4 liter shaking

[Pt_Ranger_V8]

Just changed out the p/s head gasket on my 93 4.0. Seems everything went well, except now it shudders visibly on startup/idle.

I'm thinking I didn't hook up a spark plug?

Also going to check the vacumn lines this afternoon.

Anything else I should check?

 

[Pt_Ranger_V8]

some more clues...

It stalls when I let off the gas - driving down the road... (coming to a stop sign, for example)

shakes very little when warmed up at idle, but it's noticeable...

hard to start - like there's no fuel in the line...

Tomorrow, I'm swapping the Fuel filter (cause I don't know the last time it was done), and I'll try and test the FPR as well...

any thoughts?

 

[WildSide]

You only changed one head gasket?

 

[rags]

Also make sure you got the fireing order right, I have seen it messed up a couple of times after head or intake work.

This link should help

http://autorepair.about.com/library/firing_orders/bl-fo-7260.htm

 

[MAKG]

Yup, and a REALLY common error on a 4.0L is hooking up the spark plug wires to the coil pack in numerical order.

Firing order is 142536. Coil pack order is 123564. The entire right bank will misfire if you hook up the coil pack in numerical order.

 

[Pt_Ranger_V8]

how do I tell the firing order on the coil pack?

I number the plugs (on the coil pack) 1 2 3, and hooked them up the same (I thought)

thanks!

 

[Pt_Ranger_V8]

a little more investigation reveals one wet plug.

the injector is sticking open on that cylinder.

I'll run some seafoam and see what happens.

 

[Pt_Ranger_V8]

well, the injector is still stuck.

I'm thinking I probably got crap in the nozzle of said injector.

looks like I need to pull the injector out.

 

[woodyedmiston]

Pull your valve cover off and make sure you have all of the pushrods actuating the rockers on that bank.

 

[94 splash]

yea i had the firing order off on mine and it did that

 

[Pt_Ranger_V8]

well, injectors are working fine.

no codes come up, KOEO, or KOER.

tried a cylinder balance test (hit throttle w/i 2 mins of KOER test output) to no avail.

fucker still shakes like crazy.

I did however determine the best way to install the 4.0 fuel rail... injectors into the rail, then mount rail/injectors to the intake.

I also swapped the injector, and the plug...

the plug I swapped in got all wet (didn't smell like anything really, no strong gas smell, no strong sweet smell. The original plug turned a normal color in the other cylinder. (incidentally with the original injector).

What now? Pull the heads and check 'em for straigtness? I have noticed a coolant level drop though - not much, but the rad/overflow tank aren't as full as they were ~300 miles ago.

 

[Will]

Why did you change the head gasket?

Head gaskets don't just blow. Something makes them fail.

Did you replace the head bolts? I'm guessing you did, but for those in the cheap seats, they are torque to yield--meaning the bolt is destroyed during installation and it won't clamp properly again.

I would do a balance test by grounding the plugs one at a time and see if one of them isn't contributing. I would also compression check it--something like that will show up I think. I think you have a cracked head and coolant is snuffing the plug on that cylinder, but that's from 2,000 miles away and out of my hat. A shudder like that is indicative of a cylinder not doing it's part. A burned valve can do that, for instance. Even a vacuum gauge reading at idle could give us more info to help diagnose it.

 

[Pt_Ranger_V8]

Why did you change the head gasket?

Head gaskets don't just blow. Something makes them fail.

Did you replace the head bolts? I'm guessing you did, but for those in the cheap seats, they are torque to yield--meaning the bolt is destroyed during installation and it won't clamp properly again.

I would do a balance test by grounding the plugs one at a time and see if one of them isn't contributing. I would also compression check it--something like that will show up I think. I think you have a cracked head and coolant is snuffing the plug on that cylinder, but that's from 2,000 miles away and out of my hat. A shudder like that is indicative of a cylinder not doing it's part. A burned valve can do that, for instance. Even a vacuum gauge reading at idle could give us more info to help diagnose it.

I changed the gasket because it was dribbling coolant. This was in the rear PS cylinder (#5). the fouled plug is on the middle PS cylinder (#3).

Truck was running fine up to this point. as soon as I swapped the hg, it started the shaking. I'm going to pull the valve cover and check the torque on the bolts.

when I torqued the bolts down, I did the zigzag pattern, and 3 step sequence (~50?,~70?,~85?, then 80*) per kit instructions, with new bolts included in the kit.

I did pull the wires, one at a time, and it is the same cylinder that had little to no effect. However, the #2 cylinder didn't have much effect either.

vacumn at idle is ~22 lbs or so.

the truck idles smootly, (rpm wise), but it's physically shaking. The only thing I haven't done is a compression test, due to lack of a tester. I'll try and remedy that tomorrow.

The wierdest thing is, when I'm accelerating (say, on an onramp, getting up to freeway speed) I can feel it running ragged, then it will momentarily 'catch' and run correctly. not for long, (2-3 seconds) but long enough that I can feel it. And when you go from cruising, let off the gas, the rpm's drop significantly, akin to a vacumn leak.

Is it possible I'm blocking a coolant passage? At this point, I'm sure I did something wrong, but trying to figure out what is a PITA.

 

[Pt_Ranger_V8]

finally got my hands on a comp tester. that cylinder is showing zero compression.

I vote I didn't install the lifter correctly :wall:

looks like a afun project, no?

 

[Pt_Ranger_V8]

woohoo!

got it fixed! when I reassembled everything, I didn't doublecheck my work, and left one of the lifters disconnected from the rocker. ( lifter rod was there, just sitting.)

works like a champ now