 · 11-07-2007, 07:49 PM

Pull out the multi meter again. It is not necessary to go buy parts simply because there is a check engine light for it. It could also be a wire issue.
Check the fsm for proper volatage/ohms.

camppain · 11-07-2007, 08:29 PM

Try to reground your maf wire to the engine block, Nissans have bad issues with these. I know Se-r's do at least.

Torrid · 11-08-2007, 05:06 PM

Yeah, I'm just going to clean the IACV and check voltage for now. I purposely didn't clear the codes so I would know if what I'm doing is fixing the issue. The MAF code did go away on its own after putting in a new MAF. I've checking voltage/resistance on corresponding wires based on the readings I've got compared to the expected readings, it is well within range. I'm really hoping the IACV clean is going to take care of that issue.

s13rookie · 11-08-2007, 05:15 PM

^^ you should clear the codes after you try a fix. the ecu wont always fix clear itself as a lot of times if a code was thrown the ecu wont even check to see if the problem has been corrected.

Whats up camppain? I remember getting drunk and arguing with you years ago......ah, the good old days

Torrid · 11-08-2007, 06:05 PM

The IACV looked pretty good, cleaned off any gunk I saw. Then I decided to check the idle, there's the problem. the screw was backed most of the way out, almost flush with the panel and the head of the screw was broken off! I have no idea how I'm going to get it out to put a new one in.

s13rookie · 11-08-2007, 06:09 PM

Drill the bitch!!!

....carefully though

RedtopTech · 11-08-2007, 06:17 PM

sounds like all of your issues deal with a componant with a 5 volt reference. If your MAFS only had 3.8 v powering it then that is a problem. Do you have 5 volts powering the sensor or is that coming from the signal wire?

240trooper · 11-08-2007, 06:18 PM

my friend had the same problem, we got a new maf , it ran ok for a week then started acting up agina, took to someone and he checked the wire that from dist. and fround a faulty one ,fixed it and the car ran good for a week or two then it started dieing at lights in low rpm's. so we put a stotck intake with box back on and made sure everything was egtting good airflow ,same thing when at idel it jumped up and down and coming to a stop wound die. we had the alt. check it was good. as i was putting the alt back i noticed the belt from the power steering was loose. i tightn it and the car has not died since. thus the problem was a belt at low rpms it wasnt feeding of the power wich made the car die, unlucky my friend bought a 95 ka and now dosnt need it. his has been running better than when he bought it now. My advice check ur belts and ur wire's

Torrid · 11-08-2007, 06:42 PM

Quote:

Originally Posted by RedtopTech

sounds like all of your issues deal with a componant with a 5 volt reference. If your MAFS only had 3.8 v powering it then that is a problem. Do you have 5 volts powering the sensor or is that coming from the signal wire?

No, voltage was fine, the signal wire was at 3.8 ohms, without the unit connected. The code went away and it was fine. The main issue I have is an extremely low idle and its from the screw being backed out most of the way and the head of the screw is snapped off so I'm unable to raise the idle until I can figure out a way to get it out and put a new screw in. The IAT resistance is extremely high, well over 10k ohms at 90 degrees. I know the IAT needs replaced and that's my next course of action, but I'm wondering if the resistance this far off that it's running extremely rich and causing the idle issue. I never checked it before to see where the screw was set for the idle so I don't know if it's normal. The screw is only holding the throttle back about an eighth of an inch.

s13rookie · 11-08-2007, 06:45 PM

Quote:

Originally Posted by Torrid

No, voltage was fine, the signal wire was at 3.8 ohms, without the unit if it's normal.

Looks like you measured resistance, not voltage. they are not the same

Torrid · 11-08-2007, 07:29 PM

Quote:

Originally Posted by s13rookie

Looks like you measured resistance, not voltage. they are not the same

I'm aware of that, I said voltage was fine and that was the resistance. When it comes to cars, electronics are what I know. I'm MECP first class certified.

s13rookie · 11-08-2007, 08:18 PM

I was MECP cert'd back in the day.... anyways, i was just making sure, its suprising the amount of people that misuse/ dont know how to use a mulitmeter

camppain · 11-08-2007, 10:49 PM

It's always something "simple" as in what you would have never though.

Drunk back in the days? When and where? How do I know you?

Torrid · 11-09-2007, 05:53 AM

It's just the process of going through and figuring this thing out. Its actually my wife's car and since she's had it, it's had quite a few issues as of late. I've had a Nissan, but didn't keep it very long, 2005 Spec V and realized this is one car Nissan dropped the ball on, so I traded it for a GTO. Anyway, I'm starting to wonder if some of these problems are from the bad IAT. With it reading such a high resistance it's seeing the intake air as extremely cold. If it's dumping large amounts of fuel because of this I would think that would be enough to choak it off at idle, especially considering it has been 80+ here still. I'd rather not just start adjusting the idle if it's just a bandaid fix to another issue.

Torrid · 11-18-2007, 11:45 AM

I feel like an idiot right now. Last time I worked on the car I sprayed the throttle control screw down thinking the head of the screw was broken off, hoping I could turn it by hand. I still couldn't get it out. Today I actually got in the car to go wash it and the idle flat out sucked. I popped the hood and see the screw is hanging on by a thread. I pull it out and look, hex screw! I went in, found the proper hex driver, grabbed some blue loctite, cleaned the K&N filter on the CAI, and the throttle plate. I put the screw back in, started it up and the car was idling at 2,500. Started backing the screw down and bam! 950 RPM idle, 650-700 RPM idle in gear. I'm hoping between cleaning it and adjusting the idle using the loctite, now knowing it's not going to be able to back out that it's enough to solve the the issue throwing the code. I have the IAT sensor on order and should be here tomorrow. Now all I need to figure out is why I'm getting the VSS code.

11-04-2007, 05:01 PM	#1
Torrid Join Date: Nov 2007 Location: Phoenix, AZ Age: 40 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	Mass Air Flow issue 1996 240SX. I kept getting the code for Mass Air Flow, forget the exact code. Anyway, went ahead and replaced the MAF and while the car starts better and idles better, it doesn't feel exactly like it did before I was getting this code. I finally got smart and grabbed the multimeter and checked out the connections. The one thing I read was that pin 2 in the harness for the maf was to read 5 ohms. I'm reading 3.8 ohms across this. Should I be worried or does it take time for the car to adjust to a new MAF? I know when it comes to speakers, when impedance is rated at 4 ohms, a speaker is going to read 3.2 because of the frequency at which the meter puts out, so I take it 3.8 acceptable and all I need to do is drive the vehicle more and let it sort itself out?

11-06-2007, 10:13 PM	#3
s13rookie Zilvia FREAK! Join Date: Mar 2002 Location: connecticut Age: 44 Posts: 1,129 Trader Rating: (0) Feedback Score: 0 reviews	the idle air control problem wont be fixed by cleaning the throttle body. The iacv can be cleaned on its own though. There is an adjustment screw on it, you may want to start there. Ihad a badly out of adjustment one when i got my car and it would die as i coasted to a red light. Cleaning the TB couldnt hurt though. Did you check the resistance of the tps? __________________ Ive spent most of my money on cars and women...the rest i wasted

11-07-2007, 07:49 PM	#5
Jung918 Post Whore! Join Date: Oct 2003 Location: CA Posts: 3,203 Trader Rating: (2) Feedback Score: 2 reviews	Pull out the multi meter again. It is not necessary to go buy parts simply because there is a check engine light for it. It could also be a wire issue. Check the fsm for proper volatage/ohms. __________________ Sale: Hello Kitty Horn Button S14 Rear Valences K.Y. Gordon the Thief (Tony Chen)

11-07-2007, 08:29 PM	#6
camppain Will never get banned... Join Date: Sep 2001 Location: San Diego CA Age: 45 Posts: 1,510 Trader Rating: (0) Feedback Score: 0 reviews	Try to reground your maf wire to the engine block, Nissans have bad issues with these. I know Se-r's do at least. __________________ -=-99 Sentra SE 5 speed-=- -=-95 240 SE 5 speed-=-

11-08-2007, 05:15 PM	#8
s13rookie Zilvia FREAK! Join Date: Mar 2002 Location: connecticut Age: 44 Posts: 1,129 Trader Rating: (0) Feedback Score: 0 reviews	^^ you should clear the codes after you try a fix. the ecu wont always fix clear itself as a lot of times if a code was thrown the ecu wont even check to see if the problem has been corrected. Whats up camppain? I remember getting drunk and arguing with you years ago......ah, the good old days __________________ Ive spent most of my money on cars and women...the rest i wasted

11-06-2007, 06:32 PM	#2
Torrid Join Date: Nov 2007 Location: Phoenix, AZ Age: 40 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	Ok, I drove the car a while and the code went away, but now I'm kicking a few other codes. IAT, easy fix, I'll slap a new one in as soon as I can. The second one is the Idle Air Control Valve Control Circuit. I've seen this on this site when I did a search and it appears that my first course of action will be cleaning the throttle body. The most confusing one for me right now is the Vehicle Speed Sensor malfunction code. I was told by a few places that the main issue on these cars is a bad pin-out on a failing gauge control module, which I had replaced two years ago and the code just came back this week. I don't believe it is the sensor itself or a bad connection as the speedometer never fluctuates and it is accurate at all times. There are a number of speed zones here that have the digital readout on the side of the road and the speedometer is always reading at 1 mph fast, which I know is common. First question, would a dirty throttle body cause the car to die when starting? I know it can make it idle low, so I'll try that first as I said. Second question, is there another issue I should know about with the VSS's on these cars, or am I having an unusual issue?

11-08-2007, 05:06 PM	#7
Torrid Join Date: Nov 2007 Location: Phoenix, AZ Age: 40 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	Yeah, I'm just going to clean the IACV and check voltage for now. I purposely didn't clear the codes so I would know if what I'm doing is fixing the issue. The MAF code did go away on its own after putting in a new MAF. I've checking voltage/resistance on corresponding wires based on the readings I've got compared to the expected readings, it is well within range. I'm really hoping the IACV clean is going to take care of that issue.

11-08-2007, 06:05 PM	#9
Torrid Join Date: Nov 2007 Location: Phoenix, AZ Age: 40 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	The IACV looked pretty good, cleaned off any gunk I saw. Then I decided to check the idle, there's the problem. the screw was backed most of the way out, almost flush with the panel and the head of the screw was broken off! I have no idea how I'm going to get it out to put a new one in.

11-08-2007, 06:09 PM	#10
s13rookie Zilvia FREAK! Join Date: Mar 2002 Location: connecticut Age: 44 Posts: 1,129 Trader Rating: (0) Feedback Score: 0 reviews	Drill the bitch!!! ....carefully though __________________ Ive spent most of my money on cars and women...the rest i wasted

11-08-2007, 06:17 PM	#11
RedtopTech Zilvia Member Join Date: Dec 2005 Location: Virginia Beach, VA Age: 40 Posts: 293 Trader Rating: (0) Feedback Score: 0 reviews	sounds like all of your issues deal with a componant with a 5 volt reference. If your MAFS only had 3.8 v powering it then that is a problem. Do you have 5 volts powering the sensor or is that coming from the signal wire?

11-08-2007, 06:18 PM	#12
240trooper Zilvia Addict Join Date: Sep 2003 Location: Torrance, California Posts: 791 Trader Rating: (10) Feedback Score: 10 reviews	my friend had the same problem, we got a new maf , it ran ok for a week then started acting up agina, took to someone and he checked the wire that from dist. and fround a faulty one ,fixed it and the car ran good for a week or two then it started dieing at lights in low rpm's. so we put a stotck intake with box back on and made sure everything was egtting good airflow ,same thing when at idel it jumped up and down and coming to a stop wound die. we had the alt. check it was good. as i was putting the alt back i noticed the belt from the power steering was loose. i tightn it and the car has not died since. thus the problem was a belt at low rpms it wasnt feeding of the power wich made the car die, unlucky my friend bought a 95 ka and now dosnt need it. his has been running better than when he bought it now. My advice check ur belts and ur wire's __________________ 2.7L

11-08-2007, 08:18 PM	#16
s13rookie Zilvia FREAK! Join Date: Mar 2002 Location: connecticut Age: 44 Posts: 1,129 Trader Rating: (0) Feedback Score: 0 reviews	I was MECP cert'd back in the day.... anyways, i was just making sure, its suprising the amount of people that misuse/ dont know how to use a mulitmeter __________________ Ive spent most of my money on cars and women...the rest i wasted

11-08-2007, 10:49 PM	#17
camppain Will never get banned... Join Date: Sep 2001 Location: San Diego CA Age: 45 Posts: 1,510 Trader Rating: (0) Feedback Score: 0 reviews	It's always something "simple" as in what you would have never though. Drunk back in the days? When and where? How do I know you? __________________ -=-99 Sentra SE 5 speed-=- -=-95 240 SE 5 speed-=-

11-09-2007, 05:53 AM	#18
Torrid Join Date: Nov 2007 Location: Phoenix, AZ Age: 40 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	It's just the process of going through and figuring this thing out. Its actually my wife's car and since she's had it, it's had quite a few issues as of late. I've had a Nissan, but didn't keep it very long, 2005 Spec V and realized this is one car Nissan dropped the ball on, so I traded it for a GTO. Anyway, I'm starting to wonder if some of these problems are from the bad IAT. With it reading such a high resistance it's seeing the intake air as extremely cold. If it's dumping large amounts of fuel because of this I would think that would be enough to choak it off at idle, especially considering it has been 80+ here still. I'd rather not just start adjusting the idle if it's just a bandaid fix to another issue.

11-18-2007, 11:45 AM	#19
Torrid Join Date: Nov 2007 Location: Phoenix, AZ Age: 40 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	I feel like an idiot right now. Last time I worked on the car I sprayed the throttle control screw down thinking the head of the screw was broken off, hoping I could turn it by hand. I still couldn't get it out. Today I actually got in the car to go wash it and the idle flat out sucked. I popped the hood and see the screw is hanging on by a thread. I pull it out and look, hex screw! I went in, found the proper hex driver, grabbed some blue loctite, cleaned the K&N filter on the CAI, and the throttle plate. I put the screw back in, started it up and the car was idling at 2,500. Started backing the screw down and bam! 950 RPM idle, 650-700 RPM idle in gear. I'm hoping between cleaning it and adjusting the idle using the loctite, now knowing it's not going to be able to back out that it's enough to solve the the issue throwing the code. I have the IAT sensor on order and should be here tomorrow. Now all I need to figure out is why I'm getting the VSS code.