high rpm bucking???

[91-gsx]

i was just tuning my car and when i noticed it was knocking at higher rpms, i richened the wot switch on my maft by 5% so the knock went away, but i did the same in the mid switch and that took away the knock too. so it pulled hard up until about 5,500-6,000 rpms and then it would buck a lot and it still wanted to go to redline, but it did it slowly becuase of the bucking and there was no knock logged, am i running to rich(dont think so) or is there something simple like a boost leak? any help is greatly appreciated.
thanks

 

[SpoOLxExO]

I am not familliar wiht the MAFT controls, but it is possible that you have an intercooler leak.

You might also want to check your fuel filter, plugs (Might have fouled after adjustment) and wires if you have them (Coil-on plug applys here)

Also do you have an EPROM ECU with a chip in it?

What kind of injectors do you have right now?

 

[91-gsx]

take a look at my profile, just updated it.

 

[TURFNNSURF]

Tony,

Check your PM's, I had the same problem after installing my DSMchips Eprom, for us A/T guys the neutral safety switch wire, PIN# 104 to the ECU needs to be cut and then grounded to the body. I confirmed this with a direct conversation with Jeff at DSMchips.

Good luck and happy Tuning.

 

[91-gsx]

i have a manual tranny. but it does not just stop at 5,500, it bucks and still wants to accelerate but really slowly.

 

[TURFNNSURF]

My bad Tony, But it could still be the "NO LIFT TO SHIFT" mod on the chip. You may want to check out the DSMchips forums for similar problems and the answers. It may be a faulty clutch switch.

 

[91-gsx]

you know i think you are right becuase my off the line 2 step stutterbox does not work, i can set it using the stock boost gauge but then it does not work. but as far as the no lift to shift option i have it wired up and i could always go to redline, i only could not whe i made it run a bit richer due to the knock but i think what i really have to do is turn the boost down until i put my fmic on, that should be fun. but as far as the clutch switch is that the on you have to splice in to right under the drivers dash? becuase i want my damn stutterbox to work so i coulduse it when i get a bigger turbo, for now i want to stick with the 14b, i like the little guy.

 

[ekanddsm]

Are you sure your not having a ignition misfire in the high rev, may be a sign of weak ignition. Check O2 readings when that bucking is taking place, you say it takes a long time to rev past that point.

 

[91-gsx]

i did note on one run i made a couple of days ago when the car would knock a lot that the o2 voltage would stay at .93v or so which not to bad, but then all of the sudden it would drop to .3v, i do not know why, maybe to rich the leaner it is the more knock there is and the bucking goes away. the 5% richer i made it took away the knock but it produced knocking. basically i am going to try running 15 psi instead of 18 and then tune for a leaner mid and wot. i think the air is so hot that i had to run richer just to run that boost level and allow the gas to absorb the heat.

 

[whathits14]

I had a somewhat similar problem whenever I hit boost on the new turbo after a dumbass mechanic got his filthy hands on it....turned out to be plugs/wires...might check those.

 

[ekanddsm]

Maybe I'm just being a dumbass, But it sounds like your experiencing turbo surge, You have all the right equipment on your car. Are you making small enough adjustments to your maft, and then driving it, or is your boost to high, The injectors you have are a little big, but can be controlled with major fine tuning. Smaller adjustments may be needed.

 

[ekanddsm]

GOD I HATE WHEN I SOUND LIKE A SERVICE MANUAL

 

[BoostedTalonTS]

Have you tried running a smaller plug gap? -Or at least checked the plug gaps lately? I also had a similar experience with my old(er) set of plugs... Turns out that the plug's electrode was self-gapping itself to over .044" and it was not getting a solid combustion (In my case, usually under WOT, with more than 15-18psi of boost).

 

[Cool Mr Steve]

I struggled with the same thing for a long time... I had different issues on a few occasions that caused my stutter: Fouled spark plugs, plugs gapped higher than .028, and a couple of boost leaks... Definitely do a boost leak test.

 

[miragetbo1997cc]

Bad or cheap spark plug wires will allow you to drop cylinders intill you got off it.

 

[Liger]

i had the same problem but mine was a faulty injector (that was brand new and is still broken after they "supposidly" fixed it ) it was putting too much fuel in at higher boost and was dropping a cylinder. Pull your plugs and see how rich you are running after a hard pull and the car is properly timed and cooled. I'd just definitely do what people are saying, check gaps, plugs, wires, and above all, a boost leak test. Good luck Brandon [VFRacing]

 

[91-gsx]

so i went out today and put back the Ngkbpr6es spark plugs and turned down the boost to 15 psi. the car when half throttled or floored felt really slow, becuase the mid was 5% richer as was the wot, so it did not knock at all when on those settings. but when i put it on 0 for both the mid and wot it felt faster and the bucking was all gone, but it still was not that fast, and it seemed to knock. so i said what if it is rich knock so i went 5% leaner on both the mid and wot and it dropped the knock by half. when i tried to go even leaner it felt even fast but the knock count was way too high starting at 3000 rpms or so it would hit around 20 knocks and taper down to about 17 by redline, so i tried to go 5% leaner but on both, but it just knocked some more. so to make long stories short, i ended up with the mid 5% leaner at F. and the wot 5% leaner at F on the dial. it knocked only about 10 times at most during 3,000 rpms and tappered down to 1 by redline and that was the first time i saw the timing at 20 degrees at redline, all the other times it was only at 15-17 degrees. so i said that was a good setting. the only thing is that it will change the knock count every time i floored it. the knock would go up if i tried to floor it again, but only by a few. is this becuase the stock intercooler has a tendency to heat soak very easily? and am i safe with some knock once the intercooler heat soaks?
thank you for all of your replies.

 

[SpoOLxExO]

Install the FMIC, then tune again.

Your on the right track about Heatsoak on the 1g sidemount.

P.s. Are you *Sure that your Cam angle sensor is at 5deg BTDC. Cause if it is advanced too much it will know, no matter what you do for fueling.

Keep that in mind.