Right after I installed my full TBE, I reset the ecu by unplugging the battery and took it out for a spin. I almost immediately noticed that when putting the car under load, the car would accelerate, then the engine would "cut out" for a second, then power would come back again. It was really strange that this would be happening after just putting on an exhaust. This was all happening at around 3.5-5K at around 35-55mph from the best I can remember. So its late and I figure I'll deal with it in the morning. So the next day I take the car out for a longer gallop and notice that its not really doing it anymore. Strange. So I put it in 5th at around 2500 RPMs and floor it.. I see the boost gauge spike past 1.5 BAR (almost 22psi)and the same thing happens.... engine cuts out for a second... and then power comes back again. I pay more attention to the boost gauge from here on out and notice that the boost is spiking pretty close to 1.5 BAR all the time then tapering off quickly to around 1.1 (16psi). If I get the car flashed to tune it for the intake and exhaust thats on there, and have the boost taper removed and remove the factory fuel cut, could this spiking damage the motor? I'm going to install a second boost guage soon to make sure that the one that there now is reading correct numbers (Its the dealer-installed gauge package) Have any of you experienced this with just a TBE and intake?

 

mine did the samething right after i got my tbe but it hit fuel cut on 17lbs everyone will just say check you vacum lines or theres a boost leak you know like you have not looked already I HATE FUEL CUT and spiking should not hurt anything the do it from the factory

 

Your last question is what irks me. You ask if anyone has experienced this, yet we've had 3-4 people start threads talking about this very same problem in just the last week. Yes, people have experienced it many times. When you install a TBE, it reduces the back pressure, and since you don't have an MBC (or flash) to regulate the boost, it is spiking much higher than normal. This is also exacerbated by the cold weather. The ECU is sensing the extra boost and increased air flow, then cutting fuel to protect the engine. The problem will occur more easily in the higher gears at peak torque, which is where you hit full boost (e.g. 5th gear at 3k rpm).

If you get a Dynoflash, it will remove fuel cut so that this never happens, but that still doesn't mean you can boost uncontrollably high without worry. You will need to get the boost controlled by the flash or get an MBC to regulate it manually. Try not to go over 22psi on pump gas.

 

No, you just need a tune.

Saying spiking should not hurt, because the car does it from the factory is very much wrong. The car doesn't spike that much in stock form. This is a much higher boost spike that is enough to cause fuel cut, and it can be dangerous if it is done continuously.

 

you know what im just gonna stop posting on here because im f**king corrected every time i post so i quit

 

I did do a search before I posted this and had a pretty good idea of what was occuring, but I wanted to be sure. I am planning on getting an MBC to regulate the boost as well and hope to keep it around 20psi to redline. I also figured that it was the cold weather that was causing it more the night before. I didn't realize that a flash could regulate the boost. Won't this cause the same problem over again being that this is a very unrestricted exhaust? The turbos seems to want to spool up very quick and spike. So getting the ecu to cut boost when it spikes will cause the same effect I am experiencing already. I thought that you could only cure this with a MBC or EBC of some kind.

 

First thing, was the car cold the first time you experienced this? How long did you let it warm up? Second, you are not hitting fuel cut. You don't have enough mods on your car to hit fuel cut. You are hitting boost cut. When you have an intake and exhaust, without a tune, the ECU is reading more air in and more air out. The ECU compinsates for this action and resets the max boost condition for a safety measure. Turn down your boost to 19 psi. Once you get a tune, you can turn it back up. 1.5 bar is kind of high without a fuel pump is ask me. You should set it at 1.40 bar just to be safe until you get your tune.

 

Boost cut is just another term people use to describe fuel cut. The ECU senses too much airflow and cuts fuel. This is brought on by too much boost in certain conditions. It happens all the time in situations like this during the Winter.

Nigletsyz, yes, flashes can control boost. It is not the same as the factory ECU-controlled boost, although it does utilize the BCS - it is not going to spike really high and cause fuel cut. You have the choice of an MBC, EBC, or the boost-controlling flash of your choice.

 

If you can get some kind of fuel computer such as a Apexi S-AFC, you could take 1 or 2% fuel away at the rpm it is cutting the fuel, . This always worked for me and never had it happen again.

 

LOL... a tune

He needs supporting fuel mods to boost that high. The ECU has a map that adds x amount of fuel per y amount of air. At 22 psi you are pulling in y air and the ECU inserts x gas. A tune won't get you more fuel, if anyting the stock ECU is running 10:1 at that point. What is damaging is that fact that you can't get enough octane to support 22psi in the cold weather. Get something (MBC EBC or flash) to hold your boost down.

 

yeah i tried to let the car warm up a little bit, but it was on the colder side. I don't understand by what you mean when you say
"the ECU is reading more air in and more air out. The ECU compinsates for this action and resets the max boost condition for a safety measure. "
How is the ECU resetting the max boost condition? It seems to be cutting fuel to prevent damage from overboosting instead.
On a side note, will the flash allow the "Service engine" light to go away due to the fact there is a test pipe on there and I'm throwing a code? Or do I have to buy that o2 piggyback thing for it?

 

Why would you LOL at that? The guy I responded to about the tune was the guy hitting strange fuel cuts at 17psi, not the thread originator. I have been helping slostjoe for a while now in his own thread, so I'm already familiar with everything he's already tried.

I didn't tell this guy who is spiking over 22psi that he just needed a tune. I told him he needs some boost control to keep it from spiking so high now that the TBE has reduced backpressure, and the ECU isn't properly regulating the boost accordingly.

Niglets, just get an O2 sim or mechanical fix for that. Don't rely on a flash to remove that. The fix is only like $25, or you can make your own spark plug anti-fouler or whatever for a few bucks.

 

This seems to be the opposite of what I would want to be doing for fuel cut though. Correct me if I'm wrong, but taking away fuel when there is not enough to begin with kinda seems to compound the problem more. Plus, I experienced this at various RPMs. It would instead seem better to add fuel if I wanted to boost over 1.5 BAR. And yes, it does suck that we can only get 91 octane out here, therefore my decision to set max boost at 20psi. Its seems to me that all I really need to do to cure the problem as cheap as possible is to control this boost via a MBC

 

why would you think that a tune will not give you more fuel. the purpose of a tune is to increase or subtract fuel where it's needed on the fuel curve. unless your injectors duty cycle is maxed out, you don't need a fuel pump to increase fuel. there are more than one way to increase fuel, change the fuel map, larger fuel pump, larger injectors, fuel pressure regulator.

 

There's nothing wrong with 22psi with decent gas and an ECU programmed to handle it. A decent flash vendor will have a flash to handle this (e.g. Works) or a flash and MBC combination to handle this (e.g Dynoflash).

I got my flash before I did any mods and told them (Works in this case) that I'd be putting on a TBE. When I got the flash back (with modified boost hose that's included) I immediately was peaking at 21-22 psi. When I got my TBE I was maxing out to 23 psi in some gears (3rd I think).

If you're not into "flashes" get an SAFC or full management system such as the AEM.

You can't just mod the beast and expect it's stock ECU programming to handle your changes. You need SOMEthing to help "tune" the operations of the car (i.e. ECU).

Good luck!