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Post by sleepinsol on Sept 13, 2009 19:26:12 GMT -5
this may seem typical, and yes ive done my searches and tried everything i came across. so heres the deal. car runs great when normal daily driving. absolutely superb in every manner. heres the problem tho. at WOT, i hit about 10 psi, and it sticks there for a second, hiccups, and then picks up to full boost and will carry pretty well til 4.5k rpm. all of this hiccuping happens between 3k rpm and 3.5k, then it sorts out and goes. im only running it on 15psi as of yet.
things ive done are: check for leaks in the plumbing, disconnect knock sensor, check fuel pressure, tighten down t bolts and clean up the vacuum tree (all lines there are tight as well), tighten clamp from boost valve to waste gate, change oil/filter
what im going to do soon: cap, rotor, plugs, wires, vc gasket.
i pulled codes but they were all from the continuous memory which was from before this motor went into it. cleared that and drove it home just now. before i did the above, the car would only make about 10psi and continuously break up and hiccup. the knock sensor helped a lot and im pretty sure fixing all my leaks and loose spots did as well since i picked up 5 psi and it carries more consistently.
anyone have any ideas of where i can go with this? fuel pressure is at 39psi with the line off, and like i said she runs great when normal driving. the ignition components were new, but the car sat for a year as well. im just looking for ideas at the moment. im lost on this one. go figure. thanks in advance.
-dan
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Post by Stinger on Sept 13, 2009 23:08:43 GMT -5
Does it run odd in any way when the boost "hangs" at 10psi for a second? Does it sputter, quit pulling, backfire, not pull as hard, etc?
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Post by sleepinsol on Sept 13, 2009 23:54:36 GMT -5
it sputters sort of. keep in mind im used to driving an n/a car that i can always tell when its running odd. it seems to sputter and hang at 10 psi, then cleans up and pulls. almost like im running too big a jet on a carb.
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Post by Stinger on Sept 14, 2009 10:22:26 GMT -5
It could be too rich at boost onset and takes a second to clean out and continue pulling.
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Post by oneowner88lx on Sept 14, 2009 12:12:38 GMT -5
What about checking the VAM voltage with an analog gauge while moving the door by hand and looking for "flat spots"? Could be a flat spot in there where voltage drops which would cause problems.
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Post by sleepinsol on Sept 14, 2009 13:27:52 GMT -5
i will try the voltage thingy with the vam. stinger, i set the fuel pressure at 39 psi like you reccomended. would you think advancing the timing or getting a tune up for it would help it not pig rich itself then? i know i need to get my wideband in it. that would give me a better idea of whats going on.
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Post by Stinger on Sept 14, 2009 13:50:49 GMT -5
They are pig rich in that range from the factory, increasing airflow with larger exhaust, cone filter, etc. as well as aftermarket boost valves all make the boost come on sooner and harder...only makes the problem worse.
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Post by sleepinsol on Sept 14, 2009 22:06:15 GMT -5
well dang. i was wondering what would happen if i cranked the psi up a couple more lbs thinking more air = leaner. but you answered my question. its still going to be pig rich there. any way i can fix this? couple degees extra timing? tune up? this is ruining my fun! lol
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Post by Stinger on Sept 15, 2009 11:42:01 GMT -5
More boost may fix it, nothing wrong with trying. Aside from getting a chip to tune the ecu, you need to do something to add more air at that rpm (if that's the problem).
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Post by sleepinsol on Sept 15, 2009 12:01:43 GMT -5
yes i know a chip would help big time. im going to try and notch up the boost i guess, and ill put the tune up and new vc gasket on this weekend with the roller cam. maybe that will help it too (not that a vc gasket would make it run this way). its odd how it falls flat at 3500, and from 4000 on it just cleans up and seems to nuts n get pretty good. you told me to start at 39 psi fuel pressure for my setup at 17-18 psi. im only at 14-15 now so perhaps the problem could be fixed.
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Post by sleepinsol on Sept 15, 2009 22:34:07 GMT -5
update. it was not as bad tonight after work. i was a little mad and decided i wanted to run er thru the gears. the breakup would usually start around 3200 rpm, get real bad at 3500, and then clear out by 4000 and pull nicely til i let out. now, its a slight hesitation at 3200 and its fully cleared by 3500 and pulls nicely til i let out. dunno why it was different tonight. perhaps i had bad gas or something in it. (the car had sat for about a year). ive run a couple tanks thru it of premium now tho. perhaps i should find some injector cleaner?
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Post by Stinger on Sept 17, 2009 19:43:44 GMT -5
Don't know...very difficult to diagnose intermittent problems, particularly over the internet. Wouldn't hurt though.
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Post by sleepinsol on Sept 17, 2009 22:34:21 GMT -5
i understand. im going to give the ignition components a whirl and see if that does it. if not then i suppose i check the vam voltage. ill be stumped if that doesnt track down the problem.
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Post by Stinger on Sept 18, 2009 21:28:13 GMT -5
How about just putting the wideband on it so you know wtf the air/fuel ratio is doing? That will give you a good means to diagnose the problem.
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Post by sleepinsol on Sept 18, 2009 22:03:31 GMT -5
i would, but i cant afford another dp yet. i have to give the one im using back as soon as i get the money to buy another from you. when i did that i was going to either have a bung welded in, or have you do it and pay you to  . being a poor college kid sucks. |
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. being a poor college kid sucks.