Weird problem.... need help!!!

[Stez]

Weird problem appeared after some increasing of boost (earlier boost was only 0,6 bar with t04b v trim turbo) and adding of fuel for it...
the problem is: during the hard reving of engine, rpm reachs the level somewhere close to 5 - 6k and after that enging rpm stops and start to fall down by itself, after that, if continue to open the TB i revving aggaing but soon falling again (engine does not stall).
Looking to logger, looks like there is anought of fuel (no detonation) and O2 looks ok, close to 0,8. So i think that the problem is probably in the ignition - plugs, wires, coils.... I have the Nippon Denso 20 plugs and a new wires....

May be someone ever had a similar problem, have any experiance with such problem or have any ideas what is it really can be?????

Thanks for any advise

 

[staticbrainwash]

Sounds like you may have spark issues like you said. Try ngk bpr7es plugs. The ngk's are the best plugs for our cars, and the 7es is for higer boost apps. And NGK or accel wires. There's ways to test your coils on vfaq.com.

Check for boost leaks and pre turbo exhaust leaks.

 

[pneumo]

You should not have to add fuel when you turn up the boost. The MAF will monitor airflow and the ECU will add the correct ammount of fuel for the ammount of airflow. I bet you're running so rich that the engine is misfiring and gagging on the fuel. Does the O2 volts hold steady, or does it fluctuate during a WOT pull? If it quickly spikes lean or dips down and back up, that's a misfire. Try leaning it out a few percent and see if it helps.

 

[staticbrainwash]

^^^ Or that too.

 

[Stez]

Well, may be i'm really to reach, i installed bigger injectors earlier and walbro 255hp, and the compensation wasnt that much, may be it really overflow the plugs.... anyway i already bought bpr7e plugs

O2 curve is not steady too, it is always jumping, even till 0,00... what does that mean??? i thought what that is something wrong with my O2 sensor, isnt that?

 

[pneumo]

Yes, you are running too rich. Does your O2 sensor work OK when cruising at partial throttle? The jumping O2 readings and lean spikes are a sign that the engine is misfiring. When the engine misfires it dumps lots of unburnt O2 through the exhaust and past the O2 sensor. Since it's an OXYGEN sensor it picks up all the unburnt O2 and gives you a false lean reading.

 

[Stez]

Yes, you are running too rich. Does your O2 sensor work OK when cruising at partial throttle? The jumping O2 readings and lean spikes are a sign that the engine is misfiring. When the engine misfires it dumps lots of unburnt O2 through the exhaust and past the O2 sensor. Since it's an OXYGEN sensor it picks up all the unburnt O2 and gives you a false lean reading.

I really hope that my O2 sensors works ok since i had installed it just a couple of months ago, it is almost new.
His work:
- During approximately steady Idle: it is pretty steady too, but sometimes it can fluctuate from 0,82 till somewhere 0,7, but mostly close to 0,8.
- If during Idle i sharply press the TPS - it immediately falls down to almost 0,0, then rise again - this is really STRANGE!
- During cruising and low load part throttle acceleration it is pretty steady and close to 0.8!
- During hard acceleration and hi load it is really unstable and fluctuate with spikes down to 0,0.

So.... probably this is really misfire, what is the reason? bad plugs, a lot of fuel, what else??? and how can i fight with it?

 

[staticbrainwash]

take out fuel? Do you have an AFPR for that 255? That could cause a VERY rich condition.

 

[Stez]

yes, i have an afpr and i also can take out fuel with Maft Pro, i will do that! but looks like my problem with ignition is much deeper, since there is misfire even if during idle to press TPS :-( - i also see spikes till zero at that conditions, i hope that installation of new NGK bpr7e plugs will solve that problem

 

[pneumo]

Try taking out fuel first. I'm sure it will help.

 

[Stez]

Ok, thanks everyone for advises!!!
I will install a new plugs and try to take fuel out at the weekend, will see what i'll got and post a report next week.

 

[Stez]

I installed new plugs ngk bpr7e, set all compensations to 0 and start from the very begining: due to i have 680cc i set -30% in the main scale compensation for all rpm range.

Made a few runs and what did i got:
- misfiring problem looks like was solved particulary - engine reved much better but looking to O2 graph - anyway it has a LOT of spikes down to 0, can not understand why?? The plugs and wires are new, the plug gap is 0.7mm - ignition should to be good, but im getting spikes even at idle with light press of TPS.
- crazy knocks during hard runs! moistly starting from 4k, i tried to compensate it but even with compensation of +20% there was no significant effect (i were affraide to go further because did not want to make another overreach) with boost somewhere close to only 0,8 - 1 bar and 680cc injectors DC% close to 75% - I DONT UNDERSTAND MY CAR - PLEASE HELP

 

[Stez]

I installed new plugs ngk bpr7e, set all compensations to 0 and start from the very begining: due to i have 680cc i set -30% in the main scale compensation for all rpm range.

Made a few runs and what did i got:
- misfiring problem looks like was solved particulary - engine reved much better but looking to O2 graph - anyway it has a LOT of spikes down to 0, can not understand why?? The plugs and wires are new, the plug gap is 0.7mm - ignition should to be good, but im getting spikes even at idle with light press of TPS.
- crazy knocks during hard runs! moistly starting from 4k, i tried to compensate it but even with compensation of +20% there was no significant effect (i were affraide to go further because did not want to make another overreach) with boost somewhere close to only 0,8 - 1 bar and 680cc injectors DC% close to 75% - I DONT UNDERSTAND MY CAR - PLEASE HELP

 

[pneumo]

I installed new plugs ngk bpr7e, set all compensations to 0 and start from the very begining: due to i have 680cc i set -30% in the main scale compensation for all rpm range.

Set main scale compensation to -38%. Start there.
680cc injectors are 38% bigger than stock.

 

[Stez]

so you think that my knocks were the reach knocks???

My low trim is around 81%, Mid - 100, and hi - 98%.... is this mean that i'm reach only at low load? or at all rpm range?

 

[pneumo]

so you think that my knocks were the reach knocks?

Yes. Except the correct word is 'rich knock'. I still knew what you meant.

My low trim is around 81%, Mid - 100, and hi - 98%.... is this mean that i'm reach(rich) only at low load? or at all rpm range?

It looks like you are rich mostly in the low load. I think if you drive the car more you would see the mid trim come down also. Mid trim is slowest to adjust, so it hasn't had time to change yet. Try adjusting global knob one click leaner and another click leaner for low load.

 

[Stez]

Ok, thatns, i will try to lean it