Oddball issues again. Sounds and poor vacuum

[Tedybear]

Okdokeys.

Our great 2.9 v6 is at it again.

Start up in the cold weather. Only have about 12-14 inches of vacuum. And the engine idles like crap. Coughs a lot and sputters. It did this when we first purchased it and it was clogged injectors. So naturally we attacked them first. All 6 pretty much peeing out fuel and not a mist. So they are now misting after a complete cleaning and new o-rings. (also hosed out the throttle body as well. Kinda gummed up with carbon)

Figured that would sort it out...no dice. (Fuel pressure is great. Just as expected and regulator is not leaking fuel into the intake, checked that as well)


If you start the engine and let it run for several minutes? Then it runs smoothly and the engine vacuum rides at about 18-19inches.


Now this ol' beast is a quieter one of the 2.9s. Or it was... Currently when driving down the highway or in town we have also now developed a high pitched sound that is best described as almost like a helicopter blades spinning---only at a much higher pitch. It was doing it prior to the injector work as well-- The frequency of the noise seems to be in tune with the engine RPM as well.

I'm planning on pulling the spark plugs and doing a compression test on it tomorrow (Sunday) morning. Also checking out the spark plugs to see if any are fouled. My gut feeling is something valve train related--but I hope I'm wrong, as we can't afford major engine work at this time. I'll post back the compression numbers and the plug condition. It's still drivable, just getting awful fuel mileage as well.

Sidebar notes: Also replaced the thermostat and cleaned up the housing. Hope full that will seal the hose (it was also replaced). We coated the thermostat housing with a light application of RTV Black. This was to solve the issue of the coolant seeping out of the neck when the truck isn't being driven and no pressure. (complete reverse of what it should be doing with a leak. Under pressure? No leaks. Let it sit overnight? Covered in coolant.)

Any ideas about the engine noise would be helpful. I'll post the info once done tomorrow. But judging by the louder then usual valve train noise?....my gut reaction says this will cost $$$$$

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[RonD]

Low but steady vacuum could be ignition timing.
High pitched noise could be distributor bushings
You probably have a TFI ignition system which have a 100% failure rate.

Good read here on testing TFI:
http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml


Also if you can duplicate the noise by raise RPM without driving, try removing the fan belt(s) and running engine, it will be fine for a few minutes without water pump.
Could be an accessory bearing is going out, these tend to be high pitch noises

 

[Road Angels]

2.9

Bad Idle, also low vacuum, dont think you have an egr on that one, if so start there, check the values on the temp sensor, for crap mileage, also check the fan clutch for the noise, maybe locked up

 

[Tedybear]

No egr (thankfully)

Disty was replaced a couple of years ago with a reman.

The TFI should get worse as it gets warmed up, if it's failed I would think. This is the exact reverse. Starts up stone cold running like dog crap, and after a few moments--back to normal.

I'll start with basics this morning after my bloodwork at the medical clinic. (I hate being both a cardiac mess and a cancer survivor mess).

Compression check, just for goofs. Check the plugs and wires. Cap and rotor should be decent--both got replaced with Accel parts a year ago as well.

That low vacuum has me stumped. Yes bad timing could do it--but shouldn't it do it all the time? It takes a few minutes to go into closed loop operation for the computer to take over timing--and this clears up after about 20 seconds.

I think I'll get more carb spray and hose out the IAC ports as well. It couldn't hurt at this point.

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[Tedybear]

Interesting day.

Compression test went flawless. 180 and 170's. Pretty much about the best result this ol' girl could have done.

The noise might be from an exhaust leak from the passenger side. Did find a small leak at the flange (that's going to be a treat to deal with). I'll pull the metal cover off the heat riser and see if the manifold cracked.

Now the interesting bit. This thing has some big time blow by. (Go figure? Decent compression and a lot of blow by) Pull the oil filler with the engine running--and it puffs out at a pretty good clip. And the PCV is functional and working fine.

So I'll pull the exhaust apart a bit on Tuesday and see what the condition of the manifold is. All spark plugs and wires are in great shape. Just a hair bit of carbon on the plugs. Not even worth attempting to clean. (very slight amount...barely noticeable)

Not sure about the low vacuum issue and running rough at idle for the first few moments of cold start. But slow progress and figuring out what it's not being caused by.

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[RonD]

Yes, with compression numbers in the 170's you would think rings wouldn't have alot of blow-by.

With vacuum gauge attached, engine running, open and close throttle quickly, if vacuum drops to 0 then goes to 20 you probably have bad rings, good rings would still show 2 on the test and come back up to 25 before dropping to 18 or so steady.

You could have bad valve stem seals on exhaust valves, that will blow exhaust in to valve covers, so mimic blow-by.

Leak down test dry and then with oil might be more revealing.

 

[Tedybear]

I'll admit I am a bit of a "Geek" with gadgets.

I have a 2" vacuum gauge installed in the dash <G>

The snap test is one I've not done yet. I can safely state when doing decel from highway speeds that we get about 25-26" of vacuum before it settles down to 18-19.

I left the truck at the garage (we are renovating a house with an attached garage, no heat---but no elements blowing through. Was working in a barn before.)

One would hope the upper end gasket kit I installed back when I put the truck on the road would be more "stout". (It was a FelPro set) Both heads replaced with World Products due to severe cracks. But it's something to consider, as we did reuse the valve train parts. (valves, springs, etc...New seals of course). It's been a few years, so there is no telling how things have lasted.

Pulling the shield off the manifold should tell me about that noise. It is 100% from the passenger side--and thankfully I swapped out the A/C box with a BII salvage box from a non-a/c truck. So there is a lot of room to work with.

I'll even post a youtube video of the noise. It's quiet when just idling. I had the wife mash her foot on the brake, put it into reverse and race the engine a bit. Once under a good load, the noise kicks up pretty loud. I can live with the exhaust leak for the time being, as it's to flippen cold to tear into things anymore in depth. (I just replaced the muffler and tail pipe-for the 3rd time sense I purchased this one. Totally scaled with rust to to the point it was like chunks hanging off the pipes.) Welcome to upstate NY and it's salt mine roads for ice removal.

I know this ol' girl has it's issues. The wife got her 2001 VW Beetle last year. Bought and paid for from the insurance settlement after her Tiburon got smacked into by an escort truck. As for my daily driver? This bronco has grown on me. Yeah it's very rough on the inside and out. But it's paid for and it so far has never left me stranded. (Even for the 2nd time with a blown transmission line. It still got me home--and then it wouldn't go into gear LOL. Fixed the leaky line---refilled..and it's like nothing happened? For a "crappy" A4LD? So far this one from a junk yard has been fairly good. (knock on simulated wood grain))

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[Tedybear]

Yes, with compression numbers in the 170's you would think rings wouldn't have alot of blow-by.

With vacuum gauge attached, engine running, open and close throttle quickly, if vacuum drops to 0 then goes to 20 you probably have bad rings, good rings would still show 2 on the test and come back up to 25 before dropping to 18 or so steady.

You could have bad valve stem seals on exhaust valves, that will blow exhaust in to valve covers, so mimic blow-by.

Leak down test dry and then with oil might be more revealing.

Wish I could do the leak down test. The compressor is still in the barn about 30 miles north. Not even sure if it still works, as the cold has really taken it's toll on it. I might spring for a Harbor Freight pancake compressor if money works out for the job.

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