LFX experiencing run-on every now and then

[xstuntman]

I agree.
Pulling the plugs should tell something, especially if you can pull one or several just after it runs on. Wet with fuel, carbon? Enquiring minds want to know.

[ChibiBlackSheep]

Of course the weekend that I actually have some free time, it's been pouring non-stop. I'm hoping to get time to pull plugs soon. Maybe next weekend?

For now I'm going to continue to monitor with HPT and see if it does it again.

[ChibiBlackSheep]

OK, little bit of an update. On Friday on my drive home from work, the car was running very rough when in N and idling. Anytime I had to shift out of gear in traffic and sit, the service stabilitrak would kick on, and it would idle rough. The second I put it in gear, all of the warning lights stopped, and the car smoothed out.

I did a little bit of work on the car yesterday. Took apart my intake, removed the throttle body, checked all sensors and connectors, checked all fuses, went to check plugs but realized I have the wrong size socket, so I'll need to pick up a 5/8 spark plug socket.

I've run a catch-can on the dirty side since I've owned the car, but it does look like the intake is still a little dirty. So I'm going to have to pick up a clean-side separator. I do see oil trails inside my intake tube, and my TB was filthy. I think the car is running awesome today, and I do think cleaning the TB helped. Maybe it was sticking, and throwing the sensor off?

This spring, I'll have to purchase the clean-side catch, and I think I'm going to remove the UIM and do a manual cleaning of everything. But for right now, it's running strong, actually feels better when I am coasting in gear, so I really think the dirty TB has been messing it up for a while.

[blackswan]

It's just darn weird to get run-on but hey - glad you got some improvement! FWIW, I took my throttle body off the car and disassembled the motor and lubed the gears and the pivot points of the plate's axle. I definitely have a more responsive pedal now, I think they just wear over time and why new throttle bodies help.

Originally Posted by ChibiBlackSheep

OK, little bit of an update. On Friday on my drive home from work, the car was running very rough when in N and idling. Anytime I had to shift out of gear in traffic and sit, the service stabilitrak would kick on, and it would idle rough. The second I put it in gear, all of the warning lights stopped, and the car smoothed out.

I did a little bit of work on the car yesterday. Took apart my intake, removed the throttle body, checked all sensors and connectors, checked all fuses, went to check plugs but realized I have the wrong size socket, so I'll need to pick up a 5/8 spark plug socket.

I've run a catch-can on the dirty side since I've owned the car, but it does look like the intake is still a little dirty. So I'm going to have to pick up a clean-side separator. I do see oil trails inside my intake tube, and my TB was filthy. I think the car is running awesome today, and I do think cleaning the TB helped. Maybe it was sticking, and throwing the sensor off?

This spring, I'll have to purchase the clean-side catch, and I think I'm going to remove the UIM and do a manual cleaning of everything. But for right now, it's running strong, actually feels better when I am coasting in gear, so I really think the dirty TB has been messing it up for a while.

[ChibiBlackSheep]

Originally Posted by blackswan

It's just darn weird to get run-on but hey - glad you got some improvement! FWIW, I took my throttle body off the car and disassembled the motor and lubed the gears and the pivot points of the plate's axle. I definitely have a more responsive pedal now, I think they just wear over time and why new throttle bodies help.

Yeah it has been weird. I'm wondering if the car wasn't actually closing the throttle and it was giving a little extra fueling that was staying too long and causing the run-on.

When the weather gets a little better I'm going to get my HPT back up and monitor each runs fueling and see if I'm now a little off. The past 2 nor'easters have sucked for getting stuff done.

[gringo]

Originally Posted by sixty9fordkiller

the V6 cars have a fuel pressure regulator?

I thought they did. My bad.

[ChibiBlackSheep]

Another update.

The other week my car stalled and died, wouldn't crank back up. Was only getting codes for multiple cylinder misfires.

Pulled the intake, and the plugs. The valves honestly looked decent enough, but the plugs were nasty. This car is definitely running too rich. I changed the plugs, put the car back together, and my HPTuners was now giving me data that my LTFTs were high -30s, and I was erroring that the car was running rich in both banks.

Got a new MAF sensor in, thinking the car was just getting the wrong data, but still having that issue. The run-on is back, which now we know it's because there is just way too much fuel left when I key off.

I just dropped it off at a shop. I don't have the tools to diagnose these fuel systems laying around, and I'm a little nervous working on these high pressure lines. I'll see what they say.

[ChibiBlackSheep]

High-pressure fuel pump failed. And when this pump fails you also have to replace the high-pressure fuel line, as they are only 1-time use (since it deals with such high pressures).

Not something that I am comfortable fixing on my own, and not a cheap repair. If other people run into this issue, that's what the culprit was for me.

[Dragonman]

Good to know. Thanks for keeping us updated. If you don't mind saying, how much were you quoted for the repairs?

[ChibiBlackSheep]

Originally Posted by Dragonman

Good to know. Thanks for keeping us updated. If you don't mind saying, how much were you quoted for the repairs?

I don't mind. I was quoted $1200. We'll see if the final total is that or not.

I think it was roughly $450 for the pump, $140 for the new high-pressure fuel line, and 5 book hours? I'll update the thread when I pick the car up.

Unfortunately this was a repair that I wasn't comfortable doing at my house, as it requires some special tools and aligning of the cam lobes.

[Dragonman]

^

[ChibiBlackSheep]

Ok, got the car back. Had to make a few adjustments to the tune before it was running right, but it is doing amazing right now. Feels like a totally new car. I think I've had an issue for a while now and didn't realize it until it got really bad.

Here's the final total. It was steep, but again, out of my wheelhouse to fix in my home garage.

$1468.

They were convinced my catch-can was a vacuum leak. I still highly disagree, but them putting hose clamps on the hoses made them feel better. Whatever, it's running well.

Also they tried to perform the recall, I made them reverse that and give me my switchblade back. Thankfully, they obliged and I now have 2 switchblades and 2 keys lol

[DvKillar]

Seems like a decent price to pay for that much specialized work!

couldn't help but noticed they changed your plugs... again! couldn't salvage the ones from a couple days ago?

[ChibiBlackSheep]

Originally Posted by DvKillar

Seems like a decent price to pay for that much specialized work!

couldn't help but noticed they changed your plugs... again! couldn't salvage the ones from a couple days ago?

When I say the car was running rich... I mean it was running rich. In just the 50 miles I've driven on the plugs, they were completely fouled out again. Tech did show me them, and they pretty much looked just like the ones I took out with 65,000 miles on them.

It sucked, and I offered to take the car as is to save $100 and just do the plugs again, but they needed the clean plugs to really prove the pump fixed the issue. I did agree, and had to chalk up the extra money. With them fouled out that much, it could have pinged like crazy and it wasn't worth it.