Intermittent 3800 engine trouble

[Qdog]

First time post so here goes, I‘ve driven my 2003 LeSabre Custom(87k and 3800 engine) three months without any engine trouble. About a month ago the check engine light came on and coded P0442 on AutoZone tester. I didn’t address it immediately bc I read it was a minor and common problem that ”typically doesn’t effect the engine’s performance“. I got in it 10 days ago to go to work and it started right up but then began to run terribly rough as though it was missing or getting too much/little gas. I thought it would be fine once I got it going a block or so and it actually got worse, bucking and stalling and eventually died. I got it off to the curb but couldn’t get it to start. I was late for work so left it there until I got home about 10 hours later. i got it to start but had to floor it and feather the pedal to keep it running, bucking, coughing and choking. I left it sit for about an hour, changed clothes and checked for spark on each of the plug posts by removing the wire and every one had spark BUT two of the six post had a little white corrosion on them and the wire. Got that removed and the car started right up without issue just like it always did. Took it for a short test drive and that night and the next mornin......it was fine.
PROBLEM NOT SOLVED though! Took it to run a short errand, about 10 minutes, and it wouldn’t start after I got back in the car about 20 minutes later. I left it overnight and it started the next morning as though nothing ever happened.
It’s sitting in my garage and I’m scratching my head.
I don’t own any diagnostic equipment but it sounds like that would be the next step. I can start changing parts but have no idea where to start... is it fuel or spark related?
thanks for your patience!

 

[2007LucerneCXL]

This may help on what could be causing the code, but it good to remember that a code will only tell you something is wrong and not always what part is wrong.

P0442 Engine Code | Evaporative Emission Control System—Small Leak Detected - FIXD

P0442 Error Code: Small Evaporative Emission Control System Leak due to a faulty gas cap, bad purge or vent valve, or defective charcoal canister.

www.fixdapp.com

Hopefully others may have additional information on the problem, good luck on getting it resolved.

 

[imidazol97]

The symptoms may be for multiple problems.

1)The dying and then not restarting until the engine has sat long enough to have cooled sounds like a CPS
crankshaft position sensor problem. This sensor loses magnetism with age and the heat then reduces the
effect of the magnetic field as the teeth go by. The ignition spark control module uses that signal to tell the
spark plugs when to fire. Usually this is a case where the car just quits; it doesn't misfire and die slowly.

One way to check for problem is to keep water in the car and pour it on the sensor (down by the crankshaft balancer)
when it won't start. Cooling the sensor may help the car start faster without the waiting. When the car won't start, you need
to have a spare spark plug and pull off a plug wire and connect to that spare plug which you lay on a good metal area to ground.
While someone cranks the engine, see if you've got a good spark. No spark, then you know your problem is in the electrical system.

2)Another problem with cars that age is the coolant leaking around seals on the intake manifold into the intake and getting sucked into
the engine. That causes rough running if it's heavy enough. Is your coolant level dropping? Do you see a milky effect in the
engine oil on the dip stick? That can be from coolant getting into the oil. The coolant damages the bearings. So it
needs to be fixed.

You can look on top of the intake manifold for 3 circles in the plastic that have numbers. Those are the year, month, and maybe day
it was made. If it has that, it's likely the original AC Delco intake. If it's not there, you know the intake has been replaced once. If
it's been replaced you shouldn't expect to have repeat problems for a while after a good replacement job.

3) The PO442 is a small or medium air leak in the emissions system. I got both results searching the net and I'm too lazy to go look
in my 03 factory service manual. Check the rubber and plastic vacuum lines running on top of the engine around the intake to the
purge valve sitting on top. Especially where there's a "U" and the line goes to the purge valve. That may have cracked with age or heat and may be leaking air in.

Then check the tubing going under the car to the carbon filter and the vent valve in the emissions sytem that turns on and off to
send fumes through the carbon cannister and closes for the vacuum check. Be sure to use jack stands if you're crawling under the
right rear seat area where those are.

Just check the seal on the gas cap and the area where the seal meets the metal filler tube for corrosion or crude from gasoline. Then try to check the connection between the filler tube and the tube going on down into the tank. This is viewed from under the car. I recall one or more H-body owners found a leak there.

 

[Qdog]

This may help on what could be causing the code, but it good to remember that a code will only tell you something is wrong and not always what part is wrong.

P0442 Engine Code | Evaporative Emission Control System—Small Leak Detected - FIXD

P0442 Error Code: Small Evaporative Emission Control System Leak due to a faulty gas cap, bad purge or vent valve, or defective charcoal canister.

www.fixdapp.com

Hopefully others may have additional information on the problem, good luck on getting it resolved.

Wow! I’m impressed by how quickly I received a response! Thanks for taking the time!
I do plan to replace the canister vent valve solenoid to hopefully take care of the code but yes, I think the issues are well beyond that.

 

[Qdog]

The symptoms may be for multiple problems.

1)The dying and then not restarting until the engine has sat long enough to have cooled sounds like a CPS
crankshaft position sensor problem. This sensor loses magnetism with age and the heat then reduces the
effect of the magnetic field as the teeth go by. The ignition spark control module uses that signal to tell the
spark plugs when to fire. Usually this is a case where the car just quits; it doesn't misfire and die slowly.

One way to check for problem is to keep water in the car and pour it on the sensor (down by the crankshaft balancer)
when it won't start. Cooling the sensor may help the car start faster without the waiting. When the car won't start, you need
to have a spare spark plug and pull off a plug wire and connect to that spare plug which you lay on a good metal area to ground.
While someone cranks the engine, see if you've got a good spark. No spark, then you know your problem is in the electrical system.

2)Another problem with cars that age is the coolant leaking around seals on the intake manifold into the intake and getting sucked into
the engine. That causes rough running if it's heavy enough. Is your coolant level dropping? Do you see a milky effect in the
engine oil on the dip stick? That can be from coolant getting into the oil. The coolant damages the bearings. So it
needs to be fixed.

You can look on top of the intake manifold for 3 circles in the plastic that have numbers. Those are the year, month, and maybe day
it was made. If it has that, it's likely the original AC Delco intake. If it's not there, you know the intake has been replaced once. If
it's been replaced you shouldn't expect to have repeat problems for a while after a good replacement job.

3) The PO442 is a small or medium air leak in the emissions system. I got both results searching the net and I'm too lazy to go look
in my 03 factory service manual. Check the rubber and plastic vacuum lines running on top of the engine around the intake to the
purge valve sitting on top. Especially where there's a "U" and the line goes to the purge valve. That may have cracked with age or heat and may be leaking air in.

Then check the tubing going under the car to the carbon filter and the vent valve in the emissions sytem that turns on and off to
send fumes through the carbon cannister and closes for the vacuum check. Be sure to use jack stands if you're crawling under the
right rear seat area where those are.

Just check the seal on the gas cap and the area where the seal meets the metal filler tube for corrosion or crude from gasoline. Then try to check the connection between the filler tube and the tube going on down into the tank. This is viewed from under the car. I recall one or more H-body owners found a leak there.

Thanks for the in depth analysis! Just to clarify, I was able to start the car later the same evening as the short errand but I had to really press on the accelerator and feather it to keep the engine running. I’ll experiment with your recommendations.

 

[HotZ28]

Have you checked fuel pressure when the engine don't start? Normally, an evap code will not cause an engine not to start, unless there is a major vacuum leak.

 

[imidazol97]

Fuel pressure? Some Autozones (maybe Oreillys/Checkers) and other box stores here used to loan out testers for various things
along with odd tools by charging a sale to your credit card and then refunding it when the merchandise
is returned. Fuel pressure testing can be fickle as to the problem not occurring when you want it to.
One area mechanic/genius had a radio talk show and he talked about using a fuel tester and duct taping
the tubes and gauge to the windshield so he could see it from inside the car while he drove it hoping to
get it to act up.

But to be clear IF you have a coolant leakage you should notice it in the oil color and be able to document a drop in the
coolant level, such as checked cold sitting in the same spot so the level can be compared. I marked the outside of the
reservoir with a Sharpie to record the level.

IF you can check for spark when it doesn't want to start with a spark wire laid on metal while someone cranks, that can
tell you it no spark is happening. The CPS that people have found problems with through years on forums usually die
immediately. They don't chug and lurch and gasp.

That sounds, to me, more like coolant ingested into the cylinder. I don't know if the 00 to 04 Engines had failure in the
EGR passage in the plastic leaking the coolant into the intake like my 98 did, but that description sounded a lot like my
98 leSabre when I ended up doing its second upper intake replacement at 150 K miles or so.

If you remove the spark plugs, you may see certain plugs that are clean. NO typical light color or deposits that a normal
engine puts down. The plugs will be blasted clean from the coolant water blasting them clean during the combustion. I found
that was true on my 98 during the 2nd failure. First was replacement done by dealer and they put back on the ACDelco upper intake that had the same problems as the OEM from the factory had.

As to changing the vent valve, I wouldn't replace parts without a diagnosis. The purge valves that seem to stick open or part way like one of mine did, I found aged rubber parts deteriorated and cracked open leaking air in during the emissions vacuum test were the problem. There are rubber parts between the vent valve and the carbon cannister IIRC.

And I should have said in previous post the P code doesn't stall the engine for an emissions system leak. Different parts open and close during the normal operation cycle.

 

[LARRY70GS]

If the engine starts and runs fine when cold, but the problem develops when the engine warms up, I would suspect the Mass Air Flow sensor. The MAF will not set a code unless the signal is NOT present. A really simple test is to simply unplug it. If the problem disappears, the MAF needs cleaning or replacement.

When cold, the PCM is open loop, so the engine runs on preset calibrations. When the engine warms up, the PCM loops IN the sensors. What frequently happens is the MAF sends a signal to the PCM that there is A LOT more air entering the engine then there actually is. The PCM then ramps up fuel delivery and drowns the engine out. If you disconnect the MAF, the PCM then uses other inputs to make a guess on fuel delivery. The engine doesn't run at peak efficiency, but it will be drive able. The PCM will light the CEL because it isn't seeing the MAF signal, no big deal.

Simple test, and it doesn't cost you anything.

A P0442 code can be as simple as a non sealing fuel cap. It can also come from a small leak in the EVAP system(tubing , canister, tank neck, or even rotted fuel pump mounting at the tank)

 

[Qdog]

Fuel pressure? Some Autozones (maybe Oreillys/Checkers) and other box stores here used to loan out testers for various things
along with odd tools by charging a sale to your credit card and then refunding it when the merchandise
is returned. Fuel pressure testing can be fickle as to the problem not occurring when you want it to.
One area mechanic/genius had a radio talk show and he talked about using a fuel tester and duct taping
the tubes and gauge to the windshield so he could see it from inside the car while he drove it hoping to
get it to act up.

But to be clear IF you have a coolant leakage you should notice it in the oil color and be able to document a drop in the
coolant level, such as checked cold sitting in the same spot so the level can be compared. I marked the outside of the
reservoir with a Sharpie to record the level.

IF you can check for spark when it doesn't want to start with a spark wire laid on metal while someone cranks, that can
tell you it no spark is happening. The CPS that people have found problems with through years on forums usually die
immediately. They don't chug and lurch and gasp.

That sounds, to me, more like coolant ingested into the cylinder. I don't know if the 00 to 04 Engines had failure in the
EGR passage in the plastic leaking the coolant into the intake like my 98 did, but that description sounded a lot like my
98 leSabre when I ended up doing its second upper intake replacement at 150 K miles or so.

If you remove the spark plugs, you may see certain plugs that are clean. NO typical light color or deposits that a normal
engine puts down. The plugs will be blasted clean from the coolant water blasting them clean during the combustion. I found
that was true on my 98 during the 2nd failure. First was replacement done by dealer and they put back on the ACDelco upper intake that had the same problems as the OEM from the factory had.

As to changing the vent valve, I wouldn't replace parts without a diagnosis. The purge valves that seem to stick open or part way like one of mine did, I found aged rubber parts deteriorated and cracked open leaking air in during the emissions vacuum test were the problem. There are rubber parts between the vent valve and the carbon cannister IIRC.

And I should have said in previous post the P code doesn't stall the engine for an emissions system leak. Different parts open and close during the normal operation cycle.

 

[Qdog]

Have you checked fuel pressure when the engine don't start? Normally, an evap code will not cause an engine not to start, unless there is a major vacuum leak.

I have not checked the fuel pressure yet. My schedule is such to where I won’t be able to get under the hood for 8 more days. Fortunately, the LaSabre isn’t my only vehicle!

Fuel pressure? Some Autozones (maybe Oreillys/Checkers) and other box stores here used to loan out testers for various things
along with odd tools by charging a sale to your credit card and then refunding it when the merchandise
is returned. Fuel pressure testing can be fickle as to the problem not occurring when you want it to.
One area mechanic/genius had a radio talk show and he talked about using a fuel tester and duct taping
the tubes and gauge to the windshield so he could see it from inside the car while he drove it hoping to
get it to act up.

But to be clear IF you have a coolant leakage you should notice it in the oil color and be able to document a drop in the
coolant level, such as checked cold sitting in the same spot so the level can be compared. I marked the outside of the
reservoir with a Sharpie to record the level.

IF you can check for spark when it doesn't want to start with a spark wire laid on metal while someone cranks, that can
tell you it no spark is happening. The CPS that people have found problems with through years on forums usually die
immediately. They don't chug and lurch and gasp.

That sounds, to me, more like coolant ingested into the cylinder. I don't know if the 00 to 04 Engines had failure in the
EGR passage in the plastic leaking the coolant into the intake like my 98 did, but that description sounded a lot like my
98 leSabre when I ended up doing its second upper intake replacement at 150 K miles or so.

If you remove the spark plugs, you may see certain plugs that are clean. NO typical light color or deposits that a normal
engine puts down. The plugs will be blasted clean from the coolant water blasting them clean during the combustion. I found
that was true on my 98 during the 2nd failure. First was replacement done by dealer and they put back on the ACDelco upper intake that had the same problems as the OEM from the factory had.

As to changing the vent valve, I wouldn't replace parts without a diagnosis. The purge valves that seem to stick open or part way like one of mine did, I found aged rubber parts deteriorated and cracked open leaking air in during the emissions vacuum test were the problem. There are rubber parts between the vent valve and the carbon cannister IIRC.

And I should have said in previous post the P code doesn't stall the engine for an emissions system leak. Different parts open and close during the normal operation cycle.

Perhaps this isn’t the best method, and it may be old school mentality, but i recall one indication/symptom of intake manifold leakage is white smoke coming out of the exhaust. Is this still true or only in cases when there’s major leakage?

 

[Qdog]

This

If the engine starts and runs fine when cold, but the problem develops when the engine warms up, I would suspect the Mass Air Flow sensor. The MAF will not set a code unless the signal is NOT present. A really simple test is to simply unplug it. If the problem disappears, the MAF needs cleaning or replacement.

When cold, the PCM is open loop, so the engine runs on preset calibrations. When the engine warms up, the PCM loops IN the sensors. What frequently happens is the MAF sends a signal to the PCM that there is A LOT more air entering the engine then there actually is. The PCM then ramps up fuel delivery and drowns the engine out. If you disconnect the MAF, the PCM then uses other inputs to make a guess on fuel delivery. The engine doesn't run at peak efficiency, but it will be drive able. The PCM will light the CEL because it isn't seeing the MAF signal, no big deal.

Simple test, and it doesn't cost you anything.

A P0442 code can be as simple as a non sealing fuel cap. It can also come from a small leak in the EVAP system(tubing , canister, tank neck, or even rotted fuel pump mounting at the tank)

 

[LARRY70GS]

You can also see a bad MAF by looking at the fuel trim numbers. Large negative numbers (~15%) mean the PCM is pulling fuel because of a rich condition.

 

[rtabish]

Sounds like the same issue my supercharged 98 Regal GS has been having. I did an ODB on mine, and got back P0 codes 102, 112, 440, and a P1133 code.
I discovered that the vacuum line where it connects to the fuel pressure regulator valve had a crack in the rubber connection, very probably due to age, which I fixed. I also cleaned up my MAF sensor using MAF cleaning spray. after these two fixes, I still have the SES light on, but the car hasn't had any further stalling or hard starting issues like you described. I am assuming the next thing to check is the upstream O2 sensor.

 

[Qdog]

This is probably where I’ll start bc as you said. it’s quick, easy and can be done when the problem occurs. Many Thanks!

You can also see a bad MAF by looking at the fuel trim numbers. Large negative numbers (~15%) mean the PCM is pulling fuel because of a rich condition.

Thanks for the follow up, but I’ll go with the first suggestion as the second is above my level of comprehension. I’m truly a novice among professionals based on the responses I’ve received. And I’m interested to know your thoughts on the possibility of the issue(s) being a leaking intake manifold......

 

[LARRY70GS]

Thanks for the follow up, but I’ll go with the first suggestion as the second is above my level of comprehension. I’m truly a novice among professionals based on the responses I’ve received. And I’m interested to know your thoughts on the possibility of the issue(s) being a leaking intake manifold......

Are you losing coolant relatively quickly? If not, I would not suspect the intake. I always like to check the simple things first, and go with the more likely causes.

A scan tool capable of monitoring real time sensor signals will list many parameters of engine operation that are very helpful in diagnosing things. One of those is fuel trim, short term and long term fuel trim. Fuel trim is the computer's adjustment to the fuel injector's delivery of fuel into the cylinder. The oxygen sensors tell the computer if the engine is running rich or lean. Fuel trim numbers should stay less than 5%. negative numbers mean the computer is pulling fuel in response to a rich condition. Positive numbers mean the computer is adding fuel in response to a lean condition. I mentioned fuel trim because when the MAF goes bad, you get a rich condition. The oxygen sensors tell the computer the engine mixtures are rich, and the computer pulls fuel. If you see big negative numbers in fuel trim, it is one more clue if you suspect the MAF.

 

[Qdog]

Are you losing coolant relatively quickly? If not, I would not suspect the intake. I always like to check the simple things first, and go with the more likely causes.

A scan tool capable of monitoring real time sensor signals will list many parameters of engine operation that are very helpful in diagnosing things. One of those is fuel trim, short term and long term fuel trim. Fuel trim is the computer's adjustment to the fuel injector's delivery of fuel into the cylinder. The oxygen sensors tell the computer if the engine is running rich or lean. Fuel trim numbers should stay less than 5%. negative numbers mean the computer is pulling fuel in response to a rich condition. Positive numbers mean the computer is adding fuel in response to a lean condition. I mentioned fuel trim because when the MAF goes bad, you get a rich condition. The oxygen sensors tell the computer the engine mixtures are rich, and the computer pulls fuel. If you see big negative numbers in fuel trim, it is one more clue if you suspect the MAF.

And if the intake manifold leak is a problem, wouldn’t there be more “symptoms” like white smoke from the exhaust upon initial start up?
Also, is there any harm in cleaning the MAF sensor?

 

[LARRY70GS]

Water vapor from the exhaust is completely normal especially in cold weather. Water condenses in the hot exhaust pipes as they cool down, and the catalytic converter produces water and CO2 as it works. If there is coolant entering the cylinders, you can frequently smell the burning coolant if you sniff the exhaust.

The MAF is very delicate, so you should use a cleaner specifically for that purpose.

https://www.autozone.com/miscellaneous-cleaners-and-degreasers/electrical-parts-cleaner/crc-mass-air-flow-sensor-cleaner-11oz/36011_0_0?spps.s=5281&cmpid=LIA:US:EN:AD:NL:1000000:GEN:71700000059635966&gclid=Cj0KCQiAwMP9BRCzARIsAPWTJ_GUK0xnIEL3VKY3DM7t1RP-p9Gh9OZ_8xllE1kRb-Q8_8IImrIePSUaAhvuEALw_wcB&gclsrc=aw.ds

No harm in trying to clean it. It didn't work for me, but it is worth a try. If you do end up replacing it, I advise you to also change your air filter especially if it is dirty.

 

[Qdog]

Water vapor from the exhaust is completely normal especially in cold weather. Water condenses in the hot exhaust pipes as they cool down, and the catalytic converter produces water and CO2 as it works. If there is coolant entering the cylinders, you can frequently smell the burning coolant if you sniff the exhaust.

The MAF is very delicate, so you should use a cleaner specifically for that purpose.

https://www.autozone.com/miscellaneous-cleaners-and-degreasers/electrical-parts-cleaner/crc-mass-air-flow-sensor-cleaner-11oz/36011_0_0?spps.s=5281&cmpid=LIA:US:EN:AD:NL:1000000:GEN:71700000059635966&gclid=Cj0KCQiAwMP9BRCzARIsAPWTJ_GUK0xnIEL3VKY3DM7t1RP-p9Gh9OZ_8xllE1kRb-Q8_8IImrIePSUaAhvuEALw_wcB&gclsrc=aw.ds

No harm in trying to clean it. It didn't work for me, but it is worth a try. If you do end up replacing it, I advise you to also change your air filter especially if it is dirty.

You nailed it!!! The problem was the MAF sensor! I cleaned it with the cleaner you recommended first, but no luck.

Water vapor from the exhaust is completely normal especially in cold weather. Water condenses in the hot exhaust pipes as they cool down, and the catalytic converter produces water and CO2 as it works. If there is coolant entering the cylinders, you can frequently smell the burning coolant if you sniff the exhaust.

The MAF is very delicate, so you should use a cleaner specifically for that purpose.

https://www.autozone.com/miscellaneous-cleaners-and-degreasers/electrical-parts-cleaner/crc-mass-air-flow-sensor-cleaner-11oz/36011_0_0?spps.s=5281&cmpid=LIA:US:EN:AD:NL:1000000:GEN:71700000059635966&gclid=Cj0KCQiAwMP9BRCzARIsAPWTJ_GUK0xnIEL3VKY3DM7t1RP-p9Gh9OZ_8xllE1kRb-Q8_8IImrIePSUaAhvuEALw_wcB&gclsrc=aw.ds

No harm in trying to clean it. It didn't work for me, but it is worth a try. If you do end up replacing it, I advise you to also change your air filter especially if it is dirty.

Water vapor from the exhaust is completely normal especially in cold weather. Water condenses in the hot exhaust pipes as they cool down, and the catalytic converter produces water and CO2 as it works. If there is coolant entering the cylinders, you can frequently smell the burning coolant if you sniff the exhaust.

The MAF is very delicate, so you should use a cleaner specifically for that purpose.

https://www.autozone.com/miscellaneous-cleaners-and-degreasers/electrical-parts-cleaner/crc-mass-air-flow-sensor-cleaner-11oz/36011_0_0?spps.s=5281&cmpid=LIA:US:EN:AD:NL:1000000:GEN:71700000059635966&gclid=Cj0KCQiAwMP9BRCzARIsAPWTJ_GUK0xnIEL3VKY3DM7t1RP-p9Gh9OZ_8xllE1kRb-Q8_8IImrIePSUaAhvuEALw_wcB&gclsrc=aw.ds

No harm in trying to clean it. It didn't work for me, but it is worth a try. If you do end up replacing it, I advise you to also change your air filter especially if it is dirty.

You nailed it! The problem was the MAF sensor!
I tried cleaning it first with the cleaner you recommended but no luck. Then I replaced it and was concerned bc I was expecting the engine to die when I unplugged the sensor, but it kept running. It ran a little rough at first, then smoothed out after a few minutes.
Even the check engine light when out!! I’m ecstatic!!
Now.... if I can just figure out why my anti-theft system is whacked after I changed the battery....
so strange... I went through the owners manual and followed the instructions but no luck there. So I disconnected the ground wire to the actual device that make the noise and now there’s an intermittent clicking sound coming from the dash, like the emergency flashers are on.... but they’re not. I can’t give up though... I’m afraid it may drain the battery.
i greatly appreciate your patience, time and experience though!!

 

[Alan 55]

You nailed it!!! The problem was the MAF sensor! I cleaned it with the cleaner you recommended first, but no luck.


You nailed it! The problem was the MAF sensor!
I tried cleaning it first with the cleaner you recommended but no luck. Then I replaced it and was concerned bc I was expecting the engine to die when I unplugged the sensor, but it kept running. It ran a little rough at first, then smoothed out after a few minutes.
Even the check engine light when out!! I’m ecstatic!!
Now.... if I can just figure out why my anti-theft system is whacked after I changed the battery....
so strange... I went through the owners manual and followed the instructions but no luck there. So I disconnected the ground wire to the actual device that make the noise and now there’s an intermittent clicking sound coming from the dash, like the emergency flashers are on.... but they’re not. I can’t give up though... I’m afraid it may drain the battery.
i greatly appreciate your patience, time and experience though!!

Thanks for sending this info concerning the MAF sensor. This can help others in the future.

 

[imidazol97]

My cleaning for the MAF sensor used a camel hair artist's brush and the electronic cleaner from CRC at the parts store. The camel hair
brush let me gently wisk away the small particles that were stuck tot he two wires in the MAF.