Possible Fuel Cut?

[Boosted98Clipse]

Heyy just wondering if anyone could offer me their thoughs on my situation. I have a 98 gsx with a 20g turbo, aftermarket exhaust manifold and a few other odds and ends parts. I recently put a 3in exhaust system on it turbo back, (apexi with cat delete) and an external dump for the wastegate. Now the car cuts out around 5k. It never did this before, only after thge exhaust was added. The car is running stock boost so I feel it shouldn't be cutting out at 5k. I'm not sure if this is a protection feature built into the ecu or something along those lines now that it is reading more flow, but the car runs rich up until 5k so i'm pretty sure its not a fuel issue. ( I only have a narrow band for now but it stays green up until it dies) I am running stock injectors and fuel pump but that should be fine at only stock boost. Car boosts fine and pulls up until 5k and it just basically dies. Any insight would be much appreciated.

Thanks for your time

 

[swiftdeathtsi1]

I had a similar problem. It turned out to be my plugs and wires. Have you changed them recently? Check the gap at least. Also do a boost leak test. Could be just a boost leak. Also you need a wide band to see accurate air fuel mix.

 

[Leonthefaded]

Have you done a boost leak test?

 

[Boosted98Clipse]

I appreciate it. I didn't even think plugs but they will definately be checked. I'm pretty solid on it not being a boost leak but I've been wrong before. I've gone over it quite a few times now checking for leaks, and I'm on the wideband situation, been told now by quite a few people about that haha. To me, it just feels like something with the ecu, thats its just letting the car go anymore. I know it has more after 5k I've been up past it many times, it only started when the exhaust was put on. Almost like now that the car is breathing better, the ecu threw it in a "safe mode" or something, it's hard to explain. I do appreciate the info and will be looking into plugs and plug wires and work my way from there.

 

[swiftdeathtsi1]

Im not sure if there is a safe mode. Im not terribly familiar with 2g ecus. I would check the plug gap your spark could be getting blown out.

 

[Leonthefaded]

If you have a multimeter I'd check your coilpack and sensors.

 

[macks96boltdsm]

my car doing the same i just put a tubular manifold and o2 external dump and 3 inch downpipe on my car and before i did this my car was boosting 15lbs for a 1year staright with no problems but as soon as i put on these mods it does this and my boost went from 15 where i had it at before t0 12 psi and now when i try to turn up my boost past 13 14 it does the exact same thing it cut out and bucks like but will still keep pullin afterwards ive change plugs with gaps at .28 and .32 didnt work and the only thing that stops it is turning the boost down to like 10 psi so ive ruled out wires but i just got scammed on here for 400$ on me buyin dsm link so im dsm link will fix this problem of ours

 

[Leonthefaded]

my car doing the same i just put a tubular manifold and o2 external dump and 3 inch downpipe on my car and before i did this my car was boosting 15lbs for a 1year staright with no problems but as soon as i put on these mods it does this and my boost went from 15 where i had it at before t0 12 psi and now when i try to turn up my boost past 13 14 it does the exact same thing it cut out and bucks like but will still keep pullin afterwards ive change plugs with gaps at .28 and .32 didnt work and the only thing that stops it is turning the boost down to like 10 psi so ive ruled out wires but i just got scammed on here for 400$ on me buyin dsm link so im dsm link will fix this problem of ours

DSM Link wouldnt fix that problem, I dont know everything about tuning. Did you try taking the mods you recently did off to see if that was really the culprit?

I know when I did my Full 3" exhaust system I blew all my couplers loose and it caused major boost leaks.

 

[swiftdeathtsi1]

You may also consider doing a leak down test. sometimes deposits form on the back of the valves most of the time the exhaust valves causing them not to seal properly.

 

[Boosted98Clipse]

I will get the meter out after work and check that out. Macks96 that is pretty much exactly what mine is doing. I glanced over the plugs lastnight, and there appear to be relatively new, but will be pulled today and regapped. I'm hoping its something stupid. I immediately went to thinking bigger injectors and fuel pump (which is going to happen) but I don't think that would make much of a difference at stock boost. I'll have to start reading into the ecu programing and see if there's safty features or rev limits that could have reset themselves. Leon, I didn't take the exhaust off since it was put on to see, but on the first drive after it was put on it did it. I can double check the couplers again.

 

[bryanwheat]

Do a boost leak test before anything. How are you pretty solid that it doesn't have a boost leak without testing. With a decent boost leak on that bigger turbo it will overrun the maf pretty quick.

 

[Boosted98Clipse]

What's the best way to preform a boost leak just to make sure I'm not doing it off the wall...I also noticed there's 7mm plug wires on the car. What is the best for the gsxs? I know the higher the number ex. 8.5mm the more spark it will produce, is it possible I'm lust loosing spark at higher rpms?

 

[bryanwheat]

What's the best way to preform a boost leak just to make sure I'm not doing it off the wall...I also noticed there's 7mm plug wires on the car. What is the best for the gsxs? I know the higher the number ex. 8.5mm the more spark it will produce, is it possible I'm lust loosing spark at higher rpms?

Google boost leak tester, you can make one for 10 bucks from parts at the hardware store.

 

[macks96boltdsm]

no i havent taken them off but i was leaning towards with the whole spark blow out deal as well or the ecu reading to much air flow but im going to put new wires and plugs in today and we will see what happen just going with bpr7es and ngk wires

 

[Boosted98Clipse]

I just got of the phone with JK Tuning and it is the ecu. Since I'm running the stock ecu, they are set with limitations in the a/f ratios and maf and I reached them having the bigger turbo and exhaust. So along the lines of a dsm link fixing the problem you are correct. The options are having the stock ecu reflashed, or doing the dsm link or a standalone unit. Hopefully this helps everyone out and I appreciate all the info.

 

[TrystanGST]

That makes sense. You're putting the same amount of fuel in, but a lot more air. 10psi on a 20g is not the same as 10psi on a T25.

 

[1MeanTSI]

If it was fuel cut, you'd know it. You would probably be pulling teeth out of your steering wheel haha.