Valva Float

[ahh 33 s2]

hey guys/girls

over the last few weeks my car has started to hesitate under full load, when its higher up in the rev range

quick mod list

PFC

stock turbo .8 bar

splitfires

z32

fuel pump

new plugs at .8

120km

now im not 100% sure that its vavle floata but its all i can think of, as ive experiance bad coils and it feels different,

it makes a funny noise sort of like brrbrrbbrrbrrr brrr, if u can imagine what that sounds like.

can valve float lead to other problems in the engine apart from bad performance,

i dont want to have to fix it as im about 75% the way thru a 26 rwd build and dont want to spend on the 25,

so does this soind like valve float

is there an easy way to fix

is there an easy wat to diagnose

is there going to be further issues if i dont fix it

[sh@un]

valve float is caused by huge revs that take the springs well past their ability to make the valve follow the cam profile

i doubt it'd be that unless the springs are spectacularly stuffed

[TiTAN]

if it is valve float you run the risk of the pistons hitting the valves and destroying the engine. though you are unlikely to get valve float at .8bar on the stock turbo unless the valve springs are shagged.

wrap some electrical tape around the rubber part of the splitfires just to rule out that its arcing out, does the problem dissapear with less boost? what is the PFC reporting knock at?

[ahh 33 s2]

no knock at all,

havent run at lower boost, if i turn my avcr off and just run the waste gate i still get .8 bar

apart from the coils arking out, what else could it be

[GDZ-14R]

I have been told my 26 is suffering from valve float by my tuner. He believes he has diagnosed it based upon the fact that the motor is sluggish to make any more power after 5500rpm on high boost (18psi), and pings unusually when more timing is thrown in. The end result is quality mods (cams, GTSS', fuel, ecu, z32's, splitfires, cooler, etc) not meeting their expected peak power figures. Need to change the springs to overcome the issue.

What does your tuner have to say? What do your dyno graphs look like? Is it making expected power up high?

I don't feel anything unusual driving the car - certainly no hesitation as you have described, no knock, and pulls very hard. Not sure if this info is what you're after, but hope it helps.

[R31Nismoid]

  ahh 33 s2 said:

no knock at all,

havent run at lower boost, if i turn my avcr off and just run the waste gate i still get .8 bar

apart from the coils arking out, what else could it be

poor spark comes from more than just failing coils.

The coil pack loom is also another place to look. Corroded/poor connections etc etc. If its a S1 motor the igitor box (black rear end of the head) could be failing as well.

Even things like fuel pump voltage, blocked up fuel filter etc cause all kinds of hesitational issues.