Today while driving I experienced something Ive never felt before. When I run my car all the way to 6k it feels strong and when I reach 7k-8k I notice a dip in power...kinda like a stall. My top end power just bails out on me, Im thining its a fuel/ignition related problem. Am I leaning out on top or is it a misfire? Any ideas?
7k-8krpm loss of power
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1,652 Posts
Reset the ECU and see whats up.
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its normal for the power to slope away after 7k, but it shouldn't make a noticable dip...
poorly gapped or old plugs will fail at higher rpm... check those first!
poorly gapped or old plugs will fail at higher rpm... check those first!
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change yer oil....
Not the EXACT same thing happened to me, but it wasn't revving as well, as smoothly up top. An oil change did wonders.
Not the EXACT same thing happened to me, but it wasn't revving as well, as smoothly up top. An oil change did wonders.
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Well first of all you always lose power in the really high RPM's, (VTEC lessens that), but that sounds unusal. I would check you're ignition, something might be causing you to lose spark at those RPM. on another note, 8k rpm sounds like too much for LS/Vtec on a stock LS bottom end. You forget that you changed the head, not the rods/pistons/crank. The GS-R motor has a shorter stroke, stronger rods, and more oil squirters to handle a higher RPM, the head has little to do with handling the RPM outside of allowing it to reach it in the first place. So unless you've built you're bottom end you shouldnt be revving far past the LS redline without reinforcing you're internals. Not saying that you'll throw a rod like I did missing a shift, but the stock LS bottom end isnt designed to spin at 8k.
Edit: Ok, I see you have ITR internals, so none of this applies, with that stuff you can rev to the moon
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Edit: Ok, I see you have ITR internals, so none of this applies, with that stuff you can rev to the moon
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AC sucks power all through the RPM range though. Doesnt sound like it. But hey I like my AC. And im so glad that its the same as it was on my 94, because for whatever reason my tegs (94 (deceased) and 98) ac likes to make a sound like a high speed turbine (AKA, turbo) when I step on it. So when my friends are in the car I can turn it on and their all like, "Dude? Did you get a turbo or something?". Its pretty funny until I turn the AC of and they figure it out...
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have you raised compression? Or upgraded to some wild cams? If you haven't, then the problem is simple, there is no power to be found up there
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I would say that your Vtec isn't kicking in. SImple as that. You said you have an LS/Vtec, so right off the bat you've got two things that were never ment to work together. Maybe something has fouled in the head, like the oil line has a leak/solinoid not recieving proper oil pressure. I think I know what your feeling. I have a GSR and one day I redlined before the engine was fully warmed up. Since the oil had not reached it's 180 degree minimum to activate the vtec, it just fell off right after 6k. Check you vtec, I'd bet the problems there.
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the V-AFC will tell you when power is sent to the VTEC sylinoid, it cant actually tell you it is clicking over.
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I am having this exact same problem with my 98 GSR. I just noticed it tonight as I was revving really slowly up the tach to 8k, I noticed that at about 7200 rpms or so there was a slight but sudden drop off in power, similar to turning the AC on at freeway speeds. But then it seemed like when I mashed the throttle down, there wasn't any power loss to speak of (I mean the engine wanted to bust out of the front of the car as usual at this rpm). It seemed like it only happened with the throttle on lightly. I'm wondering maybe if this is normal?
I would like as many other GSR owners to test this out and post. Just redline your car out in first or second gear really slowly so your needle is just barely climbing, and when you get just past 7000rpms see if there is any kind of a change.
I would like as many other GSR owners to test this out and post. Just redline your car out in first or second gear really slowly so your needle is just barely climbing, and when you get just past 7000rpms see if there is any kind of a change.
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21,139 Posts
many reasons can cause this:
not enough air
not enough fuel for the air once you get the right amount air
too much CR (undercamming a motor)
too much friction
too small an exhaust system (outer diameter sizing)
not enough air
not enough fuel for the air once you get the right amount air
too much CR (undercamming a motor)
too much friction
too small an exhaust system (outer diameter sizing)
i experianced a similar thing a while back when i changed my exhuarst set up and left the silencer on the new muffler i got..
would rev up then hit vtec and u could hear it change over but there was just no pull at all then i took the silencer off and it was back to the good old wheel churping days for me again.
ie Have u changed anything of recent in your cars setup?
would rev up then hit vtec and u could hear it change over but there was just no pull at all then i took the silencer off and it was back to the good old wheel churping days for me again.
ie Have u changed anything of recent in your cars setup?
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