Hey all,

I just got my 03 F-150 with the 4.6L in it and it has 113k on the clock now. However, whenever I go to shift gears and push the clutch in, I noticed the rpms either stay constant and then drop or they even go up a bit (like I hit the gas) and then drop. Is this normal for the 4.6L? I had a 96 Cobra with the 4.6L (but it was the DOHC model) and it did the same thing.

Maybe I'm old school, but I'm used to pushing in the clutch and the rpms dropping instantly...not hanging or even going up and then down.

Is it normal or is there something I can test/check to see why this is happening? I also put a thread in the trans section because I have a hard time shifting into 3rd at times (and putting it in 1st after sitting in neutral or barely rolling). I don't know if these are related or what the deal is.

Any help would be truly appreciated!

Thanks,
Mat

 

That's normal with emissions controls these days with manual trannys. Heck, it even used to be normal in the early days of emissions controls, but we just had to disconnect the dashpot on the carb to fix that. Sudden throttle closure causes a spike in emissions.

 

I seeeeee...ya, none of my Camaros really had any emissions controls on them.

But it makes sense. Cool, at least I know it's normal, so I don't feel so paranoid now. Now if I can just fix the clutch/trans issue, I'll be a damn happy camper with the truck.

Thank you for the info.

 

I dunno... My friends svt focus did this... The rpms hung out almost forever and it was the tps going bad

 

That's one reason manual trannys are going away - its getting harder and harder to comply with emissions while keeping decent driveability. Mine isn't too bad, but it definitely overruns a bit when I shift.

 

I would say that it's not as bad as my Cobra (also an SVT model) was, but it does hang a lil bit and/or goes up a touch when I shift. However, it's not too noticable unless I really watch for it. My Cobra was really noticable and I thought it was odd because my Chevy's never did that. Then again, I never had one with a stick that had real emission controls on it either, so that's a definite difference.

But thanks about the hint on the TPS. Maybe I can try and check it (if there is a testing procedure in the service manual) and see if it's going bad or not.

 

Mine drops to idle as soon as I let off the gas with the clutch in. In colder weather it takes a fraction longer but it still drops. On cold starts it lingers till the engine warms up. When it starts to linger I clean the IAC. As soon as the throttle plate is shut the PCM controls the rpm via the IAC. If it is dirty it might not react fast enough.

 

Maybe I'll try and clean the IAC. However, when I replaced that on my Cobra, it didn't change anything because that's what I thought it was as well.

But we'll see what goes. Thanks for the info!