'03 LS V8 Randomly Dies?? Desperate Help Needed!

[dba]

(This is a copy of my first post which i accidentally posted to the wrong thread..oops lol i'm a newbie )Hello! This is a last resort for me, as I've been searching this forum and many others for answers; I finally decided to set up an account and beg for help. Here's the problem. The car starts and runs just fine when it is cold (the engine temp.) but once the engine warms it will just randomly die. It doesn't make any weird noises or anything...it just dies. like somebody turned the key. But here's where it gets weird. After dying, it will start right back up with no fuss at all and run for a while.....until it dies again, but after it dies it starts right back up.

Not sure if this is related or not, but a while ago I was on the road with it and it broke down. At first it felt like it downshifted hard...but then it did that same sort of hard downshift feeling again and again and pretty soon it was was constantly doing this. I still had the gas depressed so it was accelerating and then stalling so I was getting thrown around in the car from this. Is this confusing? I'll sum it up....Basically car started stalling and then regaining power repeatedly and ever more frequently until it finally just died. Waited 1 1/2 hours to be towed 20min back home .

After it was towed back I tried to start it and it was running horribly and revving itself demonically and then stalling before eventually dying...all while sitting in park in my driveway. I eventually figured that the coils & plugs had gone bad so I knocked out the valve cover gasket job and it fixed the demonic revving issues....but now it is having the issue i mentioned in the first paragraph. PLEASE HELP ME!!


To Recap:
Car runs fine when cold but once it warms up it will abruptly die like someone turned the key off. It starts right back up but after a while it will die again.

It has new valve cover gaskets
New mass air flow sensor
New battery
New throttle body in '08
New thermostat in '08 too
New coolant hoses
New Catalytic Converters
All fuses are working


My thoughts..
Crankshaft Position Sensor? But I cant figure out where it is located on my car
Camshaft position sensors? Also cant find those
Intermittent Fuel Pump? I checked to see if it was working (It was) but that doesn't mean it couldn't be randomly cutting out.

Can anyone please help me? Please!!

2003 Lincoln LS V8 (non-sport model)
Manufacture Date 05/03
Options (because yes, it is important to know what options my car has )
Automatic Trans.
Computer Information System (but not navi)
Heated/Cooled front seats (but no heat to rears)
Sunroof (was this an option? i don't remember..)
17" chrome wheels


Please Help! Thanks for reading! (if you made it this far)

 

[joegr]

Not related to stalling, but noticed in your post:
You need to replace ALL of the plastic cooling system parts, and none with Dorman, all Motorcraft or Jaguar.
What you are calling "Computer Information System" is the message center. It is not an option. If you have a V8, you have it. If you have a V6, then you don't.

Why did you replace the throttle body?

What brand of COPs did you use? Did you replace them all? Did you replace the spark plugs at exactly the same time as the COPs? What brand? Did you verify the gap on each was 1.0mm?

What OBDII code(s) do you get?

The crankshaft sensor is at the bottom of the bellhousing. (back of the engine, underneath, can't miss it)
The camshaft sensors are at the back of each of the two intake cams, pointed at the firewall.

What happens if you unplug the electrical connector to the MAF? If things get better, then you have an air leak, or bad/dirty MAF.

Honestly, you need to connect a scan tool and log some data to get any real help with this.

 

[dba]

Not related to stalling, but noticed in your post:
You need to replace ALL of the plastic cooling system parts, and none with Dorman, all Motorcraft or Jaguar.
What you are calling "Computer Information System" is the message center. It is not an option. If you have a V8, you have it. If you have a V6, then you don't.

Why did you replace the throttle body?

What brand of COPs did you use? Did you replace them all? Did you replace the spark plugs at exactly the same time as the COPs? What brand? Did you verify the gap on each was 1.0mm?

What OBDII code(s) do you get?

The crankshaft sensor is at the bottom of the bellhousing. (back of the engine, underneath, can't miss it)
The camshaft sensors are at the back of each of the two intake cams, pointed at the firewall.

What happens if you unplug the electrical connector to the MAF? If things get better, then you have an air leak, or bad/dirty MAF.

Honestly, you need to connect a scan tool and log some data to get any real help with this.

I forgot to mention that I own a scan tool. It isn't a several thousand dollar one but it does go decently in-depth. I scanned it while it was running, then analyzed freeze frame data and scoured over everything, but nothing out of the ordinary showed. As for the cooling system.. I have absolutely no clue. This job was done by the previous owner and all I really know is that this is a common problem and it looked like a pita job so I was just glad I didn't have to do it. The same goes for the throttle body- done by previous owner. Another thing I forgot to mention is that there are no trouble codes. That is one of the most frustrating things, because when the plugs/coils failed I had no idea what went wrong. Its not like the cel doesn't work either, because it has come on for other things like the MAF. I replaced the plugs at the same time as the coils and everything is brand new. Brand wise I don't recall off hand, but I know they were of decent quality. Plugs came pre-gapped plus I double checked them. I haven't tried disconnecting the MAF recently (I have before with previous issues) but I will the next time I go out to work on it. Lincoln ownership is so enriching...

 

[joegr]

I just noticed that you said "New mass air flow sensor." Aftermarket MAFs are known to cause problems.

 

[dba]

Okay so I went back out to the car today and looked for sensors. maybe I'm just really lazy, but i physically couldn't get to or even see them. i even reached around and felt blindly. i unplugged the MAF and troubleshooted..it definitely is NOT the MAF. Whatever problem it is having is getting worse...fortunately I took videos this time! so tell me what ya think!!

This is what it normally sort of sounds like



Then it got worse and died and sounded much more awful than normal. before it was like it was someone turned a key this time it sounded like a dying cat! I'm suspecting some sort of fuel issue maybe. u can here the fuel pump go off when i turn key. after it dies and the key is in on position it goes off (like when you first start it) many several times and i shut it off. after it finally dies it sounds like fuel is still being squirted into the engine but idk. tell me what you think!

 

[joegr]

Okay so I went back out to the car today and looked for sensors. maybe I'm just really lazy, but i physically couldn't get to or even see them. ...

What sensors are you looking for? What will you do when you find them? The TPS, MAP, MAF (of course), DPFE, and fuel pressure sensors are all visible in your video. Note that the ACT is a part of the MAF. The CHT is under the intake manifold. You can see it, but to replace it, you have to remove the manifold. (Note that the CHT can't be reused. If you remove it, you have to replace it with a new one.) The knock sensors are also under the intake (one for each cylinder bank). The fuel rail temperature sensor is at the back of the fuel rail (sorry, forget which side), the cam sensors are at the back of the heads. The crank sensor is under the engine, at the back. The O2 sensors are on the exhaust (four total, two on each side, one before the main cat and one after). Oil pressure and oil temperature sensors are on the oil filter adapter. Some confuse the VCT solenoids at the front of each valve cover for sensors, but they are actually actuators.

Is the throttle closing, opening, or doing nothing when it dies?

While not likely, it is possible that your PCM is failing. How about using a mechanical fuel gauge to watch the fuel pressure when it is doing this? I believe that your 03 has a fuel pressure test port.

 

[dba]

Alright so I went back out today and I have a dilemma. Because the throttle is electric I have no way to tell what it is doing when it dies. Thoughts? If i take off airbox assembly I take the MAF with it and it wont run correctly. So I need a way to see the throttle but not disturb the MAF. The cel finally came on but it was only for an o2 sensor. I believe is was bank 1 sensor 1 signal bias (dont recall exact code) I've gotten a few o2 codes before but I always clear them because I dont think that they could cause this issue. Ugh.... Help me!

 

[joegr]

Actually, I think they can... (Bad info from bad O2 sensor causes PCM to lean out the mixture so much that the engine stalls.)

BTW, a scan tool can graph what the throttle is doing.

 

[dba]

{{{{I expect that this might work better if you would keep it all in one thread.

Latest symptom sounds like bad/marginal COPs. EMI from the COP(s) causing the PCM to crash and reboot. There's been a few cases of that. Let it go on, and it will kill your PCM. (If this is really what's happening.)}}}}

I agree, but I'm just trying to get as much help as possible so thats why i made a second one.

EMI stands for? Do you have links to threads about this cop/emi/pcm issue?

I'll look into o2 sensors

 

[joegr]

Probably 1/4 of the threads on here are about the COPs.

ElectroMagnetic Interference
also, there's
Radio Frequency Interference

 

[dba]

Lol not quite what I meant. I've already done the valve cover gasket job and I know firsthand the havoc they can wreak. Maybe I misunderstood you, but I meant the issue of the coils sending out emi which screw with the pcm. I'll do more research/ testing and report back. Thanks for all your help so far. Lets keep it coming and maybe i can fix this damn....I mean wonderful automobile.

 

[heyjewel]

Just tossing Occam's razor into the mix - could it possibly be a bad ground somewhere?

 

[dba]

A bad ground is a nice idea, but finding said ground isn't. Plus I don't think a ground would cause it to die like that. Would A bad ground have anything to do with the coil grounds located on the very top of the engine? (they are under the engine cover and on top/sides of the intake manifold towards the rear. they are held in by a single screw.) Could a faulty one of those cause an issue like this?

 

[heyjewel]

A bad ground is a nice idea, but finding said ground isn't. Plus I don't think a ground would cause it to die like that. Would A bad ground have anything to do with the coil grounds located on the very top of the engine? (they are under the engine cover and on top/sides of the intake manifold towards the rear. they are held in by a single screw.) Could a faulty one of those cause an issue like this?

A bad ground can cause lots of things, especially a loose ground wire can cause intermittent stuff. Maybe like you're seeing. I'm not saying it will solve your problem but as you're looking around, grab and wiggle any connections to frame ground. It you find loose ones, tighten them. There's a rather obvious important one about center of the hood side of the firewall at back of engine about cyl head height. At least on the V6 there is I would suspect on the V8 as well.

 

[dba]

Alright I will, thanks so much for the help. If you want ive got another thread on this issue going you could check out with the latest update on the car (spoiler: i didnt fix it ) "Is my Lincoln possessed by satan??" is the thread name