Plenum leak without oil consumption.

[Bear_Gibson]

1st, Has anyone ever had a blown plenum without the oil consumption?

A week ago as I was turning into work my truck seemed to loose all its will to get going. I left work and it felt the same, I was really afraid something was going on in the transmission because it just didn't have any low end power. After servicing the trans fluid and filter I went out and flogged it, and it's definitely not slipping. It use to knock you back when you'd take off from a stop. Not it feels spongy at low speed. With the aftermarket filter setup you can hear the throttle open, but it just feels like you're towing a house untill you get up past 2000 then it comes on like freight train. I have checked the cat with a pressure gauge and it barely moved under acceleration. I also placed a bore scope in front of the cat and it isn't clogged. It sounds great other than being gutless. All the plugs are brown and less than a year old. They still have a .040 gap. Its not using any oil other than what it is slobbering from the valve covers. No codes. No check engine light. I'm planning to do the plenum gasket this weekend if I can't find anything else. I checked to see if it still had vacuum at the valve covers after removing the PCV hose, but it read zero. I'm really at a loss here. I have no clear direction. Ideas?

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[Bear_Gibson]

*Crickets*

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[Bobby Trott]

Please let me know when you find out your answer I think mine is doing the same thing

 

[Bear_Gibson]

I have a couple threads here trying to sort this out. I'm still hunting for the issue

 

[SNAKEBIT]

have a 2011 1500 4x4 that does the same thing. dog when you put pedal to the floor.
if you let up a quarter of an inch from the floor she will start screaming!!! has to be something in the programming on mine, as it has done it since new.
also mine has 168000 miles and as of 10000 miles ago now uses a quart of oil every 1000 miles. never did before.
no leaks to be found, no smoking exhaust.

 

[Bear_Gibson]

The newer engines use such a light oil to increase that mpg that it could just be slipping past the rings. As for my ole Dodge, letting up doesn't help. It does have a tune, but I haven't seen anything when logging that throws up any red flags.

 

[ViolentMouse]

You said you have a tune? Do you have any other aftermarket parts?
What do your fuel trims look like?
Have you tried resetting the adaptives table to see if it clears up?
Have you logged your o2 sensor data?

If your timing chain is getting ready to let go, your cam timing could be ********. This will make it a dog in the bottom end and move the peak power higher up in the RPM range.

imagine, of +4 degrees of cam timing can move your powerband down 500RPM, then -4 degrees of timing will move it up, if your converter comes on at 1000rpm and you are not making power until 1600-2000RPM it will feel like a lame dog.

Check your timing chain for slop by moving the crank back and forth while watching the rotor under the distributor cap.
You can use the timing marks on the front of the motor to give you an idea of how much slop it has.

If it isn't ******** cam timing I would be looking at fuel data (trims, not fuel pressure, as that would act opposite)

the only other mechanical failure that I can think of that turns these into total dogs is when the converter is about done, it just wont come on and feel sluggish all the time. feels like driving through mud, it will rev up and get going, but still just feels heavy.

 

[Bear_Gibson]

I'm 99 percent sure the stator clutch in the torque converter has failed. It has a tune and a slightly less restrictive exhaust. Otherwise stock. I had re did the plenum a few months back thinking that was my issue. I also replaced the trans fluid and filter here.

Since then i have had to replace the fluid in the trans again from discoloration. The fluid lasted 2 months. There was no abnormal debris on the magnet. Since the only performance lost is below 2000 and I have tested everything else. The converter is the only thing left.
175 psi compression.
60+ fuel pressure driving.
Vacuum gauge steady as a rock
New catalytic converter
New o2 sensors
New map sensor
New tps sensor
New IAC valve
It is pulling a little fuel and timing out, but nothing that would warrant a significant low end power loss.

 

[ViolentMouse]

I had a 97 that fell on it's face under 2200 RPM and would just come to life after that and run hard all the way to 6k.
I replaced everything, when an old man popped my distributor cap and moved the crank back and forth to measure the lash in the chain. turned out my chain had given up the ghost and I had jumped a single tooth. I was ready to throw in the towel. I won't lie and say it didn't throw a code, but I was hell bent on fixing it without the aid of a scanner and it had a check engine light for years due to the lack of cats. Which is why now I always make sure my FI vehicles do NOT have codes laying around so I know when there is an issue lol

If the TC had a failure, they usually rattle when in gear at idle. (whereas the flexplate rattles in neutral at idle.) Also, it would shudder pretty bad going into lockup.

The stator bearing would not cause engine sluggishness, it would cause movement sluggishness. In simpler terms, the engine would have no problem accelerating but the vehicle would. Very similar to slipping. If the stator one way bearing fails, any fluid hitting it would cause it to move backwards not direct the fluid from the impeller into the turbine. This would feel more like converter flashing you would hit the throttle, the engine would rev up and the truck would slowly start moving until the impeller and turbine started to speed match at which you would feel the converter start to grab and start making power.

Again, those one way clutch bearings are roller style and if they failed, the TC would make a ton of noise.

Now you could have a rotted stator, where debris in the trans fluid have over time sand blasted the louvers on the impeller/turbine/stator witch would not make noise, would still put a ton of drag on the motor and yield no movement in return.

I would not rule out the converter, but I would 100% check mechanical timing lash first.

 

[Bear_Gibson]

I did the timing chain a few years back. Whatever broke did so when accelerating from a stop. It feels like you're taking off in second untill you get above 2000. I know that it is starting off in 1st because the engine rpms are correct and manually shifting changes nothing. I can physically feel it hit all 4 gears. The first day it messed up it was making a sound like a belt slipping on take off. I've heard that the spline shaft for the stator can break loose from the pump housing. For me a malfunction stator explains what the truck feels like. No take off power, normal opperation above stall speed.

 

[scrounge]

To the question in the OP, a qualified yes. In city traffic without heavy acceleration, my '99 with a 318 doesn't use much oil, if any. But when speeds are mostly around 70 mph (higher in Texas), it loses roughly a quart between fill-ups.