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Miss @ zero boost


actmach
08-27-2009, 01:14 PM
I have recently purchased a 91 vr-4 all stock at around 2000 rpm and or right when the boost Gage reads 0 it has a mis. I haven't owned too many cars with turbos and i have heard about turbo lag but it wouldn't miss would it ? When the boost kick in the mis goes away but the boost goes way up pegging the needle at 14+ that can't be good

quackmandude
08-27-2009, 03:21 PM
max safe boost is 14.5 but keep in mind the stock boost gauge is a pos. have u changed the plugs and wires??? maybe fuel filter? is it only when its cold or even when the engines warm. also the first gens had ecu problems but this doesnt sound like one
SAMSUNG-SGH-I617/1.0 Mozilla/4.0 (compatible; MSIE 6.0; Windows CE; IEMobile 7.6)

VR43000GT
08-27-2009, 03:36 PM
max safe boost is 14.5 but keep in mind the stock boost gauge is a pos

That is because it is not a boost gauge at all, it measures load.

To me this almost sounds like something to do with the MAS, but I am not 100% on that. If it only happens at 0 according to the load gauge which tends to show 0 pressure at the same time a boost gauge would is going to be the transition from vaccume to boost so to me it sounds like it may be having slight trouble transitioning from vaccume to boost as far as it adjusting your A/F mixture. Anyone else think that sounds plausible?

AutostradaVR4
08-27-2009, 07:35 PM
That is because it is not a boost gauge at all, it measures load.

To me this almost sounds like something to do with the MAS, but I am not 100% on that. If it only happens at 0 according to the load gauge which tends to show 0 pressure at the same time a boost gauge would is going to be the transition from vaccume to boost so to me it sounds like it may be having slight trouble transitioning from vaccume to boost as far as it adjusting your A/F mixture. Anyone else think that sounds plausible?

Sounds like you have a better idea than i do. I'd say start with the simplest things first, like checking for boost leaks and plug gaps.
:shrug:

actmach
08-27-2009, 11:22 PM
Thanks for the info
when I bought the car about 1 1/2 months ago the previous owner said he did a tune up on it (that mite be the problem right there) I can tell the wires have been changed I know the spark plugs in the front take about 15 min to change but the other 3 I'm thinking a few hours at least. So there mite be only half a tune-up I will check for leaks to. So is that normal for the stock turbo gage to peg thanks again

Stealthee
08-28-2009, 12:24 AM
Its like 15 minutes to do the rears. Really its not hard at all.

AutostradaVR4
08-28-2009, 09:22 AM
Thats the problem. people get intimidated by the rear plugs, so they just do the fronts. Theyre really not that bad...just pop the intake off, unbolt the plenum, and lift the driver's side of it so you can get in there. Just be aware that you *may* need a new plenum gasket, since the old one might break.
theres a fantastic walkthrough on stealth316

Stealthee
08-28-2009, 02:37 PM
The problem when people do it is they waste their time removing the TB and everything else when its not necessary. Remove the stay bolts, remove the 2 nuts and washers, remove the other 5 bolts, slide it up off and set it off to the side.

Alot of people end up removing the stay brackets because they are not necessary and its one less thing to remove when you have to do the rear plugs.

actmach
09-05-2009, 03:11 AM
Thanks for the info I have checked for lose and cracked intake hoses they seem ok plugs look like they all have been changed I haven't checked the fuel filter and it doesn't care if it is warmed up or not still have that mis now someone suggested it mite be the ecu and i have heard about the capacitors leaking dose anyone think that could be the problem

VR43000GT
09-05-2009, 02:32 PM
The caps are known to leak on first gen ECU's making the car act funky and eventually disabling it all together. However, I am not sure that your car missing at atmospheric pressure (0 psi) is going to be caused by your ECU. If you want to check and see if your caps are leaking just pull out your ECU and check it, it's real easy and is located behind the radio. Just take off both of the carpted side panels and unbolt the ecu to take it out.

actmach
09-06-2009, 12:48 PM
The other day I purchased an aftermarket air filter problem solved, doesn't make to much since because the stock air filter had been changed not long ago is that air box constricting that much air?

Stealthee
09-07-2009, 02:24 AM
Airbox is not that contrictive.

I still bet your MAS wasn't completelt plugged in.

AutostradaVR4
09-07-2009, 11:47 AM
maybe the little duct that leads into the stock airbox had crap in it too

Stealthee
09-07-2009, 01:05 PM
I say it was the plug in because the stock boost gauge is based off the MAS readings. If its not full connected it will totally fuck with the way the car is running, and give weird boost readings.

actmach
09-07-2009, 08:56 PM
I bet you are right that the MAS mite not been making full contact at the plug should I completely pull it off, drive it around the block to see if the problem comes back that way i will know for sure that was the problem and not the air-box?

Stealthee
09-07-2009, 11:00 PM
No, if its fine now leave it. But I can tell you the airbox was not the cause of your issue,.

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