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Old 09-30-2011, 12:13 AM   #1
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Default 1.6greddy going super lean...FIXED!!!

The problem I had is stated below. I fixed the problem by changing from the 99+ 1.8 injectors, to the 305cc green top supra 7mge injectors, and changing my fuel pump from the 255hp walbro, to the 190hp walbro.

I now see my AFR's in the 11.5 range throughout the rpm band. Im peaking at 11psi, then quickly settling to 9psi, till redline. If I go for 1psi more, I see AFRs in the high 12s and 13s. Maxxing out the current setup safely ... time for a megasquirt.



Hello everyone. Ive been dealing with this problem all day long. I have my zeitronix WB hooked up and im seeing 15.0+afrs at 9psi.. Hitting 13.3 by redline.. I know my sensor is good, just tuned an evo yesterday. Mods are in my sig, plus here are some more details on my car and what ive tried to do to fix this problem..

New fuel filter, new lines
new walbro 255hp
vortech 6:1 disk
1.8 99+ injectors
02 clamp installed w/ voltage at .30
checked all boost lines, boost leak test..
new ngk iridiums, new magnecor wires


Ive tried running it with the 02 clamp off the car, same problem. I tried adjusting it super rich .19, nothin...

the car Idles at 14.7:1 on cold start up, same when its warm...so I dont think it could be the 02sensor..

I dont know if the vortech fpr is kickin in or not since I dont have a fuel pressure gauge hooked up yet. Ill be installing a gauge tomorrow.

This has been hurting my brain.. Any thoughts?? Greatly appreciated

Last edited by amak87; 10-13-2011 at 12:18 AM. Reason: Fixed problem
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Old 09-30-2011, 02:14 AM   #2
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Fuel pressure gauge helped me a lot, showed me that the little tiny piece of fuel hose going from the pickup sock to the pump was blown. Any who don't you want 12:1 or 10:1 for your fuel? That's stock. 12:1 that is.
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Old 09-30-2011, 02:29 AM   #3
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Im running 10 psi.. A 12:1 disk would put my fuel pressure at 170psi.. I "should" have enough with the 6:1 disk... However the AFRs arent even close.. almost a 16:1 in boost.. Its like my vortech is not working.. I replaced all hoses with 400psi hose.. So im good for leaks..

:/
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Old 09-30-2011, 02:32 AM   #4
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I will check the hose in the tank you had problems with.. I know I overboosted once and probably hit over 18psi, putting my fuel pressure over 200psi.. That could be a good idea thank u
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Old 09-30-2011, 04:16 AM   #5
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Mine was replaced with brand new high pressure fuel injection hose as well when I put the walbro in. Worm hose clamp ripped the hose a bit, didn't show until it was pressurized. Use the stock spring clamps.

I was at 10psi too, and the stock disc, whatever it was (12:1?), produced the correct AFRs.
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Old 09-30-2011, 02:01 PM   #6
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Ya I havent seen the correct afrs yet. My walbro should max out at 140psi.. So running a 12:1 disk might help out once I can get some fuel in the motor. Ill be hooking the fp gauge up today
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Old 09-30-2011, 02:18 PM   #7
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I mean you still generally need x amount of extra fuel for every extra psi. If your fuel pump can't handle it, you should be turning down the boost, not running lean.
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Old 09-30-2011, 02:20 PM   #8
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There are no soft fuel hoses connected to my walbro..
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Old 09-30-2011, 02:23 PM   #9
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With my 1.8injectos and 255hp walbro, I can get a safe amount of pressure. Maybe my pump is going into.high voltage? Any fuses I should take a look at?
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Old 09-30-2011, 03:51 PM   #10
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I just inspected the fuel pump and all lines.. I clamped my return hose to get my pump to max out.. No leaks, no smells.. I just installed the stock 12:1 fpr disk.. Testing now..
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Old 09-30-2011, 03:55 PM   #11
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http://www.boostedmiata.com/FAQ/fuel_install/step6.jpg
See the black hose and spring clamp above the pump? That's what I'm talking about.

Do you have any other discs? Have you done the five minute job to replace the disc to see if that's the problem?
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Old 09-30-2011, 04:21 PM   #12
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With the 12:1disk. It seems like the 02clamp is kicking in.. Putting my afrs around 12.5 in spool up. Then they go lean to 14.5afr, then richens up to 12.3 by redline.. Any thoughts? I have 305ccs coming in the mail
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Old 09-30-2011, 04:22 PM   #13
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I see your picture.. But my pump assembly doesnt have any hose, just hardlines...
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Old 09-30-2011, 04:35 PM   #14
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Yes. I havr the vortech disk kit. The 12:1 is allowing the most fuel.. But still going lean.
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Old 09-30-2011, 05:11 PM   #15
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Can anyone chime in about adjusting the afm to get richher in boost?
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Old 09-30-2011, 10:06 PM   #16
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I think all the Walbros should have a short piece of fuel line. Did the PO say he installed it? If so I'd think he lied and you have a stock pump.

Have you used a voltmeter to adjust the kick-in point of the O2 clamp?

If you pry the cover off the AFM, you can adjust the tension on the clock spring to adjust your idle AFR. Blip the throttle with the cover open, you'll see how little it takes to open it fully. There's another adjustment in there but I forget how it works, never did it myself.

That's one of the problems with band aids. You're climbing all over the car to adjust things.
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Old 09-30-2011, 11:57 PM   #17
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I installed the 255walbro a month ago. Some fuel pumo assemblies require the short fuel line, mine doesnt. It clips right into place.

My fuel pump relay is ok, tested it.

Yes, I have the 02clamp set at .27volts..

I switched the vortech fpr lines and im getting good fuel (11.0afr) until about 4psi, then it hits lean (14.7) then riches a little at redline. I think my fuel pump must be bad..

I ordered a 190hp walbro and 305cc injectors.

I also adjusted the afm to idle at 14.7:1 with the afm bypass screw closed..

No check engine light codes either...
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Old 10-01-2011, 12:59 AM   #18
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Fyi ive instaled another walbro in a 91 miata that.didnt have.the short hose peice..
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Old 10-01-2011, 01:07 AM   #19
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Fyi ive instaled another walbro in a 91 miata that.didnt have.the short hose peice..
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Old 10-13-2011, 12:47 AM   #20
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Fixed the problemo
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