Car running rough/lower boost after modifications?

[Andybtsn]

After fitting my FMIC and decat on Sunday the car ran ok although had dropped boost wise a tiny bit, was more like 14psi and not 15psi anymore?

After driving it home from work tonight, the day had been really hot but the lag was really bad and the boost was a bit stuttery, any reasons behind this?

Did anyone ever see a big difference when fitting a FMIC?

Checked all boost pipes and they all seem ok. :?

 

[frp]

oh dear

 

[Andybtsn]

?

 

[AJ4]

saw a small drop in boost, didn't notice any more lag really

 

[Andybtsn]

Why does this occur?

Yes people I'm a newbie, "oh dear" doesn't really help me much...!

 

[Fire & skill]

it does sound like you have a leak mate, i only noticed my car being slightly more laggy after fitting the front mount, was running rough as well but all due to a hose clip had slipped off and was losing boost / drawing air

 

[Andybtsn]

Hmm, well the boost pipes that the boost gauge is connected to could be suspect as I dd have to disconnect the three pipes that connect to a T piece, the pipes going to the FMIC all seem very tight and correct

 

[Fast Guy]

Check any hoses you have fitted, any you might have disconnected while fitting and then check the exhaust manifold/turbo area for nuts coming loose.

 

[AJ4]

the boost drop and extra lag is normal. The drop is because there is a much greater volume of air being compressed with all the extra pipework. Every time you breath out of your mouth you pressurise the air of the whole world ( ! ), but because the volume of air you are blowing into is so big it doesn't have much effect overall. Blowing into a small volume increases the pressure more.

Also, colder air will drop the pressure ( just like on weather maps ). With the front mount then your intake charge temp should be lower so the boost will be lower. Boost is a combination of pressure and air temp, its possible to run a standard turbo at 1.5 bar, but the turbo is only putting out 1.3 bar really, the extra 0.2 bar is from the increase in temperature as the turbo is at the end of its tether and very inneficient. Sometimes you get more power at 1.2 bar than 1.5 bar, because the temp is lower and the net volume of air is actually more ( its volume of air in the cylinder and the temperature of it that gives you power, the 'boost' level is pretty irrelevant...

erm.. hope that answers your question

 

[Andybtsn]

Right the boost has dropped further to 12psi and the car is not running well at all.

It's so stuttery on boost now, usually it would jerk me back in my seat when the boost started but this just isn't occuring any more.



Check all boost pipes running to the intercooler and the boost pipe that my boost gauge/boost controller connect to etc. Is there anything I should check for?

I have just had a decat too but I can't see this being a problem. (fitted that same time as the FMIC)

 

[GTIR-LOZ]

if it was ok before your mods then its something to do with them, maybe the core is leaking if no pipes are? is it new or second hand

 

[Dooie Pop Pop]

any minute now your cars gonna exp;ode into 100,000,00,000 pieces

see i told you.......

 

[Gray]

What FMIC kit did you buy? I got a hybrid and the hose clips that come with it were so so bad. I bought some proper jubilee clips from B&Q. Does sound lke you have a leak to be honest - do you get any smoke out of the exhaust on boost? I had no pressure drop really and only slightly more laggy nothing to be concerned about. It can only be something to do with the front mount the decat wouldnt have an effect. If you got shitty clips replace them all with proper jubilee clips and do them up tight with a socket set

 

[leon2engines]

does it idle ok?

 

[the chief]

i think all intercoolers suffer pressure drop. the spluttering sounds like a tiered fuel pump

 

[Fire & skill]

i think all intercoolers suffer pressure drop. the spluttering sounds like a tiered fuel pump

brand new walbro 6 months ago

 

[steven_c]

What front mount have you fitted? cos some dont fit to the turbo elbow right and leak off that i had that prob..

 

[Adamantium]

What front mount have you fitted? cos some dont fit to the turbo elbow right and leak off that i had that prob..

Only 1 year, 5 months and 19 days late...

 

[kyepan]

try a mix of washing up liquid and water in a cup, paint it round the joints and watch for bubbles.. that may help you find the leak.

 

[rx jamie]

yes very true, more pipe run means more time needed for the pressure to build up.

also depending on which kit you went for you will have probably had to disturb an earth. i had this problem. i had to remove the drivers side earth behind the headlight. when i reconnected it after refitment of the fmic the car ran good for about a day. then it started hesitating and boosting irractically. also idled funny. i just removed the earth, sanded the connections down to get a good connection and sprayed wd40 on the points to drive out moisture. job done !
also the hybrid copy piping is terrible, if you over tighten the mikalor's the pipes crush. so it is hard to get a good seal.