2003 XType 2.5

Rough acceleration, seems to only be between 35 and 45 mph and then is again noticeable above 70 mph. Almost feels like a misfire. It will make the check engine light blink indicating something is wrong, but light will not stay lit and no codes stored.

If I have it in neutral or in park and rev up motor, there does not seem to be a noticeable issue, everything seems normal throughout the RPM range.

I did replace the alternator about a week ago, using the top out method. My next step is to check for a nipped coil wire.

What could contribute to this issue???
Bad Gas?
Coil beginning to fail?
Plug beginning to fail?
Tranny?
Other?

As always, thanks in advance for any help or suggestions...

 

 

Still working the issue...
At first it was just a rough acceleration as stated between 35-45mph, otherwise seemed to run okay. No codes were thrown after several attempts to generate one through various driving conditions. Went ahead and changed the plugs and the remaining 2 coils which hadn't previously not been changed. Got it all back together and still had a stumble upon acceleration. Drove for a while attempting again to trigger a code, no CEL. Put scanner on and had a Knock Sensor code (still no CEL), fortunately I had a sensor in the tool box as this is the 3rd (seems to be an issue). So tore everything back down to replace knock sensor. While in there checked all the intake gaskets for condition, all seemed good as they were replaced last time I had to do the knock sensor. Thoroughly inspected everything upon reassembly, looking for anything obvious. Started the car and immediately had a CEL (for knock sensor), cleared code and took for test drive. Now it is in full limp mode (still with no CEL), not sure how it goes to limp mode without any codes generated. Also, noticed a stumble at idle now. Drops to around 620rpm then picks up to around 750rpm.

Only thing of note was there was some oil on plug in cylinder #1. Clearly I'll have to tear it back down to put in a valve cover gasket and spark plug well seals. Would the presence of oil on the plug cause this condition. Figuring it may disrupt firing efficiency or stifle it all together, but I'd think a misfire code would be generated.

Any thought/suggestions???

Thx

 

If it's upset enough - and especially if you cleared codes previously - it may be unable to figure what code(s) to flag.

If you did clear codes and have P1000 then lots of things are blocked (suspended if you prefer) until P1111 so many codes simply can't flag because it just doesn't know what can be trusted. A sort of Catch-22.

It's why there are warnings never to clear codes without being pretty sure you've first done the right fix.

You might look at fuel trims in the hope of useful info.

Oil is bad because it tends to have things in it like soot which conducts and yes misfires are quite likely.

 

Loose bolts in the throttle body or intake?
Loose cable or wire connection ? - that can take some time to run down and verify -

 

zerochills: Just spit balling….. Check the electrical connector on the bottom of the throttle body. The plastic becomes brittle with age & engine heat, causing a loose connection, particularly if you have disconnected multiple times with each teardown. If the connector is compromised, try a zip tie for a more secure connection, or replace the connector. The part number is WPT-1269, on page 14 in this Ford catalog:

http://www.fordservicecontent.com/pu...torcatalog.pdf

https://www.nationalfleetparts.com/w...-assembly.html

 

Thanks for the suggestions... Quadruple checked every wiring harness, vacuum line connection app on my for 3rd assembly in a week. Ohmed every coil and all are reading exactly the same, so I'm ruling those out, as stated previously installed all new plugs, decided to put a valve cover gasket and plug well seal in to correct the minor oil collection in cylinder one plug well. Swaptale the knock sensor with another brand new unit, just for the heck of it since I was in there and to further rule it out. Took additional time on reassembly to inspect every O ring and Gasket and to ensure everything was reassembled correctly. CEL light is off, upon test drive Limp Mode is gone. Still have a slight stumble between 2500 - 3,000 RPM (almost feels like its starving for air or fuel. Also within about 2 minutes of starting the car the idle settles out and begins to fall and then catch itself.

Not sure where else to go??? I'm going to check the STFT and LTFT, what are the acceptable ranges for both and if I find they're out of range how do I go about adjusting them? Or is that something needing computer software?

 

Have you checked your fuel pressure with your obd while driving (i.e. Toggle "logging" on)?

 

Logged back in to update... Dell, I'll check fuel pressure while under load as soon as the never ending rain passes.

I've let go for several hundred miles in hopes that maybe a CEL would be triggered and point me in the right direction, no luck. Following all the previous attempts and part replacements to correct what was thought to be ignition related, I am now leaning more towards tranny gear issue (am I too hasty in jumping to that conclusion?) Reason being, if I ease in the acceleration it all seems fine, once I apply a heavier acceleration is when most of the issues are noticed. Best way to describe it is still feels like a misfire, but thinking it may be momentarily slipping out of gear before quickly re-engaging??? If the hick-up/slip is noticed and I switch to sport mode, it obviously drops gear and accelerates normal. Still feels like its somewhere around 4th gear when most noticeable. Tranny fluid level is fine, I drained and refilled a few months ago with "Castrol Transmax Import Multi-Vehicle" as recommended by several on the forum. Could this be the issue???

Any other thoughts?