Hi,

Sorry if this has been asked before, I'm new here and searched before asking but didn't find anything that related to this particular issue (if it's is one issue).

Recently bought 03 S-Type and it's got a bit of a noticeable miss and throwing the engine code (P0301). So, ok, ODBII confirms the miss, cylinder 1. The issue I'm having is when the missfire is present, the transmission doesn't want to shift. It's almost like it goes into neutral. When it's not popping, it seems to work just fine. There's no transmission codes on the ODBII.

Could what's happening with the miss be causing issues shifting cause of a vacuum loss or something? Is there a way for me to diagnose this?

Thanks for your help,
Roadie

 

Misfire issues on these cars are commonly caused by vacuum leaks, failing coils and occasionally, failing spark plugs. If your car has the 3.0 V6 engine, misfires are also frequently caused by the failing/leaking Intake Manifold Tuner Valve O-rings (usually referred to here on the forum as IMT O-rings). There are two of them, and the new version of them is green in color. If you have the 3.0 and the IMT O-rings have never been replaced (the old-style factory ones are colored yellow), I would start by doing that relatively easy and inexpensive job first. Search the forum using "IMT O-ring replacement" as your search phrase and you'll get the step-by-step instructions on how to do this....

If your car has the 4.0 or 4.2 V8 engine, it has no IMT O-rings so this fix will not apply....

A weak or failing battery can cause transmission problems (along with a myriad of other problems). Strong batteries in these cars are absolutely mandatory for fault-free operation....

Put your car details in your signature and you'll always get more help when you ask for it....

 

Misfires commonly interfere with shifts. Any engine fault may, also. Just fix whatever's wrong. It's putting unburnt petrol/air into the cat conv and gradually destroying it...

There are many many threads about misfires, with fix info.

 

+1 Jagv8-- fix the misfire probably coil issue so swap it with cyl 2 and see if code follows it.
The transmission glitch should disappear when fixed.

 

Thanks everyone. It's a 2002 4.0, my bad for not mentioning it earlier. If the weather up in these parts holds up this weekend, I'm going to start diagnosing it. Was just looking for a place to start.

Thanks!

 

I hope you've changed the timing chain tensioners!! On borrowed time if not.

 

Yikes! It's an interference motor? What's the replacement schedule on those?

 

ASAP

 

It is. Now.