low rpm sputtering

[onevia1800cc]

ok today i took the via out. nothing crazy pulled to 75 in 4th on a new SI then i get to a stoplight and normal takeoff was gone if you press the gass it just spit and sputtered till i let off the gas and baby it till it stops (around 2800 rpm . top end is fine. i checked the codes, i'm getting 55?? any ideas what this could be?? boost leak maybe?? i dunno as it doesn't have these symptoms all the way up the revs.

[rico05]

55 means all clear and the ECCS is working in normal open loop mode. You totally blew something loose. $5 says an intercooler pipe is loose. Check all vac lines and all intake tubes and get back with us.

A good way to test FYI is go get a few (2) cans of intake/carb cleaner. Start the motor and spray that stuff liberally all over the intake tubes, intake mani, etc. DO NOT SPRAY THE TURBO!!!!! FIRE BAD. If you spray a spot, and the motor revvs or changes idle, viola! There is your leak (the stuff gets sucked in at the leak and causes the motor to idle up for a second)

[onevia1800cc]

ok i got some carb cleaner and sprayed everything! all the lines on intake mani, all the piping??nothing?? i just checked my fsm. it says if there aren't any leaks to check fuel regoh and it goes away sometimes like i'll be driving and it acts fine then sometimes it just acts crazy sputters and backfires. idle will go from perfect to abnormal?also as i am accelerating and it is sputtering my boost gauge shows the boost flutteringthis is a headache

[slownslurious]

symptoms sound like knock sensor but that would throw a code and go up to 3500 rpm.

also a much much easier (and cleaner) method of testing for leaks in your piping is to use a pipe end cap from lowes, put it over your compressor intake, and use a compressor to pressurize the system to 10 or 15 psi, and listen for leaks.

[rico05]

My knock sensor was out for about a year and it never did this.

[onevia1800cc]

ok this might helpit doesn't do this right away,after a hot or cold start i can drive normally for about 5 miles approx. then if i have to slow down or come to a stoplight and i try to go from stop to go, it sputters and shows no boost or fluttering boost levels.if i keep on the gas it will backfire ALOT. my friend followed me and saw the black puffs, i need to do that compressor trick to check, but i am wondering about the randomness of this problem as it is off then on somtimesmore info

[r34 gtr]

gotta love those random problems the CA just looooves to give ya.

i would check to make sure you havnt had a vacuum line crack or come loose somewhere. if the boost gauge flutters wildly it kinda points to that.

you might also check the ground wires to see if any of the big ones are loose. hell, adding some wouldnt hurt either. adding 2 fat ground wires meant the difference between not even firing and running silky smooth for my car.

other than that, are there any electronics youve got that could be causing this problem? safc? boost controller?

- tim

[slownslurious]

my knock sensor is bad (throws code) and mine does that up to 3500 rpm, and then stops, but mine does all the time. Same symptoms (runs rich, backfires, boost sputters, etc).

[onevia1800cc]

ok found a small hole in the factory air cleaner pipe just above the breather tubeplugged it with good size bolt, still acts up but less often. it also goes from acting erratic to being smooth ??????????????could the boost flutter come from wastegate trouble(sticking open)still no codes

[slownslurious]

yeah I'd replace that hole... it could be wastegate but what is happening is for some reason your engine is running hella rich (thats why its backfiring and sputtering).A leak in your IC piping would cause this, as would any leak after the mafs.

[Not_a_sr]

try replacing your coolant temp sensor. it can be bad and not throw a code, i had this problem it was reading a irregular voltage and woulnt throw a code, but the computer was running in warm up mode and making it undrivable and a fireball machine.

[Not_a_sr]

also check the intake pipe to the turbo for leaks and tightness this was also problem area on mine last week. i still have slight misfiring and i always have its between -2 vacum and .5lbs of boost. it gets sputter and soon as it passes half pound of boost it begins to smooth out and pull hard.

[onevia1800cc]

try replacing your coolant temp sensor. it can be bad and not throw a code, i had this problem it was reading a irregular voltage and woulnt throw a code, but the computer was running in warm up mode and making it undrivable and a fireball machine.

this might be the cause. i unhooked the sensor (red plug) and it seemed to drive better for a moment no change really

also check the intake pipe to the turbo for leaks and tightness this was also problem area on mine last week. i still have slight misfiring and i always have its between -2 vacum and .5lbs of boost. it gets sputter and soon as it passes half pound of boost it begins to smooth out and pull hard.

intake pipe is leak free but that seems to be the same range of vac\boost as you. it also acts crazy then smoothes out and pulls hard but sometimes it builds noboost you can put your foot to the floor and no revs or boost just BRRRRRRRR changed the fuel filter no help. i checked my plugs gapped them to 1.1. plugs were somewhat dirty some buildup around\nearest the threadselectrode was clean, i cleaned and reinstalled.this is fun but you don't learn without mistakes,or problems to fix

[float_6969]

Did you try adding some grounds? It sounds to me like you might have some problems with igniton.

[onevia1800cc]

haven't tried the grounds yet

[F3600]

is yoou Ecu connector is tight ? this can give a lot of problem.

it could be ignition related.. does the car do it on idle ? take a timing light and check for erratic ignition spark...

my car was doing that and there was a short in the wiring from the ignitor to the coils. ohm everything betwen :

ECU & Ignitorignitor to coilpack.

Crosscheck all wires also..

Good luck

[onevia1800cc]

checked my harness well . dead end, found a small pinhole leak in my weld on the bung for the regulator. fixed that. still the same, ordered "platinum silicone" vacum hose,(yet to arrive). made that leak tester with a valvestem and a pvc cap, thats how i found the 1 on the bung. i am using a car tire pump the ones that hook up to the cig lighter but i can't build boost to .5 bar at allone notch lower, + the !@@#ing compressor id so loud i can't hear any hissing pressure drop's slowly after turning that thing off. i have tried the carb cleaner/2 cans and i used starting fluid1/2 a can. using this method has no results, it missed the bung, i have sprayed EVERYTHING! the entire manifold every hose around the throttle body, the regulator, vac lines, i haven't been able to get a coolant sensor yet though to try to see if that changes things as it runs good till about 5 mins of driving

[onevia1800cc]

gotta love those random problems the CA just looooves to give ya.

i would check to make sure you havnt had a vacuum line crack or come loose somewhere. if the boost gauge flutters wildly it kinda points to that.

you might also check the ground wires to see if any of the big ones are loose. hell, adding some wouldnt hurt either. adding 2 fat ground wires meant the difference between not even firing and running silky smooth for my car.

other than that, are there any electronics youve got that could be causing this problem? safc? boost controller?

- tim

sorry there are no electronicsmods are fmicpop chargero2 pipe to tip 2 1/2" to 3"stock t25boostgaugechipped ecu (unknown map) came with my swapworking 91 dohc cluster mph and rpm

[biosehnsucht]

chipped ecu (unknown map) came with my swap

[onevia1800cc]

i know i know i just ruled it out because it ran fine for like 2 weeks with said ecu

[Not_a_sr]

i second the ECU could be for number of things. although i have the problem on stock computer.

next would be the coolant sensor!!

have your alternator tested, i have a feeling mines goin out and im getting a weak spark at low RPM. its sputtering till it picks up RPM and charging ability.

[onevia1800cc]

ok huge update,i have no boost leaki have an intermittant coil (i hope) as i have stated this problem comes and goes i checked my timing 15BTDC dead onwhile i was checking timing it would act up so i changed the spark plugs no change so i went for the next thing while it was at the erratic idle i pulled #1 coilNO CHANGE!!!!! i plug it back in it goes to perfect idle blipping the throttle perfect response as opposed to bliping the throttle while idle is #$%@ed it boggs or i get spark knockanyone know the cheapest place to get new or good condition coils? are they even available in the states

[Not_a_sr]

i might just have to swap out coil packs today to see if i have a bad one also. i found a nice vacum/boost leak last night! my turbo XS BOV has a flange that attaches to it via 3 set screws. air was leaking past the seal on it and i was loosing alot of boost there , also the vacum line on top of it was loose

but the problem is still present, but gets faint after it warms up to around 70deg C it wont get any hotter then that.

[slownslurious]

search for coilpacks I posted part numbers for them at every major chain and prices, including the dealer.