I have a 2001 Lincoln LS V8 Sport with 170k miles, and I've recently changed almost a dozen parts on the car (starter, alternator, spark plug, battery, every part of the coolant system except the radiator, and a couple of window motors) except now I'm having another issue. The car cranks up and runs, but after getting warm the car starts to lose power, RPMs drop to the point where the car just shuts off. It'll crank back up after this happen with a little gas but the rpms will drop quickly back to the point where the car cuts offand from that point wont start up. The car will start up fine on a cold start and run, but does the same thing all over again after being on the road for a couple of minutes. Has anyone ever had this problem before? Any ideas on what could be the cause? the only things I havent replaced on the car regarding the engine are the cats, the ignition coils, and fuel pump. I love the car but these problems that keep showing are killing my pockets.
Car cranks on cold start, but loses power and cuts off.
- Thread starter teforne
- Start date
joegr
Dedicated LVC Member
My first thought would be clogged catalytic converters. If so, those are expensive to replace as compared to replacing the coils instead. If you do find that they are clogged, you almost certainly need to replace all your COPs (with Motorcraft ones) and all you plugs before you put the new cats on.
Remove (unscrew) the front two O2 sensors. If that reduces the power loss and stops the stalling, you'll know the cats are the problem.
Remove (unscrew) the front two O2 sensors. If that reduces the power loss and stops the stalling, you'll know the cats are the problem.
Ok thanks for the quick reply joegr, I'll try the sensors trick. It looks like i'm gonna have to replace the coils whether they are the culprit or not. Maybe with luck they are cause and my pockets dont have to get too much thinner. I forgot to add that i've already replaced the 3 of 4 o2 sensors. Are replacing cats as difficult as they are expensive?
joegr
Dedicated LVC Member
I think that the more expensive you go (factory), the less difficult the replacement is (bolt in). Note that the factory way is to replace the entire exhaust.
Fortunately, I haven't had to deal with any exhaust related problems, so I'm not the best one to ask here.
Telco
Dedicated LVC Member
I disagree with you on this one, Joe. If the car is running fine on cold start but has problems when it's warm, this points more towards a defective sensor. If it was a cat problem, it should have drivability problems at any temp. The reason is when the car is warming up it's running in open loop, which means it's running off a fuel/air mix table. When the car is warm, it goes closed loop and starts running off the sensors. I'd suspect the MAF or the O2 sensors. And, a bad O2 sensor won't necessarily show a code.
joegr
Dedicated LVC Member
Maybe so, but you need to know or look up a few things.
1. He is describing very typical clogged exhaust symptoms. The converters heat up, expand, and choke off the remaining exhaust flow.
2. The LS (like pretty much all modern cars) goes to "closed loop" control within seconds of starting. (It couldn't qualify as an LEV if it didn't.) That's why it has heated O2 sensors. At no time does it not need and use most of its sensors to run.
Maybe teforne will post his findings and then we'll know.
jjcool00
Dedicated LVC Member
When I had clogged cats I can positively say that my car never turned off, BUT it felt like it wanted to... several times. I noticed SEVERE hesitation when hitting the gas pedal. I'd press it down, maybe a second or two later it would start to move... I also noticed a severe lack of power. There were more than a few times the car felt like it was going to stall but never actually did. I can't say if it was different from a cold or hot start because I didn't notice a correlation - but maybe this info will help.
Telco
Dedicated LVC Member
Interesting. Did not know the LS went closed loop that fast since I don't have access to the LS programming. The cars I do have access to, GM vehicles, normally goes closed loop when the coolant hits around 130 degrees or so depending on the vehicle. I'm still saying sensor issue, but it won't break my heart if I'm wrong. 
1LoudLS
Dedicated LVC Member
this sounds exactly how my car acted when its cats got clogged.
would start fine, and could idle for a few mins without problems, but no matter what sooner or later, the RPMs would just drop and it would choke itself right out out, if the car was restarted right away, it would die almost immediately. let it cool for a few mins and start it and it could run again for a little bit. how long it would run for cold depended on engine speed (and probably temp) cause it could idle for a few mins, or if you started it and tried to drive it, it would choke itself out much much faster (as in couldn't be driven for even a 1/4 - 1/2 mile cold) and when driving, the power would just fade away quick as hell.
that and the fact that car has that many miles, and being known for cat damaging coil failures (if not fixed soon enough...)(Ii count marginal coils as failed, not just totally dead coils) makes this a much more likely of a problem. it just doesn't sounds like a sensor problem in an LS to me... would think a bad sensor major enough to kill the car once running and warmed up would definitely throw a pretty major code to lead you that way. he did replace most of his O2 sensors, bad cats would definitely throw codes related to readings from those O2 sensors...
the good news is that the "pulling the sensor" trick will tell you if that really is the problem or not in less than ten minutes.
would start fine, and could idle for a few mins without problems, but no matter what sooner or later, the RPMs would just drop and it would choke itself right out out, if the car was restarted right away, it would die almost immediately. let it cool for a few mins and start it and it could run again for a little bit. how long it would run for cold depended on engine speed (and probably temp) cause it could idle for a few mins, or if you started it and tried to drive it, it would choke itself out much much faster (as in couldn't be driven for even a 1/4 - 1/2 mile cold) and when driving, the power would just fade away quick as hell.
that and the fact that car has that many miles, and being known for cat damaging coil failures (if not fixed soon enough...)(Ii count marginal coils as failed, not just totally dead coils) makes this a much more likely of a problem. it just doesn't sounds like a sensor problem in an LS to me... would think a bad sensor major enough to kill the car once running and warmed up would definitely throw a pretty major code to lead you that way. he did replace most of his O2 sensors, bad cats would definitely throw codes related to readings from those O2 sensors...
the good news is that the "pulling the sensor" trick will tell you if that really is the problem or not in less than ten minutes.
Telco
Dedicated LVC Member
So what was the fix? Who was right?
