No tach until engine warm????

[Mustang5L5]

I posted this a while back but put it off til now.

I have a problem that when my car is cold, my tach sticks at idle or won't go past 2000 RPM when the engine is cold. Doesn't happen in the summer, but on a brisk morning of when the temp is in the 20's or 30's the tach will either stay at 0 and not move at all...or jump to idle and not move at all. Sometimes it will move, but won't go past 2000 RPM.

This happens until the engine warms up then it works fine. When the temp is in the 50's and 60's it takes 2-3 mins for it to be fine. When it's in the 20's/30's it might take 10-15 minutes.

I have gauge face overlays but i've checked twice the the needle is not hitting the face at all.

Does the crank position sensor control tach input? Does it control anything else?? Any way i can test this sensor? Would it trip the CEL if faulty? How much is a new one at Ford?

 

[SONIC02]

I had this problem with my silver face overlays - I checked mine twice but this still happened so i took it all apart and pulled up on the needle till it moved a little bit- With mine i could see the gas guage and speedo further away from the overlay then the tack so i pulled up on it and i haven't had the problem since.

 

[sgarlic]

My guess as I said the last time somebody (maybe you) asked this, is that the needle is slipping on the shaft because the hole in the needle is enlarged. Once it gets warmed up, and the cluster itself heats up, the shaft expands, and then fills the hole in the needle. Thus why it only happens on cold days, and works ok on the hot ones.

 

[ACSPONY]

My guess as I said the last time somebody (maybe you) asked this, is that the needle is slipping on the shaft because the hole in the needle is enlarged. Once it gets warmed up, and the cluster itself heats up, the shaft expands, and then fills the hole in the needle. Thus why it only happens on cold days, and works ok on the hot ones.

Good call, I wouldn't have thought of that

 

[Mustang5L5]

My guess as I said the last time somebody (maybe you) asked this, is that the needle is slipping on the shaft because the hole in the needle is enlarged. Once it gets warmed up, and the cluster itself heats up, the shaft expands, and then fills the hole in the needle. Thus why it only happens on cold days, and works ok on the hot ones.

Yeah but if the needle was slipping on the shaft shouldn't my tach be inaccurate by now? How does it always reset to the right RPM?

I'll check the gauges again, but i'm pretty sure the needle isn't hitting them at all.

 

[mity2]

had similer issue with my car. My solution was stop driving car altogether when cold. And got beater for winter time

 

[mity2]

had similer issue with my car. My solution was stop driving car altogether when cold. And got beater for winter time

 

[sgarlic]

Yeah but if the needle was slipping on the shaft shouldn't my tach be inaccurate by now? How does it always reset to the right RPM?

How about putting a small drip of RTV in the needle then replacing it and seeing what happens? If it doesn't fix it, at least you can eliminate that as a possibility..