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Old 10-06-2007, 09:07 PM   #1
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Default WAY too rich, still

got my diy setup running but i am having a drivablity problem. my set up is, 13g turbo off of a auto DSM, i think the wastegate is at 9psi(and thats as far as i noticed it went on the guage). first gen probe intercooler, VTA BOV with a ton of spacers so it stays closed at idle. and 310cc injectors from a 89 probe gt. and a cartec FMU.

the problem is that the car is really rich. idles around 12.5-13:1 but as soon as you hit the gas at all or try and drive around the block it basically stays pegged out at 10:1 on the guage (AEM ugeo wideband) car bogs and stutters pretty bad. timing is set to 6 btdc.

i have searched and havent turned up anything too usefull. i am going to try and adjust the afm, but i have read the screw is just for idle, and some people have adjust the spring inside the afm, but say thats also just for idle. so which is it?

and also i set the FMU by just turning on the fuel pump, engine not on. i have a adjustable fuel regulator with a guage it put in the feed line before the fuel rail with just the adjuster screwed all the way out so i just had the guage to read. i set it to 55psi with no vac on it, did i set the fmu right?

any help would be great

Last edited by bryantaylor; 10-08-2007 at 04:37 PM.
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Old 10-06-2007, 09:29 PM   #2
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there should be two adjustment screws on the FMU. one in the middle with an allen wrench, which 55psi is fine. anywhere between 48-55psi is good at no vaccum.

however, there should also be a needle vavle that allows for the rate of gain to change. sounds like you're at full 12:1 ratio. I betcha the fuel pressure is maxing out at 120psi, you probably only need like 70-80.

dont adjust your oem afm tension, it's best as is. however DO adjust the idle screw to idle at 14.7, it's under a little cap you have to drill out.
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Old 10-06-2007, 09:48 PM   #3
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there should be two adjustment screws on the FMU. one in the middle with an allen wrench, which 55psi is fine. anywhere between 48-55psi is good at no vaccum.

however, there should also be a needle vavle that allows for the rate of gain to change. sounds like you're at full 12:1 ratio. I betcha the fuel pressure is maxing out at 120psi, you probably only need like 70-80.

dont adjust your oem afm tension, it's best as is. however DO adjust the idle screw to idle at 14.7, it's under a little cap you have to drill out.
i have the bleeder valve turned out some right now. but its pegged out rich, even when it isnt under boost. i also might try and adjust the pressure on the FMU again, but while the engine is running this time. also, i have the check valve for the fmu in the vac line going to it, or does it have to be after the bleeder valve?
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Old 10-06-2007, 10:20 PM   #4
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just idle to car. make sure you have 35psi at idle. pull the vacuum line on the OEM FPR. kink the line so it doesnt foul the idle. turn the preload to hit 48-55psi. put the vacuum line back.

adjust the AFM to idle at 14.7. theres a little cylinder with a silver cap, you must drill the cap off and exposed a screw. turn it back about 1 full turn counter-clockwise. that shoudl get you to 14.7.

go driving in boost, continue to back the needle vavle more open and open untill 12:1


vacuum line goes straight into FMU. check valve on needle vavle, postitioned to prevent vacuum from pulling through the unit, boost should escape out.
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Old 10-06-2007, 11:06 PM   #5
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i will do all of that tomorow. so the guage in the feed line BEFORE the fuel rail is right?
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Old 10-07-2007, 11:22 AM   #6
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yes
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Old 10-07-2007, 01:04 PM   #7
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re-set the fmu with a new guage, and the bleeder is turn about 2/3 out, check valve after the bleeder to let boost out but no to pull vac. adjusted the idle on the AFM, so thats a little better. did about 1 1/2 turns out. but as soon as i hit the gas, pegs out rich. did a WOT 3rd gear run. turbo spools, holds 9psi, stays pegged rich on the guage. but the car just doesnt pull at all. i will try to turn out the bleeder more, but there i just not much more i can turn it out. i am starting to think these 310cc injectors are just too much for the stock ecu.
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Old 10-07-2007, 01:17 PM   #8
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I don't understand why you people keep "tuning" your FMU with a fuel pressure gauge. who gives a **** what the fuel pressure is if the a/f is way off? tune that bitch with your wideband, throw the stupid pressure gauge away. how hard could this be? you're rich. back down fuel pressure. the end.
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Old 10-07-2007, 01:19 PM   #9
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if you turn the bleeder valve all the way out and it's still pig rich, you need a restrictor on the vacuum line.


Ben, you at least need to correctly set the preload, after that the pressures are trival :gay:
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Old 10-07-2007, 01:22 PM   #10
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i am not tunning by a pressure guage, i have a AEM wideband. i have no fuel pressure guage on the car, only had one to set the base pressure on the fmu. i will bump upmy timing to 8btdc also to see if that will help it out some
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Old 10-07-2007, 02:13 PM   #11
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alright screw this im putting the stock injectors back in. even at cruise with like 10in of vac, the afr is 10.2:1 and with the bleeder screw all the way out, the leanest it ever got was 10.3:1
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Old 10-07-2007, 03:09 PM   #12
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the fmu will not effect the fueling in cruise.

i was seeing a soild 14.7 cruise with 305cc injectors with the stock ecu and afm.
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Old 10-07-2007, 04:49 PM   #13
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Quote:
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Ben, you at least need to correctly set the preload, after that the pressures are trival :gay:
Why? I didn't. Twice with 2 different FMU's.
I'm wondering if he doesn't have the center screw jacked down waaayyy too far. That would make cruise too rich.

also the needle valve only affects the rising rate, not the overall pressure. overall is adjusted with the center screw.
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Old 10-07-2007, 06:08 PM   #14
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so you at least know your not overriding the oem fpr by jacking up the pressures out of boost.

otherwise im all for the "watch your gauge" method.
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Old 10-07-2007, 07:39 PM   #15
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i am begining to hate this turbo project, put in the stock injectors and now it wont idle at all. WTF!?!?! time to re-check everything.....again.
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Old 10-07-2007, 10:01 PM   #16
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looks like some of the pintle caps and the big spacer/o-ring on the stock injectors were cracked. i will try and swap them out with the ones on the 310s and try again
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Old 10-08-2007, 04:13 PM   #17
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put the 310s back in. i can get it to idle 13-15:1 so thats not an issue. set the fmu again. base pressure is 48ish psi. kept the guage on and set it under the windsheild wiper and went for a drive. doesnt add any fuel in vac, starts adding in boost. at a full 9psi of boost, its at 65-70 psi of fuel pressure. idle afr is ok, but as soon as you start driving, stays at about 10-10.5:1 afr. looks like i need to adjust the tension spring now?
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Old 10-08-2007, 06:16 PM   #18
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went 4 clicks tighter on the AFM, little to no improvement
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Old 10-08-2007, 06:20 PM   #19
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1> is the ****** thing hooked up right? get the fuel lines crossed?
2> do you have an o2 sensor? does it work? probe it with a dmm
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Old 10-08-2007, 06:26 PM   #20
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1> is the ****** thing hooked up right? get the fuel lines crossed?
2> do you have an o2 sensor? does it work? probe it with a dmm
1-yep, fmu actually says in and out on the bottom of it. and i veryifed its working correctly

2-yes and yes. it is plugged in but its not in the downpipe, just hanging there while my wideband is in. i know it should make it a tad richer, but not as much as it is. the car has NO CEL on.
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