cam sensor update

[Guest Corvanti]

My experience is that Chevvys (SBC or 2.8-3.1) tend to burn oil & is usually valve guides. Buicks don't at least not in first 150k or so. Smoke on startup is symptomatic of valve guides, smoke running is rings.

Now is the smoke blue (oil) or black (gas) ? Have seen a bad coolant sensor make the car think it is very cold which results in an over rich mixture & stalling. MPG is also very bad then.

are you saying the ... '88/'89... GM 2.8-3.1-3.8, etc. were NOT used across the GM fleet?

there were many changes internally of the 2 cylinder "cutoff" (from the V8 short block) to construct the 231 c.i (3.8L) V6 Buick engine back in the 60's, and it took many years later to get it "right".

if my info i've grown up with is wrong, please let me know.

he did say "blue like smoke" (oil)... i also thought about the rings, but most of this type problem nowadays is a head gasket (hopefully not rings) .

agree totally if it was "black smoke", it would be a fuel problem. also, if it was "white smoke" it would be coolant leaking into the combustion system.

[Don Hudd]

Thank for the replies, something is leaking I think on the back side of engine as it is smoking there also like it is burning something off and it smells like oil. The smoke out of tail pipe clears up after idling for a while.

Cat has been removed several years ago. Mpg has not changed very much if at all. Would a bad maf sensor cause all this? I have cleaned it as posted earlier.

[Don Hudd]

quick question, I installed the cps and am wondering if not gaped correctly, how would the car run. I think I did it right, but car is still stalling

[Ronnie]

The gap will not effect how the engine will run as long as the sensor is installed correctly and isn't touching the shutter rings.

[padgett]

2.8-3.1 is a 60 degree chevvy. 3300-3.8-3800 is a 90 degree Buick. Two different engine families. Of the two (have had several of both) I like the 3800 a lot more.

[Don Hudd]

Thanks Ronnie, still trying to figure this thing out, just grasping at straws now I guess

[Guest Corvanti]

2.8-3.1 is a 60 degree chevvy. 3300-3.8-3800 is a 90 degree Buick. Two different engine families. Of the two (have had several of both) I like the 3800 a lot more.

ok, thank you. my "dementia" must have set in to forget about the 60 degree engine!

i still hold out that "maybe" buick designed the 3.8L, but most of GM used it in their vehicles by the mid-80's...

[2seater]

A bad MAF may cause all manner of issues. If the signal is bad, it may run better if disconnected. It will still not run properly, but it will tell you if it changes the behavior. Unplug the MAF and start the engine. (you should get a check engine light) See if it acts the same after it warms up. Alternately, you should be able to observe the MAF signal in diagnostics to see if it is out of the expected range or erratic. Typical warm idle MAF reading is in the single digits. The gram per second readout translates directly to air flow so it should increase smoothly as the throttle is opened, similar to the smooth increase in reading from a good Throttle Position Sensor.

Typical leaks at the rear corner of the engine would be coolant from the intake manifold gasket to the head, the valve cover gasket (oil) or exhaust from the manifold to head joint, EGR tube connection or the donut gasket at the manifold to exhaust pipe connection. You should be able to hear an exhaust leak. There is no gasket used between the exhaust manifolds and the heads from the factory but they are sold aftermarket. Headgasket, maybe. Would usually be coolant or possibly combustion gasses.

[Don Hudd]

I am going to start a new tread recapping this one and hoping for a solution, thanks to all who have helped, and hopfully someone can see what I'm missing