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I checked my vtec selonoid gaskets and screen - all is fine... also my compression was fine last I checked a few months ago ( car was driving the same then). Looking to swap my exhaust later today and see if that does anything...
The power is peaking at about 8200 RPM, which isn't out of the question for an F20C1.
How is the throttle cable adjustment? I've actually seen this on a car that had a lot of throttle cable slack and was opening the throttle body to like 90%. Unlikely, but something like this would easily explain the issue, and wouldn't be throwing any codes. There's no way you're on the low lobes up top, as it wouldn't peak power at 8200, more like 6200.
Check the plugs, see how they look. Maybe one fuel injector is clogged and it's running lean or dribbling and running rich etc. One cylinder being down ~10-15% on power would yield that result, so start checking everything you can think of.
I agree that it's not likely a vtec system issue. I can tell you that you would have noticed earlier such a drastic difference in power up top. The car hardly accelerates in that condition.
- Can you overlay your dyno graph against another with similar setup? I'm wondering if you're down 25 HP across the band or only up top.
- Can you monitor timing advance, air/fuel ratio, and throttle position during the pull? If so, compare that to what you can determine to be normal or appropriate.
- Something else unorthodox to look at would be rear brakes. Do they get particularly hot after a dyno session? One side hotter than the other? Do the pistons retract easily when replacing pads?
I agree that it's not likely a vtec system issue. I can tell you that you would have noticed earlier such a drastic difference in power up top. The car hardly accelerates in that condition.
- Can you overlay your dyno graph against another with similar setup? I'm wondering if you're down 25 HP across the band or only up top.
- Can you monitor timing advance, air/fuel ratio, and throttle position during the pull? If so, compare that to what you can determine to be normal or appropriate.
- Something else unorthodox to look at would be rear brakes. Do they get particularly hot after a dyno session? One side hotter than the other? Do the pistons retract easily when replacing pads?
I can say for sure there is something abnormal about the power drop off at 6300rpm. it should continue to climb well into the 7500-8k range when comparing other NA powerbands. Trq starts to crest and gradually taper off a bit after 7k and then hp about 8k normally. So the curve is right looking basically, just down on the graph after 6300rpm. Its like the ecu is pulling a bunch of timing, or there is some other issue with fuel or an exhaust obstruction.
Last edited by s2000Junky; 05-22-2017 at 11:46 AM.
I actually replaced all my injectors with a set my friend had ; practically new condition.. the car slightly feels better but I also noticed that 2 of my plugs are covered in white residue... we cleaned them and did a pull and cylinders 2 and 4 showed that white stuff again.
Keep in mind that these plugs have like 3000 miles on them.
Looks like your running lean. are you running a wideband to see what your afr is? if not, its a great troubleshooting tool. What kind of breathing mods do you have? How many miles on your fuel pump?
Could fit a FPR and see whats happening at the high rpm on the dyno.
maybe an air leak on inlet side ?
done a vac test ?
knock sensor would adjust timing but have you been near it or deleted it ?
Looks like your running lean. are you running a wideband to see what your afr is? if not, its a great troubleshooting tool. What kind of breathing mods do you have? How many miles on your fuel pump?
Agreed. Prolly the reason for dip after 6300R's. ECU remapping, maybe?
I do have a wideband on the car... AFR is usually near 15 when at idle... I haven't messed with a knock sensor ; wouldn't it have given me a CEL if that was bad? I have a ported intake manifold with 70mm throttle body along with a cold air intake system. I also have a single titanium exhaust that I believe is a 60mm.
05-13-2017, 05:59 AM
