2004 Engine misses while cold

[Idaho Highboy]

Hello all !

I'm in the initial troubleshooting stage for the wife's 'bird. The issue is an intermittent (i.e. it ran perfectly today when I told her to leave it home so I can work on it...) post startup (circuit?) engine stumbling. I got to see it first hand yesterday, when the engine was already warm. The car ran like it was missing (badly), but only for the first couple of minutes - then it ran perfectly, including me taking it here and there, stopping and restarting the engine, racing the RPMs to 5K, etc. The wifie says that the engine has been acting like this since it post-winter storage, but only on some days and only when she first starts the car (i.e. after it's been sitting). The car has about 77K miles on it and is driven about 5K miles per year; oil and filter are changed every spring. I've replaced all of the coils with Ford replacements (years ago), and last year I installed a new air filter and cleaned the MAF sensor. The car does throw various OBDC codes for the O2 sensors from time to time, but they stay away for a couple of weeks when I reset them. I don't know if they are being thrown due to my wife's heavy foot when the engine isn't completely warmed up 🙄. This last time (i.e. right before I started troubleshooting) it threw upstream O2 sensor codes for both sides of the exhaust. I have replaced some of the O2 sensors over the life of the car, but also believe that these codes will present when other fuel / air components are not working like the computer expects (e.g. a dirty air filter, etc.).

So... has anyone come across this issue before? My goal is to be present when the engine does it's little thing again and use a stop watch to see if it helps in the process. I believe that some components are active only immediately after starting, for a limited period of time. My stopwatch is packed and waiting.

Thank you in advance !
- IH 😎

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[doug7740]

You mentioned that various codes were set from time to time, did you clear those codes with a scan tool? If those codes were cleared, were any new codes set after the engine started misfiring? If new codes were set did you look at the freeze frame data associated with that code? It amazes me that most people don't look at the freeze data. Freeze frame data ss a snapshot of sensor or component readings (parameter values) captured at the moment when the electronic control unit detected a malfunction. In addition, the freeze frame contains the Diagnostic Trouble Code (DTC) that the computer system identified as the reason for the malfunction.

doug7740
1955 Thunderbird Blue

 

[gregl32]

You mentioned the stumbling (misfire?), classic symptom of bad coils. Conversely bad O2 sensors can cause similar issues. It generally takes 3 appropriate driving cycles for codes to be set, so the fact that the O2 codes come back after a couple weeks indicates there is a definite permanent problem. Do you have a scan tool that can do more than simple OBD codes? There could be other codes that are not showing with typical OBD scan tools. So could be coils, plugs, sensors or something else. Need to watch O2 sensor operation using a scan tool or PC with OBD connector with that capability.

 

[Idaho Highboy]

Thank you for the responses. Yes, I cleared the codes to see if they would come back immediately. I took Lisa's car out yesterday for a 15 minute drive and no codes are back (yet). My OBDC tool is a simple one, but I'll check next time to see if I can view freeze frame data (i.e. the actual performance that trips the code). I forgot to mention in my OP that I replaced the spark plugs at 49.4K miles; I could pull one and see if it tells me anything. What's odd, based on my one experience with these symptoms, is that they only presented at start up; I know I mistitled this post by using the term "cold"'; the engine was well warmed up when I started the car, although Lisa reports that it happens to her when the engine is cold. This is why I think the problem is related to something that only operates in the first minute post-startup. The engine does cycle normally through the 20 seconds of post-startup cold-operation high idle and drop like it's supposed to. The post-startup warm-operation high idle also cycles normally (shorter duration). I'll update my post in case I learn more or experience the issue again. These intermittent problems are a hoot 🙄

 

[gregl32]

Thank you for the responses. Yes, I cleared the codes to see if they would come back immediately. I took Lisa's car out yesterday for a 15 minute drive and no codes are back (yet). My OBDC tool is a simple one, but I'll check next time to see if I can view freeze frame data (i.e. the actual performance that trips the code). I forgot to mention in my OP that I replaced the spark plugs at 49.4K miles; I could pull one and see if it tells me anything. What's odd, based on my one experience with these symptoms, is that they only presented at start up; I know I mistitled this post by using the term "cold"'; the engine was well warmed up when I started the car, although Lisa reports that it happens to her when the engine is cold. This is why I think the problem is related to something that only operates in the first minute post-startup. The engine does cycle normally through the 20 seconds of post-startup cold-operation high idle and drop like it's supposed to. The post-startup warm-operation high idle also cycles normally (shorter duration). I'll update my post in case I learn more or experience the issue again. These intermittent problems are a hoot 🙄

If it really is cold start, it's possible the front O2 sensors are not working properly when cold OR not completely hot. Most sensors have a built-in heater to get them up to operating temperature quicker so the engine can go into closed loop mode sooner. I think you also need to look for any data/codes for misfires (coils/plugs) or possibly fuel injector issues. Maybe you have an intermittent faulty injector.

 

[gregl32]

If it really is cold start, it's possible the front O2 sensors are not working properly when cold OR not completely hot. Most sensors have a built-in heater to get them up to operating temperature quicker so the engine can go into closed loop mode sooner. I think you also need to look for any data/codes for misfires (coils/plugs) or possibly fuel injector issues. Maybe you have an intermittent faulty injector.

It could be the sensors are fouling. That could be fuel related - raw fuel getting into exhaust, or possibly oil but I assume your oil level is fine.

 

[KBB_of_TMC]

It may be a long shot, but I have had a similar intermittent problems in a non-Thunderbird Ford of about that vintage. Once it turned out to be a single bad ground connection down under the windshield washer pump that would occasionally prevent the fuel pump relay from turning on the fuel pump. Later, an intermittent ignition miss at highway speed turned out to be due to a failing idle air controller that still tested OK using the standard tests.

I had to go far beyond the FSM and computer codes to finally track those problems down. Good luck!

 

[Idaho Highboy]

Well folks, I gave Lisa back her car today after messing with it for days without it reproducing the symptoms. I'll update this post if I find anything out and let you know what I discover. Thank you for your ideas and comments.

 

[Idaho Highboy]

Long term update is that the issue failed to present itself over the past two weeks, so I'm closing this thread. Thank you all for your ideas and maybe someone else that has the same issue will see this and post their fix. Peace.

 

[newtbirdguy]

Hello all !

I'm in the initial troubleshooting stage for the wife's 'bird. The issue is an intermittent (i.e. it ran perfectly today when I told her to leave it home so I can work on it...) post startup (circuit?) engine stumbling. I got to see it first hand yesterday, when the engine was already warm. The car ran like it was missing (badly), but only for the first couple of minutes - then it ran perfectly, including me taking it here and there, stopping and restarting the engine, racing the RPMs to 5K, etc. The wifie says that the engine has been acting like this since it post-winter storage, but only on some days and only when she first starts the car (i.e. after it's been sitting). The car has about 77K miles on it and is driven about 5K miles per year; oil and filter are changed every spring. I've replaced all of the coils with Ford replacements (years ago), and last year I installed a new air filter and cleaned the MAF sensor. The car does throw various OBDC codes for the O2 sensors from time to time, but they stay away for a couple of weeks when I reset them. I don't know if they are being thrown due to my wife's heavy foot when the engine isn't completely warmed up 🙄. This last time (i.e. right before I started troubleshooting) it threw upstream O2 sensor codes for both sides of the exhaust. I have replaced some of the O2 sensors over the life of the car, but also believe that these codes will present when other fuel / air components are not working like the computer expects (e.g. a dirty air filter, etc.).

So... has anyone come across this issue before? My goal is to be present when the engine does it's little thing again and use a stop watch to see if it helps in the process. I believe that some components are active only immediately after starting, for a limited period of time. My stopwatch is packed and waiting.

Thank you in advance !
- IH 😎

I had something like this happen to my 04. After a lot of pulling my hair out, I was changing out the spark plugs and noticed that the plug access holes had a good bit of oil in them. The valve cover gaskets were leaking into the spark plug holes and oil collecting causing a miss when cold and under heavy acceleration. I replaced the gaskets, fixing the leak and the miss went away.

 

[Terry O'Neil]

I am just throwing my 2cents in on this stumbling issue. A few months ago I had the same problem with my 05 . OBD tester said it was the Upstream sensor, so I changed the sensors on both sides upstream to no avail. after going thru the try this and try that phase I took it to the local auto repair shop, Oh by the way I put Brand new Bosch sensors in it and like I said it didn't fix the problem. The mechanic went through the OBD tester again and he says it is your upstream sensor, I told him what I had done and that I had done some other things on the list of problems that it could be. He kept my car for 2 days and went over everything that he knew to do, all to no avail. So he took out the Bosch sensors and changed them with some new NGK sensors , and wouldn't you know it PROBLEM IS FIXED. I paid good money for those Bosch sensors, but I will never buy anything made by Bosch again. and my T-Bird has been running Excellent since.