99 Chevy tahoe is Tapping and high pressure

[schube1255]

I need some advice,
my tahoe drank some bad delaware gas and I havent serviced it in a while. It was running really rough and throwing codes. po300 - po 305 - po 172 - po175 - and oxygen sensor on cat. was bad.
I installed:
distributor cap and rotor -
new spark wire set -
new spark plugs -
oil change -

still ran like shit - rough idle and pressure changes
I took it to a mech and he said it was the fuel injector.

I replaced the fuel injector and fuel pressure sensor. lots of carbon buildup

Now it is tapping loud - but runs good - I did a compression test and read 190psi on 7 cylinder and 150 on #2 but it runs good just taps really loud and the tap isnt going away.
I pulled the valve cover and tested the pushrods and all looks good.
I dumped in a can of seafoam and it seems to be running good , It just taps or knocks really loud.
Any help would be greatly appreciated.

[SunlitComet]

:welcome:
can you give the pressure reading of the other cylinders as well please.

---------- Post added at 02:46 PM ---------- Previous post was at 02:42 PM ----------

Your truck is running really rich. What brand and # of part did you use to replace the fuel injection spider and what fuel sensor are you referring to? Also names and # of parts you have done already?

[schube1255]

all 7 cyliders are reading 190 psi #2 is at 150psi

I used AC delco parts but the injector is made by GB injectors - it is OEM part

[SunlitComet]

Cylinder #2 is below the 20% variation allow between the highest and lowest pressure and that need to be addressed. #2 valve may be burned or may be leaking a little from some of that carbon build up. How did you do your seafoam and how much exuast smoke did you get from it. Can you be sure the noise is not from a bearing or rod? What was the condition of your spark plugs when replaced?

[schube1255]

I put i can, about 12 oz. into gas and some seafoam spray into throttle body - while running - very little smoke - brand new gapped at .060 plugs

[SunlitComet]

I was asking about the plugs that were placed. And again can you be sure the noise is not from a bearing or rod? Is it possible to get a audio or video clip of it?

[retorq]

Pull a plug wire one by one while the engine is running, if the knock goes away then it's something wrong with that cylinder ...

[schube1255]

Thank you so much for the advise -I am going to try the pull the plug wire trick, and I will shoot some video of the engine -

This one has got me - really all I did was replace the spider injector - it was not tapping before ,just runnin like chit. Now it runs great but sounds like a diesel tap. I used a homemade scope and cannot pinpoint where the noise is coming from -but it is pretty loud.

I also have a computer plugged into the truck and everything shows perfect, no codes - everything working ?

[retorq]

Flywheel to converter bolt??

[BattelWagün]

That's more of a rattle though, but always a possibility.

I'm thinking its carbon buildup from that bad gas causing a valve not to seal properly.

[SunlitComet]

If the noise goes away when you remove a plug like retorq said that would be a rod knocking at your door.

---------- Post added at 11:31 AM ---------- Previous post was at 11:28 AM ----------

That's more of a rattle though, but always a possibility.

I'm thinking its carbon buildup from that bad gas causing a valve not to seal properly.

I have had a tranny bolt do that too.

[schube1255]

Here is a picture and video of my 99 Chevy bitch 120000 mi


http://i126.photobucket.com/albums/p105/eezzeee/t99.jpg

Click the link for the video - its louder on the vid than in real time

http://s126.photobucket.com/albums/p105/eezzeee/?action=view&current=100_0799.mp4

---------- Post added at 02:41 PM ---------- Previous post was at 02:35 PM ----------

Here is a video of my 99 Chevy bitch 120000mi - click link - it is louder on the vid than in real time

[ezdaar]

Tapping is more than likely a deqd or stickng lifter.
I will share a old school trick that was used long before any cleaning chemicals was avalible.
Trans fluid, get yourself a shotglass, have engine fully warmed up.
Pour one shot of trans fluid into oil fill, let idle for 15 mins.
If it doesnt go away or start to change volume, pour in second shot.
Listen carefully for changes! By se ond 15 min idle if. Noise doesnt go away, let it sit over night.
Fire it up and let warm up. Noise should be gone completly.
If not its dead lifter, bent pushrod or rod knock.
Regaurdless, change oil.
To check for bent push rod. Pull one at a time, clean it with steel wool then roll it on glass, if it wobbles. Replace it. Also that lifter is suspicious.
Write anything you fi. Down and check them all.

You can start on your low compression cylinder, as its suspicious alrdy.

Btw, after running the trans fluid, recheck compression. You may find its higher than the initial 150, as comperssii. Rings do stick due to carbon fouling.
Pouring a shot of trans fluid directly into that cyclnders spark plug hole, and lettng soak over night is best method of freeing stuck rings.
then while plug is out and coil unpluged, crank motor over untill no more trans fluid sprays out of plug hole.

You will want to change oil after these methods as trans fluid is a bigtime detergant and will eat up all oil sludge, carbon etc. But will ruin the oil.

Back in tye day we would pour in almost a quart of tranny fluid to clean out severly gunked up engines, even would pou it down the carb throat to clean valves.
Just now days with everyone going green and a million types of cleaners. The old but best methods are forgotten.

GL on tracking that noise down.

---------- Post added at 02:06 PM ---------- Previous post was at 02:05 PM ----------

Btw, i typed all that on my iphone.

[SunlitComet]

valve train buddy.

you may have to reinspect them all and perehaps remove the heads if you can't see anything with a boroscope thru the plug holes.

[schube1255]

Thanks - I was told that tranny fuild might work but I was worried about the detergent .
I will give it a shot.

EzDAAR - I hope you were driving while textin that

[ezdaar]

O I certainly was!
Was on freeway doing 90! and putting on my eyeliner!

Do both the trans fluid in oil and trans in cylinder back to back so you only change oil once, and it lets the detergeants work longer in oil.

[schube1255]

Well - I tried the tranny fluid in the oil trick and it worked ok but did not rid the noise.
It is a lot better, but when I give it gas it taps.
All of the lifters and rods look like new - the comp. test now is 150 psi at all cylinders
and it runs and drives good. It just taps or knocks.
I did notice a missing screw tab ( made of metal ) inside the plenum . and previous work done.
maybe it shot through and bent a valve. I really cant pinpoint the knock yet, and really dont know how to replacevalves and such.

[SunlitComet]

you start by removing the heads. valves are easy stuff.

[retorq]

Replacing the valves is easy but you gotta be careful and you have to have the right tools.

I had a screw in stud loosen up on me, sounded a little like that. Did you check your rocker arms to make sure none were loose??

[schube1255]

Thanks for all the help -
but I need a little more advice..

If by some chance the new fuel injector was numbered wrong or if I crossed the injectors would it run - what would it do??
I mean like when I installed the new injector - if by mistake I put 6 into 8 and 8 into six --- or 5 into seven. ??? would it run ???
the injector was numbered and the manifold was numbered 1 - 8 I dont think I messed them up but I did rush.


I took it out for a spin today - it ran awesome - uphill, down all over runs great , but it still taps on idle - when i get to about 30 mph I cant hear any noise at all , like its perfect. but when I take off it taps. - the tap has quieted down but is still there.

[ezdaar]

post a new vid.
this time hold cam down by oil pan, torque convertor cover,
Both left and right valve cover..

Hold it nice and still for like 10 seconds each location..

Try to get a feel for where the sound is the loudest...
You can take a PVC pipe or basicly any long tube ( I like to use paper towl tubes), Hold it to your ear and point it towards various sections of the engine.. You WILL find where its coming from..

When you changed oil, did you inspect it? how mutch metal flake was on the magnet drainplug?

Do you by chance still have the old oil?
Was conatainer clean before draining oil into it?
if so go pour it from one container to another through a coffee filter.. look for chunks..

You need to pop them valve covers off, pull plugs and while rotating engine.
Watch for each valve to completly close.. Check rocker for play. both side to side and up n down..

Now that you ran trans through it.. since noise hasnt shut up and and all cylinders have come back with 150 across the board.
Its time to look for collapsed lifter. If you dont find one, its most definatly rod knock.

I would start thinking about what your going to do if indeed it comes to rod knock.

[schube1255]

The old oil came out thick and black - I did an oil/filter change 1 week ago - nothing in the oil - no metal - thick and nasty but no - lumps or anything hard. I will reshoot vid tomm.

If it is rod knock, I have full coverage ins. I guess I will run it into a tree ---

[SunlitComet]

The engine is cast iron so make sure your drive real fast and hit the tree real hard:D

[schube1255]

Hello - here is a vid of the underside of the engine - sounds like its right in the middle bottom - really dark for some reason but there are no leaks

http://s126.photobucket.com/albums/p105/eezzeee/?action=view&current=100_0807.mp4

and here is the top again -

http://s126.photobucket.com/albums/p105/eezzeee/?action=view&current=100_0806.mp4

I tried to pinpoint noise with a 2 foot piece of plastic pipe - I think bottom passenger side - but still not sure - rods and lifters looks fine on both sides

here is a pic of a the bad injector and you can see the gas was leaking from the fuel regulator - cleaned that side nicely.

http://i126.photobucket.com/albums/p105/eezzeee/100_0796.jpg

[Trippers99hoe]

If the trans fluid trick helped ,Try a fresh oil change with a quart of Marvel mystery oil replacing 1 quart of oil.
I have an 01 montana that developed a stuck lifter and have been running like this for 2 years....

I listened to the vid....if that is a lifter it is fully collapsed hard to say for sure from the clip,but it sounds deep......