This is starting to concern me. Three or four times now since I've installed my test pipe in place of the cat. Did not do the rear o2 delete, let the CEL stay on for all I care. Always fourth gear under wot and full 19-20lbs of boost. A/m intake, full exhaust w/o cat, nothing else engine wise. Boost gauge says 19, then at about 5-6k rpms, i feel a surge from the turbo, boost gauge pegs to 30lbs, then a huge backfire + cloud of black/brown smoke and then a complete cut of power until I get back on the gas.

Halp? I've gone through the vacuum lines, pretty sure I don't have any leaks. I'll smoke test it tomorrow, but man this is starting to get me. I went to UTI and work as a service manager, but I just don't know enough about turbo cars. Thoughts?

 

based on your title id say misfire / spark blowout / .. either ignition or plug gap related. but boost spiking to 30 out of no where? is the boost controller connected wrong?

 

Although it could be an ignition problem, most of the time is a fouled plug.

 

OP, you are hitting boost cut. This needs to be adjusted in your ECU via an experienced tuner or friend.

Basically, your engine is producing a higher load than prescribed in a specific table for that RPM. You will find more info in the ECUFlash forum.

On a side note, my car did this right after installing my Buschur 3" TBE exhaust in 2004 and I thought I ruined the car heh.

Good luck. Put the CAT back in for now and reset your CEL by removing the battery ground for a minute or two.

 

^This. It's a safety feature to prevent your motor/turbo dying in the event of a wastegate/boost controller failure. Also, you may not know it since you have the rear O2 CEL on, but you likely have the overboost code on there too if you got a ODBII scanner and pulled your codes.

 

ya after re-reading i think you guys are right. what through me off was his avatar. it looks like hes a serious road racer so i just assumed the car was already tuned lol.. so much for assuming.

its very easy to edit the fuel cut tables. id recommend throwing tephra v7 on the car tho and utilizing the fuel cut load X2 instead of just completely removing it via trigger delay. or patch your existing rom with the x2.

 

If it's a fairly violent cut, like you nearly lose a tooth on the steering wheel, it's likely to be fuel cut. (Possibly the same thing as boost cut, I keep reading different things on boost cut).

The definition for fuel cut is that your load is exceeding a certain amount for more than a certain amount of time. Load is relative to boost, so basically your boost is too high for too long. The time is a matter of seconds. I don't know the amount of boost that triggers fuel cut in a factory ROM. My IX fuel cuts at 23 psi, but it has been tuned.

Boosting 30 psi is a bit much. If you don't have a boost controller it sounds like your wastegate isn't doing it's job, faulty or not being controlled properly.

Adjusting the fuel cut is fine if it's done someone who knows what they're doing. It is possible to delete fuel cut but I would never recommend that, it's like taking away your brakes cause you don't plan on slowing down.

Personally I would look into why your boost is going that high before looking at changing your fuel cut.

 

i recently got retuned, and sometimes when i WOT in 5th gear starting around 2.5k-3k it'll build boost and then i also experience a big boom/misfire....is this fuel cut too?

happend before in 3rd same thing but a very steep incline/on ramp....if it is, i'm going to talk to the tuner....however when i smoothly transition into WOT it pulls fine. I'm running the HKS 7460r

 

its because its named boost cut in some xml's and fuel cut in others .. thats why you're reading those 2 terminologies on the forum.. its the same thing.

mitsubishi has been putting fuel cut in their ecu's for over 10 years now.

 

The fuel is cut because the boost is too high. Both names make sense in a way.

 

sure. 4th and 5th gear are going to spool the turbo up quicker which can result in a boost spike and you could very well be hitting fuel cut if your tuner didnt adjust the tables properly.

if it doesnt happen in first,2nd,3rd its most likely not spark blowout. although it very well could be if its more boost and the ignition is weak.

 

Not sure if it helps much but i was running an intake for about a month and would do fine no problems but as soon as i installed my 3inch TBE after 2 pulls it started doing what sounds like yours is and ive been told its just the boost/fuel cut especially living in seattle and the weather getting more dense due to the drop in temp but the only difference is mine isnt hitting 30psi... thank god for ER's dyno day on the 20th no more bs for me!

 

ya they do. before mr fred created the x2 fuel cut table mod everyone had to set the trigger delay ms extremely high which completely removes the safety feature altogether.

now at least we can use the x2 on any modified vehicle.. and it is very handy when you're running low octane fuel thats knock prone if the wastegate line flys off and you overboost it could save you from a catastrophe.

 

I also have this problem with my car. I havent fixed it yet, but with everyones knowhow here I have a better understanding about what the problem could be.

 

Boost cut, fuel cut. Potatos, potatos .

On a side note, the violent cut that it creates is not necessarily safe for things like your turbo or engine internals--especially at the high load that it occurs at. I wish it was a soft[er] cut. Once I had this happen on my GT35R due to *accidentally not maxing out the tables and I could've swore I bent a fin but it just machined itself or straightened away after a while .