1998 GS-T 132 FWHP Stock? What could be wrong?

[andrewzpsu]

Hey guys, I just bought a 1998 GS-T today, it is my second GS-T, I used to own a 95 back when I was in highschool. This one felt substantially slower so shortly after buying it I brought it back to my shop to dyno it. Well, not to my surprise, dynoing in only 3rd gear, it only put down 132 fwhp with a pig rich AFR... under 10.0 AFR.

Well since I knew a thing or two about tuning (I work on GM cars), I removed two honeycombs from infront of the MAF... the side ones specifically. The AFR bumped up to an acceptable level, starting at around 12.4 and ending at around 11.6 at redline. The horsepower went up to 150 then and I decided I didn't need to try to dial it in more as this was close enough.

The car seems to be in good shape, but I'm not sure why the power is so low.

I'm going to hook up a boost gauge probably next week... just a cheapo one from advanced auto or something just so I could get a reading on the boost level.

One of the things I noticed is that compared to my old GS-T, the boost takes forever to come on.

Maybe my wastegate is stuck open? How could I fix that if that is the root cause of the low power?

I'm also going to run a compression check.

Anything else I should look into?


Thanks a ton! I'm excited to have one of these cars again! =)

 

[xhackerekx]

for stock boost BPR6ES for boost over 15psi use only NGK BPR7ES or BP7ES coper plugs no use another or take u engine to junkyard very fast.

 

[wkmitsu]

Wrong. Keep in mind that every company is in business to make money. If convincing you made NGK a couple more bucks, then that plug got done what it needed to. The vast majority of people running DSMs use copper plugs without problems... don't waste the money or time.

I guess you didn't read the whole post. I just explained everything.

 

[summerisway2hot]

I would like to see your "proof" of all of those claims.

My proof lies in the fact that the majority of the community sucessfully uses copper plugs.

I read your post. My opinion is, and will always remain, that iridium plugs on DSMs and most other vehicles are a gimmick.

 

[wkmitsu]

I would like to see your "proof" of all of those claims.

My proof lies in the fact that the majority of the community sucessfully uses copper plugs.

I read your post. My opinion is, and will always remain, that iridium plugs on DSMs and most other vehicles are a gimmick.

Ok, since thats the way you feel, I don't think anything I say will ever make a difference. But when you think about it, it makes sense. Iridium is well suited for use in spark plugs because of its ability to withstand extremely high temperatures. Sorry I don't have personal test results at hand to throw at you.

 

[summerisway2hot]

Aside from my opinion, it just seemed kind of odd to me that you started off talking about iridium plugs and ended up talking about diesel glow plugs. Even on diesels equipped with glow plugs (many, many, many diesels do not have them), glow plugs only operate in order to allow the engine to warm up to the point to create combustion. Once that is done, the glow plugs shut off and the engine keeps running. The diesel in fact runs on the heat of the compression of the air charge in the engine when it moves up on the compression stroke.

Also, if you are really that worried about the faster cool down rate, keep in mind that the spark plug is only an extremely small fraction of the area of your head...

 

[wkmitsu]

Aside from my opinion, it just seemed kind of odd to me that you started off talking about iridium plugs and ended up talking about diesel glow plugs. Even on diesels equipped with glow plugs (many, many, many diesels do not have them), glow plugs only operate in order to allow the engine to warm up to the point to create combustion. Once that is done, the glow plugs shut off and the engine keeps running. The diesel in fact runs on the heat of the compression of the air charge in the engine when it moves up on the compression stroke.

Also, if you are really that worried about the faster cool down rate, keep in mind that the spark plug is only an extremely small fraction of the area of your head...

I know all of that. I was just trying to back up my point that a spark plug can cause knock, which is what a glow plug does while its working. Glow plugs are different than a spark plug, yes, but they induce detonation just like a spark plug thats too hot will, proving the theory that too hot of a plug can cause knock. Therefore a plug that can cool off quicker between pulses will reduce the likelihood of knock at higher RPM. Decreasing the chances of knock is what the cool down rate helps with, not the overall temperature of the cylinder head...

 

[summerisway2hot]

Alright, I get what you were saying now.

As is, and will always be, everyone is entitled to their own opinion. How about this for advice...

No matter what plugs you get, Gap them to .028" or else...

 

[proteusx301]

I know all of that. I was just trying to back up my point that a spark plug can cause knock, which is what a glow plug does while its working. Glow plugs are different than a spark plug, yes, but they induce detonation just like a spark plug thats too hot will, proving the theory that too hot of a plug can cause knock. Therefore a plug that can cool off quicker between pulses will reduce the likelihood of knock at higher RPM. Decreasing the chances of knock is what the cool down rate helps with, not the overall temperature of the cylinder head...

Glow plugs do not induce detonation or cause knock. The sole purpose of a glow plug is to modify the rate of thermal diffusion of the materials surrounding the combustion chamber, nothing more. Glow plugs are disabled immediately upon cranking and in no way contribute to combustion.

 

[wkmitsu]

Glow plugs do not induce detonation or cause knock. The sole purpose of a glow plug is to modify the rate of thermal diffusion of the materials surrounding the combustion chamber, nothing more. Glow plugs are disabled immediately upon cranking and in no way contribute to combustion.

Forget it, I was wrong about that, it was a bad example.

 

[colbyc]

I use 6es's and always have. Hope this helps.

 

[andrewzpsu]

Ok, so found two boost leaks... fixed one.

The other one is the BOV.

Any suggestions, or anyone want to mail me their stock BOV? =)

Andrew

 

[defury]

I think 2g BOV's come stock leaking, I always just assume they are leaking cause they usually are.

But hey if people are giving away 1g BOV's sign me up, I need one

Where was the first leak?

 

[colbyc]

No, get a hard uicp flanged for a 1g bov. Then well of course buy a 1g bov, and your set.

 

[Bluedragondsm]

Whats the best way to check for a boost leak? need to check mine this weekend and have somewhat limited tools

 

[colbyc]

A BOOST LEAK TESTER!!! and soapy water

 

[Bluedragondsm]

A BOOST LEAK TESTER!!! and soapy water

Well what i mean was is there an actual place I can buy a boost leak tester? or do I have to try and fab one?

 

[colbyc]

Yeah, well are you needing it by this weekend or what? If so you'll need to make one, which is very very simple.

 

[Bluedragondsm]

Yeah, well are you needing it by this weekend or what? If so you'll need to make one, which is very very simple.

Which one would you say is the best do it yourself one?

 

[colbyc]

Which one would you say is the best do it yourself one?

Go the home depot way
any works though, and if you feel lazy and don't want to make yourself like I did at one point..... Boostpro.net : Specializing in performance makes really good ones. But all in all its just a coupler, base with valve on it, takes 10-20 min. max making it yourself and maybe 10 bucks.

 

[Bluedragondsm]

Go the home depot way
any works though, and if you feel lazy and don't want to make yourself like I did at one point..... Boostpro.net : Specializing in performance makes really good ones. But all in all its just a coupler, base with valve on it, takes 10-20 min. max making it yourself and maybe 10 bucks.

I am super lazy and for an extra 20$ ill buy the tester.

I am assuming I need double pop gauged with tire adapter? Sounds like it would be the easiest.

 

[colbyc]

yup either is fine, but the might as well pay the extra for the gauge, it's really conveinant

 

[andrewzpsu]

So here is my new update...

Car makes 152 rwhp after replacing the intake and the BOV (got an injen with maf and the greddy used for $300).

The boost seems to spike pretty good, but then bleeds off dramatically, down to 8 psi at redline.

There are no more boost leaks that I could find either. However with the new maf the AFR seems ok, still richer than what I think it should be, but not as bad as my original maf with all the honeycombs in.


It puts down 180 torque, but because the boost dies, so does the power. If it would just stay that would be perfect.




Any more suggestions?

 

[Bluedragondsm]

What all did you check? did you check the intake seals? exhaust for leaks? Turbo seals? manifolds? and throttle body etc.

 

[dsmdeliveryboy]

How are you making 152rwhp with a FWD car? Lol
What turbo are you running? If your still on the stock t25, the boost is never going to hold steady.

 

[andrewzpsu]

How are you making 152rwhp with a FWD car? Lol
What turbo are you running? If your still on the stock t25, the boost is never going to hold steady.

Hahah, sorry. My tuning business is all GM stuff like my Corvette, GTOs, G8s, Camaros... yep, all rwd haha. So I'm not used to talking about fwd haha.

I am using the stock turbo, just surprised that it keeps dropping down to 8 psi.



I'm going to slap the boost leak checker back on this puppy next time I'm at the shop. We'll see if I missed any leaks now that the BOV is fixed.