violent jerk trying to go wot

[neverlift]

ok guys rebuilt ka24det running t25 at 5psi with fmic and stock injectors on high base pressure.

I am getting a very violent cutout when trying to go wot, the a/f ratios seem fine and steady(I lift when it happens), spark gap is sett way low .028 for 5psi is stupid, they are brand new ngk vpower plugs. Cap and rotor are also new, coil is on a relay and is an msd blaster ss... I broke my manifold loose and retorqued it to stock specs. Still no change.

The car will run at wot if you go past the break up it will smooth out SOME. please I know its getting old with me asking newb questions but Ive tried it all and I'm stumped

[coolbone28]

What is your timing set at? What is your fuel pressure at? what are you using to monitor a/f ratio and what are they doing when you have this breakup? also what rpm does it do it at?

[neverlift]

timing is set to stock, then my ecu (tuned) is controlling timing in boost and what not afr monitor via a plx smafr,like 65psi without vac before boost(making my injectors almost 350cc) a/f stays at 11.8ish. I can smell what seems to be unburnt fuel right after it happens.

Only thing I am thinking at this point is my t/b gasket may have cracked when I took the bolt out to take the vac line gimmic off.

I'm thinking of removed scv butterflies as the culprit, the turbo is spooling way faster now, with the copper exhaust gasket.And my motor had close to no grounding at 13.3 ohms(IDK wgat happen I checked it before I put the sohc ecu in WAY before turboing) z32 maf voltage at idle is 1.2volts(good IIRC)

ANY rpm.

[WDRacing]

IC Pipe or coupler? I had a crack in one, ran fine when I was off boost. Then bogged and bucked when boost hit.

Does it happen when your in boost and not WOT? Have you checked your TPS settings?

[neverlift]

well it builds boost probably till redline(have not took it over 4k cuause its rebuilt), but it holds fine. I have ****ty couplers so I will investigate them.

However only 2 are after my maf, 1 at maf other at throttle body. They were all fine before I rebuilt tho I dont get it. Well it happens before wot and will clear if you hold it.idle maf voltage is .46(a bit low IIRC) is that good. I know my ecu should be seeing like .5 volts. I was in process of adjusting and it started raining on me. lol so it basically happens trying to get to wot. or in boost(t25 so thats anything over 6%throttle) at more than 25%throttle. I 'd like to say its fuel related but the damn monitor says its good still. I have some q45 injectors but the tops are cracking, would that hurt performance in any way?or my freind has some from an sr for like a bill...

[WDRacing]

What are your TPS settings? I think I'm gonna change your titlte to "Violent Jerk"...

[neverlift]

that would be sweet mod privileges...

IDK I could only get it to read something like 5.14 at idle on the black/red wire. It was raining and dark. lol I think I'll check my couplers in the morning and adjust my tps, I'll let you know. Also use some one minute gasket maker on it and see if its from my t/b gasket. I migh even pull the intake manifol dback off and use some on the felpro gaskets to give it a better seal

[Riubens]

also check if your MAF is connected good with nothing loose ,my car used to do the same thing, come to find out my MAF was a little loose, I noticed it because of the safc, the % in the MAF would go haywire on WOT so I figured I would check it out, and wala solved the prob.

[neverlift]

I'll have to check that, its soldered on the maf itself but the wiring is spliced in wiht the sohc pigtail but it should be good, everything was fine before. I'm getting frustrated

[WDRacing]

ANy updates?

[neverlift]

yeah 1minute gasket is awesome and will hold about 6psi I had some vac leaks cause the gay arse felpro gaskets were ripped yes ripped, BOTH intake manifold gaskets! Vac jumped from steady 17ish to and steady 20.

BUT the problem is still here So after doing the rtv gasket I was listening and making sure I didnt hear any leaks I noticed fuel pressure was down(walbro hp255) so I took the vac line off pressure rose only 5psi. Then decided to raise base pressure 3psi, did that and it went back to what it was, withou me adjusting any more wd is it dead or what man I could wife is gonna divorce me cause its turned into 50psrts being bad from 4 broke pipstons. wtf murphy

[WDRacing]

So it drives fine unless you go WOT?

[neverlift]

yeah I got like 50miles or so on it... It happens at any rpm in all gears, it does it while trying to get to wot, but the stumble starts >30% throttle. clears till about 3800 then stumbles hard again. I have not went over 4200rpms btw. the car pulls friggin hard as hell when out of boost or in boost at low throttle. so does it sound like my pump is failing?

[neverlift]

well I'll kno wmore thursday night or friday day... just ordered ANOTHER walbro, this time from injected maybe it wont have the nico banned sponsor curse like this one, but then again maybe always runnign under half tank and 65psi base pressure doesnt help look for update in a couple days

[xekushnr]

lol, I thought from the thread title you were calling yourself a violent jerk. Like you beat someone up, called them a name, then tried to speed away.

I know there was (meaning a few years ago, dunno about now) a FLOOD of Walbro knockoff pumps that were POORLY made in China and look almost exactly like a Walbro. They were all sold AS Walbros. Perhaps your got your hands on one of these pumps.

[neverlift]

actually I thought that but the thousands sold would have turned up more than just mine being bad... it was purchased from expreefuelpump threw a group discount on nico... I hoestly think it would still be fine if I was at a safer pressure, btu I'm not, nor do I intend to run around with a full tank all the time the title would fit tho, why do you think when wd said he'd make my custom title that, I was like sure I've probably done what you said and worse

[WDRacing]

Violent Jerk it is

Sadly, I seriously doubt its the fuel pump.

[neverlift]

what could it be then? I am almost positive thats what it is. It seriously feels like fuel cut, fuel pumps that are in proper working order dont lose pressure then have it raised and drop back down to an exact same number.... It was making raped whore noises lastnight too seriously what do you think it is

[neverlift]

how anout this to back up the bad pump theory.. the damn gauge was bouncing violently up and down today, wiht or without vac applied.

[deviousKA]

Its too rich, especially during boost transition (0-3 psi). Ive this happen all the time tuning civics and mitsus with low boost.

It probably wouldnt show up quite so bad if you were running more total boost, but in any case, you dont need to be that rich during initial boost transition.

[neverlift]

same tune I was running kinda, I ended up havng to adjust my k some to get stoich, I had awfull grounding.

Then noticed my pump was low, then today I saw the bouncing and its kinda telling me the pump is dying, I mean only a total of 2x has the pump been fully submerged in fuel, its been stressed at 75psi daily for abou 8k miles..... IDK why it would be too rich, its cutting out liek it has NO fuel

long time btw bro!

[deviousKA]

Which wideband do you have?

Run a log, if you have a fuel pump problem or massive loss of fuel pressure it should be quite obvious.

If the AFR is relatively steady when this happens though, and you are running richer than 12:1 at these boost levels, try leaning it out to about 13:1 at 1-2 psi, and 12.5-12:1 at 4-5 psi.

Could be your pump I guess causing some problems, 75psi is rough. You would see your AFR jumping all over the place if it was cutting out. You running 270cc injectors? If your going to replace anything, might as well find some larger injectors so you can drop your pressure.

[neverlift]

plx smafr on narrow band same thing they state will be a cheap and highly accurate setup... hasnt let me down in a couple years lol.

funny you say that, it was my plan to get some 370's my freind has for 75 bux, turn pressure down to about 55 plus boost. A walbro hp is desighned to be at higher pressures, I am thinking my pump is from the chinese knock off set, 90% of the people using them are not ever seeing 60psi or more.

I'll give leaning it out a shot, but I still dont think the pump is workign in proper fashion, pressure should be steady at idle not bouncing all over the place. vac is SOLID around 19. I mean a 8psi or so bounce is a lot imo.

[eazye2000]

Some information for future reference:

I got my Genuine, Walbro 255 HP Pump, with install kit and sock, for 85$ shipped. Marty, at Injected Performance hooked it up. They're a sponsor of the site. Go check out the Advertisers Marketplace. They have some good deals once in a while. But I think the pump is an every day price.

zeroforum?id=145

[240sxvaj]

i think you should go bigger injectors. i got my 450cc from dwerks and walbro 255pump, nismo fpr type-b. Right after i installed my fuel pump everything was good and ran better but then car started going crazy after a few weeks when going in boost, so i found out stock injectors went bad. replaced that and car ran way better but then a week later found out that fpr was bad because it wouldnt start up. got that fix this week w/nismo fpr. Last thing was that rpm drops really low and sometime dies after boost so i took for dyno tune and after that everything was running really good and doesnt die anymore.. so i think it is too rich if thats what you're experiencing and my fuel pressure is at 36.5 .

i'm kind of a noob so i dont know what you guys mean by WOT.

[WDRacing]

Wide Open Throttle

[neverlift]

already spoke with IIRC ryan, pump should be here tomorrow, we will see.

I'm not 100% its too rich(IN MY CASE GABE) it feels like blow out OR lack of fuel, rich boggs feel different from my experieces on this ka.

so wd what do you think it is if its not the pump/ youwere kinda leaning towards it then switched on me????

[WDRacing]

I guess we'll keep troubleshooting if the pump doesn't fix it.

[neverlift]

yeah it wont be here till friday from atl already I might take my nine to it if the pump isnt the problem, and my other 300zx filter is NIA (ninja in action ) all the ****in sudden like it has legs or some ****. Its strange I think even if it wasnt boosted it would be cutting out. Everytime I try to hit wot it stumbles, I can ease into it and boost all day, it really seems like the fuel cant keep up with demand. does that make sense?

[WDRacing]

Well lets assume it's not a boost issue at all. If you're already in full boost without being WOT, then it's ECU or signal going to the ecu when the tps registers WOT.

I still think your tps is fvcked. You can atleast try screwing with it a little. Under WOT the TPS and MAF should be the only signals used by the ecu. I wish you were using a wideband...

You have a Multi Meter right? Turn the key to acc mode, measure the TPS output when closed and then WOT. IIRC it should be like .5 and 5v like the MAF. I'd have to check the manual though to be sure.

I messed with the TPS on my Skyline before I knew what I was doing and jacked it all up. Car ran like utter crap under various throttle applications.

Just something to mess with until that pump gets here.