Question for Larry B - Intake manifold.

[Jin1976]

I'll try to explain the current situation as best as possible. The shop where I sent my NSX to had tempered with the two screws that control the opening in the intake manifold. The screws are painted yellow by factory and is located under the throttle body. My friend who is also an expert mechanics wants me to ask the forum what is the best procedure to remedy this situation. What he want to know is to what position should the two screw be adjusted and what is the minimum opening the holes in the intake manifold should have. I've tried to find the procedure in the repair manual but couldn't find it because I don't know what the holes in the intake manifold are called and what they look like. When the throttle is pressed the sound under the manifold cover is like a typewriter.

Many thanks in advance.

 

[Larry Bastanza]

Hi Jin1976,

Sorry to say, I cannot advise on this. The reason there is nothing in the service manual is these should never be tampered with. I do not know the preset values for the butterflies.

Good Luck,
Regards,
LarryB

 

[drew]

I spoke to Basch about this a while back. He states there is no calibration process outside of the factory for certain yellow painted screws.

I suspect your unit is junk if they cannot line up the screws with the factory applied markings.

Good luck

Drew

 

[Larry Bastanza]

The only other option here is the have one that has not been messed with and compare the measurements.

Not sure this helps, but.....

LarryB

 

[Jin1976]

Thanks Larry and Drew for the advise. Btw how much is the new TB cost?

 

[Briank]

Are you talking about the throttle plate stop or the stops for the varable induction butterflys? Can you post a picture??

 

[Jin1976]

Its the one under the intake manifold. The screws that control the six holes is located under the throttle body painted yellow. When I got time I'll take a photo of it.

Are you talking about the throttle plate stop or the stops for the varable induction butterflys? Can you post a picture??

 

[ScienceofSpeed]

I think you're talking about the stops for the VVIS - factory adjustable intake system. These prevent the steel throttle plates from galling into the aluminum casting of the intake manifold. You'll need to remove the intake manifold to reset the stop position to do it correctly. Once removed you'll be able to see the butterflies and be able to set the stop screw.

No need to buy a new one.

take care,
-- Chris

 

[Jin1976]

That is the one. Straight to the point Chris. Is there any proper procedure to do this as I can't find it in the repair manual. Any measurement involve? Thanks.

I think you're talking about the stops for the VVIS - factory adjustable intake system. These prevent the steel throttle plates from galling into the aluminum casting of the intake manifold. You'll need to remove the intake manifold to reset the stop position to do it correctly. Once removed you'll be able to see the butterflies and be able to set the stop screw.

No need to buy a new one.

take care,
-- Chris

 

[Jin1976]

My mechanic friend manage to bring back the setting for the opening of the butterfly valves inside the intake manifold. He also checked the resistance of each fuel injectors and found that one injector has 2.4 ohms, four with 2.5 ohms and one with 2.6 ohms. I guess the injectors are nearing the end of the service lives. Could that be the reason why my engine has been running rich lately? Btw the photo I took for the intake manifold was not bright enough as we were doing it around 6PM and its already getting dark. Idling now seems to be stable.

 

[Larry Bastanza]

Chirs,

With that in mind, it would seem best to set the throttle plates by using a light source, and just closing them until they are sealed. Make sense?

Regards,
LarryB

 

[Jin1976]

Yes. That was exactly what he did. That's why my photo was not very clear. Maybe I'll post it tomorrow. He just adjusted the two screws that controlled the butterfly opening. No more typewriter sound from under the manifold.:smile:

Chirs,

With that in mind, it would seem best to set the throttle plates by using a light source, and just closing them until they are sealed. Make sense?

Regards,
LarryB

 

[chado]

Bump.

Ramon looked at and listened to mine again today and came up with the possibility that one or more of the screws on one or more of the butterfly valves could be loose and therefore causing the rattling that is heard when they are openned under acceleration.
He's going to pull the intake manifold and check all of them. Tom (another mechanic also agreed) as they've seen this on one other car that was raced. These screws should be good for life from the factory.. why my car!! :frown:

Larry, Chris, Brian... any of you guys have any futher experience with this?

Just curious...

Thanks,

chad

 

[Briank]

I have never heard of a problem with the screws coming loose and it's even more unlikely to have happened. Any parts that could fall off and be ingested into the engine are lock tighted or staked to make sure they don't come loose. I my opinion its more likelly they are just rattling against the manifold or the stops if the noise is coming from the VVIS at all.

 

[Larry Bastanza]

I have seen this on a car I installed a CTSC on. I removed the air inatake and set it aside. When I was cleaning up after the job, I moved the intake and it rattled. I disassembled it, and found a few of the butterfly screws laying in the manifold.

If you think this is it, do not really drive the car, get it checked. Sucking in one of those screws would make for a very bad day for both your engine and wallet.

HTH,
LarryB

 

[chado]

I have seen this on a car I installed a CTSC on. I removed the air inatake and set it aside. When I was cleaning up after the job, I moved the intake and it rattled. I disassembled it, and found a few of the butterfly screws laying in the manifold.

If you think this is it, do not really drive the car, get it checked. Sucking in one of those screws would make for a very bad day for both your engine and wallet.

HTH,
LarryB

Exactly!

Thanks Brian and Larry. The car is just sitting and I've placed an order for replacement gaskets. Hopefully I can get Ramon to do it Friday so that I can drive it on Saturday!
Scary thought that one little screw can have huge consequences!