Multiple problems = Multiple questions

[Krazysmit]

Just installed an RNR Racing 3 inch turbo back last night. Took the car out this afternoon for some test drivin'. Now I'm hitting fuel cut in all gears when the pedal is on the floor. I used to only get it when it was cold outside and in gears 2 and 3, but its high 50's here right now! My first question: is this normal when putting on a free flowing exhaust? My second: Should I try to take out the lower honeycomb of the MAS? I've heard its a cheap fix for problems like this. Mind you, all the other mods I've really done are removed silencer from MAS, hacked airbox, and dejon tool intake.

On another note, the spool up seems slower. Could that be from boost creep? Due to budget restrictions I havent got a boost gauge yet, but I should be getting one within the next two weeks or so...so I'm not sure. Would crushing the BOV help me in this situation...if so, how much can you crush without ruining the valve?

Thanks for the help!

 

[Krazysmit]

Oh yeah, I cleaned out the intercooler 4 days ago, I'm not sure if that would be affecting anything.

 

[fish3rboi]

Colder air does make fuel cut happen more often. You could run 16lbs in 70 degree weather and be fine, and do the same the next day with 30 degrees and hit fuel cut left and right. I personally don't think removing the honeycombs is smart. Just my opinion. Wait til it warms up a bit more, get a boost controller and gauge, and then try it again.

What did you clean your intercooler with?

 

[Spln_Hrd]

stop romping on it, get a boost gauge, then tell me how much boost you are hitting.

did you get a tubular o2 housing too?

spoolup should be faster, going from a test pipe w/ cat back to a full 3 inch(w/ o2 housing) from rnr my spoolup increase 300-400 rpms

do you still have a cat?

you are probly boost creeping but we cannot know for sure.

also its abnormal that you hit fuel cut before you put on the exhaust, do you have your stock boost controller still hooked up properly?

 

[crankbender]

Seriously get a boost gauge. When you change the flow of exhaust you run the risk of causing boost creep. You could possibly be pushing 17-18 psi and detonating (pulling timing so you don't feel the power increase).

Get the gauge it is alot cheaper than a set of pistons and not even comparable to a full rebuild.

 

[K Dan]

A 3" turbo-back doesn't cause fuel cut, and I'd leave the honey-combs in. So your problem is elsewhere, what rpm are you shifting at? sounds like your going well into the red zone, yes you might have boost creep so if your relying on the stock boost gauge and your flooring it that might be the problem.

 

[Spln_Hrd]

Originally posted by K Dan
A 3" turbo-back doesn't cause fuel cut, and I'd leave the honey-combs in. So your problem is elsewhere, what rpm are you shifting at?

a 3 inch turboback will cause boost creep, and boost creep will cause fuel cut. i am not saying it will on every car, but it does on mine. with my boost set at 10 psi i can hit 22 by 6k rpm, and i know my wastegate works properly due to a external dump o2 housing.

your right leave the honeycombs in, it will just cause you to lean out on high boost, it may cure your fuel cut. but it may also give you topless pistons because you lean out and they start to melt.

just stay out of the peddle NO MATTER WHAT!!! until you get a boost gauge. also if you have boost creep pm me i can get you a external wastegate setup pretty cheap.

 

[98spydert]

It's not a matter of boost creep! Don't listen to that trash.

It has nothing to do with your bov, and jacking up the maft might help but it's a lot simpler than that.

I did the same thing about 3 weeks ago. I already had a boost controller and autometer gauge with boost set at a steady 15 psi. I put my 3 inch DP, cat, and RSR exhaust on and then I was hitting a constant 19 psi with mad fuel cut. All I did is turn down my boost controller and it's sits at 15 psi again without creeping.

 

[Krazysmit]

Thanks for all the suggestions. I think it's pretty clear that I better chill out on the rpms till I get that boost gauge. As far as everything else goes, I did put on a high flow cat when I changed exhuast, I don't know what the difference might have been if I just used a test pipe...

The main problem I have is that I can hit fuel cut at ~ 4000 rpms, but sometimes as high as 6 in EVERY gear which is worse than it was before. As far as I know, the turbo and stuff is performing normally, and is boosting at stock levels (14psi?).

As far as getting rid of the fuel cut, would an ext wastegate be my best option for a low modded car?

 

[crankbender]

Originally posted by 98spydert
It's not a matter of boost creep! Don't listen to that trash.

It has nothing to do with your bov, and jacking up the maft might help but it's a lot simpler than that.

I did the same thing about 3 weeks ago. I already had a boost controller and autometer gauge with boost set at a steady 15 psi. I put my 3 inch DP, cat, and RSR exhaust on and then I was hitting a constant 19 psi with mad fuel cut. All I did is turn down my boost controller and it's sits at 15 psi again without creeping.

He said he was still stock on the boost.

Please don't tell people not to listen to advice that can save their car. He really really really reallllllllllllllyyyyyy needs a boost gauge. Overboosting the car will destroy the pistons because of detonation caused by high intake temps, and higher effective CRs.

Once you have that gauge (phook it buy an air pressure gauge, analog not the slide kind, and valve stem at autozone for 2.99 and rig up a ghetto boost gauge if you have to) and you are not creeping look into a possible boost leak as you will get higher intake temps and loose power while hitting fuel cut.

 

[98spydert]

Originally posted by crankbender
He said he was still stock on the boost.

Please don't tell people not to listen to advice that can save their car. He really really really reallllllllllllllyyyyyy needs a boost gauge. Overboosting the car will destroy the pistons because of detonation caused by high intake temps, and higher effective CRs.

Once you have that gauge (phook it buy an air pressure gauge, analog not the slide kind, and valve stem at autozone for 2.99 and rig up a ghetto boost gauge if you have to) and you are not creeping look into a possible boost leak as you will get higher intake temps and loose power while hitting fuel cut.

It doesn't matter what boost he was running before the aftermarket exhaust, stock psi or not. I guess I have to spell it out for you.

Again... I was set at 15 psi... I put on 3" dp, high flow cat, and 3" cat back... With out changing my mbc or ANYTHING else, just like he did, I was then running 19 psi.. 15... then 19... 19psi gave me mad fuel cut just like him. The fact that I had a boost gauge and mbc let me turn it back down to 15 and then I had no more problems. I don't know how to make it any more clear that we had the same problem and I just had the right equipment to fix it. So you're all right about the boost gauge. he also needs some way to turn his boost back down to where he was.

I don't know the physics well enough to explain it, but the high flowing exhaust with less back pressure lets the turbo spool to a higher psi.