4.0L rough idle post timing chain replacement

[ahuggins6]

So I replaced my chains and tensioners a few weeks back. 2nd engine I've done this on over the years. Swore the first time I'd never do it again. Sold the first one. Was given a 99 in great condition. I started driving it at about 150k, now its at 215k.

It's got a slight vibration/rough idle now since the engine went back together. Also, fuel mileage dropped shortly before the tensioners finally let go, and it hasn't recovered as I expect it would. It runs great, even at idle, but it's got that vibration at idle that gets old sitting at red lights and drive thru windows and such.

I didn't have instructions and I was in a hurry when setting the timing. The only thing I can think of is that I was supposed to rotate the engine 360 before tighting the second cam. I'm thinking that the cams are timed such that two cylinders are on the same stroke at any given time. This would make the MAF read really big air flow at one time and nearly zero the next--if the air flow can even vary that much..??

Another possibility is that my tool kit is just a cheap piece of junk that doesn't work perfectly. It's the diamond power setup. I was going to pick up the OTC tool like i'd used before, but at the time the tensioners came apart, I was too broke to get a good setup. Anyway, this crank pulley holder tool is built so that it wiggles around on the pulley and doesn't seat well. I think it's still pretty accurate in where it locates the crank relative to the spot it hits on the block. This is why I think it's a matter of turning the engine one rev before going to the second cam.

I installed new platinum plugs before putting the engine back in the vehicle, so I guess I could have one that's cracked or something?

What do you folks think?

 

[masospaghetti]

I would expect it not to run great at any speed if your timing was off, or if the firing order is incorrect, but I am not the expert at all on the SOHC engines...

 

[fast_dave]

ahuggins6

DISCLAIMER: I've never owned or worked on an SOHC, but have read a lot about it on this and other forums.

So what I'm going on is what you've written to the forum - and it's a concise, easy to read, understandable post.

OK - so the way I read it, there's about 4 possible pitfalls that could be causing your headache.

The first is that you were in a rush - we've all been there ;-)

Second is (assuming you were still in a rush as this would be your last step) you might have cracked a spark plug.

Third is (because you wrote you were in a rush) you might have screwed up the cam timing or an associated sequential "tightening" procedure associated with the cams.

Forth is you weren't using the brand/type of tool that you were familiar/trusting - I feel for you because it flat out sucks when you pretty much know that you have the wrong tool for the job - especially when you've had the correct tool in a previous repair situation to compare it to.

So that's why I'm suggesting to start from square one - start EASY and removing & checking your spark plugs, and when re-installing them that your wires are securely connecting to them.

If that doesn't change your Ex's vibration condition, before going to check your cam timing, consult some online guides/videos here on the forum of on the internet. Something you see in the guide/video might jog your memory.

You wrote a good post and I think I'm just confirming what you know you need to do - keep in touch and let us know how things work out. Well-written posts like yours keep the forum going ;-)

 

[ahuggins6]

When I say I was in a hurry, I don't mean that I was rushing. I just didn't want to take the time to look up instructions for setting the timing. It seemed pretty simple to me...until driving it down the road, admiring how much power I didn't realize I had lost with the worn guides. (Maybe it was the slight rattle I was driving around with that made it seem weak???) Anyway, I just got to thinking about how an engine works and realized it could be pulling intake stroke on two cylinders at the same time--I think. I suppose being a V6, there may not be two cylinders doing the same thing at any given time. I know it'd be possible on a V8 OHC engine, but I have never been into one of those.

I really don't think its a bad plug, or timed wrong. Maybe just a couple degrees off. I'm too tired to think about it tonight or I'd spend some time searching for instructions or a video.

 

[974X4BLACKSPORT]

Perform a cranking compression test on each cylinder, this will tell you the exact mechanical state of the engine such as cam timing, piston rings, valve seats. If you have cylinder pressure loss due to a mechanical problem with the engine enough to cause a vibration, it should show up with a cylinder low PSI when cranking when compared to the others. I know it's alot of work to do, but you can tell alot about an engines "health" state by a cranking PSI test.

 

[ahuggins6]

Haven’t done a pressure test. But I know I’ve got a leak at the oil pan gasket/timing cover/block. I didn’t put sealant there before putting the oil pan on. Could this be a vacuum leak causing the slightly rough idle?

 

[MrQ]

No vacuum there, but you may have a vacuum leak. That sounds more indicative of your MPG and vibration issue than bad timing.

 

[Turdle]

One very common error I have made and am sure others have, is to have the spark plug wires installed in the wrong order on the driver side of engine. Double check that.

 

[ahuggins6]

The PCV valve pulls vacuum on the crank case. But there’s also another tube that goes straight from the intake tube into the valve cover. If I recall. So I think there is some vacuum on the crank case, but will a hole in the oil pan gasket let enough through to make a difference .

 

[Tech By Trade]

Do you smell gas, when I did mine, one of the rubber gromets on the fuel injectors was toast. it was making a mess, and throwing a miss code. Found it on inspection. Could smell it too.

 

[ahuggins6]

Only smell is burnt oil.

 

[ahuggins6]

Update on this thing:

I’ve got a noticeable oil leak, but I haven’t pinned down it’s location yet. Thought it might be the valve covers or the oil pan gaskets... after washing and driving, I’m pretty sure it’s not. So maybe a PS leak because there is a mess covering all the hoses under the pump. And the fan appears to be throwing the oil around. But the drip comes off the rear of the engine/maybe the front of the transmission. #soconfusedoverthisPOS.

Also, there is still a significant chain rattle even after only 6k miles since replaced. There is an erratic clacking noise that sounds like two pieces of wood being slapped together. I can’t pinpoint where the sounds are coming from because both my stethoscopes are missing from my tool bags.

Has anyone else dealt with these issues?