So I have a 98 1.8t AEB. All it has is a gutted cat, CAI, in cabin MBC, BOV, and a AFPR. I was pushing around 14 psi. After I made a better CAI I can't get past 9 psi. It hits the boost cut. There is no limp mode no CEL nothing. I checked all vac lines. Fuel is set at 65 psi. That's what it was set at when I was at 14 psi for boost. I have changed nothing other then make the intake better. And no there is no leaks in the intake. It dose run perfect at 9 psi. But it did run perfect at 14 psi. Could it be that I need to reset the ECU? I wouldn't think I would becuase I don't have a CEL. Some ideas would be helpfull. Thanks.

 

Do a boostleak tester to determine if you have a leak or not....try that first and see where you get

 

I had a long reply typed out about your "tune" lacking important factors such as mapped out fuel, timing, boost, like a real ecu tune provides, and how your mbc and afpr cannot accomplish the same or even similar thing... But then I saw the video in your signature and realized you must already know all that. So whatever... If you were messing with your intake- make sure the maf is in the right direction, and that all the hoses, etc. that were disconnected are reconnected.

 

I did a boost leak test and it's holding at 20 psi so no leaks. Every thing runs perfectly fine at 9 psi. Every thing is hooked up right and facing the right way. I can tell you it is spark cut when I go past 9 psi. It will back fire a lil right after the cut. Could it be that I had a little leak in my old intake? The motor is taking in more air then what the maf is reading. I would think I would get less boost as it would run lean. Would the ecu send spark cut if it was to rich? I did up the fuel psi a little. I just don't understand how I was pushing 14 psi spike and holding 10 psi. Now 9psi is max. What is the ecu reading to give me this spark cut with no cel?

 

this, but check your actual v requested boost, also log your fuel air..... anything you think could be wrong


i don't know how 9 v 14 is the same.... but it is your car.... and i really wouldn't push my boost that high unless i was trying to blow something

 

I understand about how every thing needs to be tuned. How changing the ecu is the only way to get more power. But you can change things to push the ecu to it limits. Not to get a 10 psi increase but 5 more psi on a stock tune is very possible. Now running stock fuel psi limits you on any thing as you will run lean and the ecu will read that. Now if you up just the fuel psi you will run richer which the o2s will read and allow the maf to read more air for more boost. On top of that the ecu will adjust timing on it own so you don't hit knock. How much idk but it's safe to say at least -20 to +20. All ecus I have messed with did at least that.

Now you know as I do you can't blow these motors on a stock ecu. The ecu just won't let you. This ecu is such a tuchy bitch where every thing has to be right for it to run right. Now I'm not looking to get 300 whp. I was happy at my 14/10 psi. So was my motor it to was happy with that. All I was looking for is what could of happened for me to only get 9 psi. Realy it's at 9/5 which realy sucks. Could it be bad o2s with no cel. I just don't know how I lost 5 psi when nothing has changed. I was just looking for ideas on what could cus this. I do have the maf up and down. You think me putting it side ways would make any difference. I wouldn't think so as it only reads air but what do you think. Dose the maf read air temp? If so it would be reading cooler air as I put it in a better spot for cooler air. I just need some ideas here.

 

check reeadieness codes...




and like i said give us logs