Hi broz/sis.

Engine: 3SGTE ST-205

On first gear i can rev fully to 7k with no problem.
On second, i can rev to about 6.6k coz it starts to jerk a bit.
On 3rd gear, the jerks start as from 5.6k:(
4th....5k:(
No need to tell u about 5th gear:(

What can it be? Anyone of u got this kind of problem in the past?
Can it be the spark plugs? i got iridium denso on it (IK20) i ran only like 20,000km with it.
Can it be the spark plug wires? I have the OEM wires which ran only 90,000kms.
Can it be the fuel system? To start with Fuel pump? I have the Walbro 255lph fitted some months ago.
Injectors? Used an injector cleaner recently but nothing has changed (unless i have to change the cleaner itslef:()
BTW CAN SOMEONE TELL ME WHICH % OF FUELING IS OK AT IDLE for injectors? ACTUALLY AM AT ABOUT 90%.

Is it the boost? Am boosting to a max of 1.1 bar (about 17psi) sometimes it hit 1.15bar. I lowered the boost recently but the problem still persist.

Is it evil? Havent met the priest the past 2years:-/ plz help...what can it b? what should i do? I can't race correctly with this bump...

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I've had this problems a few times. First was because i just did an engine change and after about a thousand or so miles tried a fully power blast but would only go to about 120 with some jerking. So shot some injector cleaner thru and it was all good and once the engine broke itself in a bit more. Another reason is the knock sensor breaks so you get the engine light on and limits your ignition timing so you cant go full power, this can give you a few jerks. If its not them then it sounds like it has something to do with the fuel system.

ok will try some more injector cleaners. i forgot to add, when i get this jolt black smoke come off my exhaust...is that normal?

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No i never had that, you got me stumped there. Have you reset the ecu and see if that makes any difference?

This post has been edited by cloqwise: Jan 14, 2009 - 7:30 AM

I think you are hitting boost cut.

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Black smoke is unburned fuel, you're still getting fuel, it's your ignition thats cutting out. Either the ECM is fully retarding ignition timing for some reason (somebody said knock sensor earlier) or your ignition system itself has a problem. When the ECM hits any type of limiter, be it for boost or revs or anything like that, it should cut out fuel not ignition. No ECM has EVER been programmed from the factory to dump raw fuel down the exhaust, that would just be dumb.

This post has been edited by silver6gc: Jan 14, 2009 - 9:55 PM

ok thnx the next things am gona try is:

Reset the ECU

Check the ignition system, wires n plugs.

Check the ignition timing.

Ill continue the fuel system cleaner.

As silver said, i must still b getting fuel if black smoke coming off when the jerks occur. Knock sensor? Well my engine light is off so i guess the knock must be ok...

Thnx broz ill let u know if i solved the problem.

If u have any other ideas plz let me know i verify everything:)

i had similar problem, turned out to be the ignition leads. they disintigrated when i took them out. been fine since

No brainer here but fuel cleaner isnt fuel.. Make sure ur only putting in as much as u should (eg, 1 bottle usually treats 1 or 2 FULL tanks)... Last time I used a fuel cleaner the car spat out a whole lot of black **** and stuttered past a certain workload of the engine.

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I would agree, it has happened to me on track days - black smoke, and jerking due to boost spiking and hitting the cut point. Although it was in every gear for me, so maybe not.