abnormal Lean at idle

jesus

jesus

Greenie N00B Member
Greenie Member
Lately I've been having a issue where the car will randomly run lean at idle. Some times when the lean condition happens the HPFP psi will drop down to the lower 400s. Other times pressure will hang around 420-430psi but will still lean out. At times even getting to 16.38 for a second or two. I have some logs showing the conditions & want to see if anyone else sees something I'm not catching. any help or advice would be greatly appreciated.
 

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There is a cleaning how to somewhere on here take it apart check for scoring and clean everything
 
Easter Bunny said:
There is a cleaning how to somewhere on here take it apart check for scoring and clean everything
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https://mazdaspeeds.org/index.php?t...nd-spill-valve-michael-rey-facebook-kit.8069/

This is what you're after. Cleaning is good especially on that spill valve that being said checking the status of the PRV might be prudent, test needs to be done with engine hot
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So I went and tried out the relief test today and notice it takes forever to climb up to pressure we’re talking like more then 5+ mins of watching it and the most it got up to was 1107psi and started to fall down. Would this be a bad valve I’m seeing ?
 
jesus said:
So I went and tried out the relief test today and notice it takes forever to climb up to pressure we’re talking like more then 5+ mins of watching it and the most it got up to was 1107psi and started to fall down. Would this be a bad valve I’m seeing ?
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Probably - was it done with a completely warm engine? You can get the PRV much cheaper on ebay through a japanese retailer than you can from most domestic sources, and they are OEM. The CX-7 PRV is the same exact model number.
 
jesus said:
So I went and tried out the relief test today and notice it takes forever to climb up to pressure we’re talking like more then 5+ mins of watching it and the most it got up to was 1107psi and started to fall down. Would this be a bad valve I’m seeing ?
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Yes
 
So i ended up doing another test on my way home and this time car was ran on highway at 85mph @ 3500k rpm for a good 40 mins straight and soon as i arrived i turned car off and then turned the key back to the on position and watched the psi rise faster and got to 1788psi & then valve opened up. When i first tested it i drove about 20miles city driving then turned car off & key on and that's when i got the slow climbing psi & early opening valve symptom.
 
Okay so the valve is needing to be replaced, do they make upgraded relief valves ? i know in his video he mentioned it but didn't know what you get from upgrading it. Also is the valve I'm looking for the brass valve at the end of the fuel rail or the spill sensor on the top of the HPFP? I'll see if I have one laying around the house tomorrow if not make an effort to find a cx7 and take it from it see what happens.
 
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they don't make upgraded PRV's. only can be replaced with a Stock oem and yes is the brass valve at the end of the fuel rail. make sure u put u don't forget to put the washer back on when u install the new one.
 
jesus said:
Okay so the valve is needing to be replaced, do they make upgraded relief valves ? i know in his video he mentioned it but didn't know what you get from upgrading it. Also is the valve I'm looking for the brass valve at the end of the fuel rail or the spill sensor on the top of the HPFP? I'll see if I have one laying around the house tomorrow if not make an effort to find a cx7 and take it from it see what happens.
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Pressure relief valve
= brass valve on fuel rail Mazda pn: L3K9-13-2J0
https://edgeautosport.com/mazda-oem...7-2013-mazdaspeed-6-2006-2007-cx-7-2007-2012/

I don't recall any washer on this part when I removed it on my gen2 to flush my fuel rail and replace the filter basket inside the valve

Spill valve is something else entirely and refered to as such if anything it typically just needs a clean
 
How much psi did that one end up holding ? I went to the local junk yard to get the valve and they had 3 cx-7 in the yard and took all of the PRV from them and came back home and tested them. So far out of the 3 that i grabbed only one hold 1868psi the others would drop around the 1660-1750 range. AFR has changed up a bit from running lean at idle to settling alright between 14.4-14.9 but i can tell it wants to add fuel to keep that ratio still.
 
jesus said:
How much psi did that one end up holding ? I went to the local junk yard to get the valve and they had 3 cx-7 in the yard and took all of the PRV from them and came back home and tested them. So far out of the 3 that i grabbed only one hold 1868psi the others would drop around the 1660-1750 range. AFR has changed up a bit from running lean at idle to settling alright between 14.4-14.9 but i can tell it wants to add fuel to keep that ratio still.
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The Ebay is an OEM valve, so they're rated to crack at 1800, but you can see above at WOT. I would go with the junkyard valve that passes the KOEO test and also holds the highest pressures at WOT. 400 at idle, above 1600 at WOT is the standard for an okay valve if I'm remembering correctly.

They are a wear item, and will go bad eventually, it's not a bad idea to swap out with a new OEM eventually.
 
Yeah that's what i was thinking about at this point was to just buy a new oem one. I'll run one more test tomorrow see what turns out as far as WOT test
 
So after a couple days of having the new PRV in the car it started to run lean again compensating 13%+ at times. Could this be a MAF issue or vacuum issue? Also on that note i went ahead and did an oil change on the car and added in some VR1 oil in it and noticed some slight change to the afr and stft. Afr would be around 14.41 more often than that of 14.99-15.14 & stft would be around 6-8%
 
jesus said:
So after a couple days of having the new PRV in the car it started to run lean again compensating 13%+ at times. Could this be a MAF issue or vacuum issue? Also on that note i went ahead and did an oil change on the car and added in some VR1 oil in it and noticed some slight change to the afr and stft. Afr would be around 14.41 more often than that of 14.99-15.14 & stft would be around 6-8%
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+ltft usually means vacuum leak, are you stock or what mods?
 
chris' speed 3 said:
+ltft usually means vacuum leak, are you stock or what mods?
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No built motor bnrs4 with supporting mods. I was able to get a log today of the car both when it wanted to run lean & when it wanted to run rich. is there something you guys see that I'm not catching? I notice that the MAF reading in lean condition runs closer to 1.93-2.0 g/s than rich running passed 2.3g/s. Would this be pointing at a failing MAF sensor ? The sensor its self is a denso MAF
 

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