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Old 03-13-2012, 12:10 AM   #1
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Default Idle fuel setting wants to be really rich

I don't understand why I'm having to add so much fuel just to get it to idle. Car is 00 with Rev's PnP unit. There's probably a setting I screwed up. See the attched stuff. Hopefully this will help. Also the 255 Walbro has 90 psi at idle.
Thanks for the help
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File Type: msq 2012-02-13_21.27.57.msq SAVED 2-13-12.msq (83.7 KB, 92 views)
File Type: zip 2012-03-12_17.48.08.zip (657.2 KB, 54 views)
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Old 03-13-2012, 12:54 AM   #2
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sorry, that wasn't the current tune, hopefully this is. Do I have to attach the ini file? I just tried, it didn't show up.
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File Type: msq CurrentTune.msq (83.9 KB, 89 views)
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Old 03-13-2012, 09:09 AM   #3
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What does you wideband read at idle?
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Old 03-13-2012, 09:56 AM   #4
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you shouldn't be seeing 90psi at idle.

there's just no way with that amount of pressure the injectors can cycle fast enough to provide anything BUT a rich idle.
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Old 03-13-2012, 11:10 AM   #5
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Quote:
Originally Posted by 2manyhobyz View Post
Also the 255 Walbro has 90 psi at idle.
Why? That's 50% (30 psi) too high.

Did you remove the fuel pressure regulator from the tank?
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Old 03-13-2012, 09:46 PM   #6
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Quote:
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Why? That's 50% (30 psi) too high.

Did you remove the fuel pressure regulator from the tank?
I'm gonna have to open it up and see what the previous owner did when he installed the Walbro. On this year of car with the Walbro and a properly working pressure regulator, what's closer to right?
Here's the weird thing, really hard to start (10-15 sec crank) rich, (10-11 afr) for first 4-5 min. This is with the warm up set down about 75. AFR for this start I tried at about 70 just to see if it would start any better. It didn't. 4-5 min I would see 13.5-14. Normally I have to set the first four cels at 82 just to get a 14.5-15 (although this swings all over the place from 13 to 16.5 nothing close to stable) and as the engine continues at normal temp it reads leaner. I've richened to an 85-87 number which seems way wrong since I just found out about the 90 psi problem. The rest of the numbers in the rest of the table don't look to bad in comparison with what I'm suppose to see on the AFR. I also pulled the LC-1 and re-calibrated in fresh air-no difference.

Sorry about the picture, apparently I'm also failing at trying to get the VE table to make it to the manage attachments. (Help here would be appreciated too)
So it just seems weird that despite the fact that it's got all this pressure at idle the AFR says give me more fuel I'm idling too lean!
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Idle fuel setting wants to be really rich-th_p1020204.jpg   Idle fuel setting wants to be really rich-p1020204.jpg  
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Old 03-14-2012, 10:09 AM   #7
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It does if your injectors are struggling to open against a fuel pressure they were never designed to handle. Fix your fuel pressure first.
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Old 03-14-2012, 10:26 AM   #8
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A rich misfire will increase O2 in the exhaust and give you a lean reading on an AFR gauge.
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Old 03-14-2012, 07:06 PM   #9
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I have more info. I have the older RX-7 550 purple injectors. They were never designed to operate at that pressure. Talking to one of the mazda techs, it seems that the returnless systems operate in the 70 psi range. I guess everything from 99 and newer is returnless. So he's saying that the walbro at 85-90 isn't that far over the stock system. He suggested to help diagnose the problem would be to put in the stock injectors to see if the idle could be brought under control. No boost cause it would go too lean with the stockers. I'm just trying to not spend $140 on a pressure regulator when Maybe I should put that money toward some Deatch works high pressure injectors. What do you guys that are running returnless systems think?
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Old 03-14-2012, 09:15 PM   #10
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it should be at 60psi. mazda tech fail.

at 90psi is 50% more pressure. that's significant. mazda math fail.

you need to fix the problem, which is getting the pressures back down the 60psi by figuring out why they are at 90psi. once you solve this, you'll solve you rich idle issue.
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Old 03-14-2012, 11:05 PM   #11
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Just fyi, depending on the exhaust/location of the lambda sensor, sometimes there is not enough exhaust flow at idle to get accurate lambda readings. I usually just tune idle by feel/sound. Also, +1 to hornetball if it is misfiring.

Also, I would be surprised if the injectors can't handle 90 psi (in terms of being able to open properly, you should at least be able to get the car to idle fine).
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Old 03-25-2012, 01:45 AM   #12
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Update. FPR fail. Decided to to a return system. Bought a Aeromotive (13109). Fabbed an outlet off the end of the fuel rail to the FPR and return to the tank. Now I'm able to adjust the pressure and go forward with the tune. Thanks for everyones help. Good triumphs over evil. You guys rock. Millertime.




Attached Thumbnails
Idle fuel setting wants to be really rich-p1000701.jpg   Idle fuel setting wants to be really rich-p1000703.jpg   Idle fuel setting wants to be really rich-p1000697.jpg   Idle fuel setting wants to be really rich-p1000695.jpg  
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Old 03-25-2012, 10:00 AM   #13
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How thick is that OBX gasket?
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Old 03-25-2012, 10:57 AM   #14
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Quote:
Originally Posted by y8s View Post
How thick is that OBX gasket?
It looks like 3.5 mm. This has been setting on the work bench for 3 months. You'd think I'd be smart enough to get a before temperature reading-fail.
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