Timing issue causing car to be sluggish?

[Skym]

With a airleak to IACV (IACV is connected to intake plenum) or AACV, engine probably won't start. IACV is only used when engine is cold, so engine needs to be warmed up, driven (to make sure it's up to temp) before you disconnect IACV.

AACV is the valve facing firewall and is used when engine is warm.

IACV is the valve that's located on the bottom runners, under top half of intake plenum, right next to throttlebody and is only used when engine is cold (known as a automatic choke). Once engine is warm it's not used anymore.

On early 80's Nissan's, old school muscle cars, etc you would have known it as a knob on dash that you press in as engine warms up (manual choke). They switched to automatic choke, so can drive car while engine warms up.

Hose to AACV goes like this -

Intake pipe that goes over top of engine > hose > T fitting > hose > AACV.

Off the T fitting it goes like this -

hose > IACV > hose > nipple on bottom of top half of intake plenum.

What you do is -

Remove hose going to IACV from T fitting
Block hose going to IACV so there's no intake airleaks
Block T fitting so there's no intake airleaks to AACV

Start engine and if idle is around 650rpm you have found your problem.

[krystalized_jdm]

Okay, thanks for explaining I will try that in the morning!

Hopefully it is the IACV as I have an extra I picked up a while ago

Thanks sky!

[krystalized_jdm]

Did everything you said to test iacv (one below throttle body) and it didn't change the idle. Where should I go from here?

[krystalized_jdm]

Had a bit of hesitation tonight at WOT. Car pulls harder an accelerates faster at under half throttle then it does at WOT. Any suggestions?


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[krystalized_jdm]

I am sad to admit that this may be a cause, and I will be ordering a new gasket tonight.

When I first purchased the car, it had a terrible misfire problem to the point it could barely run, after taking it to a **** mechanic that spit so much B.S even knowing nothing about cars I knew he was wrong.

I had a flapping noise near my turbo, the turbo was missing nuts on the manifold (as in 2/4 bolts were holding the turbo on)

I'm thinking that after reading this

http://www.boostcruising.com.au/forums/index.php?showtopic=435186

that the gasket is pooched.

This thread is getting ranty, I wish my car would magically fix itself -.-

[Skym]

You're welcome. AACV might be adjusted too high to compensate for exhaust leak or similar, or have intake leak on intake plenum somewhere (common problem on RB20, RB25, RB26 where the intake gasket's blow, Cometic has upgraded gasket's for RB20).

The nuts coming undone on exhaust manifold to turbo joint is common if don't have the locking tabs there and cause a whistling sound at higher rpm (gasket being played like a reed in instrument). That gasket can blow and is a use once only type of gasket (should be replaced if remove, fit second hand or hybrid turbo). If have no locking tabs, then that might be a problem.

[krystalized_jdm]

There is locking tabs, but I did not replace the gasket. I have not touched the intake plenum in any way, shape or form. Is there a way of checking if my turbo is leaking? Possibly spraying water/soap and see if it bubbles?


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[krystalized_jdm]

Ran a propane torch around my vacuum an intercooler lines, no vacuum leaks. I tightened the bolts on my turbo and 3/4 weren't tight (they were snug but I got about another 1/4-1/2 turn more out of them) my car pulls harder on boost now but 4-5.5ish it feels flat and unresponsive.


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[Skym]

That's normal, ECU pulls ignition timing, runs slightly richer in that rpm range due to engine running leaner than it should. Might want to look at getting ECU tune before it blows the headgasket, rings, etc. Or at least fit a bigger lph fuel pump, hardwire fuel pump for 13.5 volts. Then it should run richer (safer) in that rpm range, so can save up for ECU tune which should correct engine running rich.

[krystalized_jdm]

Fair enough I don't drive my car hard so I should be okay putting aronud town. I plan to do a bit more before I venture over to calgary to get nistune (about 800-900 km from where I live) so I will just baby it until next season.

Thanks skym