Sohc hangs at high rpm's

[Gonzo]

Why, when I rev the engine, do the rpm's not come down for about 3 seconds? Example: Say I rev it to 3500 and take my foot off the gas. It will stay at 3500 for at about 3 seconds before it starts to come down. I was thinking maybe the Sohc have a heavy flywheel, or maybe there is less friction since it only has one camshaft. Just curious.

 

[frickea86]

i think it might be normal but the other guyz will have to back me up on that but mine does the same thing almost. It won't stay at 3500 rpms but it does take a little bit for it to drop back down to idle...sorry i can't really help with this...i know the other guyz will...

adam

 

[BensBud]

Yup. Happens to me too. I have a '98 XLT (stock for now). I'm fairly sure I have a minor vacuum leak on the right side, so I may not be a good gauge of "normal" behavior. I get a subtle hissing sound when the truck is under heavy acceleration (not floored) - particularly when it's about to shift into a higher gear, so the torque is picking up. My old '93 never did this (the hanging thing). I've gotten used to it, but I hate it.

 

[Nate1]

My apten helped ALOT with this, but there is a TSB out for the tranny that fixes low pressure and delayed shifting. You can tell you need the fix if your tranny does not brake when you put it in 1..... but I think it is $$$ although it probably extends the life of the transmission.

 

[izackary]

me too! me too!

I have a sucking sound coming out of the right side of the motor, too, when i pull the throttle cable back a bit. i've had the smae problem with my former lincoln mark viii (4.6L DOHC V8) and it turned out to be a cracked fuel injector o-ring. but what that car did was when the motor was cold(-ish) it would seriously bog down horribly from an idle. it even stalled on a couple occasions...when pulling into traffic! the explorer's symptoms aren't nearly as severe, but i feel a low-end power loss, and definately hear the hissing sound on the right bank. might it be o-rings again? or maybe the valve cover gasket? i'd much prefer it's the o-rings. since i have some, and i hate to have to remove a valve cover. but now that winter's coming along with cold weather, it'll only get worse. any clues??

 

[frickea86]

i have a hissing sound sometimes coming from mine but its the IAC Valve. Its probly going bad but i just keep cleaning to prolong buying it, but the sound goes away after i clean it up a bit.

adam

 

[izackary]

i thought that, but it definately comes from the right side. the IAC is dead-center.