I have the AEB pushing 12-13 psi. Some times (once every two weeks) ill get that boost cut. It would cut every time if I have it set at 15 psi. The colder it is the more I get this boost cut. This is the weird part, when I turn the car off then start it the problem is gone. Through every thing i have done or that has happen i never get a CEL. Its really not a problem just trying to figure out what is making this boost cut. Now I'm thinking that the ecu is making this happen but what is the ecu reading thats out of wak. Wouldn't I get a CEL if any thing out of normal? Its just weird the colder it gets the more it cuts but it gos away when I restart the car.

One other thing, when it dose cut it dosent stop. It would cut every time I go over 10 psi. As soon as I restart, it is gone and dosent come back for a week or so.

 

sounds like limp mode. No CEL does not imply no codes. You should scan the car for DTCs.

 

Yup limp... But then again limp mode is 5 psi. I'm guessing your tuned? What software? And you could possibly be having your N75 valve on it's way out.

Josh

 

Stock tune. I put a MBC in. The N75 is plugged in but not hooked up. When it dose cut it will drive fine untell I hit 11psi. I can sit there at 10psi but as soon as I push a lil harder it cuts. Seems like a spark cut but I just put in new plugs gaped at 28. No CEL for a misfire. I did one time get a p1136 lean in bank one. I cleared it and never saw it again. I checked the plugs and they look perfect. This all goes away when I restart the car. I thought to get out of limp mode you have to disconnect the batt. Thats why I don't think its limp mode. With the car dead cold I can hit 16psi no problem. As soon as it warms up it will cut every time. Thats why I have it set at 13psi. I can drive fine with that all day. At night when it gets cold it will cut, I just restart and it gos away.

Is there a max air flow on the maf for a stock tune? The ecu is reading some thing wrong but wont show me what. Weird ****. I did scan it for codes and nothing comes up. The p1136 came up last week and I have been scanning it for codes every day since.

 

limp mode can be reset by turning off the car (depending on the condition that triggered limp mode)

Sounds like you have a air to fuel ratio problem. If the car is not tuned to run at higher psi it will cause problems. Limp mode is kicking in when your boost levels exceed the expected levels. Thats why people buy chips and dont just use a MBC to turn up the boost.

 

DUDE! Take the MBC off... Hook the N75 Back up and get a tune if you want more power!!! You will seriously burn your motor up doing what your doing... the reason why your getting throttle cut is because your just increasing boost (which increases the amount of air in the engine) and NOT adjusting the fueling. The car can adapt a bit but not to the levels your going. Every time it cuts it's saving your motor from serious damage.

Our cars are not like others. Actually a lot of cars you can't just add boost and think everything is hunky dory... you need to do it right. Hopefully you don't/didn't mess something else up.

josh

 

I wish I could buy a chip. If you buy it I will use it lol.

So your saying I can hit limp mode and not have a cel and still push 10psi?

The air/fuel ratio makes sense. Colder the air the more it will effect the ratio. So the readings from the maf and o2s are telling the ecu that my a/f ratio are out of wak and this (cut) happens?

You can add as much psi you want if the a/f ratio is in spec. Same goes for n2o, add all you want as long as the a/f is right. If you add to much you will snap a rod like I did. The air/fuel didn't cause this, to much power caused it. Comes to my point I'm no wheres near fing my motor up. My plugs look perfect, So the a/f is not that far off to do any damage. It is off enough to get this cut but no wheres near blowing my motor up. The plugs can tell you every thing. You my not see it as it happens but you can see the after math. So my car can cut all it wants and will not hurm it at all. At this point my car runs perfect, not to rich, lean, no knocks or pings, no detonation, I have the right gap, right heat rage. Theres not one sing of any damaging factors.

I have a question, dose any one know how to read a plug to see if its the right heat range? What do you look for to find out if its to cold or to hot of a plug? What dose detonation look like on a plug?? If you know this and my plugs look perfect, then you know my motor is just fine.


What it comes down to is the ECU is a touchy bitch and dosent like change.

 

The cut is happening for a lot of reasons:

1. Your going past the stock specified safe boost levels. The car thinks somethings wrong and cuts throttle/boost to save itself.

2. Even if your not getting throttle cut your A/F is going to be leaner since your pushing more air w/out adding more fuel. This is a guarantee that you will burn your motor up over time.

3. Getting throttle cut/boost cut is not good on the motor at all.

If you can't afford a chip and to do it right then your are REALLY going to be screwed when your motor goes south on you. Take the MBC off and keep it stock till you can do it right.

Josh

 

fantastic way to destroy your engine. keep going and you wont have a car to drive.

 

Wow I'm thinking this is your first car you have tried getting more power out of. Your forgetting about timing. The car dose pull timing to a point you know. So if I add air and it runs lean it will pull timing to a point. Right now I'm at the edge of where the ecu will adjust for the amount of boost. When I get the cut means the ecu can not adjust any further. Yes the cut it self is bad but the reason behind it is not going to blow my motor or shorten it. Like I said the ecu is a touchy bitch. It won't let you blow the motor. Have you ever even heard of some blowing a motor adding more boost on a stock tune. Most Likely not as the ecu won't let you.

I have built a GN pushing 28 psi at 550 whp. And a 2000 s/c 383 vett at 600whp. The GN was not at all a touchy bitch and could blow up to easy. The vett, I didn't even mess with the ecu. Just got it dyno tuned. The point is all cars are differnt. This a4 has a very touchy ecu and will not let you blow the motor. Yes if I sit there and drive it when it's cutting I will get problems. As for me it only happens once in a great while. As soon as it happens I restart the car then it's fine. There's not one sing ANY where that I'm damaging ANY thing. You should answer the ? Above about the plugs just so I know you know your ****. If the car runs any thing ( lean,rich,detonation) any thing the plugs WILL show it. Dosent matter when it happens it will be there. Seems like you guys never took a motor to the edge where reading plugs is a must.

Do you know how to truely read a plug? The details that come with it. Cutting your plugs inhalf to see what you can't see.

Like I said what it comes down to is the ecu is a touchy bitch and no I will not even come close to blowing my motor up with 12psi. If it was I would see at least one sing of it on my plugs.