Revs Droping

[Like_A_Sum_Bootay]

Every time i push the clutch in the car seems like its about to die revs drop then come back up and are erratic also tonight the car died twice and had to restart it. Anybody ever had this happen to them or know what the problem is? If you do i would appreciated some feed back. If you need any other details then just ask.

Car is a 1989 GTS-T RB20DET

[Skym]

TPS not touching idle contact or is faulty. If you put aircon, light's, etc on and load engine up with clutch, revs can drop on engine and could stall. More so when going up a steep hill.

There probably will be a TPS error code on ECU. Sometimes there isn't.

TPS (Throttle Position Sensor) is part of what ECU looks at for transient throttle enrichment. Basically is a electronic version of a accelerator pump on a carb engine. TPS sensor is located on side of throttlebody.

[Like_A_Sum_Bootay]

I've been hearing from other places that say just spray the throttle body with brake cleaner should i take the TPS off first?

[Skym]

Check ECU for error codes.

Can buy this cable, software which helps in checking for error codes, looking voltage from each sensor, etc -

http://www.blazt.biz/products/car_cable.php

Or go to local Nissan dealer where they use Consult (Nissan's hand held diagnostic computer). But they need the right cartridge for your model. A Nissan dealership that sells Skylines should be a Skyline specialist and have the correct cartridge for Consult.

In some cases throttle cable needs adjusting or throttlebody gets oil deposits around throttle plate due to oil from blowby via PCV system or blown turbo. Same with ide valves that sometimes need cleaning.

[Like_A_Sum_Bootay]

Also on rare occasions the car doesn't start till i give it a little bit of gas. Dunno if its because of the cold or another symptom.

[Skym]

Airleaks (intake hoseclamps not tight enough, cracked or old / hard rubber joiners)
TPS adjustment (touches idle contact which makes ECU switch to idle tables)
Incorrect oil
ECU start up tables need to be retuned
Leaking exhaust manifold
Fauty CAS (usually engine is hard to start when cold, hot and get CAS error code on ECU)

These can make engine harder to start. It's a process of elimination. But TPS might be the cause, as when combined with ECU start up tables being too rich, makes engine hard to start.

[Like_A_Sum_Bootay]

Would problems with the IAC (Idle Air Control Valve) cause any of this, anybody know where it is so that i can clean it out and try to see if it helps.

[Skym]

Most of the the time ECU tune is the cause. But airleaks, exhaust leaks, etc make it worse.

IACV is located on top of runners on lower part of intake plenum. If you look from front of car, it's just behind throttlebody.

AACV is located on top half of back of intake plenum (need new gasket if you remove it or make your own).

[beacher1B0]

If u havent cleaned your Iacv and aacv valves, you should. It will definetly help some.
Get yourself the RB engine service manual, check for ecu codes and youll be able to test/repair/adjust all sensors with that manual. And a consult cable would be a gift from god for diagnosing sensors.

Also, do u have an atmospheric BOV? That could cause your revs to go low or even stall inbetween shifts.
Does your car almost die when sitting still instead of driving?

[Like_A_Sum_Bootay]

If u havent cleaned your Iacv and aacv valves, you should. It will definetly help some.
Get yourself the RB engine service manual, check for ecu codes and youll be able to test/repair/adjust all sensors with that manual. And a consult cable would be a gift from god for diagnosing sensors.

Also, do u have an atmospheric BOV? That could cause your revs to go low or even stall inbetween shifts.
Does your car almost die when sitting still instead of driving?

I have a HKS SSQV and the car idles perfect problems happen when the clutch is pushed in or out.

[beacher1B0]

Sorry should of been more clear. Does your car rev drop/stall when u push in the clutch while vehicle is stationary?

[Like_A_Sum_Bootay]

Sorry should of been more clear. Does your car rev drop/stall when u push in the clutch while vehicle is stationary?

Yes it does. Well it doesn't almost die the RPM's just are a little erratic.

[beacher1B0]

Huh!
Try unplugging the clutch pedal switch, I think if it does make a difference its ECU related(sensors etc).
What other related mods do you have?
It sounds like its IACV related too me.

[Skym]

I see. Maybe HKS BOV is set too soft with preload nut (if it has one)???

[Like_A_Sum_Bootay]

Huh!
Try unplugging the clutch pedal switch, I think if it does make a difference its ECU related(sensors etc).
What other related mods do you have?
It sounds like its IACV related too me.

Its not jumping up and down crazy it just goes up or down an settles there till i lift off the pedal or push down again. As For mods the only performance mods are the BOV, Intake filter, and the turbo back exhaust.

I see. Maybe HKS BOV is set too soft with preload nut (if it has one)???

Theres no nut on the back like the older ones so i cant.