Yet another OHV won't idle thread

[Meat_PoPsiclez]

Pulled my side chick (97 Sport 4x4 4.0l OHV) out of retirement (hadn't been on the road in a decade) and decided to press it back into service.

It ran, but was leaking oil (a lot of oil) from the valve cover gaskets, so I opened it up. Pulled the AC compressor, alternator, and upper air intake off, changed out valve cover and upper intake gaskets, stuck it all back together.

Now it won't idle, or even start past an initial lope if you don't hold it open. At 3k and up it sounds healthy, but as soon as I left off the throttle it will start to miss and hesitate. At 1500 it sounds like it's missing on most cylinders, and off the throttle entirely it will cough and die instantly.

I've checked and rechecked firing order, and don't see any missed vacuum lines or wiring harness/plugs.

Seem to have lost my code reader, so I have to wait to pick another one up before I can really delve into what's going on myself, but was hoping someone might say "hey this moron did the same thing I did!" and be able to point the way

Pics of surgery, and bonus **** of my other Ex (slowly) getting 42s on 1 tons
Burn it to the ground

 

[lobo411]

Now it won't idle, or even start past an initial lope if you don't hold it open. At 3k and up it sounds healthy, but as soon as I left off the throttle it will start to miss and hesitate. At 1500 it sounds like it's missing on most cylinders, and off the throttle entirely it will cough and die instantly.

I realize you said you checked/rechecked the firing order, but this (missing and struggling at idle, but ran fine under throttle) happened to me once and it was the firing order. I'd check that again, and also look at the wires...maybe they're damaged.

I suppose you could also check for a vacuum leak. I'd be looking at those tiny hard lines that go around the top of the block from the fuel pressure regulator to the sensors on the driver's side.

 

[96eb96]

Pulled my side chick (97 Sport 4x4 4.0l OHV) out of retirement (hadn't been on the road in a decade) and decided to press it back into service.

It ran, but was leaking oil (a lot of oil) from the valve cover gaskets, so I opened it up. Pulled the AC compressor, alternator, and upper air intake off, changed out valve cover and upper intake gaskets, stuck it all back together.

Now it won't idle, or even start past an initial lope if you don't hold it open. At 3k and up it sounds healthy, but as soon as I left off the throttle it will start to miss and hesitate. At 1500 it sounds like it's missing on most cylinders, and off the throttle entirely it will cough and die instantly.

I've checked and rechecked firing order, and don't see any missed vacuum lines or wiring harness/plugs.

Seem to have lost my code reader, so I have to wait to pick another one up before I can really delve into what's going on myself, but was hoping someone might say "hey this moron did the same thing I did!" and be able to point the way

Pics of surgery, and bonus **** of my other Ex (slowly) getting 42s on 1 tons
Burn it to the ground

Clean your maf sensor. At least disconnect it to see if anything changes. Dirty MAF sensor creates a "Mental Illness" type vacuum leak.

 

[fast_dave]

@Meat_PoPsiclez

Just a side note on the 4.0 OHV: I hope you didn't use Fel-Pro valve cover gaskets made out of cork.

Steel core rubber is the way to go for longevity, oil leak resistance, and air leak resistance.

 

[ibstang]

Old school trick...Have someone steady the revs at 1500 (your note above), and use a can of ether quick-start to explore the vacuum system with judicious "schnorts". Modern motors have countless places for vacuum leaks to develop (especially after an under-hood wrasslin' match), but few can hide from this old trick...