The Stupid Engine Questions Thread

[Hezsus]

Hezsus, you'd need some kind of scanner that can read the CMPRET PID (cam offset retard) to get the cam position 100%, its REALLY sensitive, you might be able to mark and reinstall the distributor and get it close enough to not throw a code, which is fine, but for it to be 100% you'd definitely need a scanner, a shop or dealer should be able to check it for you if you wanted, but I don't know what they'd charge, its really easy, but they might have to charge an hour's rate or something even though it's only like a 15 minute job...

-12 to -14 trims are pretty rich. though with the poppets and only a mail order tune there may not be much you can do about it...the gas cap code might be due to the cap not sealing well enough, the gasket in the cap does wear out after a while...

I guess i should have mentioned I burn a fair bit of oil too, about half a quart or more every fillup, Its never really bothered me before but latley i've noticed more smoke, possibly because of the addition of a cat.
I know it misses and burns oil with stock pcm as well though, havent checked the trims stock though, i'll look into that.
The engine was rebuilt when I bought it so it could be possible the dizzy was not set proper then.

 

[Aloicious]

you may be wise to do a compression test if you're burning that much oil. mine has roughly 150k miles and I go through less than a quart per 3000-5000 miles...1/2 quart or more every fillup is really excessive, do you have any leaks, or is it all getting burnt off?....if you're getting smoke I don't think it has much to do with adding a cat, or any PCM related issue...I'd say its more likely either valve seals, or rings...

as far as the distributor, this is how to install and set it, you can pull it and re-install it very close, enough to not set the code. but you'll definitely need a scanner to set the CMP offset 100% accurately...
http://www.gmtruckcentral.com/articles/distributor.html

 

[Hezsus]

I figured It was valves or something, But I was also told that knock or ping can cause oil burning as well.
My valves are noisy, mabye if one is too loose I could burn oil?
I'll check out the distributor more tonight, try pulling it to see what the gear looks like, then go from there

 

[Aloicious]

loose valves wouldn't cause oil to be burnt, though it can cause unnecissary wear to valvetrain components, and depending on how 'off' they are, they can cause other problems...I don't really see how pre-detonation could cause oil to burn either (any appreciable amount anyways, unless there is major damage it has caused) however, the reverse of that is true, oil deposits combusting into carbon in the combustion chamber can result in ping...

from the sound of things, that engine might have some serious problems...definitely do a compression test on it...how many miles has it had since the rebuild you mentioned? ping/pre-detonation is NEVER normal, in fact the PCM should be pulling timing as soon as it detects any pre-ping (before you would even hear it)....the fact that you are hearing it is a bad sign...what octane fuel do you run on it? try running the highest octane fuel you can get in your area for a few tanks and see if the ping improves at all...

 

[Hezsus]

loose valves wouldn't cause oil to be burnt, though it can cause unnecissary wear to valvetrain components, and depending on how 'off' they are, they can cause other problems...I don't really see how pre-detonation could cause oil to burn either (any appreciable amount anyways, unless there is major damage it has caused) however, the reverse of that is true, oil deposits combusting into carbon in the combustion chamber can result in ping...

from the sound of things, that engine might have some serious problems...definitely do a compression test on it...how many miles has it had since the rebuild you mentioned? ping/pre-detonation is NEVER normal, in fact the PCM should be pulling timing as soon as it detects any pre-ping (before you would even hear it)....the fact that you are hearing it is a bad sign...what octane fuel do you run on it? try running the highest octane fuel you can get in your area for a few tanks and see if the ping improves at all...

I pulled the dizzy last night and the gear looks good, a slight ammount of play in the shaft though, and I broke the cork? seal it had, less play without the seal though.
I think i can buy an update for my scanxl software to let me see the cmprt pid and i'll check it to make sire it is right on.
right now i'm running regular octane, 87 i think it is here. I tried all 3 of my pcm's last night (stock, mileage and performace and there was ping on all of them, least on stock most on performace, performance is designed for 93 octane though)
Mabye part of my recent oil burning is that i switched from running 10-40 to 10-30 because of availability, I'll try switching back and see as soon as i get some more 10-40
I'll also try higher octane as soon as this tank is done.
There is 100k kms on the rebuild and I was told when I bought it that it had noisy lifters since the rebuild, I've also been told noisy means there not overtight which is worse I guess?
Engine also has a mild cam, and msd ign module if that means anything.
It does foul plugs becuase of how lean it is running as well, I've tried a few diferent types and im using rapidfires now.
I'll do a compression test as soon as i get a guage and post the results.
ps, is there a way to take off drivers valve cover without removing a/c bracket assembly?

 

[Aloicious]

you shouldn't be burning that much oil with 10w30 either, stock spec is for 5w30...the ping is likely a direct cause of the lean condition, especially if you're fouling plugs that it's burning so lean, that is definitely not a good thing. were your tunes setup for the cam you're running? if you're getting less ping on the stock tune, I'd run that one until you get it figured out.

the valves should be adjusted for ~1/2 turn past zero lash...some specs may be a little more, some less, most are going to be between 1/2 and 1 full turn past zero lash....over tightening is just as bad as undertightening...

you don't need to fully remove the AC bracket, you can loosen it up a little and just pull it away from the block slightly and you should be able to get the valve cover off.

 

[Hezsus]

you shouldn't be burning that much oil with 10w30 either, stock spec is for 5w30...the ping is likely a direct cause of the lean condition, especially if you're fouling plugs that it's burning so lean, that is definitely not a good thing. were your tunes setup for the cam you're running? if you're getting less ping on the stock tune, I'd run that one until you get it figured out.

the valves should be adjusted for ~1/2 turn past zero lash...some specs may be a little more, some less, most are going to be between 1/2 and 1 full turn past zero lash....over tightening is just as bad as undertightening...

you don't need to fully remove the AC bracket, you can loosen it up a little and just pull it away from the block slightly and you should be able to get the valve cover off.

Alright, I'll check my cmp retard, then tighten valves, check compression and fuel pressure(and change filter since its year old).

Ill try and burn through that tank of gas this weekend and put some premium in

 

[Hezsus]

Also while i have the plugs out what should I gap them to? I believe I had them at 50, should I open them back up to 60?

 

[Aloicious]

yeah, I'd just do a running valve adjustment if you're familiar with doing that....the compression test should help out too, in fact if you do that before pulling the valve covers, it might save you some time since the compression test will help determine if it's the piston rings that are letting the oil past, or not. if it's not the piston rings, then its most likely the valve seals which can be replaced when you remove the valve covers...if you have an aircompressor and adapter to compress the cylinders with it through the spark plug hole...

also I don't know how familiar you are with compression testing, but run the test on the engine as is, the lowest cylinder should be within 10% of the highest...and post up your numbers too...then run the test again but squirt a little oil in the cylinders first...if the compression test goes up with the oil, then its likely you need rings....if the oil doesn't affect the compression, and your numbers are okay, then your compression is okay and you likely just need some valve seals....if the oil doesn't change the compression and your numbers are low, then you might need a valve job (i.e. seating the valves to the head correctly done by a machinist), and you may still need valve seals with that scenario too...

 

[Aloicious]

Also while i have the plugs out what should I gap them to? I believe I had them at 50, should I open them back up to 60?

.060 is stock specs, gapping them at .050 won't make much of a difference, I wouldn't worry about that, but you can open them up to spec if you want....I ran at .045 when I had my supercharger on.