Running lean on stock boost

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I have been pulling my plugs since the engine rebuild and they have all been coming out white.

currently I don't have a boost controller, boost gauge or a wideband o2 sensor so my means of getting information are a bit old school.
still I am defiantly lean, though i haven't noticed any significant knock or anything under boost.

I have a fresh fuel filter on the car so i know its not that. the fuel pump has not been rewired yet, i'll get to that this month unless that could be the problem in which case I will do it tomorrow morning.

relevant modifications:
6 bolt swap,
new intake pipe & cone filter,
FP big T28,
6 bolt head, intake mani & TB
3 inch turbo back exhaust


thats all that seems relevant right now... what do you guys think is going on here.

as a side note to avoid detonation i have been running a half tank of 93 octane with an extra gallon of 100 octane race gas mixed in.

 

[silver bullit]

Stock fuel system on a non stock turbo.

The t28 flows more than the t25.

 

[endeffect0]

Yes it does;

However the stock fuel system should be good until 14 or 15 psi correct? Now i recognize that the 1st gen head is more efficient with larger intake ports as well as larger runners and larger TB. so that combined with a more efficient turbo i Am flowing more air at the same PSI compared to the stock 2g set up.

but i still am running stock boost. so in order for me to be really over the top of the stock fuel system i would have to be effectively flowing more air than a t25 at 15 psi. that just doesn't seem likely to me.

is their any other reason i could be running lean? is their an adjustment that could be off some where?

 

[1999silverGSX]

you say you don't have a boost gauge or mbc? hrmm... seems like you may want to invest in those two things that way 1. you can tell how much boost you are really running ( stock boost gauge which you probably know is a pos. ) 2. after you get a boost gauge get the mbc hooked up and set it at maybe 10-12 psi until you get the supporting mods. I made the mistake of letting my cousin put a mbc on my car when i had no boost gauge and he swares he only turn it up one or two more psi. Later that night my engine went ka-boom after the dealer replaced the motor and i had a boost gauge i told him to do the exact same thing this time and he did. Turns out i was running 18psi on stock turbo / fuel system = not good, put the car back at 12psi.

 

[JayRolla]

You are most likely getting some boost creep from that exhaust. I bet you are seeing over 15psi by redline, you need a boost gauge ASAP.

 

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I have a 2 stage MBC on my turbo mr2 i could pull as well as a boost gauge. i didn't think this was necessary however, i figured that if i didn't run a boost controller and just hooked it up to the stock valve it would run lowest possible boost. am i wrong?

 

[JayRolla]

The mitsu housings have an issue with boost creep, you hit your set 12psi and slowly creep up all the way to redline. You could be seeing close to 20psi. Research "boost creep" and you will see what I mean. Your large exhaust is causing it too happen if it is happening. Turbo needs to be ported to allow more air to reach the wastegate flapper.

 

[endeffect0]

Wow.
I didn't think i would have that much issue with boost creep with this turbo. I should have shelled out that extra little bit for waist gate porting.

I imagine whats happening is because I'm flowing more air at the same psi as the stock turbo as well as getting a little boost creep it could have the effect of flowing more air than the stock turbo at 15 psi... ill go hook up a boost gauge and see what happens.

 

[endeffect0]

I dont think its the turbo, but i havent hooked up the boost gage, i just let it idle for 10 mins and then pulled a spark plug and it came out lean as hell. SO now i think it could be a problem with mas or fuel pressure. Also every time i drive it even after re-setting the ecu im throwing p0300 cel which is multiple cylinder misfire.
Any thoughts?

 

[DSMsOwnYourV8]

A boost gauge should be your very first mod man.

 

[JayRolla]

Its perfect because you have not hit boost and gone lean yet, hook up the guage.

 

[endeffect0]

Oh sorry my bad. I did not mean clean. I meant White. I'll go back and edit that post. I have the boost gauge pulled off the mr2 and I'll hook it up in a few mins.

Honestly my biggest concern it the multiple cylinder misfire that I've been running into at cursing speed. I have yet to figure that out.


so just to recap. I am LEAN at idle. and I'm getting a CEL P03000 multiple cylinder misfire at cruising speed.

 

[hypnoticpimp]

I have a fp big t-28 with a megan racing o2 housing...I have it hooked up to straight wastgate and i still get creep to 15 psi...yes get a boost gauge

 

[endeffect0]

good to know man. Thanks for the first hand advice. Ill hook that boost gauge up. any one have ideas on why I'm lean at Idle, that and the CEL P0300 have me worried

 

[JayRolla]

Get ahold of a logger or have that code read.

 

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that code is multiple cylinder misfire. its higher up in the thread.

 

[silver bullit]

Well you get a boost gauge hooked up to it yet?

 

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Ok so i ran a boost gauge today and it peaked at .90 bar which is roughly 13ish psi.

I am still running lean on stock boost, AND at idle. I also threw the p0300 code again but im not too worried about that beacuse its common with the six bolt swaps and i will be going to DSM link this summer which will take care of that nicely.

Any ideas why I am lean at idle?