Help me out with a Ford Crown Vic

[jonathon]

It's a '97 Police Interceptor...

We've been trying to figure out why it runs poorly when cold and why the CEL is on. My dad took the car to Shucks and had them pull the codes, and they said all 4 O2 sensors were bad, so he bought 4 new Bosch sensors(which the two in the front are different than the two rear ones, which we got sorted out). After installing and having the codes cleared, the CEL came back on and the same codes were present. Unfortunately I wasn't there to get the exact codes, only the numbnuts at Shucks said the sensors were bad(new Bosch O2 sensors).

So what do you guys think?

It runs rough when cold, and at first start wants to stall and die till it warms up and then all is good. Going up hills or putting any other high load on the engine causes it to sputter and lug, but cruising the highway it's fine. As far as I know, no other codes were sent other than ones related to the O2 sensors..

 

[Jason4x4]

I would assume that if they said it needed 4 o2's it musta had lean codes for both banks. if that is the case, check for vacuum leaks, and pull the MAF out and see if the sensor is dirty.

 

[ciffer]

i am VERY familiar with 97 p71 crown victorias, i own one myself. what is the mileage on the vehicle? what codes are you getting?

i highly doubt that all 4 o2 sensors are bad. you have 2 on each bank, one is upstream of the converters, the second is downstream. the upstream sensors monitor rich/lean and last about 100k miles then start to lose function. the downstream only monitor the functioning of the converters to make sure the converters are operating efficiently and typically last the life the vehicle. if the sensors actually do need to be replaced, DO NOT USE Bosch sensors, use Motorcraft, they are much better sensors and will get then engine running in closed loop much quicker.

one very common issue that can cause problems on those engines is the MAF sensor getting dirty. go and purchase a can of electrical contact cleaner at an auto parts store and a set of tamper-resistant bits. the MAF is located just after the air filter box. carefully remove the two tamper resistant screws from the MAF assembly and carefully remove the sensor from the housing. spray the thin wires with the cleaner, let it dry for 5 minutes or so, then carefully reinsert the sensor into the housing and lightly snug the screws. disconnect the battery for 10-15 minutes, then start the engine. doing this helped my car a lot.

if you are having trouble with the engine stalling at idle, Idle Air Controllers are also a very common problem for that engine. they are simple to replace, and are available for about $78 at autozone. i have a lightly used IAC, PM me if interested. feel free to PM me with other questions about that car. there is a very good forum dedicated to those cars, PM me and i can give you the address for that as well.

 

[DR]

My crown vic had problems with the speed sensors at the wheels. It ran all kinds of wierd when they would go bad. It would stall out, rev hi for no reason... all kinds of off things. But, the codes given were for the speed sensors.

 

[jonathon]

i am VERY familiar with 97 p71 crown victorias, i own one myself. what is the mileage on the vehicle? what codes are you getting?

i highly doubt that all 4 o2 sensors are bad. you have 2 on each bank, one is upstream of the converters, the second is downstream. the upstream sensors monitor rich/lean and last about 100k miles then start to lose function. the downstream only monitor the functioning of the converters to make sure the converters are operating efficiently and typically last the life the vehicle. if the sensors actually do need to be replaced, DO NOT USE Bosch sensors, use Motorcraft, they are much better sensors and will get then engine running in closed loop much quicker.

one very common issue that can cause problems on those engines is the MAF sensor getting dirty. go and purchase a can of electrical contact cleaner at an auto parts store and a set of tamper-resistant bits. the MAF is located just after the air filter box. carefully remove the two tamper resistant screws from the MAF assembly and carefully remove the sensor from the housing. spray the thin wires with the cleaner, let it dry for 5 minutes or so, then carefully reinsert the sensor into the housing and lightly snug the screws. disconnect the battery for 10-15 minutes, then start the engine. doing this helped my car a lot.

if you are having trouble with the engine stalling at idle, Idle Air Controllers are also a very common problem for that engine. they are simple to replace, and are available for about $78 at autozone. i have a lightly used IAC, PM me if interested. feel free to PM me with other questions about that car. there is a very good forum dedicated to those cars, PM me and i can give you the address for that as well.

That is excellent info

This one has almost 190K on it and seems to be running pretty good still other than this issue. I'm pulling the sensors on Sunday to return them. Unfortunately my dad sorta let maintenance slide till he started having issues, and my gut feeling was it was a bunch of problems all at the same time simply because all he's done since he bought it with 88K on it is change the oil, air filter, and put gas in it

The MAF sensor makes sense as well.. we live on a long gravel drive and have to change filters fairly frequently. I'll look into the IAC as well.

For what it's worth.. these cars are some of the best Ford has ever made in my opinion, from what I see at work and how many miles my dad got out of this one so far(well over 100K) I'm impressed.

 

[Blue85]

Good advice above. If it doesn't pay off I would also look for exhaust leaks and vacuum leaks.

 

[ciffer]

That is excellent info

This one has almost 190K on it and seems to be running pretty good still other than this issue. I'm pulling the sensors on Sunday to return them. Unfortunately my dad sorta let maintenance slide till he started having issues, and my gut feeling was it was a bunch of problems all at the same time simply because all he's done since he bought it with 88K on it is change the oil, air filter, and put gas in it

The MAF sensor makes sense as well.. we live on a long gravel drive and have to change filters fairly frequently. I'll look into the IAC as well.

For what it's worth.. these cars are some of the best Ford has ever made in my opinion, from what I see at work and how many miles my dad got out of this one so far(well over 100K) I'm impressed.

if you get the actual codes, i can look them up for you. besides the MAF, i'd also look at all the normal things, plugs/wires etc.

as far as the lugging up hills, the MAF may help that. i had some pinging going up hills before i cleaned mine. but also you'll need to keep in mind that the programming in those vehicles is to get into overdrive and stay there as much as possible for gas mileage reasons. even a perfectly healthy crown victoria will have a certain amount of lugging when going up hills on the highway.

those cars don't really wear out if maintained, and they are very resilient as far as neglect.

 

[K5-Kelly]

Our 03 P71 had similiar problems, we changed the fuel filter and ran injector clean through and it helped quite a bit. Seems as if the metal pump in the tank is designed to rust.

 

[chevyuser74]

can u get into the computer at all?

 

[jonathon]

First things I did were plugs, wires, and a fuel filter. That helped good bit as far as having trouble up. I'll be taking the car to town Sunday and have the codes read and post 'em.

 

[jonathon]

Mass airflow made a huge difference, still throwing a CEL. I didn't get a chance to work on it today, spent the day at the range since it was so beautiful

I think IAC is the next step.. still need to get the o2 sensors swapped but that is pretty easy.

 

[ciffer]

just do the front o2, motorcraft sensors are available from rock auto for $50 each.

some symptoms that can point to a bad IAC are low idle, low voltage at idle, stalling at idle especially when cold. for some reason, a bad IAC will sometimes make a moose/foghorn sound/vibration at idle and low throttle.

it might be a good idea to hold off on futher work until you know the codes, that will point you in a better direction instead of starting to throw parts at the car.

 

[jonathon]

just do the front o2, motorcraft sensors are available from rock auto for $50 each.

some symptoms that can point to a bad IAC are low idle, low voltage at idle, stalling at idle especially when cold. for some reason, a bad IAC will sometimes make a moose/foghorn sound/vibration at idle and low throttle.

it might be a good idea to hold off on futher work until you know the codes, that will point you in a better direction instead of starting to throw parts at the car.

That's what the plan is. First thing I am going to check though is to make sure the right sensors are in the right places(My dad is now thinking the kid at Shucks told him wrong which were upstream and which were downstream ). Pulling the codes when I get a chance... that comes first.

 

[jonathon]

codes are:

p0171
p0174
p0307

I'm thinking it's still a MAF problem as far as the running lean. On the cylinder 7 misfire.. don't know. I'm going to check the wires and plugs and make sure I have spark. I think the misfire would explain the poor running...

 

[ciffer]

sounds like you have it figured out, but i'll post the codes anyways.

P0171 System Too Lean (Bank 1)
P0174 System Too Lean (Bank 2)
P0307 Cylinder #7 Misfire Detected

it is entirely possible that the lean condition is causing the misfire, but plugs and wires are always a good idea. be VERY careful with the spark plugs. the aluminum heads do not tolerate over-torquing well. the plugs MUST be installed DRY, no anti-seize. the plugs MUST be torqued to 84-180 in/lbs (7-15 ft/lbs). anti-seize lubricates the threads, gives an inaccurate torque reading and will cause the plugs to be over-torqued. over-torquing the plugs into the heads can cause the engine to launch the plugs from the head while running, this is not uncommon with incorrectly installed plugs.

only thing i can think of for your fuel issue is to change the fuel filter if you have not done so already, then check fuel pressure.