4.6 timing question

[crowncrazy87]

Ok. So I am no stranger to the Ford 4.6 and 5.4 engines. I have owned a few and currently have 3 vehicles with them and even rebuilt my 5.4 100k miles ago.

I have an issue with a rig I just bought I just can't figure out. It's a 1997 with the 4.6L. Showing lean both banks and idles horrible, runs horrible, pings badly under load but no misfire codes, and other than it sputtering and pinging no odd noises. Its really un driveable! Checked live data and posted results in the first gen forum and consensus was plugged up cats.

So far I have given it a full tune up, plugs, wires, fuel filter, etc. I have checked for vacuum leaks, checked egr and iac function, checked MAF and MAP sensor, had the injectors checked and cleaned, checked for good spark, verified fuel pressure, dropped the exhaust to rule out clogged cats, checked o2 sensors.

It's almost as if it has gotten slightly out of time. I know these are interference engines (I remember being extremely careful when rebuilding my 5.4 2v) but is it possible the chains got a little slack from either a worn/broken guide or bad tensioner and not caused damage? And done this without the usual clattering sound from the front cover?

 

[1955moose]

If it did jump time, I'd think you'd bend a valve. Did you ever do a old school compression test on all 8 banks? Short of pulling timing cover to check, I don't think theirs a scanner that would tell you that info. In the old days, a car or truck could run, although poorly with a jumped belt or chain. Yours would be a first here that had such a stretched chain to jump a tooth, but anything's possible. As you know from working on the 4.6's with the long chains, they do stretch out fairly quickly. On the cats you could gut them out, to see if your power comes back, but then you'd have to deal with smog or state inspection.

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[TobyU]

I would be looking for a bad vacuum or intake leak. The intakes leak on the gaskets badly and the plastic ones or parts crack and suck air.

 

[crowncrazy87]

I may be over thinking everything just being frustrated lol. Luckily no inspections required at all where I live! The times I've heard of people loosing a tensioner or guide they had a lot of noise from the chains and valve train which I do not have.

It's gotta be something I'm over looking. I haven't tried putting a noid light on the injector plugs so I may try that out. I've checked the injectors themselves. So far other than plugs and wires I have zero invested other than the $900 I spent on the vehicle itself. Luckily I've been able to swap some easy to get to parts off my 98 f150 to use as testera lmao!

 

[TobyU]

If you are suspecting injectors not firing you can take a spray bottle with gas and spray into intake and crack throttle a little to see if it runs ok with extra fuel. You should be able to feel the clicking of each inj with fingers though, or put a long screwdriver on it and put end on your ear.

 

[crowncrazy87]

The thing is though if they were not firing should that not give me mis fire code?

 

[1955moose]

Should. And if you had a clogged injector, it would show on a scanner as a short duration of fuel spray. Like Toby said do a smoke test for intake leaks. You can spray everything with carb spray, and be missing an area like hidden part of intake, or pcv hose. A smoker through brake booster hose will bring out smoke everywhere. Now you know why it was $900.00

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[crowncrazy87]

Eh. I always buy cheap broken stuff (often to my wife's dismay lmao). I did mean to mention I did do a compression test and all cylinders were within a few psi of each other, can't remember the exact numbers but we're well over 100 and from what I've read anything over 110 is acceptable on these...

What's the best way to smoke test? Do they make a tool to force the smoke into the intake through the booster hose?

 

[1955moose]

Look at our members posts. Their as cheap as $40.00 up to around $160.00 for the better ones. You can also build your own, theirs a sticky back in 2016 that shows how. Since you like fixing old neglected vehicles, kuddos by the way, I'd definitely get or build a smoker. As far as where to hook it to, the easiest/best spot is, pull the big hose that goes to brake booster, and feed the smoke through there. You'd be surprised where smoke starts coming out from. Even the exaust manifolds if their leaking exaust. You've got a bit of a project, but as long as your compressions good, you've got a sound motor. How many miles on your 4.6? 105-140 is the norm for compression. The important thing is their all balanced within each other, no one cylinder 20 or more pounds down from others.

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[crowncrazy87]

This one has 170k. My truck with 4.6 has 201k and my wife's expy with the 5.4 has 300k. I rebuilt it at 200k. That was the first time I've rebuilt a ford modular.