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help me decide, (long but could be helpful)

738 Views 5 Replies 2 Participants Last post by  lild
if i'm going in the right direction on this.
the problem is the famous cold start 30 sec. rough idle.
i have just about replaced every thing to fix it. let's see
the secoundary air pump,with air control valve ( had check engine light), just about all vaccum hoses, both pre cat 02's(also had light), ect sensor (the one for the ecu/also know as a double temp sensor) cam pos. sensor, fuel filter, plugs/coil boots, maf (needed too), had valve cover leak, so put on new gasket, which was done well before the rough idle, new stock air filter. also twice i got po170 codes, which in turn killed my bank 1 sensor 1 02 twice.

so in researching the 0170 code everything pointed to a intake manifold leak. so 2 weekends ago i did a complete intake manifold gasket rebuild. replace both intake gaskets, the air temp sensor gasket, cleaned the air temp sensor itself, clean the intake, beat i could, replace both tb gaskets, and cleaned the tb's. now i must say, this was money right here well spent. i have regain throttle response i didn't even know i had.

but still rough idle on cold start. so now i belive it is a fuel delivery problem. like as in, needin a new fuel pressure regulator. when i start the car, the rpm's go up smoothly to 1200 and smoth back down to 800 rpm, and then rough idles a little. the past couple of days i keep my foot on the gas to keep up between 12-1500 rpm's for a few secs. and it's fine.

so what ya think? new fuel pres. reg.? i'm think on a cold start it use's what fuel is in the rail, and then has to really suck to get gas, or it's losing fuel pressure durring long sits.
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Idle sensor???

i thought that, but it idle's fine after it does it's thing. after that for the rest of the day it starts fine, runs strong. it only does it if it sits more than 4hrs.
I used to have that "after 4hrs" thing (or basically in the morning and after work). I fixed it with replacing all the vacuum lines (which you did). I also replaced the crankcase vent / oil separator at the same time. Basically it boiled down to misfire.

But if somebody can verify that idle control sensor or camshaft positioning sensor will either play, or not play a part in your problem.

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