drugblock12a

iTrader: (7)

okay everytime i come up to 10 psi it breaks ups doesn't matter what rpm it's as soon as it hits 10 psi. I have made more than 10 ponds of boost before but after some tuning it won't go past 10psi. i can't figure it out. It's running a lt8s and a bnr stage 4. i will provide whatever info is needed to trouble shoot this problem.

rx72c

iTrader: (8)

What tuning did you do?
What afr ratio are you running?

Ignition break up is either bad spark plugs, too much fuel, or a bad ground in the car.

drugblock12a

iTrader: (7)

street tuning WOT is pretty steady at about 12.5 to 13.8.

wouldn't ignition breakup be hit or miss for a bad ground?

it's only at 10 psi that causes the breakup.......plugs are fresh and a known good

i think fuel.....

rx72c

iTrader: (8)

13.8 at WOT at 10psi?
LOL are you crazy?


Bring it down to 12:1.

Sounds like you have gone too lean. lol And it should be steady their.

myfc3s

iTrader: (2)

I would suggest A/F at 11-11.5 at that boost to be safe. Also does it backfire on boost?

rx72c

iTrader: (8)

The above afr is good as well.
From what he describes id say it is.

dean23

ever sort this problem out? im having the same issue. just put in new plugs also, nothing (but better as mileage hahah)

rx72c

iTrader: (8)

what are your afrs at 10psi.

dean23

well its at low and mid 11's up to 10psi, then it stumbles and that casues the afr reading to bounce around. i cant really see the fuel map being a problem, maybee the timing.

BluRR

iTrader: (1)

1) Check your fuel pressure.
2) Check your max boost in the options map

dean23

im not real sure how to check my fuel press. at 10psi
and i dont have a boost max set.

BluRR

iTrader: (1)

is it leaning out at the 10psi? I was having a similar problem..Not sure if its exactly the same problem. But my pump was wired thru the stock system with speed relay and all i guess. When i reach around 10-11psi it would lean out..even after maxing the injetors same thing. So i rewired the pump to start power on with no relay..and i have since run it up to 16 psi with no probs

rx72c

iTrader: (8)

Good point.
Id check the above.
Timing is very simple.
Use a timing gun to check that on idle that your CAS is in the right place.

Then run around 17-18 degrees of timing at 10psi.

dean23

i have a fd fuel pump wired with a 12v ign from the stock harness, the power comes straight from the batt..

cas should be fine. what map should i change for the timing?

rx72c

iTrader: (8)

So does the microtech trigger the relay for the fuel pump or no?

Get the timing light out and check it.

BluRR

iTrader: (1)

What exactly happens when it breaks up? Are you running a wideband? what happens to the afr at the point it breaks up?

dean23

ill shoot a video of it tonight.

rx72c - what do you mean? the fuel pump is running all the time that the microtech is on, why would 10psi change that?

dean23

well im still having this problem. i wouldnt think im making too much power for the bosch coils to withstand. theyre the ones that come with the lt12 iirc. and my trailing wont fire. the ignitors are fine (or thats what the microtech company tells me) and its all hooked up right, but no spark. coils should be fine too. my block is grounded in several places so thats no an issue either.

rx72c

iTrader: (8)

When you put a test light on the back of trailing coil packs on the negative terminal, does it pulse?

Microtechs are very simple in the sense. If you have no spark, its either ignitor, wiring, or coil packs. DONT ASSUME anything is good AND DONT TAKE ANYONES WORD, test everything your self otherwise you will keep dancing around the problem.

dean23

well i paid for them to fix the ignitors, which they said were fine, so i beleve them about the ignitors. ill test everything else tomoro. i also noticed that while using a voltmeter my plug wires are putting out .55 volts and .45 at the plug tip.

dean23

know breakup occurs at 3-4 psi... im starting to become concerned. . .

BluRR

iTrader: (1)

How new are the plug wires? and how is the tune at that point?

dean23

the tune is good. im not sure about plug wires. ill replace them latr today and see what happens.

rx72c

iTrader: (8)

if the break up is getting worse.

Check your voltage on the handset, see what its doing as it comes to breaking up/when its actually breaking up.

Add another earth from chassis to block, and battery to block.

2 above things usually cause break up.

taz8924pr

iTrader: (1)

Hey man that why I replace the 3rd gen fuel pump with walbro 255 since then no problem.