Stock Boost Levels

[96Turbo]

Hi. Yesterday I put in a boost gauge awaiting my MBC. Every since I got my car (4 months ago) it hasn't boosted all the way. It won't quite go through the yellow. My mechanic took a look at it, and he thought that once it got "used" to premium gas it would boost right. After about 7 tanks through it, nothing's changed. Now with my boost gauge on, it's only making about 7psi. Also, It doesn't seem to boost any less in 1st or 2nd than the rest of the gears. My question is, should I just tune the MBC to run what I want (I'm thinking about 13psi) or do I need to have it looked at to see why it's not boosting right with the ECU controlling boost? Thanks

[Stalker]

Well, not quite thru the yellow sounds pretty norm to me... (although the 7psi reding does sound low) Id say just throw it on there (mbc that is). You do have an intake right? And of course get gap your plugs, premium gas, and good synth oil for the mbc use.

Im afraid im gonna have to see a pic of the gauge install there...

[96Turbo]

Well I guess I described it wrong, it barely goes above HALF of yellow, obviously low (my mom and dad both have saab turbos and they go right up to the end of yellow). I do use premium gas, I need to change the oil soon, and i'll put in synthetic. However, for the plugs, I need to get them gapped? What would be the advantage of new plugs? Here's some pics of the gauge, it looks really cool especially with the red light. Sorry the pics are so crappy, I never get around to taking pics in the daylight.

[Stalker]

Yea you should get some new plugs. w/o the right plugs and correct gap, you can lose some power. The plugs are BCPR-7ES availible at advanced on a next day delivery basis. They should be gapped to .035" (they also carry the gapping tools) It does sound like it is underboosting a little, but since its not a huge amount i wouldnt worry, maybe just a bpc problem (which youre about to bypass anyway )

Gauge looks good. What model and make is it? Couldnt tell from the pic...

Stalker

[96Turbo]

It's an autometer. How bout aftermarket plugs, any suggestions, is it worth it?


http://store.summitracing.com/defaul...=egnsearch.asp

[mg_td]

aftermarket plugs? umm, i believe you only want some ngk bcpr7es-11

[96Turbo]

would these be worth the extra money? (do they cost more) Or should I just go with the stock plugs because my engine isn't modified that much (only a cat back exhaust)

[mg_td]

they cost me 2.35 each. they are the preferred, and stock plug. we need special plugs because of the way the ignition crap works, they serve as a knock detector too, someone else can explain better. but those are the kind you NEED to run right

[96Turbo]

would these be worth the extra money? (do they cost more) Or should I just go with the stock plugs because my engine isn't modified that much (only a cat back exhaust)

[mg_td]

does a double post warrant double replies? haha, kidding... but yah bcpr7es-11 gapped to .035"

[redline514]

I don't want to discredit your boost gauge instal, but maybe you are loosing just a little bit of air somewhere? And factory "boost gauges" are known to be inconsistent. Trust me, mine will stay the same even when my boost gauge (calibrated) goes up and down.

If you can somehow take a bike tire or basketball or something, read the psi with a proper hand-help gauge. Then compare this reading to your boost gauge. That is if you can figure out how to hook your boost gauge to the bike tire/basketball.

Otherwise, I would say maybe the factory bpc, so you won't have to worry about that for long. But I know this isn't good if there is another problem, because you would then just be ignoring it.

[Adrian W]

Redline, do you have a T7 car? On a T7 car the "boost gauge" is more like an "air-mass/combustion" gauge. If the intake temps are hot the factory gauge will read the same, but an aftermarket boost gauge will read higher. The opposite is true when intake temps are quite low.

[redline514]

I've got a gauge installed on both a T5 and a T7 car.

[96Turbo]

I suppose it's possible my lines aren't all air tight. I used teflon tape on all threads and cranked them down as far as i could...so I don't know. It's always seemed a little low though, my dads car (900 vert) seems to have a little more go with it boosting where it should. What should my psi be?

[Stalker]

Did you use some airtite tape or whatever the heck its called when u made the boost tap t? Try that, how does it vaccum at idle? If theres a leak it will show on the vaccum as well. Should be around 15-20 mmHg (-).

[96Turbo]

It idles at about 11, and when i'm driving if i let of the gas quickly, it drops to about 20.

[96Turbo]

but my gauge's vacuum is measured in in hg, not mm hg

[Stalker]

Sorry, i really meant inHG.... Was thinkin with my science stuff the whole mmHG. 11 inHG sounds a little low (like 13 or so would be more normal) There might be a leak in the tap somewhere.

[Marks900SE]

Mine used to idle over 20in/HG now its just over 18. I though that was normal.

Exact psi for stock car is 7/8psi in 1st and 2nd then 10/11psi in 3rd through 5th.

[96Turbo]

correction, i was reading my gauge wrong. It actually idles at about 15 inhg. The dots are by 2s, not 1s. (Duh!)