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CEL after fill up of 89 octane

1316 Views 14 Replies 3 Participants Last post by  prototype99
Ok so this is a weird one that I can't even begin to understand. My car keeps throwing a P2187 code everytime I fill up with 89 or higher octane. I am putting 89 in since that seems to have worked best for my setup in the past with the advanced timing mod. I have a 2004 Mazda3 2.3 hatchback. Current mods are AEM CAI, Trubendz 2.5" SS exhaust with race pipe (standard kit), grounded tb, tb coolant bypass, advanced timing mod, AWR rear motor mount, SU pass and driver side mounts. If I fill up with 87 octane the CEL will go away after a few start ups on its own. I don't top off and I have already checked the gas cap. I've checked the MAF wires (I already have them extended out about 5" so pulling them should not be any concern), cleaned the MAF, check all fluids. I haven't checked the plugs yet but they only have like 10k miles on them so that should be it.

I also noticed last night that when I was getting on the freeway leaving work that when i pressed the gas the car was fine till it got about 3k rpm on 2nd gear then it shot up to redline hit the redline like 1-2 times. Shifted to 3rd and shot to redline like i have never seen it shoot up so fast. This was in a matter of probably 5 seconds. I wasn't even flooring it. I had the pedal probably 50% down if not less. Definitely didn't feel right. Car was almost all the way warmed up. As soon as that happened I let off the gas. Then gave it a little bit and it was running fine. I drove all the way home without another hiccup like that. Not sure if it was related or not.

I can post an AutoEnginuity report on here with all the sensors if anyone can take a look at it and let me know if they notice anything weird on it. I ran it this morning on my way to work (about 25 miles). I'm going to try clearing the code on my way home tonight to see if it comes back again.

Could my purge solenoid valve be going bad? Has anyone else seen this?
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Forgot to mention that this is after I had my motor replaced due to a hydrolock. My original motor that had 71k miles on it did not have this issue. This current motor has about 67k miles on it. It was replaced by the insurance company at my local Mazda dealership.
Does anyone have the most current Purge solenoid valve part number? I have found like 3 different part numbers for it. Also, does anyone know if the new valve and hose come with a test cap or if only Mazda gets that part. I'm not 100% sure one what one is the most updated part #. I'm also not 100% that it's the problem yet but wanted to have the part # just in case it is.
The RPMs shooting up issue sounds like the clutch is going bad. Doesn't sound like a purge solenoid valve problem to me at all; if that were the problem the car would probably be very difficult to start up after filling up without giving it some gas.
I have an automatic........
Still sounds more like a transmission problem than an engine problem. The only way the RPMs can shoot up faster than normal is because of slippage between the crank and the wheels somewhere... most likely between the clutch/flywheel (or whatever the equivalent is in an auto)
I'm guessing that would be the torque converter... Not 100% on that. Do you think it could be a one time thing? The rev'ing thing didn't happen at all this morning. It was no warmer or colder this morning then it was last night.
It can happen pretty randomly at first, but will probably get worse over time. However, the RPMs slipping up is definitely not directly related to your CEL, which is for "too lean at idle" -- sounds like there's a leak in the intake system somewhere.
I have the AEM which is one piece except for where the filter mounts to the pipe and were the pipe mounts to the TB. I'll check these connection points when I get home tonight. I know the MAF is on there good since I always make sure to have it screwed in good and seated in the correct spot.
It could also be a loose connection at the valve cover breather (follow that extra little hose on your intake back to the corner of the engine nearest the firewall and battery) or the purge solenoid hose (not a problem with the valve itself per se, just a loose connection).
I actually have the valve cover breather inlet on the intake plugged up with a rubber stopper and I have a small breather filter on the valve cover. This is how I have run it since I got my intake. Put about 40k+ miles on my old motor like this and about 2-3k on the current motor.
That could very well be what's causing the CEL. Normally the breather is connected to metered air that flows through the MAF, but you're pulling in unmetered air that it's not expecting to be thrown into the mix. You're also decreasing the pressure in the crankcase, which can lead to increased blow-by and extra emissions. Try connecting that correctly and see if the CEL goes away.
Thanks. I'll give that a try and update tomorrow.
Incidentally "lean off idle" was the code I was getting when my purge valve went bad (all four times!). If you have a '04 and it hasn't been replaced then you probably need for it to be.

The revving problem is definitely not related to the purge valve though. Is it possible it's something to do with the throttle position sensor? Don't know, just fielding ideas for the smarter (and more mechanically minded) people.
Where is the throttle position sensor located? I'm guessing close to the TB... Anyone have a diagram to show its exact location?
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