JWhit197

Alright dudes a few weeks ago I ran through a pretty deep puddle and ever since then I've had hard shifting, CELs and horrible gas mileage. Before the puddle I was throwing a code for misfire cyl 4 so after the puddle I replaced spark plugs, cleaned MAF sensor, and just yesterday I replaced the cyl 4 ignition coil pack... I think my MAF just needs to be replaced but read on and maybe you can tell me if i'm mistaken.

The codes I read before replacing coil pack (after puddle):
P0102 MAF or VAF circuit low
P0131 02 sensor circuit low volts (bank 1 sensor 1) (where is that?)
P0304 cyl 4 misfire
P0171 system lean bank 1

After coil pack I deleted codes but it still misfired and shifted hard. Started it up today and the CEL came back on after warming up. It's a really aggressive misfire and a pretty hard shift (it makes my belt squeak somehow ha) so I read the codes again and it said:
P0304 cyl 4 misfire
P0171 system lean bank 1(where is that?)
P1133 insufficient switching sensor 1 (where is that?)

I'm guessing sensor 1 is the MAF?? Either way, I replaced cyl 4 spark plug AND coil pack so why is it still only cyl 4 misfiring? I'm thinking it's the MAF sensor because it's the only thing that makes sense to me.. It would be the first thing to get wet in a puddle, it would cause it to run lean cause the air/fuel ratio is off and (i think?) it would explain the hard shifting and misfire...

Any help you can offer would be great I just don't wanna go spend any more money on a MAF if there's nothing wrong with mine. I cleaned it and I'm having the same problems so at this point it either needs to be replaced or the problem lies elsewhere. Please don't tell me it's the head gasket haha but do these problems relate to the head gasket??

dannysauer

iTrader: (3)

Well the 131 and 1133 r the first o2 sensor the one on the header before the cat so replace that clean the maf and filter also but that should help with the other codes u got

BartSS

Theyre all cause because of the bad o2 sensor

boosted05ss

iTrader: (10)

orrrr you sucked up so much water your engine is toast

BartSS

whooops didnt read anything but the CEls lol

JWhit197

I already cleaned the maf but what's up with this o2 sensor? How would an o2 sensor cause such a horrible misfire? When I replaced my plugs the coil pack in cyl 4 was corvered in a brown soot so I was sure it needed to be replaced. The engine isn't ruined this happened a month ago and its still running strong it just has a misfire and I need some help fixing it. I'll replace the o2 in the header and go from there. If the motor was gonna hydrolock it would've done it by now

BartSS

If your o2 is bad it will either cause you to go too lean or too rich and it will misfire homey.

JWhit197

Okay then my next question is why ONLY cylinder 4? Is an o2 cheaper than a maf?

JWhit197

Talked to a guy at Auto Zone with an LSJ and he said he's willing to bet it's not the O2 it sounds like a bad injector on cylinder 4... Which explains the misfire after a new coil pack and spark plug and it explains the other codes but what about the hard shifting? That sounds like something related to an O2.. Or could a bad injector cause that as well? Also, he told me that the ACDelco spark plug gaps are NOT preset as the other idiot told me who worked there. So I've been rolling around with an incorrect spark plug gap (way too big), a failing injector and possibly a failed O2 or MAF sensor... Is there some sort of test I can do to be certain which it is or do I need to replace them all haha

dannysauer

iTrader: (3)

Well if the injector is bad it will throw a code for it so don't think that's the issue and dot buy the o2 from them go to the dealer cost more but it will work I went through about 3 of the autozone ones before I just went with the dealer

JWhit197

Well he said they have a cheap brand and then they have a better brand.. But the OEM one is $10 more than their more expensive one ha. But how certain are you that's the problem? I took the fuel rail off and looked at all of the injectors.. They were clean and seemed to be in good shape. I put in new spark plugs and actually set the correct gap but I'm still misfiring. I'm gonna clear the codes at the shop tomorrow and see what codes come up after that. Hopefully it's System Lean and Insufficient Switching Sensor 1 cause then I KNOW its the o2.
Also just confirming.. Sensor 1 is located in the exhaust manifold/header correct? I know there's one in the downpipe as well.. Thanks! Trying to get this resolved ASAP

Also, are these the codes you were throwing when you replaced your o2???

Coblasts

Check the wires leading to injector for cyl 4 for chaffing.
You could check all connectors for water intrusion.

But as I recall cyl 4 is the one that always sees the leaness if there is a problem with the afr.
There could still ne a sensor issue.

LS6Rally

iTrader: (14)

swap the inject with cyl 1 and see if it moves. if i doesnt then i would chase the O2 sensor, or find someone who can watch your car on a data stream from a scanner (if you have a friend that works at a shop)

JWhit197

I work at a shop haha so what do I need to do? I really think the injector is fine honestly it isn't running THAT bad it feels likeca sensor esp with the hard shifting

LS6Rally

iTrader: (14)

i told you what i thought. swap the plug see if it moves, if not try the injector.

or go your route and throw parts at it all day till you get it.

Coblasts

Try this to eliminate the cause mechanically but check the wire for shorts to ground first for cyl 4 injector first ,if you dont see anything carry on with the swapping.

JWhit197

I have swapped the plugs, injectors and coil packs and it has never moved. Wiring looks good to me. But someone just said when its running lean cyl 4 takes most of the hit so that's what I'm saying this whole time who's not to say that's the only thing that's been causing the misfire?

JWhit197

And earlier it was said that if the injector is bad it'll throw a code for it

Coblasts

Heres something straight from a tsb
inspect the fuel injector harness for a potential short to ground at the air conditioning line bracket at the rear of the head, above the transmission. If signs of a short to ground are present, repair and reposition the circuit/harness as necessary.

JWhit197

Okay I'll check it out but the only thing I've seen is just the plastic wire housing somewhat dry-rotted it's gonna be hard to see any damage to the wiring. Tech IV at my shop said he highly doubts its the o2 as well so I'm kinda stuck.. It's either the injector itself or a faulty connection. The only place I may see a problem with wiring is the connector that leads from cyl 4 and snaps in on top of the intake manifold.. That entire thing could have easily gotten soaked. Is the dealer the only place I can go to have them watch the data stream or are there other places that will do that as well.
Honestly I don't feel like I know enough about the Cobalt's electrical system to diagnose a problem with it.

JWhit197

It was the o2 sensor.
Said screw it, its gonna need to be replaced anyways.. Runs like a charm and you can't even feel it idling.
wish I woulda just replaced they in the first place..