the engine been running really good and yesurday took it out for a drive and when i try to boost it it started to jerk and not boosting ( stock jdm turbo) can it be i need a tune or my greddy BCD is mess up ?


ricky

 

sorry guys when i said jerking is more like a mising firing =)

 

Maf? idk, could be a lot of issues.

 

not getting enough fuel? do you have a wideband? when is the last time you changed the spark plugs or fuel filter?

i ran into the similar problem but way way worse. to much to type on your thread but you can read the thread i recently made. i ended up buying a better fuel pump and spark plugs and the whole time it was a vacuum line.



edit- did it not go into boost at all?? or it started to go into boost then "jerking"?

 

i get boost and then jerking

 

Some people shouldn't own turbo cars. There's so many variables here that could do this and my gut says you have no clue where to start. If you don't have a wideband and a boost gauge that reads vacuum, then get them. And while you're waiting, you should pull the plugs and make sure you're not going lean. AAnd I'm guessing you'll need someone to determine that for you. Also, while waiting for the suggested items, I'd avoid boosting at all costs.

If you don't wanna cough up the money for the tools to properly diagnose/monitor the car, then sell it.

 

i do have both wideband and boost gauge and i also running neo to up my fuel

 

what are you fuel corrections set at? are you on stock injectors? could be hitting fuel cut.

 

i do have the bcd from greddy im trying to do it at 11 when boosting but is hard when it jerking cant get a real reading from it and yes im running the jdm 440 injector

 

does it cut in and out, if so im pretty sure you have cracked coilpacks, remove your coils, remove the blue boots, and inspect the bottom edges for cracks in the plastic. If you have large cracks, thats the problem under boost the coils tend to just ground out the spark to the head and not fire off, its one of the more common GTE problems when it is cutting out in boost..

also on 440's you shouldn't need to add much fuel via the neo cause those are the stock injectors, especially at 11 psi your wideband should already be very rich. I can't imagine needing to add fuel below 14-16 psi most remove fuel. Do reazlize the more fuel you add via the neo, the earlier you will hit boost cut because you are making the map sensor voltage larger. since you have a boost cut controller which clamps the signal at 4.8V, adding fuel just makes you add more fuel up to WOT, and then you end up with the same fuel with or without the neo cause the BCC will clamp it past a certain point. maybe at 11 psi there is a slight difference but I doubt you need more fuel at 11 psi, I bet without any correction your afr's are 11:1 or richer (10:1 etc..).

you should be using a safc to pull fuel on stock injectors. If you want to add fuel, you need to increase the injector size first to 550's at least, so then when you are actually adding fuel and since the neo will still be in the negative values the map sensor voltage will be lower and the BCC wont clamp it till a much higher psi, and then things will work alot better and you will actually be able to raise your fuel alot before it gets clamped.

 

i will check it later =) thankz for the info

 

also im boosting at 17psi =) i mod the turbo

 

Why are you trying to add fuel at 17 psi? is it lean? if it is you should turn down the boost because you cannot get more fuel out of 440cc injectors above 14 psi levels when using a boost cut controller on the factory ecu, it wont happen, you already have max fuel on those injectors.

being above boost cut clamp @ 17 psi changes alot, so basically you are doing the thing I said wasn't good.
factory fuel cut is around 14 psi.
the max fuel the gte ecu will put out is whatever the BCC clamps the map sensor at ~4.8V (right before 14 psi).

so adding fuel via the neo is really raising the voltage of the map sensor but since you clamp your sensor before 14 psi, you really are not adding any more fuel at 17 psi, because all fuelling above 14 psi will be the same where its clamped. You are, however, adding more fuel before 14 psi which is not needed at all, and probably confuses the ecu alot, lowers the timing curve up to WOT, and is more or less counter productive.

I would strongly recommend you zero out your neo settings and try again but keep an eye on your wideband at 17 psi you are getting close to what the 440's can do, and no piggyback is going to give you more fuel with those injectors unless it can alter pulse widths directly like the FIC

to do what you are doing and for it to work right, you need some 550's, because when you install larger injectors you can turn the map voltage down just to get the same fuel as with the 440's. If you follow you have alot more voltage between where you were and 4.8V with the larger injectors which is basically raising your boost cut so you can now add more fuel before hitting 4.8V, but once you hit that 4.8V again you will not be able to add more fuel, and will need larger injectors again if you need more fuel. Thats why people normally use larger injectors with a safc, it does not work the same with the original injectors at all unless you are talking about pulling fuel, pulling fuel is fine and will work on stock injectors.

 

Sounds like your trying to mod your piston rings and cylinder walls going 17 psi on 440s. but im a nub so who knows.

 

yeah i been looking for some 550 injector but no luck yet and now my car over heat sigh never ending repair