ping/spark knock/pre-detonation going to replace intake gasket

[freak]

2000 4.0 OHV. I've got pretty bad ping when accelerating. Getting P0171 code. No other obvious vac leaks, I replaced the intake gaskets quite a while ago. When these things get an intake plenum leak is it usually just the upper gasket? I really hate to disturb the injectors. I went through all the orings not too long ago.

 

[poker4me007]

You say you did the intake gaskets quite a while ago.(how long ago?)Try cleaning your maf sensor, there's other things you can check as well before doing the intake gaskets.

Ford P0171 & P0174 Lean Codes

 

[freak]

10+ years and ~200,000 miles. 311,000+ now.

 

[poker4me007]

10+ years and ~200,000 miles. 311,000+ now.

Maybe it does need a new gasket, seems these engines go through them a lot.
I haven't needed one yet (knock on wood).
Here's one way to look for a gasket leak. (I would be careful though).

 

[freak]

yeah I tried carb cleaner today. a lot of tight spaces though.

 

[Runnin'OnEmpty]

I also have a 2000 ohv (2 of them in fact). A while back one ran rough at start-up and smoothed out after a couple minutes. There were no codes present. However, I thought it was a leaky plenum causing a lean condition. Before replacing the upper O-rings, I checked the manifold studs/nuts and some had loosened up from the last time the manifold was off, several years ago. After re-torqueing the nuts, the roughness was gone and it runs smooth as silk. Apparently the gaskets shrink or the heat cycles loosen the manifold bolts, so I'd check them first. They're real easy to access on an OHV; 10 minutes with a 1/4" ratchet.

 

[poker4me007]

I also have a 2000 ohv (2 of them in fact). A while back one ran rough at start-up and smoothed out after a couple minutes. There were no codes present. However, I thought it was a leaky plenum causing a lean condition. Before replacing the upper O-rings, I checked the manifold studs/nuts and some had loosened up from the last time the manifold was off, several years ago. After re-torqueing the nuts, the roughness was gone and it runs smooth as silk. Apparently the gaskets shrink or the heat cycles loosen the manifold bolts, so I'd check them first. They're real easy to access on an OHV; 10 minutes with a 1/4" ratchet.

Good Point. I would try this first also before taking it all apart.(can't hurt).

 

[German Engineer]

You say you did the intake gaskets quite a while ago.(how long ago?)Try cleaning your maf sensor, there's other things you can check as well before doing the intake gaskets.

Ford P0171 & P0174 Lean Codes

Just a short comment on the method in the video:
Been there done that and it's not really a very great idea.

Here's a MUCH BETTER method:
Unplug the thick vacuum hose to the brake booster (the big pot in the back on the driver side) at the end by the break booster.
Get a reasonably long (6 feet or so) and preferably transparent plastic hose that fit's snug inside of the hose going to the brake booster.
Stick your plastic hose inside there deep enough to get the hoses seal with each other somewhat. (It doesn't need to be a perfect seal)

Get a cigar light it up and blow the smoke into your transparent hose and play human smoke machine.
And while you keep blowing smoke into the intake manifold via the hose look all around the engine compartment wherever a vacuum hose goes (and they're almost everywhere). If you can see smoke coming out that's where a leak is.
A flashlight might help when doing that.

And while you blow the smoke in there avoid getting too much saliva into the intake manifold and make sure you don't get any little bits from the cigar in there. That's why a transparent hose is much better, because you can see when there's too much saliva adding up in the hose.

If you don't smoke yourself then just go ask a friend who does, if he wants to give your car a "********".