Whats the problem?

[2g4me]

Ok we installed a EVOIII turbo in my friends 2g AWD talon he just got and hasnt even driven yet (got it without a motor, previous owner blew it), dropped a 7bolt in it with a built bottom end and rebuilt head, everythings good...starts, runs and drives no problem, but heres were the problem lies...Goes into boost when it should, stays steady about 15-16psi and pulls good, RPM's shoot up till about 5k then just slowly climbs to redline. Theres no hesitation as far as cutting out or stuttering or anything like that, it just acts like it doesnt want to go anymore even tho the boost is there. Now my GSX will hit redline (9.5k on mine) like it cant wait to get there and ive never had this lagging problem so i dont know what to tell him...Brand new stock injectors o-rings and seals, new walbro 255, new fuel filter and FPR.......Any thoughts why this might be happening?

 

[Gysgt Guy]

What's the psi past 5k?

 

[dracon8780]

It might be your injectors
Stock injectors are 450cc and can only handle about 10-11 psi from a 16g, even with a bigger fuel pump.
So at higher, rpm it starts running lean. Try lowering your boost to about 10 psi and see if it helps.
If so you need bigger injectors!

 

[blkgst97]

As stated maybe the injectors aren't enough and you possibly are pulling timing due to knock. Have you done a BLT as well?

 

[2g4me]

It might be your injectors
Stock injectors are 450cc and can only handle about 10-11 psi from a 16g, even with a bigger fuel pump.
So at higher, rpm it starts running lean. Try lowering your boost to about 10 psi and see if it helps.
If so you need bigger injectors!

Wrong, stock injectors, hell stock fuel system will handle 16psi no problem before fuel cut, many others here will agree to that. Even if that was the case why would i lower it 10psi and run only 5-6psi, it wont run for sh*t then let alone pull good at 16psi. Injectors are fine.

What's the psi past 5k?

Boost stays steady at 15-16psi.

 

[blkgst97]

You say built bottom end, higher compression or stock? Is that a stock rebuild on the head or is that built ass well?

 

[boostdawd]

+1 on doing a BLT just to get that out of the way!Maybe the car is changing timing after a certain rpm?

 

[2g4me]

Boost is good, AFR's 10.2-11.5 (on stock ECU no flash) so fuel and injectors are perfect...And no im not gonna turn my boost down to 5psi when stock boost is around 10-11psi, itll take forever just to get thru the RPM's......Noob's

+1 on doing a BLT just to get that out of the way!Maybe the car is changing timing after a certain rpm?

BLT was done first, that was my first instinct and everything checked out good, well, there was a VERY minor one at the TB (1G N/T TB) but nothing a dab of RTV didnt fix, otherwise good now.

 

[Tfitch90]

He never said turn your boost down to 5 or 6 PSI....he said turn it down to 10 not take 10 away from 15 or 16.

 

[Doubleot]

Do a BLT. It really shouldn't have any trouble getting to 16psi on stock everything, it probably just won't be very efficient.

 

[blkgst97]

I never said anything about turning your boost down to 5psi. You still have yet to answer any of my questions. What octane gas are you running? stock side mount? verified no boost leaks? bcs hooked up? if not you would not gt fuel cut. 11.5 afrs on 91 octane with a stock smic on a 16g at 16psi im sure might cause knock. We need some more questions answered. You are the one with a gsx revving to 9.5k but cant figure out why a 16g cant pull hard past 5k. If you would elaborate a little more im sure you will get your answer.

 

[Tfitch90]

I never said anything about turning your boost down to 5psi. You still have yet to answer any of my questions. What octane gas are you running? stock side mount? verified no boost leaks? bcs hooked up? if not you would not gt fuel cut. 11.5 afrs on 91 octane with a stock smic on a 16g at 16psi im sure might cause knock. We need some more questions answered. You are the one with a gsx revving to 9.5k but cant figure out why a 16g cant pull hard past 5k. If you would elaborate a little more im sure you will get your answer.

I think he was talking about the probationary member.

 

[gusu]

Wrong, stock injectors, hell stock fuel system will handle 16psi no problem before fuel cut, many others here will agree to that. Even if that was the case why would i lower it 10psi and run only 5-6psi, it wont run for sh*t then let alone pull good at 16psi. Injectors are fine.



Boost stays steady at 15-16psi.

Not, at 10 PSI on a 16g you are flowing enough air to be close to maxing out your injectors. You are really running them way to hard, it will seem as though everything is running okay even on a wideband reading but the truth is passed a certain point your injectors will basically turn into a spray instead of a mist. You may be able to get 11 PSI but even that is pushing it.

Fuel cut is also caused by the ECU pulling timing and obviously cutting fuel (*edit* I should have added that I'm not sure if timing is pulled on all cars but from what I have read it IS pulled on other cars I have not yet confirmed it on DSMs although I can check) from reading too much air from the MAF, it is also caused by overrun when your MAF simply can't accurately read any more air (typically the ECU in most cars is set to this point anyway but some are not). It has NOTHING to do with the limits of your fuel system. The absence of less fuel means a bigger boom, the fuel is not to keep something burning but in this case to do almost the opposite. The fuel is almost acting as if it is water causing a slower burn, more fuel equals less of a detonation. So if you over run your fuel system to long and start dumping extra fuel you will notice power loss as your injectors are dumping so much fuel you aren't burning all the oxygen you took in.

I also think the only people on here that will agree with 16 PSI being able to be ran fine, (with a 16g) are idiots. If you don't want to believe me have fun with your dead injectors.




*edit* My explanation to fuel cut sucked, this one is awesome. http://members.shaw.ca/costall/ECUprimer/ECU_ch7.html

 

[delta448]

gusu, you have the right idea, but I don't completely agree that more than 10psi on a 16G would with any certainty cause him to reach fuel cut or staticly open the injectors. IIRC, 1G fuel cut is reached at a lower airflow than the 2G limit. I ran 17-18psi spiking to 20ish on a 14b with a stock 2G fuel system and MAS and never logged more than 90% IDC. Use a datalogger. If you see more than 90% IDC or more than about 2.3-2.4 grams per revolution of airflow (stock 2G fuel cut happens at 2.5 g/rev) turn the boost down. If you hit fuel cut, you'll know it without a doubt. When the injectors are shut off at speed, it feels like you just slammed into a brick wall.

2g4me, the stock ROM is very conservative in the upper rpm range, it targets richer than 10:1 AFR in some cells. Try leaning it out a little there and see if you can add a couple degrees of timing without getting knock. I'll bet the car will feel much better. -Now, with all that said, you should be installing bigger injectors very soon.

 

[Tfitch90]

Ive never experience fel cut but when you say it feels like you slammed into a brick wall do you mean litteraly ? Does it hurt ? Haha exscuse my ignorance.

 

[vteckiller2000]

You need to log IDC and knock counts for us to be able to help. You are looking at this thinking you know everything about the fuel system and its capabilities, but you are mistaken. Log it and get back to us.

Ive never experience fel cut but when you say it feels like you slammed into a brick wall do you mean litteraly ? Does it hurt ? Haha exscuse my ignorance.

Pretty much feels like your car just blew up for a split second.

 

[landon95dsm]

stock clutch?

 

[Tfitch90]

I did have this problem before on a completely stock 3000gt once and I was to thinking clutch. It wuld squeel everytime I got to 6k and then stop when I upshifted.

 

[2g4me]

Ok sorry for the confusion with the 5 psi deal im using my phone so just bare with me on this....Stock injectors arent close to maxed out at 10psi, for one stock they run at +/-10psi and a stock fuel system will push 16 before fuel cut. My GSX when it was stock with minor boltons was at 16psi with the 16g he has now and ran perfect and pulled decent hard all the way to redline.

His talon is on 91oct (highest we have here), has a front mount, greddy profec b spec 2 boost controller, HKS SSQV, new ACT2600 clutch, bottom end is built with stock compression wiseco pistons, head is a stock rebuild with revised 3g lifters, arp studs and cometic HG. There is nothing wrong with the functionality of the car except this one issue which has us stumped, i've never has his issue before so dont criticize me for it.

When were rollin in any gear, i floor it and it hits 15-16psi no problem and pulls nice with 10-11.5afr's (so its not injectors, i know its not anyway) then once it hits about 5k its like it just loses power but still at 15-16psi and slowly climbs to redline if i stay on it long enough to get it there. BLT has been done twice, 1st time found a very small one but no sign of any leaks now. The FMIC is my old one i used for maybe 2 years with no issues and i was between 20-32psi with it (high and low boost settings) so the mods he has are plenty sufficient to get the car rollin like it should, and it is other than this setback we cant figure out.

 

[vteckiller2000]

Ok sorry for the confusion with the 5 psi deal im using my phone so just bare with me on this....Stock injectors arent close to maxed out at 10psi, for one stock they run at +/-10psi and a stock fuel system will push 16 before fuel cut. My GSX when it was stock with minor boltons was at 16psi with the 16g he has now and ran perfect and pulled decent hard all the way to redline.

His talon is on 91oct (highest we have here), has a front mount, greddy profec b spec 2 boost controller, HKS SSQV, new ACT2600 clutch, bottom end is built with stock compression wiseco pistons, head is a stock rebuild with revised 3g lifters, arp studs and cometic HG. There is nothing wrong with the functionality of the car except this one issue which has us stumped, i've never has his issue before so dont criticize me for it.

When were rollin in any gear, i floor it and it hits 15-16psi no problem and pulls nice with 10-11.5afr's (so its not injectors, i know its not anyway) then once it hits about 5k its like it just loses power but still at 15-16psi and slowly climbs to redline if i stay on it long enough to get it there. BLT has been done twice, 1st time found a very small one but no sign of any leaks now. The FMIC is my old one i used for maybe 2 years with no issues and i was between 20-32psi with it (high and low boost settings) so the mods he has are plenty sufficient to get the car rollin like it should, and it is other than this setback we cant figure out.

Do you have dsmlink or a logger?

 

[2g4me]

The fuel is good its nowhere near lean, we could throw bigger ones in there but all that will do it cause it to run too rich being as its fine with the stock 450's. We ID however lower the boost to 10psi and it does the same thing, pulls ok till 5k and same thing so i have no idea where the issue is. The motor has maybe 4k miles on it since it was built, came from a wrecked (in the rear) 97 GSX and i know the guy who owned it, he never had this problem with it and even hes confused as to why its acting like this so throw some more ideas at us, im open to anything at this point.......

Do you have dsmlink or a logger?

No DSMLINK, logger shows normal readings...

 

[vteckiller2000]

No DSMLINK, logger shows normal readings...

Are you watching the timing or knock?

 

[2g4me]

timing is fine, theres no knock and by the AFR reading alone its plenty rich

 

[vteckiller2000]

What kind of timing advance numbers are you seeing?

 

[boostdawd]

Maf or ECU I would assume.