vj20 wastegate problems

[boostedescort]

Well i am having problems with my gtx swapped escort gt. I know the wastegate on the vj 20 is small but i can't even stay at stock boost setting. My car has corksport downpipe and custom 2.5" exhaust with fmic. The car boosts to 14 psi and falls back to 10 psi with no boost controller just running off wastegate spring. In third,fourth,and fifth it will boost to 14 psi at 2800 rpms, then hit fuel cut. The wastegate is opening i seen wastegate acuator rod moving. So i was wondering what my problem could be, any input would be so helpful.

[Zexcort]

what vaf are you running and have you boost leak tested it?.....with it spiking like that and not staying at stock boost it sounds like a boost leak to me because i had the same problem with it running 14 psi...it was a boost leak it souldn't change if you don't have a boost controller gotta be a leak...... to get rid of the fuel cut i switched from the stock vaf to the code b vaf

[mx-3_4evr]

I have a B-code VAF if you need one

[Mazda_Powered]

most people will bore out the wastegate port before they install them, i know i sure did.

sounds like that may be your issue, you have lots of bolt ons that increase velocity and flow, and this dinky wastegate port that's supposed to dump all the extras somewhere.

just my 2 cents

[bomdoutscort]

Really sounds like you need a new wastegate. All these suggestions aren't looking at the main problem. Boost creep is normal but not for a stock wastegate to be boosting 14 and making the car hit cut, unless its cold out. Oh and you'll hit boostcut in the higher gears if you try to get on it too hard in the higher gears. You need to be about 4500 to actually hit on it past 3rd and even second sometimes.

[boostedescort]

I have a b-code vaf and like 4 u-codes it does it with all of them. I checked for boost leaks and could not find any. Im glad to know that other cars hit fuel cut below 4500 in 3rd on up through . Im going to try bomdoutscorts idea and try to find another wastergate. Its awsome how helpful everyone is on here thanks everyone for suggestions.

[Mazda_Powered]

please tell me if this fixes your issue, this frequent talk of fuel cut scares me from having a properly runnig car lol

[bomdoutscort]

i was told it the wastegate and it cant control the boost too well and you get boost spikes. I think the best bet would be to port the wastegate between 1 to 1.5inches then get a new flapper. I hope to cure this problem with a external wastegate.

[boostedescort]

So it seems like alot of peoples cars hit fuel cut in higher gears but does a stock gtx do that, I mean if you bought a gtx new would it hit fuel cut in high gears. If not why do ours.

[CaymenEGT91]

Really sounds like you need a new wastegate. All these suggestions aren't looking at the main problem. Boost creep is normal but not for a stock wastegate to be boosting 14 and making the car hit cut, unless its cold out. Oh and you'll hit boostcut in the higher gears if you try to get on it too hard in the higher gears. You need to be about 4500 to actually hit on it past 3rd and even second sometimes.

exactly what mine did.. mine was running 14psi all day with the corksport downpipe, and 2.5" straight pipe exhaust no boost controller.... If I would try to be in 3rd or 4th crusing around low RPM it would hit boost cut but if you were getting on it from 4000RPM or so it'd be fine.

[323driver]

Because of the free flowing exhaust. The stock exhaust is very restrictive and slows the exhaust gas flow enough to keep the pressure at 8 psi.

[Mazda_Powered]

sweet so i shouldn't have much of an issue for now haha, running the oem LX exhaust with a vj-20 setup.

still going to port the vj-20 out a bit more i think tho...

[bomdoutscort]

Because of the free flowing exhaust. The stock exhaust is very restrictive and slows the exhaust gas flow enough to keep the pressure at 8 psi.

Great explanation.

[bam]

Same issues here. At about the same RPM's too. With an open exhaust it is normal. I run a B-code VAF and leaned it out to right before it doesn't want to cycle at idle to try and make the ECU see less air flow......and still bounce fuel cut a lot.

If it's any consellation with a VJ-20 and GTX injectors you won't blow anything up.

[yunvmyegt]

ya know, reading all the complaints about boost cut is why i posted my spair gtx ecu for sale.... if i ever need it ill plug the stock one in ....