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Old 01-10-2007, 09:51 AM   #1
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Default stumbling and choking after 5,000 rpm?

Hi would anyone know these symptoms and has the right remedy for it?

I've just installed an Vortech 12:1 FMU and 1.8 injector(clean and even flow).

Waiting to install Walbro 190hp FP, as soon as I could fix this problem.
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Old 01-10-2007, 10:29 AM   #2
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First, what is your timing?

Second, how much boost?
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Old 01-10-2007, 11:15 AM   #3
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10BTDC and 5psi boost
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Old 01-10-2007, 11:37 AM   #4
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throw in the Walbro....your current FP may not be up to the task of fueling at a substained output. It's a 30min job to see if its the problem.
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Old 01-10-2007, 11:43 AM   #5
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The only thing set me back from that is with my Vortech 12:1 and 140psi from Walbro, I dunno if that will blow my 1.8 injectors.
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Old 01-10-2007, 12:04 PM   #6
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HMM... I wonder if the 12:1 is deadheading your oem fuel pump?

I ran up to 8psi with my 12:1 and walbro and 1.6 injectors. The pressure isn't the problem per se. It's how much flow you get at that pressure that makes your top end super rich. It's the o2 sensor or cat that can be harmed from being so rich. And maybe paint aroudn the tail pipe. There is no, or almost no, damage potential to the injectors.
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Old 01-10-2007, 12:11 PM   #7
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12 x 5 + 50 = 110psi

Those injectors will be fine and can fuel around 190rwhp at 110psi.


Corky suggests 200psi is the safe limit for injectors under 50 Lbs/Hr, 100psi over 50 Lbs/Hr
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Old 01-10-2007, 12:34 PM   #8
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Pull your timing back to 6 BTDC. You may be detonating. The OEM fuel pump will handle the 1.8's at up to 8psi if it isn't shot. Did you check your max fuel pressure? Make sure the Vortech is connected correctly and maybe open it to make sure you actually have the 12:1 disc in there(unless you got it new from GReddy)
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Old 01-10-2007, 11:33 PM   #9
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I hope this may look a correct installation for you guys?
Attached Images
File Type: jpg install Vortech.JPG (25.4 KB, 51 views)
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Old 01-10-2007, 11:55 PM   #10
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yes it does. test the capabilites of your current pump...i fear it may be losing substained pressure flow.
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Old 01-11-2007, 01:34 AM   #11
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OK.. .just spent 20 mins install the walbro... ! but the problem still the same, and now is comes in earlier before 5k rpm! AHHHHHHHHHHH!!

at half thottle, it was no problem up to 6k rpm... but WOT it chokes.

Could I be putting fuel in the system?
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Old 01-11-2007, 01:52 AM   #12
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You sure you FPR isn't in backwards? Sounds like FP is going through the roof.
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Old 01-11-2007, 02:09 AM   #13
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HI Jayc, does the photos showing my FPR looks correct?

Also, rev at stop the car seems to drop idle lower than usual.
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Old 01-11-2007, 05:38 AM   #14
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Sigh......! After another day at the shop looking though the system and decided to put in another FMU with dose 44psi at idle. (just for a try) The problem still not solved. Adding to that, as adviced by Olderguy, I put my timming back to 6 BTDC.

3-4 rpm holding at 3 psi boost, and doesn't want to creep up. once around 5k rpm starts to stumbles and choke again.

What i might do tomorrow is take out the AFPR, retain the OEM FPR... install the EMB, than put that on the DYNO.



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Old 01-11-2007, 05:57 AM   #15
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these cars really suck sometimes eh?
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Old 01-11-2007, 06:19 AM   #16
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More thoughts, could this be time for O2 clamp? Am I being intrupted by my Stock ECU?
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Old 01-11-2007, 06:52 AM   #17
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hhmhmmmm....i dont have one either. but would this problem not have shown up way before?

I have been greddy turbo'd since 2004.

either the fueling is fucked.

My new o2 sensor has only been in 2 days and is going crazy on the AF guage.

somrtimes it just goes off na dcomes back on randomly and when i let of fthe gas.. really strange.
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Old 01-11-2007, 07:42 AM   #18
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Tabs, if you're saying that when you let off the gas, the AF gauge goes off the chart lean, there is nothing odd about that. Maybe I misunderstood you.
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Old 01-11-2007, 09:08 AM   #19
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no goes off the chart completely....not registering.

makes me think there is somthing seriously wrong!
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Old 01-11-2007, 09:14 AM   #20
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That's what I mean...going so lean that it doesn't register on the gauge when letting off. That's normal for n/a, should be as well for turbo.
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