Need some advice

[airbrushdel]

I've been looking through the threads and haven't come across my exact problem. Wondering what you all think it could be.

I just had the timing chain slip on my 97 blazer, after it was replaced, i have a total loss of power when you step on the gas. It idles fine, and moves a little. I've had it up to about 50 going down a slight decline, but if you push on the gas past a certain point, the engine slows, and if you push hard, it misfires a little. The first codes said it was the o2 sensors, which i replaced. (the left and right front ones) Now it still does the same thing, and the codes say low voltage on the o2 censors (131) (151). It also said it could be low fuel pressure, which was checked, and was ok.

I cleaned the maf sensor, replaced fuel filter, bank 1 and 2 number 1 o2 sensors.

Any other ideas of what it could be?

Thanks,
Del

[Joshua M. Smith]

It sounds like you're either a tooth off on the chain or you've bent a valve.

I've not heard of the 4.3 letting a valve contact the piston even with a snapped chain however, so I'd go with one tooth too advanced or retarded.

Josh <><

[Gabe25]

It really sounds like your timing chain is off 1 or 2 tooths.

[airbrushdel]

I was wondering about that. My brother inlaw did the timing chain, but i ruled it out since it idles just like it use to. Something to check out.
Thanks,
Del

[TRACYCULBERSON]

Originally Posted by airbrushdel

I was wondering about that. My brother inlaw did the timing chain, but i ruled it out since it idles just like it use to. Something to check out.
Thanks,
Del

I have seen this before .
They may idle fine but the timing is just a notch or two off.That is were the back fire and the power loss comes to play . I agree with the other replys

[rlith]

Agree with everyone else...Also if when he did your chain and didn't align it properly could be adding to the issue.

[airbrushdel]

One more quick question, When changing a timing chain, in a Haynes manual it says to set number 4 piston at top dead center on the compresson stroke. Is that right? I've always done it with number 1 top dead center.

This is the 97 4.3 vortec with the non adjustable distributor.

[rlith]

Originally Posted by airbrushdel

One more quick question, When changing a timing chain, in a Haynes manual it says to set number 4 piston at top dead center on the compresson stroke. Is that right? I've always done it with number 1 top dead center.

This is the 97 4.3 vortec with the non adjustable distributor.

Basically just make sure that the dots on the gears are aligned and away from eachother. Then when you drop the dist in, #1 should be TDC...Be are though, it's tricky. If you know everything is ok, and it doesn't start, more than likely you are a tooth of in either direction and you will have to pull the dist and reseat it... Takes me about 4 or 5 times usually (pain) a couple of times I've dropped it in perfect... Just wanted you to be aware