Higher boost problems

[thalj]

i have a twin turbo 2uzfe

twin turbonetic hp72 turbos 0.58 a/r

motec m800 + motec cdi 8 ignition system + 8 msd coils installed

made 904 hp at 1.8 bar boost from the first program but i have faced a problem

the car starts to lose electric.. it kinda want to shuto off

the car starts normaly but on boost it starts to act wierd

on 1.3 boost there is no problems.. the problems started at the higher boost what you recomend guys any proffesional guys here ?

 

[cribbj]

Do you have enough seat pressure with your valve springs to keep them closed under boost? Your exhaust manifold could be seeing 2x or 3x your actual boost, so if you're not running springs with 100lbs of seat pressure, then valve bounce could be your problem.

It can sound and feel like ignition breakup too.

 

[thalj]

nop i got springs installed.. somtimes before it hit maximum boost it starts to jerk even

 

[cribbj]

Could it be your overboost or your overrev limiter?

 

[JBrady]

The higher the boost the harder it is for the spark to jump the gap on the plugs. Make sure you have good ingition voltage. You may want to try less gap.

 

[thalj]

well the cdi 8 and the msb coils are installed no problem with spark.. my problem is the voltage will suddenly drop and cause car to jerk.. the higher the rpm the more it will do that.. i checked my alternator its ok..how can i fix this voltage problem

 

[cribbj]

Have you confirmed that it's the overall 12v system voltage that is dropping ?

If it's "browning out", where the voltage is falling, but not cutting out completely, then the alternator may not be supplying enough current for the system. For this, either an oversize alternator or a bigger battery is the answer.

If the voltage isn't browning out, but is cutting out completely, then there's a bad or loose connection somewhere.

It would be useful to know if you're seeing this problem on the whole system, or just the ignition. Can you put a voltmeter temporarily on the alternator/battery output, and then on the ignition output to see where the problem is?

 

[thalj]

the motec shows that there is problem with the battery

thanks for the advice ill try tommorow and see how it will go

 

[cribbj]

Wow, if the MoTeC is showing a battery voltage problem, then it must REALLY be low. I think MoTeC rate their ECU's to run OK at ridiculously low voltages (8.5 volts IIRC?)

A fluctuating voltage is going to do bad things for your injector opening/closing times as well. If I were you, with all the money you've obviously already spent on that system, I'd consider getting a Kenne Bell Boost-a-Pump or Boost-a-Spark, and run your ignition and injectors off of it.

One of the really nice, but not widely publicised features of these boxes is their ability to act as a voltage regulator, ie they'll hold a constant output voltage regardless how the input varies. So even if your 12v system drops to 8.5 volts, with one of these boxes, your injectors and ignition would still get 14 volts (or up to 18 or 20 volts if you want)

 

[hungryforinfo]

A fluctuating voltage is going to do bad things for your injector opening/closing times as well. If I were you, with all the money you've obviously already spent on that system, I'd consider getting a Kenne Bell Boost-a-Pump or Boost-a-Spark, and run your ignition and injectors off of it.

Boost-a-Spark, is a good suggestion. Other things are putting the coil right on the plug (you may already have done this?) called COP

 

[gloverman]

Have you had a oscilloscope on the alternator?

Cheers

 

[XR8tt]

If battery is in the boot / trunk ?? Your current electrical load maybe too high ??
Check alternator and wire size, connections. Including earth's..
Had similar issues with what seemed good engine to body earth...
Apparently it wasn't enough.. An extra earth strap fixed the problem...

 

[MonsterTriton]

it sounds more like that you have a problem with your battery ground.... make sure it has a clean contact, remove paint from the bolt ground area, to clean the surface to make a better contact area....

otherwise, try checking all grounds are connected to the chassis ground rather than direct grounds from the ecu/standalone etc.

 

[Zuffen]

Last time my car was on the dyno it did the same thing. Dropped voltage at around 5,000rpm.

I fitted a Lextrme 160amp alternator it it didn't solve the problem.

I haven't addressed it yet but I plan on running a new battery earth lead and some additional chassis/body (separate chassis & body) earth straps to see if this solves it.

If not it's Boost-A-Spark time.

 

[spf_lexus]

my problem is the voltage will suddenly drop and cause car to jerk.. the higher the rpm the more it will do that.. i checked my alternator its ok..how can i fix this voltage problem

A guy in NZ had a TT issue where his car would cut out at 4500rpm after 2 laps of WOT on the track and it ended up being excessive coil resistance that was increasing as the turbos heated up, ( couple inches away). With 1,100 whp + heat... it could be cause for concern. All he did was move them farther away and it ran great.

Is it possible that the coils are drawing larger and larger amounts of current as they heat up, causing effeciency to dip? Maybe over-taxing the alt?

 

[XR8tt]

Yes esp with 1000 h.p.. They would be atleast 85Lb low impedance injectors..
When they are at full or near full load. With thermo fans, coil etc it doesn't take much to draw 100 or so amps...