Help with airflow question ( "Y" pipe)

[300ZXttZMAN]

okk so you know how the on the z32 where the air filter is, there is that "Y" pipe (where the air filter hooks up to and then the plastic pipe splits to the right and the left) my car does not have the Y pipe it has an addapted filter that just mounts right up to the intake pipe... Could this cause my car not to be able to rev past 3500 rpm??? Has anyone else ran in to this "rev limit" problem??? does anyone else run their car this way without the "Y" pipe

I have changed all vacum lines
maf sensor
iac sensor
fuel filter
air filter
tps sensor
iac sensor

thanks for all the help

(my car is a 90 tt)

[300ZXttZMAN]

Update: if you text me ill send you a pic of what piece im talking about I have the "Y" pipe infront of me that i just went and took off my parts car unfortunetly its no good the car was in a front impact my phone number is 337 802 8848

[marty1mc]

If I am reading this correctly, you have an air filter mounted to one of the two intake pipes? If so, what is on the other one and where is the MAF mounted?

[300ZXttZMAN]

accually i miss understood the mechanic everything is set up right i just cant figure out what the hell is making it rev limit!!!!!!!!!!!!!

IF anyone has experienced a "rev-limit" please chime in

[itsa300zx]

okk so you know how the on the z32 where the air filter is, there is that "Y" pipe (where the air filter hooks up to and then the plastic pipe splits to the right and the left) my car does not have the Y pipe it has an addapted filter that just mounts right up to the intake pipe... Could this cause my car not to be able to rev past 3500 rpm??? Has anyone else ran in to this "rev limit" problem??? does anyone else run their car this way without the "Y" pipe

I have changed all vacum lines
maf sensor
iac sensor
fuel filter
air filter
tps sensor
iac sensor

thanks for all the help

(my car is a 90 tt)

Where are you mounting the MAF if you do not have the Y connector? THe MAF need to measure the total airflow into both sides (Land R). THe way you describe, sound like you are only measuring flow on one side. A picture would help?
Can you find a used Y connector?

[marty1mc]

Have you pulled codes? If so, are you getting any?

[300ZXttZMAN]

see thats the wierdest thing im not getting any codes its like the shop may have messed up on routing the hoses becasue my car didnt do that before i brought it to them... so they are lookiing at it but still if anyone knows about what would be making it
"rev limit" let me know plzz..... i miss my z

[300ZXttZMAN]

okk so you know how the on the z32 where the air filter is, there is that "Y" pipe (where the air filter hooks up to and then the plastic pipe splits to the right and the left) my car does not have the Y pipe it has an addapted filter that just mounts right up to the intake pipe... Could this cause my car not to be able to rev past 3500 rpm??? Has anyone else ran in to this "rev limit" problem??? does anyone else run their car this way without the "Y" pipe

I have changed all vacum lines
maf sensor
iac sensor
fuel filter
air filter
tps sensor
iac sensor

thanks for all the help

(my car is a 90 tt)

Where are you mounting the MAF if you do not have the Y connector? THe MAF need to measure the total airflow into both sides (Land R). THe way you describe, sound like you are only measuring flow on one side. A picture would help?
Can you find a used Y connector?

well i have a miss understanding with the shop who is working on my car they said that everything is normal as far as air intake is concerned the y pipe and everything are there but my question now is why on earth is my car doing this rev limit crapp which it didnt do that before i brought my car to the shop and now it does that so it almost seems like it has to be a vacum line not in the right place... ehh so close but yet still at the finished line

[BigTDogg (MA)]

see thats the wierdest thing im not getting any codes its like the shop may have messed up on routing the hoses becasue my car didnt do that before i brought it to them... so they are lookiing at it but still if anyone knows about what would be making it
"rev limit" let me know plzz..... i miss my z

sounds like an issue with the MAF circuit. Or your base timing (set by the CAS)

What work was recently done for your car to be at the mechanic?

[300ZXttZMAN]

alright bigTdog here is what i had the mechanic do
change both o2 sensors
change all boost/vac lines
replace valve cover gaskets
replace injectors and fuel rail plus injector o-rings
change iacv
change maf
change fuel filter
clean air filter (k&N)

and this is what my car was doing before i brought it to him
oil leak out of passenger side valve cover
fuel leak out of one of the injectors
would not hold idle (as soon as it was warmed up and i would clutch in at a redlight or something it would die)
and not very responsive (as far as the throttle response)

and now this is what my car is doing
fuel leak, idle problem, oil leak, acceleration are all fixed
BUT now the current problem is that the motor wont rev past 4kish rpm if you step into it hard BUT if you ease on the throttle the mechanic said it will go past 4k

all help is great also share other experiences

[NolimitZ32]

I dont get why its not going past 4k, if it was in limp mode it should cut out at 2.5k so I'm guessing you are getting a missfire around 4k. s the new MAF OEM or Chinese?

[300ZXttZMAN]

oem used that i ordered in and it improved response it just didnt cure the rev limit... So im begining to think that no one has ever heard of this problem.. i dont know what to do im going to try and get a video up by sometime next week but im taking it out of the shop today and im going to test different things this weekend...

So nobody has ever heard of this problem... just my luck

[nissanfreak12]

Is it possible that maybe the computer is cutting the fuel at that rpm range?

Have you tried to put on a fuel pressure gauge and see what happens when this is going on? Doesn't the tt have a dual stage fuel pump, or something to that effect, maybe when you floor it the pump cant handle that high amount of pressure that fast. Im just shooting stuff out here, but it almost sounds like a fuel issue since it cuts out at high rpm's.

[300ZXttZMAN]

good idea ill take a look at that and the fuel pressure regulator tonight... come on everyone give me more ideas im so close to be able to drive my z

[300ZXttZMAN]

also it sounds like it has a miss what is the sparkplug gap supposed to be???

[NolimitZ32]

Gap is .044 and FPR sounds like it could be a culprit or maybe your fuel pump is dieing either way check your active fuel pressure as in hook up a gauge to the system and go drive around make sure you're not loosing fuel pressure at higher rpm

[BigTDogg (MA)]

Gap is .044 and FPR sounds like it could be a culprit or maybe your fuel pump is dieing either way check your active fuel pressure as in hook up a gauge to the system and go drive around make sure you're not loosing fuel pressure at higher rpm

Losing fuel pressure would cause a studder, but also cause detonation. May be tough to hear over the studdering, but listen for it as well.

.044" for stock TTs is what's recommended. .035" for modified TTs running higher than stock boost

Fuel pressure is what needs to be checked next though.

None of the work you listed would cause this issue, IME. Provided he didn't over-oil the K&N

[300ZXttZMAN]

ok update my dad said he talked to him and he did already check fuel pressure that was the first thing he checked

[300ZXttZMAN]

sorry about the double post everyone

[dudewtf]

best bet post a video, a detailed video.

my guess are

spark plugs
ignition coils
timing
air restriction of some sort.

did you ever reset the computer yourself? not the mechanic, you. unplug the batter let it sit over night plug her bak in and start her up.

sometimes these mechanics over look simple s*** like this.

[BigTDogg (MA)]

You only need 30 minutes on a battery disconnect to reset the ECU, maybe even less.

[NolimitZ32]

did he check the fuel pressure at idle or under load, those are 2 very different conditions.

[BigTDogg (MA)]

did he check the fuel pressure at idle or under load, those are 2 very different conditions.

Correct, and a quick check to see if the regulator is working correctly is to disconnect the vacuum hose at idle. Should jump from 36ish PSI to 45ish PSI IIRC.