Why does my GSX keep getting slower with each upgrade?

volkerding95GSX · Nov 28, 2011

Hey guys! I usually try and figure this stuff out by myself, but I have no idea what to do next and I am in way over my head. Any help would be GREATLY appriciated. So thanks in advance.

I am stuck in a rut with my DSM build and was hoping you could give me some advice and/or motivation to finish it. It's been disheartening because it seems like every "upgrade" I do to it makes it slower and run worse than before. This car is the first I've ever modified and I have next to no mechanical experience besides the few bolt-ons I've put on.

The eclipse felt the fastest when I first bought it. It pulled hard and never missed out. The only mods it had when I bought it was a small 16g, 1g BOV, K&N fpik air filter, HKS cat-back, Apexi electronic boot controller and a bigger fuel pump (unknown size). At this time everything was great and I had no CEL.

Fast forward after all the bolt ons I've added: (4" Forced Performance intake recirculated, Punishment racing SMIC hard pipes, Stainless steel tubular exhaust manifold, stainless steel 02 housing dumped to the atmosphere, Megan 3" downpipe and 3" Megan cat back with cat-delete.) Now it idles just a little rough, I have a CEL, and the car feel WAY slower than it used to. It doesn't pull hard under boost. The boost gauge reads 10 psi, however I feel nothing but a slow car.

I've done a boost leak test and there was a huge leak in the coupler right after the turbo amoung a few others, so I fixed all the leaks, but it only helped minimally. Still the same symptoms. The oil, spark plugs, and wires are brand new.

Where did I go wrong? Why is my car slower after I upgraded the bolt on parts? Is it a matter of installing too many breathing upgrades and no fuel upgrades? Or should my car still run strong with the upgrades I have?

I still have plans to buy bigger injectors, a wideband, and ECMLink, but that wont be for a long while, so I was wondering if there's anything I can do with my current set-up to make it run strong again. If not, I would love if you guys could give me a rule out check list or a list of parts I would need to get my car running right again. Let me know if you need any follow-up questions from me and I will do my best to answer. Thank you!

PotatoFlakeSTi · Nov 28, 2011

Tuning the car would probably go a long way.

nek · Nov 28, 2011

Well you should start by looking at that cel

Otherwise there are two things that usually happen to us as owners.
1, our idea of fast changes and what seems like 300 horses now only feels like 85
2, our cars are upgraded in stages. Dsms were designed with parts that work efficently with each other. By changing out items, such as turbos, you need to get all the support mods before you can actually feel the benefits such as fuel mods, exhaust, tuning equipment etc. Also, make sure your tuning your car... you cant just slap parts on and hope the ecu gives you some more horses, you got to tell the ecu these parts are aftermarket and work differently.

jtmcinder · Nov 28, 2011

volkerding95GSX said:
I still have plans to buy bigger injectors, a wideband, and ECMLink, but that wont be for a long while,...

That's the problem. A car with oodles of bolt-ons but hasn't been tuned can easily be slower than a car without the bolt-ons. Move ECMLink to the top of the list is my suggestion.

Aproductions · Nov 28, 2011

Check for boost leaks again.

What plugs?

What was the CEL for?

Sounds to me like you just need a tune/wideband.

1983gsp · Nov 28, 2011

Its like baking a cake. You can have all the ingredients, but, if they are in the wrong proportions, it will taste like the northbound end of a southbound mule.

A good tune is like getting all the ingredients right, making all the parts work together in harmony,

H@xtGSX · Nov 28, 2011

You need to make that wideband, bigger injectors, and some sort of Air/Fuel controller priority #1, my friend... The reason you are getting slower is because all that stuff is allowing that turbo to breathe deep and you are running way too lean. If you don't have anything to increase your fuel ratio, you are seriously headed towards a burnt up motor. You need to keep the boost way down and really watch your temps carefully until you know for a fact you have injectors that can deliver the amount of fuel you need, a fuel pump that can supply them, a fuel regulator to control the pressure on the fuel rail, and at least a piggyback A/F controller like an SAFC to correct the MAF signal so the ECU can put enough fuel in the cylinders. I am willing to bet your computer is absolutely maxed out on its fuel trim correction and can't compensate anymore for how much air you are moving. If there wasn't anything to adjust the fuel ratio before, it was already on the very edge of what the ECU can handle on the stock settings, if not slightly past it. You MUST get the fuel to match ASAP or you WILL be paying for a rebuild at best or a new motor if it blows up...

You didn't say if the Apexi is their boost controller of an SAFC... If it's an SAFC, you need to up the percent correction across the entire range.

Personally, I wouldn't even drive it in that state. I can guarantee that CEL is from the fuel trim out of range code. It won't take a heck of a lot when it is that far out of whack to burn up a piston, blow out the head gasket, etc... It's already right on the very edge of any of those things happening.

volkerding95GSX · Nov 28, 2011

Spark Plugs = bpr7es, gapped properly

I haven't checked the CEL yet, and honestly I don't know how either, I will look into it and do that.

I guess I don't understand why I ran fine with no CEL when I got it b/c it had increased airflow with stock fuel supply and yet ran fine. I guess I don't understand how a downpipe and IC piping and a ex manifold can cause a fine running car to turn into sluggish and slow under boost.

So there's nothing I can do with what I have now? ECMLink and a wideband are the answers to my problem?

asrdave · Nov 28, 2011

is boost hitting when it should be? check for preturbo exhaust leaks that could be the root of your problem

volkerding95GSX · Nov 28, 2011

asrdave said:
is boost hitting when it should be? check for preturbo exhaust leaks that could be the root of your problem

It seems to build boost at the same RPMs like it used to and it will stop building boost where it is supposed to as well, there is no boost creep. Under boost it just feels and even kinda sounds like none of the boost is getting into the engine. Forgive my ignorance, but pre turbo exaust leak like exhaust gas leaking from the exhaust manifold?

Also, the Apexi is not a SAFC, it's an electronic boost controller. Would a MBC help the situation out any?

91stocker · Nov 28, 2011

volkerding95GSX said:
So there's nothing I can do with what I have now? ECMLink and a wideband are the answers to my problem?

Well atleast a logger. That way you can see whats going on, plus most can read and clear cels. But it does look like your ready for some tuning. Link v3 is a pretty nice set up.

jtmcinder · Nov 28, 2011

volkerding95GSX said:
I guess I don't understand why I ran fine with no CEL when I got it b/c it had increased airflow with stock fuel supply and yet ran fine. I guess I don't understand how a downpipe and IC piping and a ex manifold can cause a fine running car to turn into sluggish and slow under boost.

It could be a variety and/or combination of things. If you pointed a gun at me and said: "what's the single most-likely problem" I would first take the gun away from you, then kick you a few extra times somewhere between your thighs and belly-button (because I don't like having guns pointed at me), and then, as a parting shot, answer your question, anyway (because I'd be feeling a bit guilty because a guy isn't supposed to kick another guy in that place): "lack of timing."

volkerding95GSX · Nov 28, 2011

jtmcinder said:
It could be a variety and/or combination of things. If you pointed a gun at me and said: "what's the single most-likely problem" I would first take the gun away from you, then kick you a few extra times somewhere between your thighs and belly-button (because I don't like having guns pointed at me), and then, as a parting shot, answer your question, anyway (because I'd be feeling a bit guilty because a guy isn't supposed to kick another guy in that place): "lack of timing."

haha, It was just a water gun, relax! Now my crotch hurts, and I don't know what you mean by "lack of timing". We talking cam timing or what?

H@xtGSX · Nov 28, 2011

It ran fine when you got it because it was choked up just enough for the ecu to compensate... Now it isn't choked up at all and you are moving too much air and not enough fuel. I promise you that if you are running that set up with stock injectors and no way to increase the A/F ratio, you are rediculously lean. That is why it runs like crap, I am absolutely sure of that. If you are on stock injectors with what you listed, you're lean. Really lean, to the point of burning stuff lean. If you want verification, go get a ir themometer from a shop and check the temp of your exhaust manifold while it is running. I bet it is near red hot at just 2k rpm.

It isn't anything else, you are too lean plain and simple. Don't fart around with anything else until you can get more fuel into the motor or you will burn it and be rebuilding very soon.

volkerding95GSX · Nov 28, 2011

H@xtGSX said:
It ran fine when you got it because it was choked up just enough for the ecu to compensate... Now it isn't choked up at all and you are moving too much air and not enough fuel. I promise you that if you are running that set up with stock injectors and no way to increase the A/F ratio, you are rediculously lean. That is why it runs like crap, I am sure.

Okay, sounds good.

Bigger injectors, ECMLink, and a wideband should solve my problems then?

I haven't been running the car hard at all, it's not a DD. I turn the boost as low as it will go, and only get on it for a split second to test it after I "fix" it. That's only been 2-3 times, so I don't think I've compromised any internals.

jtmcinder · Nov 28, 2011

Timing = ignition advance. Knock pulls timing. Too much airflow for your tune leads to knock. Hence my guess.

GSXSixteenG · Nov 28, 2011

Check your knock sensor to ensure it is working properly. Could be knock or phantom knock causing the ecu to pull timing.

Calan · Nov 28, 2011

H@xtGSX said:
It ran fine when you got it because it was choked up just enough for the ecu to compensate... Now it isn't choked up at all and you are moving too much air and not enough fuel. I promise you that if you are running that set up with stock injectors and no way to increase the A/F ratio, you are rediculously lean. That is why it runs like crap, I am absolutely sure of that.

It doesn't sound like he's over-running the MAF and hitting fuel cut yet (especially at only 10 psi of boost), so why would he be "rediculously lean"?

OP - Do as Cinder said and move ECMLink to the top of your list. You'll be surprised what you can accomplish with a good tune and a way to see exactly what's going on with your motor.

volkerding95GSX · Nov 28, 2011

Yes, I've read about fuel cut, and I'm almost sure I haven't hit that yet. I think that's because the turbocharged air isn't even combusting b/c how slow the car is. That makes me think it's a boost leak, but it holds pressure fine when doing a leak down test.

H@xtGSX · Nov 28, 2011

Calan said:
It doesn't sound like he's over-running the MAF and hitting fuel cut yet (especially at only 10 psi of boost), so why would he be "rediculously lean"?

OP - Do as Cinder said and move ECMLink to the top of your list. You'll be surprised what you can accomplish with a good tune and a way to see exactly what's going on with your motor.

It sounds to me as if he hasn't run it to the point of knowing if it'll hit fuel cut. Look at that list of upgrades.... I can overrun 450's with my 14b and barely half of that list. Thats why I say rediculously lean. If it were running like crap I wouldn't push it either, therefore fuel cut may be just outside of "romping on it" . That list of parts, in the exact same car as mine, with stock injectors is going to be lean. There is no way around that.

Fix the fuel and you will be good to go. Ecmlink, if you have the money to get it now, and some 650cc injectors, and you'll be in much better shape. Heck, get 850cc's if you have EcmLink, just for the bigger margin. You can adjust it to where you need it with link, regardless of the size of injector, so I'd go bigger than I needed and tune them back.

volkerding95GSX · Nov 28, 2011

Yep, Link will def be the next purchase. Worth every penny, but it is NOT cheap! Shoulda never touched my car! haha, I can't leave it alone though.

Calan · Nov 28, 2011

OP - are you still on the stock MAF?

volkerding95GSX · Nov 28, 2011

Calan said:
OP - are you still on the stock MAF?

Yes, nothing has been done with the MAF, ECU, or injectors. I do have an EPROM chip, so that's good news for when I buy Link

clipto · Nov 28, 2011

The only thing I don't like is you don't know what kind of fuel pump you put in your car.Running stock boost controller aka the bcs? It not really ganna allow you to flow that turbo, maybe taking out the little plastic restictor in it will help.Smart thing for you for your setup is check what size fuel pump you have and get injectors, dsmlink, wideband and manual or electronic boost controller.Then you will feel the 16g power.As long as it is not a ebay 16g.I ran 71% inejector duty cycle on my with 550cc injectors on my 14b at 15psi ,I would just get FIC 1050cc future proof yourself call it good. :thumb:

volkerding95GSX · Nov 28, 2011

clipto said:
The only thing I don't like is you don't know what kind of fuel pump you put in your car.Running stock boost controller aka the bcs? It not really ganna allow you to flow that turbo, maybe taking out the little plastic restictor in it will help.Smart thing for you for your setup is check what size fuel pump you have and get injectors, dsmlink, wideband and manual or electronic boost controller.Then you will feel the 16g power.As long as it is not a ebay 16g.I ran 71% inejector duty cycle on my with 550cc injectors on my 14b at 15psi ,I would just get FIC 1050cc future proof yourself call it good.

Thanks. Ya, the previous owner was really good about writing down exactly everything he did to the car, but all he wrote was "HKS fuel pump." so idk how big or what type it is as I have never had to get it out for any reason yet.

It is a MHI small 16g, no worries! =)

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Why does my GSX keep getting slower with each upgrade?

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