GSX wont go past 40mph

[Gt Boost]

so today i was comin home fine from work and the car drove good. then a couple hours later i went to drive the car to pic up my kids from the sitter the car would not go past 40MPH. when i would come to a complete stop for the lights or stop signe my car would just die then i would start it back up and go but it sounded like my car was farting through the first 2 gears then when i hit third it get to 35mph then do the same sound so i was driving in 4th gear at 40MPH.

Also my car when i turn the ignition to the on position the car shows boost being halfway. and when i would rev the car up car doesnt sound like its boosting and it shoots black smoke.

Car

98 GSX

Mods

16g turbo
evo 9 FMIC
Dejon intake with apexi filter
also have a manual boost controller


thanks for all the help in advance i called the company i got my turbo from and they are sending me a new one i should have it by thursday.

 

[H4G64T]

You have a large boost leak.

 

[Chaosweaver]

More than likely a boost leak, there is also a possibility of the ignition control module being bad. I had the same symptoms with no boost leaks, turned out to be the ICM (also called the transistor).

 

[Gt Boost]

where is this icm located at is that the same as the idle control

 

[nek]

I forgot to plug in my maf plug one time and could not go above 30. Check it out.

 

[Chaosweaver]

It should be bolted onto the intake manifold, this is what it will look like:

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[miguelmcv]

Also check your Throttle Position Sensor, If it is bad or not calibrated, It will do the same thing.

 

[Gt Boost]

thanks chaos miguel wheres the tps at is that the throttle cable sry im not familiar with the engine much unless its simple bolt on things

 

[miguelmcv]

This is the Throttle Position Sensor.
RREs  Eclipse 2G Turbo 1G Throttle Body Swap
The site tells you how to Adjust the TPS, But it doesn't tell you how to test it.

 

[wicked98gsx]

Im going to agree with the boost leak idea. I burst the coupler on the j-pipe and car wouldn't get ove 20mph full throttle

 

[xxNocturnalxx]

The black smoke would be from running too rich due to your boost leak.

The maf is good start also.

 

[Gt Boost]

Im gonna call around today and price out a tps and icm sensors and also the idle air control sensor and ill replace them and make them new instead of worrying if this happens again

 

[rlacasse1]

Have you even done a boost leak test?

Your issue is more than likely to be solved by putting an intercooler hose back on whatever it blew off of, or tracking down a leak.

With out doing that test, chances are you will just be throwing money at nothing.

 

[spyderdrifter]

That happened to me last year and I ended up having bad compression in all 4 cylinders. May want to do a compression check to be on the safe side.

 

[xxNocturnalxx]

Have you even done a boost leak test?

Your issue is more than likely to be solved by putting an intercooler hose back on whatever it blew off of, or tracking down a leak.

With out doing that test, chances are you will just be throwing money at nothing.

^agreed.

I am sure you have a least some boost leaks weather they are your problem or not they should be addressed, the throttle body is a popular area.

 

[Riceburning101]

Dsm's are money pits without diy diagnosing and trouble shooting. Most shops probably don't even know what dsm stands for so BLT that thing already

 

[psychbiker1966]

I bet a coupler loosened and came apart (Boost leak) or your TPS went bad.

 

[T is for TURBO]

Are you getting a check engine light? If it were throttle position related, I would most likely throw a code.
Even if it doesn't, they are easy enough to diagnose with a simple multimeter.

OP: Don't start replaceing sensors until you have figured out the problem. You can't just slap a new TPS on the car and call it a day. It has to be calibrated properly, and if you don't calibrate it, and the tps isn't the problem, you will just start burying the problem underneath other problems. There are some good suggestions already posted. I would, in this order

Check codes
Check all connectors
Boost leak test
Compression test

 

[Gt Boost]

Ya my cell code is on from my idle control sensor

 

[NathanCarlK]

Very well could be a boost leak, but also just check under the car and make sure all the pipes(intercooling pipe) are hooked up and nice and tight, once one of mine came off and I couldn't go much over 20.

 

[GSTurbo1]

bad turbo?

 

[Gt Boost]

so i feel like a real noob here . i pulled off my bumper and the shop did a 2 piece piping on my car 2 on each side and they came apart so i am redoing all my piping today and tomorrow and will give you guys all an update and see if it fixes the problem. i hope this does i miss drivin my car.

 

[greybush]

^agreed.

I am sure you have a least some boost leaks weather they are your problem or not they should be addressed, the throttle body is a popular area.

^^ Ditto, ^^
The second day I had my 1G years ago, I had down shifted into high RPM's - call it bad shifting- third to fourth ended up being third to second. It was only for a second but it blew off a vacuum line and blew a coolant line. I had the black smoke issue and could only limp home.

 

[rlacasse1]

so i feel like a real noob here . i pulled off my bumper and the shop did a 2 piece piping on my car 2 on each side and they came apart so i am redoing all my piping today and tomorrow and will give you guys all an update and see if it fixes the problem. i hope this does i miss drivin my car.

OH, imagine that. Just what EVERYONE was trying to tell you.

Aren't you glad you didn't go throwing money at your car now for no reason.

 

[Gt Boost]

Haha ya but still went out and bought ngk plugs any suggestion on wires