Weird idle issue, can anybody chime in?

modmonster2008

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Sep 9, 2008
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timing marks are fine when pulley is at 0* TDC, they align with the top marks on the rear timing cover, as well as when the car is running and the jumper connectors are jumped the ignition timing is at 10* BTDC
 

modmonster2008

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CPS is sending a cosntant signal via oscilloscope, checked out the input coming to the coils the pulse on each igniter does not seem to be evenly distributed, What I think it is now is the igniter is not giving a strong constant pulse maybe that could be it?
 

boostcraver

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Mar 13, 2010
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I just read this whole thread and I thought i would put in a query of my own. Op, have you thought of putting a stock airbox and filter back on it or relocating the air filter a short distance further away from the AFM? I've seen a few cars (including one of my own) that acted funny like your describing and didn't want to run 100% when the air filter was too close to the AFM. Just puttin' it out there, don't know if it will help, but at this point I think you've tried everything else:)
 

modmonster2008

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Sep 9, 2008
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Thanks for the point outs guys. But I have seem to focus on something right now. I want to know because the fuel pressure-up has a VSV that controls when the fuel pressure regulator should be activated or not right? What part in the electrical system gives signal or voltage to the fuel pressure up vsv to allow the regulator to work? Seems like most of the time the thing is off so the regulator is always activated all the time, when i remove the regulator the idle runs a LOT more smoother?
 

hvyman

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Apr 17, 2007
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What filter is on?

And did you verify that the cylinder was on tdc rather than just going off the crank pulley?

You have all the egr/emissions hooked up? Cali cars are special and i wouldnt remove any of that on them. You can see in the epc that they have special ecu's.
 

modmonster2008

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Sep 9, 2008
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EGR and emissions etc are hooked up, I just noticed that when the FPR vacuum hose is off the car idles a lot smoother, yes vacuum hose is plugged off. i am running a stock airbox, i was using a dry flow filter but the differences arent much (only noise differs). Everything is hooked up, no misrouted hoses or wires, but the idle is still rough for the first 15 mins of driving
 

modmonster2008

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Sep 9, 2008
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Wow. so after a month long of extensive research and collection of data on the electrical parts that make up the whole engine. I was almost about to give up till i decided to buy some carb cleaner and sprayed around the intake manifold area where i heard a loud HISS at idle and when the throttle is opened the hissing would disappear. Ordered a new intake manifold gasket set, fuel injector seal kit, and some other crap to seal the throttle gasket and ISCV gasket with, she idles perfectly around 700 rpm, will do some adjustments later on, but the multiple sources of unmetered intake leaks caused the huge mystery that is now solved!!
 

modmonster2008

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Sep 9, 2008
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Now my problem is that at times when its started up in the morning, the idle speed would be at around 2000-3000rpm's, and never wants to drop. Throttle linkage is fine not stuck. No codes at all just the regular flashing of the CEL light when the diag terminals are jumpered. Then at times when the temp is warmed up the idle would hunt from 1200-2000 rpm and just keep doing so. I noticed that the ISC valve doesnt make the constant tick when shut off more like a kinda click noise that you hear when something is jamming it inside. Though i have replaced the ISC with another known good working one and does the same kinda crap. Can anybody help me in on this one? Thanks
 

modmonster2008

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Sep 9, 2008
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Answered my own question. Some wires that lead to the ISCV were actually broken off at the terminal so i bought one off the yard and reconnected the wires to the existing harness, she runs great now!