How important is it for the temp sensor to be in front of the MAF sensor?
01-05-2001, 05:48 PM
#1
Not DAVEB the parts guy
Thread Starter
Join Date: Aug 2000
Posts: 8,555
This is confusing so read carefully:
In the quest to get rid of the stock intake resonator on the intake tract, something caught my eye. My HKS intake is a bit different from the standard POP intake because the HKS actually has a section of metal 3" pipe in which the temp sensor bolts in to. On the other side of this pipe is a 1/2" vacumn hole for the 240sx application. This hole is capped off since the Max doesn't use it. Anyways, I played around with the HKS intake and pulled out the stock intake resonator. The HKS intake system works without the intake resontor if I take the metal pipe with the temp sensor and attach it to the intake elbow off the throttle body. I then took some hose "T's" and bought some extra vacumn hose and connected the three vacumn lines to the HKS metal pipe via the unused 1/2" hole I discussed earlier. The HKS air filter attaches via a silcone hose onto the MAF. The setup reads like this starting at the throttle body and working it self towards the filter:
Throttle body->temp sensor and vacumn lines->MAF->air filter
Is this okay? I don't see why not. I drove around for a good 20 minutes and gave a it few WOT bursts. The engine set off no codes and ran perfectly fine at all rpms. The intake is quite bit deeper sounding now. I can't tell much from my butt dyno when you're adding maybe 1-2hp at best.
Is this okay to do?
Dave
In the quest to get rid of the stock intake resonator on the intake tract, something caught my eye. My HKS intake is a bit different from the standard POP intake because the HKS actually has a section of metal 3" pipe in which the temp sensor bolts in to. On the other side of this pipe is a 1/2" vacumn hole for the 240sx application. This hole is capped off since the Max doesn't use it. Anyways, I played around with the HKS intake and pulled out the stock intake resonator. The HKS intake system works without the intake resontor if I take the metal pipe with the temp sensor and attach it to the intake elbow off the throttle body. I then took some hose "T's" and bought some extra vacumn hose and connected the three vacumn lines to the HKS metal pipe via the unused 1/2" hole I discussed earlier. The HKS air filter attaches via a silcone hose onto the MAF. The setup reads like this starting at the throttle body and working it self towards the filter:
Throttle body->temp sensor and vacumn lines->MAF->air filter
Is this okay? I don't see why not. I drove around for a good 20 minutes and gave a it few WOT bursts. The engine set off no codes and ran perfectly fine at all rpms. The intake is quite bit deeper sounding now. I can't tell much from my butt dyno when you're adding maybe 1-2hp at best.
Is this okay to do?
Dave
01-05-2001, 06:53 PM
#2
As long as its in the direct path of the air flow thats fine.
I have heard conflicting stories on wht the IAT actually effects. It probablly effects the fine tuning of fuel & timing maps. The Nissan shop manual says it is used for diagnostics only? I have a feeling that it does more than that...
I have heard conflicting stories on wht the IAT actually effects. It probablly effects the fine tuning of fuel & timing maps. The Nissan shop manual says it is used for diagnostics only? I have a feeling that it does more than that...
01-05-2001, 07:20 PM
#3
Not DAVEB the parts guy
Thread Starter
Join Date: Aug 2000
Posts: 8,555
Thanks for the input.
I think it's purpose is directly related to fuel and timing because the motor uses the information to determine the correct fuel mixture for the temperature of the incoming air. I figured it would be okay as long as the sensor is in the direct path on incoming air and the temp sensor and MAF are still within close proximity of each other. We'll see how it goes.
Dave
I think it's purpose is directly related to fuel and timing because the motor uses the information to determine the correct fuel mixture for the temperature of the incoming air. I figured it would be okay as long as the sensor is in the direct path on incoming air and the temp sensor and MAF are still within close proximity of each other. We'll see how it goes.
Dave
01-05-2001, 09:08 PM
#4
Member
Join Date: Dec 2000
Posts: 253
The air intake temperature sensor is only there because OBD II says it needs to be there. It has NOTHING to do with changing any fuel curves, injector pulse width, or any thing else.
The VQ30DE's fuel injection is "mass air flow" (MAF), and because the MAF sensor is measuring MASS, the ECU does not care what the temperature is. Air is more dense as the temperature drops, and the MAF sensor reading will indicate a higher mass, and the ECU figures out the rest.
Other (cheaper) fuel injection systems are "Speed Density", and the MUST have a air intake temperature sensor because the use the current air pressure, throttle position, intake vacuum, and some even use a humidity sensor to calculate how much fuel is needed at that time.
The VQ30DE's fuel injection is "mass air flow" (MAF), and because the MAF sensor is measuring MASS, the ECU does not care what the temperature is. Air is more dense as the temperature drops, and the MAF sensor reading will indicate a higher mass, and the ECU figures out the rest.
Other (cheaper) fuel injection systems are "Speed Density", and the MUST have a air intake temperature sensor because the use the current air pressure, throttle position, intake vacuum, and some even use a humidity sensor to calculate how much fuel is needed at that time.
01-06-2001, 07:33 AM
#5
MAXVQ, You know this because why? Are you a Nissan tech? Or have you already tried to play with the sensor signal? No flame, just curious.
I am considering putting a resistor in line with the IAT signal to the ECU to trick the ECU. I dont have a way to view timing yet, OBDII scan tool, so I will be doing it blind.
I'm a DIY and usually believe what I read. Is the LS1, LT1 with MAF's speed density? They have a mod to trick the ecu that plays with the IAT.
http://www.sscamaro.com/view_product...RTNUMBER=63010
I am considering putting a resistor in line with the IAT signal to the ECU to trick the ECU. I dont have a way to view timing yet, OBDII scan tool, so I will be doing it blind.
I'm a DIY and usually believe what I read. Is the LS1, LT1 with MAF's speed density? They have a mod to trick the ecu that plays with the IAT.
http://www.sscamaro.com/view_product...RTNUMBER=63010
01-10-2001, 08:47 PM
#6
Member
Join Date: Dec 2000
Posts: 253
MardiGrasMax,
Sorry for the late reply.
I don't know too much about the LS1 & LT1 motors.
By "tricking" the IAT sensor to be a colder engine on a SPEED Density fuel injection system, the mixture will be richer.
The theory is more gas = more power.
Some mass air fuel injection systems use an air flow sensor that measures air flow, with out taking into consideration air density (AKA temperature) One example is the FLAP type air flow meter on a 89 Ford Escort GT.
With the Maxima (and many others) the MAF is a hot wire type. This does take into consideration air density.
The current flowing thru the "hot wire" is in the path of the intake air. As the air flows over this heated wire, the wire is cooled, the resistance changes, and the MAF increases the current to heat the wire more. This increase in current = more air flow.
The flap type has no idea about air density, and uses a IAT sensor to find this out.
After all this has been said, I think the Vette motor is MAF, with a hot wire system. So I have no clue how the 5-7 HP can be. (after all, this is less than a 2% improvment)
To answer your FIRST question, I know this because I have many, many SAE books all around me.
Sorry for the late reply.
I don't know too much about the LS1 & LT1 motors.
By "tricking" the IAT sensor to be a colder engine on a SPEED Density fuel injection system, the mixture will be richer.
The theory is more gas = more power.
Some mass air fuel injection systems use an air flow sensor that measures air flow, with out taking into consideration air density (AKA temperature) One example is the FLAP type air flow meter on a 89 Ford Escort GT.
With the Maxima (and many others) the MAF is a hot wire type. This does take into consideration air density.
The current flowing thru the "hot wire" is in the path of the intake air. As the air flows over this heated wire, the wire is cooled, the resistance changes, and the MAF increases the current to heat the wire more. This increase in current = more air flow.
The flap type has no idea about air density, and uses a IAT sensor to find this out.
After all this has been said, I think the Vette motor is MAF, with a hot wire system. So I have no clue how the 5-7 HP can be. (after all, this is less than a 2% improvment)
To answer your FIRST question, I know this because I have many, many SAE books all around me.
01-10-2001, 09:42 PM
#7
Senior Member
Join Date: Sep 2000
Posts: 886
more gas doesn't equal more power
the leaner you can run a car with out detonation the more power it can achieve in a sense
i have seen it done on a dyno. there is a fine line between rich, perfect, and detonation
the automoeter and cyberdyne a/f gauges can't do this. you need a wide band O2. to even figure it out
or just look at my lap top. at wide open in run 13.0 a/f
kinda rich in a sense. but when boost hits. it leans out to a point
in the safe zone
dave. just drill a hole in the intake pipe itself and shove that IAT sensor in it.
my max didn't have one
the leaner you can run a car with out detonation the more power it can achieve in a sense
i have seen it done on a dyno. there is a fine line between rich, perfect, and detonation
the automoeter and cyberdyne a/f gauges can't do this. you need a wide band O2. to even figure it out
or just look at my lap top. at wide open in run 13.0 a/f
kinda rich in a sense. but when boost hits. it leans out to a point
in the safe zone
dave. just drill a hole in the intake pipe itself and shove that IAT sensor in it.
my max didn't have one
Thread
Thread Starter
Forum
Replies
Last Post
kjlouis
4th Generation Maxima (1995-1999)
11
11-24-2018 06:09 AM
vingodine
5th Generation Classifieds (2000-2003)
45
05-21-2016 12:46 PM