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! =)

 

[tsi1991awd]

First thing to do....check for boost leaks.

This is probably your number 1 cause...and it would explain why your AFR is off.

The wastegate COULD be a problem, but I doubt it. Easy way to check is to hook an air compressor to the actuator and put 10psi through it and watch it open up.

 

[DSMDriver69]

Sounds like a boost leak to me. Also have you checked for any abnormal shaft play on the turbo?

 

[blkgst97]

slow spool = possible pre turbo exhaust leak

 

[EclipticalGS]

well, 150hp stock at the wheels is normal. our cars have 215~ crank HP, Fwd WHP stock should be around 155-165, awd -10%.

http://www.dsmtuners.com/forums/newbie-forum/373863-dsm-stock-whp.html

Boost leak, plugs (ngkbpres gapped .028), wires, check for preturbo exhaust leaks,..That would get you to where stock Whp would be.

 

[PieEyedPiper]

Removing the honeycombs on a 2g is problematic. Too much turbulence causes strange and unreliable airflow readings. AFR's of 12 or high 11's is also problematic on pump gas. What octane are you running? What logging methods are you using? Can you log knock or timing advance?

I would imagine you're knocking pretty good with AFR's that lean. It's common for people to find the sweet spot on 91-93 octane to be around 10.9-11.5.

I second the Boost Leak Test motion. It's likely you're losing metered air causing an even more rich than stock (9.6 AFR I think?).

What plugs are you using and what are they gapped to?
NGK BPR6es are recommended @ .028"

 

[jrohner]

Well what was the boost at? That's the most important thing to know to figure out if your hp was at a normal level. The rich afr's are normal, as the stock fuel maps are in the 9's.

What kind of dyno was this on? It's pointless to worry about DD or Mustang #'s if you're used to a dynojet.

AFR's of 12 or high 11's is also problematic on pump gas. What octane are you running? What logging methods are you using? Can you log knock or timing advance?

I would imagine you're knocking pretty good with AFR's that lean. It's common for people to find the sweet spot on 91-93 octane to be around 10.9-11.5.

Not if he's at stockish boost levels on a stock car.

 

[PieEyedPiper]

Well what was the boost at? That's the most important thing to know to figure out if your hp was at a normal level. The rich afr's are normal, as the stock fuel maps are in the 9's.

What kind of dyno was this on? It's pointless to worry about DD or Mustang #'s if you're used to a dynojet.



Not if he's at stockish boost levels on a stock car.

I made the statement assuming 15psi, 91 oct and stock smic. I know that I'd be knocking at 11.6 or even 12's for an AFR.

You make a good point though. 11's and 12-14psi on a stock setup might work really well. I've not tested a scenario like that. I'll defer to your tuning expertise over mine

 

[andrewzpsu]

Thanks for the ideas guys. I don't have any logging tools for the eclipse yet, I will probably buy DSM-Link as it seems to be pretty powerful and close to what I'm used to for tuning GM cars (HP Tuners).

I have a dynojet dyno and I used its wideband to read the AFR at the tail pipe. I use the Innovate LM-1 Portable Wideband for street tuning, or tuning GM cars since it interfaces with my tuning program.



So Here are my action items in order to fix it all...

Things to buy immediately:
1) Boost Gauge (cheapo from Advanced Auto just to read for the time being)
2) Halmann Manual Boost Controller - dealer close to me


Things to do in order until problem is fixed:
1) Check/Fix Boost Leaks
2) Check/Fix the wastegate and turbo
3) Check/Fix the BOV



I think Import Intelligence, they are the shop behind mine, may have DSM Link... I'll see if I can borrow it for some logging.



Thanks again guys, I'll keep you all posted in what I find probably sometime next week. Taking the vette to the shore this weekend =P

 

[PieEyedPiper]

You should also put your honeycombs back.

 

[andrewzpsu]

You should also put your honeycombs back.

I will if the AFR at WOT is unsafe once I find this boost leak. (I suspect with 99% certainty that is what I'll be doing.)

What_dyno_did_you_use?

My dynojet.

I have a shop in West Chester but only work on domestic cars.... for now.

 

[lilbro717]

also try a compression test, doesnt hurt to check

 

[dsm-onster]

My dynojet.

I have a shop in West Chester but only work on domestic cars.... for now.

damn, I thought I deleted it before you saw. I overlooked that in your previous post. I'm sorry

 

[andrewzpsu]

So I may have found the problem.

The waste gate solenoid's bottom hose was off.

But I can't figure out what to connect it to... for anyone interested, it is that "free" modification you can do that I'm talking about.

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Where does this connect to?

 

[kimcheefists]

I believe that bottom hose is supposed to hook into the air intake before the turbo. Is there a T from the compressor housing to the wastegate? If so, that T is also supposed to hook into the wastegate solenoid.

 

[andrewzpsu]

I believe that bottom hose is supposed to hook into the air intake before the turbo.

Got it thank you.

However, still doesn't seem to be making power

The search continues.

 

[jrohner]

WHAT WAS THE BOOST AT?

If you don't have a gauge, stop worrying about hp until you know what the boost is at.

 

[andrewzpsu]

WHAT WAS THE BOOST AT?

If you don't have a gauge, stop worrying about hp until you know what the boost is at.

Well I found a cracked bov line... hooked up my boost gauge to that and it is holding 12... car seems to feel faster right now. Putting it on the dyno now to see if that solved it... and then if it did... MBC goes on.

 

[wkmitsu]

Give the car a thorough tune up, new plugs, maybe some larger diameter wires, fuel filter, PCV valve, air filter, clean the MAF, etc. If there are any CELs, sort that out. Use NGK BPR6EIX spark plugs, you will feel a difference. And I would put the honeycombs back in your MAF. If you're feeling really ambitious take your intake manifold off and clean it out.

 

[andrewzpsu]

Boost is actually not holding 12. It is spiking to 15, going down to 12 and then by redline it is at 8 psi.

 

[dsm-onster]

Boost leak or cracked wastegate hole.

 

[talonalex92]

Give the car a thorough tune up, new plugs, maybe some larger diameter wires, fuel filter, PCV valve, air filter, clean the MAF, etc. If there are any CELs, sort that out. Use NGK BPR6EIX spark plugs, you will feel a difference. And I would put the honeycombs back in your MAF. If you're feeling really ambitious take your intake manifold off and clean it out.

There is no reason to waste your money on iridium plug. At all.

 

[JEFFREYCASTGSX]

Its a 98 check for a black plastic ecu, if you do then you have the flashable ecu, you can use the ecuflash/evoscan and last ceddymods on it. http://www.dsmtuners.com/forums/tuning-engine-management/347070-ceddymod-v1-ecuflash.html

Unfortunately you cannot use DSMlink on the current ecu, DSMlink is more of a package to tune/datalog. Get a regular datalogger specifically for a 2g.

 

[wkmitsu]

There is no reason to waste your money on iridium plug. At all.

NGK IRIDIUMS are the recommended plug for high hp applications I run them in my car and they are great plugs. A colder plug is going to help prevent knock. Iridium plugs offer faster cool down rates between pulses because the harder material core doesn't have to be as thick and will not retain as much heat between firing which will help in the higher RPM range. The smaller surface area of material gives you a greater and more direct spark energy, thus it decreases the chances of blow out under high cylinder pressures and improves combustion. Obviously not every car with copper plugs is gonna knock, but because of the plugs being what they are its just one less area to skimp on. And if you have never heard of a plug causing knock then you've never seen a diesel before. Glow plugs are essentially constantly hot plugs to enduce knock, it's what diesels run on. Engineers wouldn't put so much research and development and expensive build materials into something if a lesser product was superior, right?

 

[summerisway2hot]

Engineers wouldn't put so much research and development and expensive build materials into something if a lesser product was superior, right?

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.

Considering you are stock now, I'd recommend the BPR6ES's, as you build up more power move to a BPR7ES, etc.

Good luck.