I am giving my 2004 Accord Ex V-6 a 300,000 mile tuneup (I was running fine before I started working on it) I replaced the timing belt, water pump, plugs, filters etc. I just put it back together and started it up and it ran rough, raw gas out of exhaust. I went through and unplugged each coil pack as it is running and cylinders 4-5 & 6 were firing. I then went to the back and unplugged 1-2 & 3 and no change??? The check engine light came on after it warmed up and threw error code PO134. I shut the old girl down and checked all of the connectors, wires, etc and it seems all in order???
I have good compression on all 6 cylinders
I'm not sure where to go from here??? ECU???

 

FYI, it is P0134 (zero not the letter O). That can help when searching the web for information on codes. P0134 is an error code for the heater circuit of the O2 sensor.

Since you just did the timing belt, and one bank of cylinders is off, recheck your timing marks. You may be off a tooth.

 

Thanks for your reply,
So I went back into it this morning, pulled the plugs, checked compression-All cylinders 175 lbs or higher. cylinders1,2,3 plugs are wet & fouled, 4,5 & 6 clean.
I removed the timing belt covers & made sure crank mark was perfectly aligned. Then checked both cam marks & they are right on.
I still have it apart & am wondering what else I should be looking for.
Any suggestions???

 

Check for spark cylinders 1, 2, & 3

 

Wiring that goes to the rear coil packs? Any obscure part of the wiring harness that isn't properly plugged back in?

 

Still trying to diagnose. Pulled coil packs on Cylinders 1-2-3 no spark. Engine still runs barley. I've checked all connections, looked for pinched wires, etc still found nothing. Now getting error code P2195-Rear A/F Sensor 1 Bank 1 Signal stuck Lean-Not sure if primary cause or a symptom of 3 dead cylinders. Auto parts store say upper O2 sensor??? Looking for advice on next steps...

 

The "lean" reading for those cylinders can be caused by lack of spark. What it really measured is oxygen, so if there's proper fuel but it never ignites, then there IS excess oxygen in that exhaust manifold.

I don't have a circuit drawing for that V-6 so I'm not sure where else to suggest looking for bad wiring connections.

 

If there is no spark at cylinders 1, 2, 3 - sort this out first and don't bother about other codes. Yes, O2 can be stuck lean because of 3 dead cylinders, air/fuel mix is not ignited in those cylinders = too much air comming out = "false lean" condition = error code. Don't bother about O2 sensor signals when half of cylinders do not work - fix that first. Check wiring, coils, connections, even plugs - everything. Get a wiring diagram.

 

Each coil should have 2 wires. Each coil has a blk/wht wire. That wire should measure 12V touching with the red meter lead. The key should be in the II position and you negative volt meter lead touching a good ground (negative battery post or a metal valve cover bolt).