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Discussion Starter #1
Hey All!


So a few weeks ago my car started (what I think is) misfiring. Intermittently, the engine would sound like it's hiccuping and loose power. This happens when it is cold or warm. I had an issue with my ignition coils before, so I replaced them with no effect. I then replaced the spark plugs with no effect. I gave it to a shop, who said that it may be due to the ECU being corrupted, and pointed out that the ECT-2 sensor is reading as -40*F at all times, but when they plug in a scanner it reads normal. Is there any way to determine if this is an ECU issue and not mechanical?

I have a flashpro and did some datalogs and also reflashed a stock map. The stock map seemed to make a small difference, but the (misfires?) keep happening. I have no CEL or error codes on the datalog. Any ideas? My next try will be to find a tuner to see if they can rule out the ECU.

Datalog: Civic Si

Mods:
  • RDX Injectors (410cc)
  • 3" CAI
  • Skunk2 Exhaust
 

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does it do this in every gear? at idle only? when you let off the gas? when you stomp on the gas what happens?
 

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Discussion Starter #3
Yup, every gear and at idle. Stomping on the gas doesn't make a difference.
I cleared the ECU again and now I'm getting a few error codes. Two of them are complaining about the o2 sensor which I've removed, and the third is a misfire in 3. It seems to run much more smoothly now, so I'm not sure why the other flashes didn't work.
My next step is going to be to get a shop to check the injectors. I'm hoping it's a loose O-Ring or a dirty injector. Maybe the fuel pump, as I've never replaced the fuel filter.
 

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dirty fuel filters will cause issues like this due to poor fuel flow, and if you're specifically seeing it in cyl 3 could have a true obstruction in the line going into the cyl or very clogged injector. You should be seeing about 45 psi on your fuel system for pressure to be running normally, also that 02 sensor you removed could be causing an issue due to the engine not having that information and not knowing how much fuel to air ratio you have.
 

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Depending on you're tune, you might need better plugs, gapped to a specific spec, from .023" to .028".

It's incredible how important the EXACT gap is!

Find out your gap, then close it by .001, install, run it again.

Crappy gas doent help either...I suggest 93 octane minimum.


Hope it's a fast fix.

Worst case, have a tuner pull some ignition from your car, since it seems to run hot.
 

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Ps.

If you get new 02 sensors, make sure the "element" is never touched, and care is taken installing it in the bung.

If the sensors element is grabbed by hand, it's now useless...contaminated, and will read falsely.
 
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