2G Hitting a brick wall in 3rd gear

[96talontso]

It doesnt seem to happen in first or second, but in third when i really get on the throttle, once i get past about 6000 rpms, it feels like im hitting a brick wall. Its only happened twice, but ive only gotten on my throttle alot twice.... PLEASE help

 

[SOADweskey]

What if any modifications are done to your car? It really help others diagnose your problems if your profile is up to date with all the parts installed on the car.

This sounds like fuel cut but it is impossible to be sure without more information.

 

[96talontso]

Full Intake, NGR Type S BOV, Turbo back exhaust. Other than that completely stock.

 

[SOADweskey]

Well then with intake and exhaust done to much air may be going through the system. Also make a boost leak tester and check for boost leaks as a large leak will make the car think significantly more air is going into the engine then there actually is and it will cut fuel supply to protect the engine from detonation.

 

[Bud92gsx]

+2 on the boost leak..Are you seeing boost creep with the turbo back exhaust? You have a boost gauge right?

 

[96talontso]

I dont even know how to run a boost leak test...

:/ Not yet brochacho i was gonna order one this week.

And if it was fuel cut wouldnt the engine shut off? mine doesnt i just put it back in gear and baby it home haha

 

[Bud92gsx]

Get a boost gauge..You can make a boost leak tester or buy one for about 20 bux.. http://www.dsmtuners.com/forums/art...-boost-leak-test-how-boostpro-net-tester.html

 

[dsm03]

Do you have a boost gauge? Aftermarket that is..

Whats the vacuum reading at idle, and two check if it is creeping past the boost settings in just one gear or all..

BLT

 

[Jstue]

Get a boost gauge..You can make a boost leak tester or buy one for about 20 bux.. http://www.dsmtuners.com/forums/art...-boost-leak-test-how-boostpro-net-tester.html

I think its a boost leak as well. pump her full of air and see if she falls off. you should hear it.

 

[gsxeclipse97]

Boost leak.. I highly doubt that you are having boost creep on a t25.

 

[AWD_Launch]

Assuming you don't have a boost leak, it could be knock and the fact thats the T-25 runs out of steam before 6K. Your powerband stops probably around 5.5-6K.

 

[Calan]

I'm with Wes on this one. $10 says you're hitting fuel cut.

You've increased the amount of air the engine can take in, but have done nothing with the fuel supply or with the ECU to tell it how to handle this extra air. So as soon as the MAF sees a certain amount of airflow, the ECU is cutting off the injectors to save your engine, since it knows that you will go dangerously lean with your stock fuel system.

You could certainly also have one or more boost leaks, but you would likely be blowing black smoke and you would see these effects in every gear. Since the "hitting a brick wall" only happens in third gear when airflow and load are highest, that leads me to believe that your main issue is good old-fashioned (and normal) fuel cut.

 

[Nasty Dream]

Since the "hitting a brick wall" only happens in third gear when airflow and load are highest, that leads me to believe that your main issue is good old-fashioned (and normal) fuel cut.

I think this is probably right, honestly, and good explanation.

96talontso, with your mostly stock setup, the powerband dies off quite a bit at about 6K RPM. Is that what you're talking about?

Its only happened twice, but ive only gotten on my throttle alot twice...

So we don't know yet if it happens every time.

Have you tried only flooring it in 3rd gear, starting at say 2K RPM? It will still loose performance at about 6K RPM, but the turbo won't be overheated this time so it shouldn't be as bad. Don't run through the gears, I mean.

Again, is that what you're talking about then? It shouldn't be a drop-off enough to call it "hitting a brick wall", but you will definitely feel the loss in power.


Does it sputter or anything? Because it could also be improperly gaped spark plug/s. That will feel like the engine cut off for a second. And it tends to happen at higher RPMs, heavy on the throttle.

But don't mess with your plugs unless the engine is stone cold. Aluminum is soft and easy to strip.

 

[Calan]

It shouldn't be a drop-off enough to call it "hitting a brick wall"...

It will if it's fuel cut. He'll be looking in his rear-view mirror for tranny parts.

... it could also be improperly gaped spark plug/s. That will feel like the engine cut off for a second. And it tends to happen at higher RPMs, heavy on the throttle.

Spark blowout will feel sound/like a machine gun, with a corresponding drop in power. But on a mostly stock car, he should be nowhere close to having blow-out issues as long as his plugs and wires are in half-way decent shape. Still, never hurts to check.

But don't mess with your plugs unless the engine is stone cold. Aluminum is soft and easy to strip.

Not sure what the engine temp has to do with that one.

 

[Nasty Dream]

It will if it's fuel cut.

Yeah, like I said, that was the best explanation. In my defense, I don't think you had posted yet by the time I started writing my reply. Also, I've never actually experienced it, so I was thinking of my experiences, you see.

What do you mean about tranny parts anyway? Fuel cut is that drastic?

Spark blowout will feel sound/like a machine gun, with a corresponding drop in power.

Machine gun acceleration. I like that. Yeah, so it's basically like, you floor it and the horses start to get up, then falter, then giddy up, then falter. Intermittent hesitation under heavy load. "Like high RPM in 3rd gear."

But I remember it more clearly now that you describe it. That happened when I first got the car and was doing all the newb stuff like new plugs.


I mean, I'm not sure why I'm so intent on defending my reasoning

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See this person is calling this a brick wall, when the power clearly comes back on!



OK, OK, enough with the save face similes. Sorry.

OK, I just wasn't sure if he stayed on the gas... and I mean it can also just trip up over itself that way and the power dies long enough for you to stop pressing the throttle. Well, I CONSIDER IT A WALL

But on a mostly stock car, he should be nowhere close to having blow-out issues as long as his plugs and wires are in half-way decent shape. Still, never hurts to check.

Blow-out is when the spark plug comes out of the head, or the plug wire pops off, right? No, not blow-out, that's not what I'm talking about.

Side note, I've actually had that happen as well. Terrifying to think what just blew up in your engine, but a huge relief to find the plug wire just popped off.

Just misfire. And maybe you'd be surprised. I had the machine gun hesitation issue for almost a year, spent countless hours diagnosing and replacing every boost hose and tightening and doubling up on every clamp "IT'S A BOOST LEAK ", replacing pipe joiners and being frustrated, and it turns out it was simply because my spark-plugs were gapped to far.

A year like that! Wanted to give up on the car... and did many times. That's why I was trying to help, because I remember as a newb how it feels.

Boost leak, it was not. Everyone always thinks it is, it's like swine flu or something.

And you are right, a spark plug wire can cause the same issue, because I've had one of my OEM wires give out too.

Not sure what the engine temp has to do with that one.

Aluminum is relatively soft. The head gets relatively hot. Metal is softer when it is hot, so it's even easier to strip the plug holes.

Say you make a spirited drive to the store to get new plugs, come home and brave the hot surfaces to put in new plugs and they screw in forever!


Anyway, I'm sorry for getting on your nerves already, mah friend. (if applicable) :extra smilies on top:

 

[1gAWT]

sounds like fuel cut if you havent hacked the maf...

 

[Calan]

Anyway, I'm sorry for getting on your nerves already, mah friend. (if applicable) :extra smilies on top:

Not at all.

******

True fuel cut is a sudden loss of all fuel to the cylinders commanded by the ECU, and it really is somewhat like hitting a wall. Your engine goes from positive torque output to negative torque in a matter of one or two revolutions...so it is "noticeable" to say the least. People joke around about looking in the mirror to see if any of their drivetrain got yanked out when it happens. If you ever experience it you won't soon forget it.

Spark blowout is caused by a combination of too weak a spark and too much cylinder pressure. The spark literally gets blown out. Since it almost always happens at higher RPMs it has a very rapid "machine gun" like sound. You don't feel it as a hesitation or a misfire so much as just a drop in power....depending on how severe it is. Like fuel cut, it is a very distinct effect and you'll know it immediately. A narrower plug gap will usually eliminate it, but it sometimes requires a stronger ignition or better plugs (iridium).

BTW - I always seem change my plugs hot... usually right after a compression test.

 

[PieEyedPiper]

Iridium in a DSM? Do tell.

 

[Calan]

Yep... NGK iridiums gapped to .022" ... only thing that stopped my blow-out issues. (including 3 stock coils, 3 different sets of wires, every flavor or BR and BPR plugs down to .019" gap, 2 different PTUs, MSD Dis-2, custom COP).

I'm now on a non-CDI COP with iridiums at .022", and no blowout issues up to 30 psi (57ish lbs/min) on E85.

 

[Boostinsideways]

Unless he is running a failing fuel pump I doubt its fuel cut on a t-25.

My profile is up to date on mods. I am not running any fuel, or any tuning yet what so ever, and I am running wastegate pressure on the 16g, no fuel cut.

Bad boost leak can feel similar to fuel cut. I had a one that was not really leaking at all until 12+ psi so I would have that "brick wall" effect occasionally around 6k rpms if I was gunning it. It was a pretty bad leak though. The coupler between the elbow and upper pipe was about to slip off when I checked it. Really need to get myself a longer coupler or gm-maf.

 

[96talontso]

Im getting a boost leak test tomorrow, But yes its stock, and it freaked me out enough when it happened that i didnt stay on the power. I also did look behind me for my tranny

 

[SOADweskey]

Unless he is running a failing fuel pump I doubt its fuel cut on a t-25.

Fuel cut has nothing to do with actually running out of fuel. IT is caused by the MAF sensor detecting to much air going in compared to what the factory decided was a safe amount of air that fuel could be added for. Even if there really is plenty of fuel there the ECU will instantly turn off all the injectors to save the engine.

 

[shockracer]

Is your BOV dumping back into your intake or is it open to atmosphere?