Problems with startup and knock after getting stage 2 cams.

[redhotjamedjimi]

Hey guys. I have been tuning my cobalt for years. I've had it since 07. Last summer I had a mishap in a large puddle and decided to rebuilt the top half of my engine after finding rust on the cams. I have zzp stage 2 cams now with 78# springs. I also have 60# injectors and a full 3" exhaust and an aftermarket intake.

I never had problems before with startup and or knock. Now I can't get rid of either problem. I have tried playing with timing and fuel and constantly have about the same knock. I just changed both axles and front bearing with no help.

Also my start up is a mess. It usually isn't starting the first time around. And I think I now have a chipped tooth on the flywheel from misc bad starting. I just had a new clutch put in this year as well. Basically an upgraded oem one.

If there any advice on what that knock could possibly be? (I am going to seafoam clean this guy soon I hope.)

Also any advice on a tune that would make start up work better would be great. It almost seems like it isn't spinning fast enough or something. My spark plugs are fine. (one step cold ngks.) And it back fires a bit after a failed start up.

I have included my tune and the latest scanner results. Thanks in advance for any help. This has been aggravating me for over a year now.

I would go as far as even paypalling the individual who can remedy my problems. Well worth it.9-29-14.hplcobalt2014.54startupwork.hpt

[codename Bil Doe]

1) More info on the puddle? Was it a puddle or more of a pool/lake?

2) What is bad about the startup? Not firing, shaking itself to death, sputtering, turning over rough, etc

3) Is the knock in the logs only when the engine is cold and gone when it warms up? Or, is it just because the car won't fire?

Paypal a "pro". Around here, help is for free.

[cobaltssoverbooster]

Did you replace the rods

[codename Bil Doe]

I don't have exp with this, but CCSOB definitely does. With LNF histos I can't see much of what's going on, but I can see your MAF is way off down low. It's upwards of 21% on the rich side.

[cobaltssoverbooster]

also did you follow the gm technical repair manual when timing the cams?
did you pull the entire front cover off to do the re-time?
did you remove the crank sprocket?

[redhotjamedjimi]

1) More info on the puddle? Was it a puddle or more of a pool/lake?

2) What is bad about the startup? Not firing, shaking itself to death, sputtering, turning over rough, etc

3) Is the knock in the logs only when the engine is cold and gone when it warms up? Or, is it just because the car won't fire?

Paypal a "pro". Around here, help is for free.

1) the puddle was a very large puddle slightly over a foot deep. I have a cold air intake and I sucked in enough to kill the spark. It wasn't entirely locked. It would still turn. The main problem at that time was the power in my car was dead for days and I couldn't get into my truck for a couple days.

2) It almost sputters, I tend to backfire once when I let go of the key. Once it starts, at all, it is good to go. It seems like it doesn't turn as fast now that I have heavier springs etc. I also am interested in what it will be like after sea form. Maybe sludge is making it go slow.

3) The knock is always. I usually never use those rpms for cruising. It is mostly when it is recovering after I go into neutral.

I have tried using a regular O2 a wide band and no O2 with all the same results knock wise.

[redhotjamedjimi]

I replaced all the valves, which in this car is the rods. I replace the idlers, springs and valves. Only thing stock is the rockers. When I tune it for maf accuracy I can easily get 1% accuracy up and down. I don't think it is a problem with one piston being weird.

[redhotjamedjimi]

That is 20% lean. I need 20% more gas. This is probably from dfco (also I have it only reading above 1500 rpm. no idle.) . I wasn't tuning for maf accuracy. I had just put an original oem 02 into the mix the computer uses. I figured this would help idle etc as widebands are bad at that. This is the wideband reading that isn't affecting the engine.

[redhotjamedjimi]

I used the gm and other manuals. I timed it cover off more than once for various reasons. It is timed correct. I never removed the crank sprocket. Though I think it has a notch so I couldn't mess that up anyway? I had a funnnn time doing all of that but I feel it is for sure correct. The aggressive cams I assume was just the different in idling and start up. I was hoping someone has heard of tips for big cams to start etc. Some trick of the trade.

[codename Bil Doe]

Yup lean my bad. If it was rich answer would be the same. Go back and fix that first. CCSOB is the man for everything else.

As an FYI for the future, if you ever hydrolock an engine and it dies the engine is fine as long as you don't try to start it again. You HAVE to pull the plugs and turn the engine over to expel the water or you will instantly damage it.

[redhotjamedjimi]

Thank you. And i know after much research. It basically sputtered dead originally and I had made it through the puddle. So it wasn't like I landed in a lake. I don't think that is my problem now. Though it may be the cause.

[cobaltssoverbooster]

so you took block apart as well?
you said this..."I replaced all the valves, which in this car is the rods"
this is an incorrect statement on its own. if you replaced the valves then you replaced the valves. the rods are in the block and on every motor valves are not rods.

Answer this, Did you remove the pistons from the block? i need to know the official answer for these questions or we can't help you very much

[redhotjamedjimi]

No I did not take the block apart. For the record it shouldn't matter after some playing around today.

I played with timing tables. Making them all the same and I lowered the timing and I lowered the fueling for the start.

It now starts fine. I may play with it a little more for quicker start.

The issue now that I have found out is that when the LTFT's reset, I assume from boundaries, is when it knocks when I am coming out of idle. I have a feeling I need to readjust the LTFT boundaries so they are constant through when I am in idle until I release the clutch. I am 90% sure how the boundaries work and am now trying to figure out the most effective way to move those boundaries to reduce this knock while not creating more problems.

Here is my tune and the scan from today. You can tell when the LTFT goes to 0 is when the knock comes into play. And only when that happens it seems.

I am sorry for the confusion and thankful for the help everyone. cobalt2014.57startupwork.hpt9-30-14.2.hpl

[redhotjamedjimi]

I thought you meant lifter rods. I didn't relace the pistons and rods as I wasn't ever completely water logged to the point it would bend them. Only enough water to stop my power at the time and such.

[cobaltssoverbooster]

well truth is you didn't measure the rods to check for bent ones period. there are no pushrods in an ecotec...please do some more reading.
good luck with your adventures

[redhotjamedjimi]

well truth is you didn't measure the rods to check for bent ones period. there are no pushrods in an ecotec...please do some more reading.
good luck with your adventures

I know there aren't push rods. I though that is what you meant lol. My car has been running for over a year and a half. It has nothing to do with that. I wish you didn't turn this whole thread into something that had nothing to do with my problem.

The knock ended up just being burst knock. Easy fix.

I am still working on the start up. It is better, but I'd love to know for sure what spark table my engine is using at startup. I assume the low and high octane tables. I assume mostly the high octane as the AFR is commanded rich. Would anyone like to clarify that for me?

[Speedytec]

ZZP LSJ Stage 2 cams...??
Did you measure cam lobe timing and base circle diameter? There were some faulty natches of these...

[redhotjamedjimi]

ZZP LSJ Stage 2 cams...??
Did you measure cam lobe timing and base circle diameter? There were some faulty natches of these...

I did not actually. I had not heard of this problem. It is running fine. I have it tuned all within 1% now. Could this be a problem for me?