himynameiswyatt

Hi everyone.

I'm having some issues with my 04' EX. Automatic. 150k. I'll start at the beginning..

I bought the car back in September because i was getting tired of putting all the miles (80 miles/day for work) on my Focus RS. Car needed a camshaft sensor and a primary O2 replaced but didn't throw any hard red flags at the time of purchase. The car was about a block away from me, so my girlfriend drove it home and i replaced the camshaft sensor. Figured all would be good.. I can keep the miles off my car!

Then, everything just seemed to go wrong with this thing. And the lil' old lady pulled a fast one on me whether it was an accident or on purpose.

I put the camshaft sensor in and the code goes away. Great! But now,when i go to start it, it will turn over and act like i'm dumping fuel into the cylinders on start up. Crank-Crank-Crank Pop and then it will start up. Usually it will rev up and then buck down and stall out. 2nd start up goes the same way....Crank-Crank-Crank Pop and then starts up. Almost dies and then goes to idle...It idles perfect. 1kish. No misfires. Nothing! So i go to drive it... and it's in limp mode. Will NOT go to a higher RPM. I'm hearing what sounds like a mechanical failure (tick tick tick tick tick). Great... something is leaking. I automatically think it is the exhaust manifold gasket.

I replace the gasket and the donut to the cat-pipe because they are in poor shape / blown out. But, no dice. Still having issues. I finally narrow it down to a plugged cat. I hallowed out the cat and it fixes the limp mode issue. None-the-less, the start issue is still there.

So, long story short, it will pop and back fire and not want to start... but as soon as it starts and idles, it will idle PERFECT. No misfires. Doesn't skip a beat.

So, i got on a shopping spree. Literally ANY sensor i could buy i felt like. MAP, IAT, Primary O2 (Denso OEM sensor), coolant temp and fan switch. I have replaced the fuel pump assembly hoping that it would fix it. New spark plugs. Fuel Relays. Valve cover gaskets because of oil in the spark plug valleys.. i have a spread sheet with everything i have done to this thing and it's starting to add up. The only one i have not been able to get to is the crankshaft sensor.

The timing belt was replaced 5,000 miles ago. Timing marks all looked good the 400000 times i have taken it apart and looked at it. I just put an alternator in. I have ran new grounds from the block to chassis to battery..I have cleaned the injectors and ohm'd them out (13ohms). I have adjusted the valves but i'm still getting a tick coming from the engine bay that sounds like it is coming from the fuel rail area.

I did a leak down test and they all came back <15% leak down. My compression gauge was broken and i will have a new one here monday afternoon to be able to check them. I figure since my leak down came back with what it did with a semi-cold engine, the compression test would not come back horrendous.

I'm running out of viable options at this point. I'm about to go pull an ECU out of a junk yard car and see if it will do anything for me. I'm still getting a P0134 code for the primary O2 sensor even with a new Denso sensor. All wiring looks good from the sensor to the ECU (Continuity tested). The sensor itself is outputting what it is supposed to. It is getting sufficient power. I'm 100% stumped on what more it could possibly want.

Maybe the head gasket is taking a poop because of the clogged cat? It blew the donut gasket out, i'm not sure what it would do to the head. BUT, i would think it would run like crap or i would see oil in the coolant or coolant in the oil. Which, i'm seeing neither of.

Someone please be my hero and save my day so i can drive this thing before i replace every since piece that is on it Super clean for what it is. No rust at all.

Colin42

Were the other sensors OEM as well?
Did you buy the OEM sensor for dirt cheap online, or somewhere reputable?

himynameiswyatt

OEM parts supplier for everything. O2 was an Amazon denso. Swapped parts with the other EX we have at hometo make sure.

Colin42

Ok, some people have gotten counterfeit Denso parts, but since you swapped with a known good it looks like you got a legit one. Got a scanner that can do live data? Cleaned the intake, sensors, and IAC valve?

himynameiswyatt

iac is clean. I cleaned the EGR. Map is new but ran the same with the OEM sensor. IAT is clean and reading correct temps. Pulled another sensor at the junk yard today so ill see what that looks like. Thing has been a difficult save for me! Compression gauge will be here tomorrow but i expect that to go well judging by the leak down numbers.

himynameiswyatt

Compression test came back good.
cyl 1 - 130
cyl 2 - 125
cyl 3 - 125
cyl 4 - 130

Need to get something to test the fuel pressure to see if it's dumping fuel at the rail. O2 is not working and giving me a P0134 still. F

Colin42

Checked the wires and connector for the sensor yet?

himynameiswyatt

yes all connections are verified good back to the ECU

jeep8589

Fuel pressure and I would check for sticking injector. Sounds like it is dumping too much fuel, which is why you can't get the O2 reading in line with specs.

himynameiswyatt

Cleaned injectors. Replaced one that I broke. Replaced all seals. No luck.. This thing is driving me nuts!! Lol. Need to find a male quick connect so I can test for fuel pressure.

Wankenstein

During the leakdown test did you leave the radiator cap off to look for bubbles in the radiator due to breached head gasket? Any oil loss issues?

himynameiswyatt

I did not leave the rad cap off during the leak down. Figured the numbers that i saw were good enough that it wasn't looking like a gasket issue. Haven't noticed any oil loss and the coolant that i just drained out looked good...or as good as 16 year old coolant can look. New rad hoses put on and coolant was flushed. Took apart the thermostat housing and cleaned around the engine. Replaced the camshaft cap while i was in there.

What are signs of a bad crankshaft sensor? i had an "oem" one that i put in and it immediately showed it was a bad sensor because it wouldn't fire up and run.

Need to try and test fuel pressure this weekend. Getting the RS maintained along with the GF's VW so it may be another stagnant weekend. Debating on whether i keep this or the G8 for a commute car. Depends on which one gets fixed first i guess.

Wankenstein

Does it sputter from cold start to operating temp and then idle okay from that point onward?
Are the spark plugs wet after engine cools down?

Gallegos1982

I had this same issue after my timing belt snapped. Changed 3 auto store crank sensors before the 4th OEM one actually worked. Then had very hard start . I would have to floor it to start the car. It would sputter and then start up and idle fine. It was just extremely hard to start. Compression and leak down test completed then I changed the camshaft sensor and immediately fired up with no issues. Now I have to go back in and change my tension because the one I got was a counterfeit. It came in an OEM box and everything.