Car bucking when hitting 4k WOT
 

I'm being tuned with uberdata and me and my tuner were working on it and did two 3rd gear pulls. And everyrthing was fine. But then on the third one, the car started to buck like it was stalling out at 5k rpms. And we tried everything to fix it. I'm going to try and get Matt to post in here also and tell you what happened (he's tuning it)

I used to have a VAFC but got rid of it. Could the way the VAFC was wired cause any problems with Uberdata? We are out of ideas other than the wiring. Any help would be appreciated.

If you need any specs on the car or the turbo components please tell me.

Re: Car bucking when hitting 4k WOT
 

any cel?

Re: Car bucking when hitting 4k WOT
 

Did you tighten up your plug gap or even install new plugs? 99% sure that is your problem.

Re: Car bucking when hitting 4k WOT
 

No

Re: Car bucking when hitting 4k WOT
 

I didn't do the install, so I would have to ask. But if not how would I go about doing this? I've never heard of this or anything, so could you explain it somewhat? THanks, I'm trying to learn all I can so I can do the install myself next time.

Re: Car bucking when hitting 4k WOT
 

Search GOOGLE on "How to Properly Gap Spark Plugs"

Re: Car bucking when hitting 4k WOT
 

Alright figured it out, if I don't need new spark plugs, what should be a good gap size? And I've heard good things about NGK spark plugs, should i get those if new ones are needed?

Re: Car bucking when hitting 4k WOT
 

Cant go wrong with .030, one or two step colder NGKs havent let me down. Denso's work ok too but generally foul out quicker and start misfiring more easily than the NGKs

Re: Car bucking when hitting 4k WOT
 

http://www.sparkplugs.com/more_info....15733&pid=2530

Do these seem fine? Any better websites to get them at? And how much do spark plug gap tools run? Thanks and sorry for all these questions. I just need to make sure this is right.

Re: Car bucking when hitting 4k WOT
 

Bucking can also be caused by the engine runing out of gas.

Re: Car bucking when hitting 4k WOT
 

If you have a Prelude/H22, those are stock spark plugs, but platinum.
go with ZFR7F-11 which are a heat range colder and only $2.44 each at ngk.com

Re: Car bucking when hitting 4k WOT
 

1/2 a tank.

Re: Car bucking when hitting 4k WOT
 

No could be a full tank.
But stuff like fuel pump not keeping up. Injector issues, cloged filter etc.
My reasoning is its only hapening at WOT. Fuel stravation and WOT tend to go hand in hand.

But hey be an optomist and hope its just the plugs. ;D

Re: Car bucking when hitting 4k WOT
 

try your cap and rotor had that problem

Re: Car bucking when hitting 4k WOT
 

Hey I'm the guy working on tuning this car. Its acting really strange. Its bucking even when the afr reads fine...like right around 11-12:1. Thats a good suggestion about the plugs though i didn't think about that. Whats really strange to me though is that one map i tried worked great on his car. It pulled hard fairly strong all the way to redline. We did a number of pulls with it. Then i went back and tried tuning it a little and again it was back to the bucking. Then i put the original map back in(the one that worked perfect) and it was bucking ???. From there on out i couldn't put a map in that wouldn't do this. I even tried somebody elses tuned h22 boost map on his car and it did the same thing. To me it seems like some kind of wiring problem...like maybe the map signal is reading funny or something. After all this we took a look at his wiring harness and it looked like there was some weird stuff going on under there where the afc had been wired. I'm not much of a wiring guy though so i wasn't going to screw around with it.

Re: Car bucking when hitting 4k WOT
 

Check the rotor in the dizzy?

Make sure the screw or allen screw isnt loose and none of the contacts or corroded or plastic chipped...

Re: Car bucking when hitting 4k WOT
 

Well I've got a brand new 255lph fuel pump in there and 450's that were working fine, but then when we tried using uberdata and scraping the afc, it started doing it.

And I checked out the dizzy about a month ago and it checked out fine. I can check it again for any loose bolts but I highly doubt it.

Re: Car bucking when hitting 4k WOT
 

yea i don't think its fuel starvation because it was bucking even when the afr's were fine.

Re: Car bucking when hitting 4k WOT
 

check your fuel filter?

Re: Car bucking when hitting 4k WOT
 

It's only two months old, and it's not fuel starvation. The afr's are fine.

Re: Car bucking when hitting 4k WOT
 

have you done a compression and leak down test on this?

and does it only buck based on AFRs? is it low load, medium load, high load?

does it buck in boost?

Re: Car bucking when hitting 4k WOT
 

it seems to buck worse based on load.

Re: Car bucking when hitting 4k WOT
 

so the harder you push it, the more it bucks ::scratches head::

too much fuel would cause it to bog, too little would cause it to buck...

any way the MAP sensor or TPS wires are screwed up, loose? Maybe a bad ground?

if you rev it at idle, does it does this at all?

Re: Car bucking when hitting 4k WOT
 

If you rev it, it doesn't do it. It's probably the plug gap, I just pulled them and they are at stock .44. But I have to go to work now so I'll re gap them later. And Matt, the wiring looks odd but it's fine. Anthony said the only two wires that he screwed with that would need to be fixed were the two wires that were cut.

Re: Car bucking when hitting 4k WOT
 

yea hopefully the plug gap has something to do with it. Are your plugs 2 step colder? If not you should get some that are. Make sure they are 7 series plugs.

As far as it running lean or rich I've tried adding and taking away fuel from that are with no luck. Something is fishy. It still seems like a loose wire or something to me though. Its strange that it acted fine that one time and then on the same exact map acted totally screwed up a minute later.

Re: Car bucking when hitting 4k WOT
 

Plug gap really shouldnt make any difference until higher boost levels where the excessive pressure would be "blowing out" the spark because of the large gap.

If its happening consistantly in vacuum, most likely its not the plugs..

Re: Car bucking when hitting 4k WOT
 

Well it doesn't happen when there is no boost, by the time I get to 4k, I'm already spooled. And I'm at like 8.5 psi.

And Matt, someone up a little bit in the thread recomended the ZFR7F-11 from ngk.com. Those should be fine, correct?

Re: Car bucking when hitting 4k WOT
 

yes those plugs should be fine.

Re: Car bucking when hitting 4k WOT
 

Alright well I'm going to gap them tonight after work. What's the best way to test to see if that is possibly the problem before I come out to your house again? Can I go do a run on the map you gave me? If the plugs were the problem, it should run fine, correct?

Re: Car bucking when hitting 4k WOT
 

Yes you can test them out on that map. The map i left you with was that one we pulled off of the uber forums. Its extremely conservative in timing and fuel. It may not necessarily run fine since a lot of timing is pulled on that map and a lot of fuel is being dumped in, but you should be able to tell a difference I would think.

Re: Car bucking when hitting 4k WOT
 

So it might bog down a little but it shouldn't buck.

Re: Car bucking when hitting 4k WOT
 

honestly i can't say without having the wideband hooked up. Those maps were definintly rich though. Just look to see if it runs any better or will at least make it through the rpm band without the rpms completely cutting out.

Re: Car bucking when hitting 4k WOT
 

Alright, gapped the spark plugs last night and ran it all the way through 2nd and third and everything is good, otehr than it's a little bit too rich I think around 5000/Vtec crossover because it kind of bogs down. But I think the spark plugs were the source of the problems. If you can finish the tuning tommorow Matt that would be great.

Thanks for everyones help!

Re: Car bucking when hitting 4k WOT
 

Wow man that is good to hear. So you really felt a difference after changing them? Swap back to the other spark plugs and run it just to be sure that was the problem and its not just randomly working alright again because i wanna make sure its not doing that stuff before we try tuning again.

Re: Car bucking when hitting 4k WOT
 

I didn't change the spark plugs, the previous owner had already replaced them with NGK's. I have the number of them at home. But anyways I'm almost 100% sure that was the problem, because yesterday I got on it in 2nd and it didn't go anywhere and bucked and made that horrible popping noise like it's misfiring. But today it was perfectly smooth all the way to 5000. So if iy's ok with you can we tune it tommorow?

Re: Car bucking when hitting 4k WOT
 

I love it when the student doesnt listen to the tuner...

Man, go throw the other plugs in there so he doesnt come out to waste his time and tomorrow the same ---- happens. MAKE SURE IT WAS THE PLUGS


...ummm Kay

Re: Car bucking when hitting 4k WOT
 

I just tested it this morning, and it ran fine, it didn't buck. I didn't order or get new spark plugs becuase I din'd think it was really nessecary. I gapped them and it runs fine, I'm going to do it again this afternoon and if it starts to ---- up I'll change them, but until I find reason to change them, I'm not going to.

Re: Car bucking when hitting 4k WOT
 

I want you to make sure they are 7 series 2-step colder plugs before we retune. Pull them out and tell me what the number is. Also try doing a few more pulls and see how it feels. Remember it worked fine for one or two pulls when we were tuning, but after that it would feel like crap on the same tune. You should be safe on that map. The fuel values were pretty rich and the guy said he tuned it with a bigger turbo than you have. Also the timing values are way low...like less than I even run on my y8 motor so you should be fine.

Re: Car bucking when hitting 4k WOT
 

Alright I'll get the number off them and if they aren't what you are thinking of I'll get the ones from a few posts up.

Re: Car bucking when hitting 4k WOT
 

Replaced them, gapped them to .030 and it runs smooth through 2nd and 3rd all the way to redline. Thanks for the help guys.