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99 Suburban 5.7 Vortec timing

Hi,

Sorry for the long post.

My waterpump developed a leak from the weephole so I changed out the water pump. It immediately started pukeing coolant from the driver side intake manifold gasket. I pulled the intake and changed out the gaskets.

I've put it all back together and it starts but idles very rough . It'll pick up RPMS but if I put it in gear and try to move it it pings like mad and dies.

It cools fine now and doesn't leak any water.

I'm 99% certain I got all vacum lines and electrical connections hooked back up properly.

I rented an ODBII scanner and it reported P300, random misfires.

My timing procedure was this...

1 - pull #1 spark plug

2 -rotate engine with socket on crank till compression is felt in #1 cylinder.

3 - continue rotating engine till mark on harmonic balancer aligns with timeing mark on chain cover.

4 - line up dimple on distributer shaft with white line.

5 - rotate oil pump drive shaft with screw driver.

6 - test rotor pointing at the 8 on the distributer housing.

7 - repeat steps 4,5,6 many times until rotor is pointed exactly at 8.

8 - Cuss a lot from all the bruised nuckles from the socket slipping off the crank while one finger is shoved in #1 Cyl.

Did I miss some obvious pertinant step?!?

Any other causes of the horrible running/pinging besides timing?

Thanks Rusty

Reply to
wilmesr
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I checked the ODB scanner again this morning and it's reporting a misfire on #4 (p0304).

I didn't let it run long but suspect it would report the random misfire

again. Its running way too rough to be just the #4 cylinder.

Reply to
wilmesr

My '99 Suburban, 5.7L, has been failing w/ the P0304 for over a year or more. Normally only does it under a strain on long hills at highway speeds. I did a complete ignition tune-up from the distributor through the plugs since it was around 75K miles and still had the issue. Had to replace the intake manifold gaskets as expected on that engine so replaced the #4 injector while there. While it runs better and rarely throws the P0304 anymore, IT STILL HAS done it. Runs like crud for a few seconds then settles down and never has issues for some time. Don't know if some carbon is building during those times or what. It's a mystery!

Reply to
Kevin

Heck - at least you can drive it! :)

The only thing I can figure out is that either the timing is really hosed or the manifold didn't seat on the gaskets properly. I'm not getting any water into the oil and a timing light shows the marker about 5 degrees BTDC.

I'm seriously stumped.

Reply to
wilmesr

No input at all?

TIA, Rusty

Reply to
wilmesr

What would you like to know?

Reply to
Slap

You can't check the timing that way. There is no adjustment for "timing"on these engines. All you can adjust is the camshaft sensor and you need a scan tool for that.

Ian

Reply to
shiden_kai

I was only using the fact that I can see the timing mark with the light as a rough indicator that it's somewhere *near* where it's supposed to be.

I found a GM forum here

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After many variations I'm still in the same boat.

The only consitency is the p0304 error. Could one misfireing cylinder cause the truck to barely run at all?

Reply to
wilmesr

My gut feeling here is that you have a massive vacum leak which would explain rough idle and lean mixture wanting to ping and sensors are out od whack because of leak. I would tear it back dow and recheck everything because I think you problem is there. TImes generally will not make a engine really rough but vacum leaks will.

Reply to
SnoMan

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