hey guys i have a problem. i just installed ported heads and intake and now with 19 psi when i go full throttle my boost gauge flutters from 20 to 17 flickering and the car sputters and noses over then finally shift after 3 seconds then starts all over. i have no knock b.t.w. what can it be. also when it is wot the tach says 4800 in all gears
boost flutter at wot along with sputtering
- Thread starter QUIP'6'
- Start date
I had the same "general" description happen last night, trying to up the boost a little. After reading numerous posts today, I found it could be countless stuff. I tried the easy/free thing, regapped my plugs to .032 and seems ok now.
I searched "high rpm misfire" and found many cases and many possible repairs.
I am sure there will be many "this fixed mine" replies, hopefully one of them helps you without spending to much time or money.
Not sure if mine is really fixed yet, time will tell. Be sure to let us all know what fixes yours, we can never have enough info.
Good luck
I searched "high rpm misfire" and found many cases and many possible repairs.
I am sure there will be many "this fixed mine" replies, hopefully one of them helps you without spending to much time or money.
Not sure if mine is really fixed yet, time will tell. Be sure to let us all know what fixes yours, we can never have enough info.
Good luck
i had the same problem when i was around 20-23 psi, i turned it up to 26 and seems to be ok, or just not as noticable. but mine wasnt nosing over, that seems like it may be ignition related. but try giving it some more boost. how are the 02's? i would think you would have had to give more fuel for the ported heads, maybe you gave it to much.
- Joined
- Feb 18, 2006
When the turbo makes more than the motor can eat, thats what happens. ch ch ch ch ch ch ch ch ch ch ch ch
On a car with stock heads and a big turbo this condition can be pretty extreme.
On my car I have a 70gtq and ported irons. I get flutter between 5 and 15 psi. On a car with stock heads it could flutter up to 20psi or maybe more.
Like what was said already. Turn up the boost and it should smooth out.
On a car with stock heads and a big turbo this condition can be pretty extreme.
On my car I have a 70gtq and ported irons. I get flutter between 5 and 15 psi. On a car with stock heads it could flutter up to 20psi or maybe more.
Like what was said already. Turn up the boost and it should smooth out.
bmackinnon
Active Member
- Joined
- Feb 24, 2005
Sure seems like alot of conjecture.... but where is the data and what is it saying? Fuel pressure behaving properly? O2's? etc, etc, etc... could be ignition, fuel, or like mentioned, your change in combination may have put the turbo solidly in the 'surge' zone of the compressor map..... and in that case, turning up the boost may indeed be the fix.... will need to make sure everything else is 'turned up' too...
- Joined
- Feb 18, 2006
Good points Brian.
Something else I just noticed. Looks like Paul is using a LS-1 draw thru set up. That can make things allot worse. Turbo surge could also be triggering fuel with that configuration. Food for thought.
Something else I just noticed. Looks like Paul is using a LS-1 draw thru set up. That can make things allot worse. Turbo surge could also be triggering fuel with that configuration. Food for thought.
Try raising your fuel pressure. That could be a simple fix that no one has mentioned yet.
meanchicken
gallo vicioso
- Joined
- Oct 6, 2007
Mine did the same thing several months back at 20psi and it ended up being the plugs. I switched from R44 to R43 and problem was solved.
I put the heads and intake on a month ago and everything was fine except i put in ngk ur5's and i was getting some detonation at 17 psi and the boost was fluttering minimally. well i remembered last year that i got knock from these plugs so i switched back to autolite 24's and gapped them at loose .030 well now it is breaking up at 4800 rpm. before when i first posted it was 19 psi and now i lowered boost to 15 and it is still doing it. the car runs beautiful in all gears idle to 3/4 pedal but wot it does this. now with the lower boost i thought that it would not be blowing the spark out but do you guys think that with the ported heads and intake that it has alot more air even at 15 psi. this car is awesome at 15 psi wayyy faster than at 24 psi with stock heads. by the way i had the ngks at .028 gap. do you think i need to lower the gap? also i ohmed the coil pack and they were high 11's
bmackinnon
Active Member
- Joined
- Feb 24, 2005
spark is not 'blown out' by the amount/flow rate of air, but rather the increased charge density resulting from higher boost pressure, where the spark is unable to jump the gap in the now denser atmosphere... while it may well flow more now at 15 psi, spark 'blowing out' doesn't appear to be your problem... decreasing the plug gap further would not be my recommendation... I think you are experiencing classic compressor surge....
before when i first posted it was 19 psi and now i lowered boost to 15 and it is still doing it. the car runs beautiful in all gears idle to 3/4 pedal but wot it does this. now with the lower boost i thought that it would not be blowing the spark out
Yeah now after reading this youre, right it shouldnt do it if you turned the boost back down so at least you've ruled that out, sorry you may want to put them back at the .30 range, the only reason i suggested was also at 20 mine would skip & spudder but down at 17 it didnt.
So now the next thing to check.........:smile:
So if the same turbo...... but different intake & heads that you put on....... (just thinkin outloud here & to myself)........
do you have a power plate on backwards, or one of those ground wires missing or tight? (could have dislodged a wire or connection or somethin somewhere doing the change over.) make sure all 6 plugs/wires are gettin good connection all the way through & not crossed. do you have a spare ignition module to swap with? I didnt read before can you monitor your fuel psi up to that point to make sure the filter isnt clogged or something? just suggestions bud, you may have already checked these simple things though.If you do find it post back.
before when i first posted it was 19 psi and now i lowered boost to 15 and it is still doing it. the car runs beautiful in all gears idle to 3/4 pedal but wot it does this. now with the lower boost i thought that it would not be blowing the spark out
Yeah now after reading this youre, right it shouldnt do it if you turned the boost back down so at least you've ruled that out, sorry you may want to put them back at the .30 range, the only reason i suggested was also at 20 mine would skip & spudder but down at 17 it didnt.
So now the next thing to check.........:smile:
So if the same turbo...... but different intake & heads that you put on....... (just thinkin outloud here & to myself)........
do you have a power plate on backwards, or one of those ground wires missing or tight? (could have dislodged a wire or connection or somethin somewhere doing the change over.) make sure all 6 plugs/wires are gettin good connection all the way through & not crossed. do you have a spare ignition module to swap with? I didnt read before can you monitor your fuel psi up to that point to make sure the filter isnt clogged or something? just suggestions bud, you may have already checked these simple things though.
thanks. i have the gap at .030 to .031 so i am going to try .028 and report back.
update
well i gapped plugs to .028 and took it out and the same thing happened. came back changed the coil pack and the same thing happened. car runs beautifull till you go wot then it sputters and nosedives. the maf was 255 and didnt bounce around. also i upped the boost to 24 and it didnt clear up.
well i gapped plugs to .028 and took it out and the same thing happened. came back changed the coil pack and the same thing happened. car runs beautifull till you go wot then it sputters and nosedives. the maf was 255 and didnt bounce around. also i upped the boost to 24 and it didnt clear up.
- Joined
- Feb 18, 2006
Damn Paul, you have a real bastard gremlin there.
I think at this point I would be taking a look at the valvetrain / rockers / pushrods / cam. Sounding more like a valve is not opening all the way.
Flat tappet cam?
I think at this point I would be taking a look at the valvetrain / rockers / pushrods / cam. Sounding more like a valve is not opening all the way.
Flat tappet cam?
yes i do. i have a flat tappet cam . when i put the heads on the cam and lifters were mint
what about the ignition module under the coil pack did you swap?
you say your mafs ok what about a changed ox. sens could be sending a false reading if contaminated.?
So you are idling ok right, no spitting out the exhaust or loping like you have a big cam or something, right? ok.... lets see.
i was reading some where to disconnect the IAC connector, pull a plug wire with insulated pliers one by one then put back on to notice a drop. should be with in 50rpms of each other that may rule out the plugs/ wires (but not the gap and deposit build up).
also to ohm out the wires if it reads 30k ohms or higher --replace. (I keep an old new, cheap set around to swap things out to test like that):biggrin:
aheem. further i also read to check and pull ea. injector with the car idling with the IAC connected to see if theres a difference if you dont have a noid light. could not be gettin enough fuel.
and other than the valve train , which i doubt if its not idling bad, i dont know unless it is a loose/broken wire somewhere on that car but who knows I wonder if the chip was burned for the NEW heads set up or if it needs to be, i know i put all that info down when i got my chip from eric.
you say your mafs ok what about a changed ox. sens could be sending a false reading if contaminated.?
So you are idling ok right, no spitting out the exhaust or loping like you have a big cam or something, right? ok.... lets see.
i was reading some where to disconnect the IAC connector, pull a plug wire with insulated pliers one by one then put back on to notice a drop. should be with in 50rpms of each other that may rule out the plugs/ wires (but not the gap and deposit build up).
also to ohm out the wires if it reads 30k ohms or higher --replace. (I keep an old new, cheap set around to swap things out to test like that):biggrin:
aheem. further i also read to check and pull ea. injector with the car idling with the IAC connected to see if theres a difference if you dont have a noid light. could not be gettin enough fuel.
and other than the valve train , which i doubt if its not idling bad, i dont know unless it is a loose/broken wire somewhere on that car but who knows I wonder if the chip was burned for the NEW heads set up or if it needs to be, i know i put all that info down when i got my chip from eric.
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