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No cel but dead cylinder?


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Starts fine, idles fine, but under load going up steep hill in 1st, dogs or bogs until 2500 rpm, then feels like the dead cylinder kicks in. Also noticed from complete stop, sluggish till 2500 then instant on. Confirmed CEL light does work at start up mode. Soo if problem is plug or plug wire, would CEL definitely come on ?

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Possibly bad knock sensor or vacuum leak.

The ECU doesn't always pick up misfires right away, especially on MT cars where the crankshaft is connected directly to the drivetrain through the clutch.

When did it last get spark plugs and wires? Have you removed spark plugs to check their condition and gap?

Also, what year and engine?

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Sorry 1999 impreza L 2.2. I'll check replace plugs today, & then if problem still exist, replace plug wires. (I located ngk wires). I wouldn't think vacuum, idles smooth. I bought car about 8 months ago with 146k on odo. Did timing belt kit, replaced all fluids & filters.

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Just changed plugs, all electrodes looked ok but enlarged gap. (approx.050-.055) 2 & 4 were autolite , 3&4 were ngk. # 2 well had a bunch of oil. cleaned out as best as I could. put all 4 new ngk's. Test drive & still same. Wires are blue 7mm Belden(napa?) . I suppose I'll change them next to ngk wires. Is this best, next, choice for elimination?

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Beldins are napa lifetime wires I use them in all my subies they usually work well. I would do a visual inspection of the knock sensor and see if it is cracked and check the ohms reading on it to sometimes they corrode on the bottom and cause it to malfunction

Edited by mikaleda
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Good way to get zapped. Easier to unplug fuel injectors.

 

By covered in oil do you mean the electrode was oil fouled or was there oil in the plug well (where the wire goes)?

Oil in the plug well means it needs valve cover gaskets. This would also damage the plug wire which could cause it to arc to the head.

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Beldin wires really arent that great, i used to test them against OE, they failed quickly. If that was the issue they would fail a water mist test.

 

Check your knock sensor, it sounds like it can cause this.

 

The nice thing about beldin is if they do fail napa has to replace them for free

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Ok put ngk wires on & still have problem. I did change the knock sensor when I 1st got car about 8 months ago. & made sure not to put it on hump & torque down & stress it. (in other words put it in correctly) & CEL went away.(back then) About a month ago there was an o2 code that was tripping but hasn't come back for a few weeks.

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About a month ago there was an o2 code that was tripping but hasn't come back for a few weeks.

 

have had alot of that era of subarus with bad front o2 makes it surge and weak on hills

 

i'm no rocket scientist but I can connect two dots together sometimes...change out o2 sensor see if it helps

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Knock sensor should be roughly 580k ohm. It's probably fine if it has already been replaced. If there is any corrosion on the housing that can alter the voltage signal.

 

O2 sensors either Denso or Bosch is OE. I've seen both on the soobs ive worked on and either seems to work fine.

If you get the Bosch universal fit make sure you know which wires to connect.

Denso exact fit sensors are usually pretty cheap through Rockauto.com. (Around $50)

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It grounds to the engine block through the base. Put one lead on the block somewhere easy to get to. You may have to scratch some dirt out of the way to get a good connection. If that doesn't work unbolt it and check resistance to the base of the sensor. There could be some corrosion on the block under the sensor.

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I remember polishing block before knock sen install. Well took off & all still looked polished. I checked resistance from wire to metal base on sensor, still NO reading. unplugged little short pigtail from unit & checked male fingers. Still NO reading. Hope the thing is still under warrentee. I'll let you know when I get new one in. (& will check readings before install.)

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Manual set multimeter and yes get reading when leads together. Found my sensor receipt, lifetime replacement!!! Went to Advance auto , & checked new sensor at counter. Same thing, No reading. Counter dude got his meter out & same thing. He gave me new one anyhow. I tripped the check engine light when I started car with sensor unplugged. So I took off neg bat lug while installing new sensor. hooked all back up & CEL still on. let engine get up to normal temp & took for test drive. Pep is back !!!:clap: Now to scan for code. But still puzzled on testing knock sensor?

 

On edit; code was 0325, so I cleared it with my scanner & so far it stayed off, time will tell. wander why battery disconnect did not clear it?

Edited by bork
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Dis you set the meter to the Mega-ohm scale? Did you try anywhere else besides the base like the metal part on top? Sensor should test somewhere around 580K (580,000) ohms. If the sensor were open internally the ECU would have set a code just like if it was unplugged. Perhaps there was a cold solder joint where the signal wire joined the sensor element causing very high resistance but not enough to trigger a CEL. Maybe the sensor design is different and the base is electrically isolated from the element. Hard to say. Either way, a new sensor should pass the ohm test just fine. Very strange that it doesn't.

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