SVT with sudden rough idle, power loss

[swansong]

Originally Posted by rycodge

It sounds like you're getting fuel. Did they check for spark?

I recently bought a focus with a malfunctioning crank sensor and a dead O2 sensor. Drove like crap!

Maybe your crank sensor has died? Maybe a bunch of bits of nasty that wrecked your fuel pump is now in the injectors?

Should be getting spark, my guess is fuel isn't getting into cylinders. Fuel pressure is good at the rail, but is it possible the computer isn't telling the injectors to fire properly?

I'll add crank sensor to the To-Check list.

Other things (I'm adding things as they come to my mind, otherwise I'll forget them!)

• Check crank sensor and wiring. On trans bell housing, near exhaust header? "The crankshaft position sensor connector melted."
• Coil wiring and stuff. Links here and here
• Reset ECU by disconnecting negative battery cable. Apparently shop forgot to do this.
• Check if fuel cut-off switch was set or is malfunctioning. The one in the passenger footwell. "You can bypass the inertia switch if you think it might be the problem. All you have to do is bridge across the connector with a piece of solid insulated wire, or a paperclip as long as you make sure there's nothing it can short on. I would not make this permanent, but it can serve the purpose of identifying if that is the problem. "
• Fuel pump relay - R7. Fuel pump fuse - 12.
• Fuel pump driver module. "passenger side, flip the back seat forward and pull the carpet up and you'll see the fuel pump driver module"
  __________________

[svtguy88]

Crank it and pull the plugs. Are they wet/smell like fuel? I don't think you have a fuel problem. I'm still thinking it's electrical -- especially if the shop had it running at one point.

Check for reliable spark at the plugs...maybe a bad coil.

IIRC, the coil on our cars is sort of split into two (one part, but I think it's divided internally). I remember getting strong spark on two cylinders, and basically nothing on the other two at one point.

[swansong]

Originally Posted by svtguy88

Crank it and pull the plugs. Are they wet/smell like fuel? I don't think you have a fuel problem. I'm still thinking it's electrical -- especially if the shop had it running at one point.

Check for reliable spark at the plugs...maybe a bad coil.

IIRC, the coil on our cars is sort of split into two (one part, but I think it's divided internally). I remember getting strong spark on two cylinders, and basically nothing on the other two at one point.

I'll get the car back in the morning. Gonna take a half day of work, maybe whole day, to try to figure this out. I'm thinking it might be the crankshaft position sensor, or its connector/wiring. Or coil pack and its connector/wiring.

How exactly do I check for good spark at the plugs (the safe way)? I believe they are getting spark, since the shop did have it running, but not sure if the spark is reliable, like you said.

[LouBomb]

I had a similar issue, and it turned out to be a bad ground, and bad fuel module... The bad ground i noticed because everytime i hit a bump the car would shut off... tightned it and then the car started to run like crap.. replaced the fuel module and that fixed my issues.. it also solve a sputtering issue i had over 5k rpm.. im having a slight sputtering issue again but i think its the plugs.. i will be changing those soon.

[svtguy88]

Originally Posted by swansong

How exactly do I check for good spark at the plugs (the safe way)?

The safe way, you ask? Sorry...can't help you there....lol

[swansong]

Saga continues. Car is home in garage now, still won't start. Cranks fine, and occasionally sounds like it's getting both spark and fuel, but won't run. All wiring looks ok, but that can be deceiving. Still no CEL. I have tried resetting ECU, pushing the inertia fuel cutoff switch button, and repluging various sensors. Got a catalog as well, and from what i can tell, fuel pressure, MAF counts, and throttle position look good. I sent it off to Tom for confirmation.

But alas, all of this is the least of my worries now. I tried to load the stock tune back on, but the SCT tuner fails the download and car is dead. I've had lots of problems with my tuner before, but thought I had it cleared up.

If I can't get the stock tune back on, and if SCT cannot help, I may have to replace the ECU...

[svtguy88]

Ugh. I borked my SCT once. Something went awry during a firmware update. I think I just paid to have them fix it, if I remember right.

What does your tuner do now? Anything at all??

[swansong]

Originally Posted by svtguy88

Ugh. I borked my SCT once. Something went awry during a firmware update. I think I just paid to have them fix it, if I remember right.

What does your tuner do now? Anything at all??

Car is tuned right now. I cannot load custom tunes to it because the tuner complains about "..custom tune failed, return to stock, yadayada." When trying to install stock tune, it gets to around 11%-17% complete, then beeps and says tune failed to load. Error 1016 I believe.

I have fuses 46 and 61 pulled. Gonna buy a battery charger after work to make sure battery didn't just get stressed out from all the failed starts. I've heard the SCT tuners are picky about battery voltage.

[svtguy88]

Well, at least it still tries to load the stock tune -- that's a good sign, as long as the stock tune is still intact on the tuner.

The battery idea makes sense, especially if it's been cranking the engine in the cold for a few days now...

Might be time to give SCT a call otherwise.

[swansong]

Car is back to stock tune. Yay. What worked was pulling fuses 20, 46, and 61, turning the key to RUN as soon as it prompts it, and lots of swearing and threatening language towards the tuner lol. It's not a tune problem anyway, so returning it to stock just made me give myself more of a headache than I needed lol.

Tom (1turbofocus) suggested doing a compression test before moving further. I think I'll so that. I won't be able to work on the car until Sunday though, which sucks. If the compression is low, I'll be one sad dude...