begins missing at 2000rpm

[heavychevy98]

compression test should show up a valve not sealing for whatever reason. And did you say there was an issue with tps? if it was bad and if the tps ran it lean bad enough for long enough, you may have warped some valves.

 

[trx88]

thanks for the reply, yes the tps was trash.. im thinking it sucked in a lower intake gasket which sucks because I just put a spider in it and had all that sh&t off there..

ill run a compression test on it and reply the findings, im off today..

 

[trx88]

yeah heres my compression findings

1 3 5 7 all have 176 psi
2 has 176
4 has 160
6 has 80?!
8 has 176

what does this mean? head gasket most likely? damn

 

[sewlow]

No compression on one cylinder could be a few different things. Broken ring, broken pston, bent valve, broken or collapsed valve spring, intake gasket f'd up, cracked or warped head.
Ouch, that'a a lot of possibilities.

 

[trx88]

i know 160 is close but im assuming the two are related..

i guess i need to pull the valve covers? or look for a crate motor..

anyone have any suggestions?

No compression on one cylinder could be a few different things. Broken ring, broken pston, bent valve, broken or collapsed valve spring, intake gasket f'd up, cracked or warped head.
Ouch, that'a a lot of possibilities.

 

[trx88]

can a lower intake manifold gasket cause this issue? lord wouldnt that be sweet..

i know nothing of valve lash or adjustments..

 

[heavychevy98]

i'd say not. its outside of the compustion chamber so it'd be hard for that to make it lose compression. only other thing you could check without pulling the heads would be the valve springs, which would probably be obvious once the valve cover is off.
BTW, I believe when sewlow58 said intake gasket, he probably meant head gasket.

 

[SAATR]

Pull the valve cover and inspect the valve springs, rocker, and pushrod. Shouldn't be a lifter or valvetrain issue as you would definitely hear some noise out of a loose rocker or broken spring, but it's best to check. Squirt some oil down the cylinder and recheck compression. If it comes up substantially you have a ring issue or scored cylinder. Either would necessitate a rebuild or new short block. If it doesn't come up it could potentially be a head gasket, cracked cylinder, or cracked head issue, but you typically get overheating, push coolant, or get water/oil mixing with those. On rare occasions you can have gasket or head issues with no apparent symptoms aside from a loss of compression, and those are usually accompanied by a very, very clean piston and spark plug (steam cleaned). If none of those are present then a bent valve is possible. In any case, check what's mentioned above, and if you find nothing and you still have the compression issue then the head needs to come off.

 

[heavychevy98]

have you found anything yet?

 

[trx88]

havent looked yet i work a crazy schedule 12 hr nights two on two off three on two off two on three off..
im just now getting back and settled in but i will keep you all posted ill check everything tomorrow, thank you for the info

if it makes any difference the plugs had lots of ash on them on that side under those valves..

ill pull the valve covers and check it all out