part throttle higher load miss

[edcmat-l1]

you did lose me at the secondary ignition part though. no clue on that one lol

All automotive ignition systems are known as "Kettering" ignition systems named after the guy that invented it.

An ignition coil is basically a transformer, or "Tesla coil". They have a primary and secondary winding.

Automotive ignition systems are broken down into 2 parts for diagnostic and explanation purposes, primary and secondary.

The primary side consists of supply voltage and assorted wiring, triggering mechanism (points, electronic module, PCM driver, etc.) and associated wiring, and primary side of the coil (primary winding).

The secondary side consists of the secondary winding, spark plug wire, boot, etc. and spark plug.

Instead of saying it has an ignition miss I'm just being more specific in that it is definitely a secondary ignition miss, and not on the primary side, which would have a completely different set of symptoms.

HTH

[GHuggins]

i did do a compression and leak down test and everything seemed good. leakdown was less the 20% compression i think my lowest was 189 highest was 220.
did them all cold with cheap amazon tools, so figure the numbers aren't the most accurate but nothing really stuck out.

haven't gotten a wot run yet. tore the valve train apart making sure rockers and springs where good visually. everything seemed good. rockers all operated smooth, pushrods looked fine, springs i couldn't move any by hand and nothing looked broken.
probably wont get it back together till the weekend... its going to be hot as shit all week lol

thought about pulling the intake and inspecting/replacing the seals since i did reuse the old ones.

Your compression ranged from 189 to 220? You did a cylinder leak test and had as high as 20% (5 to 10 % is enough to signify stuck rings cylinder to cylinder)? Sounds like you found your problem to me... I'd start the leak test at 20psi and listen for air then crank it up to the 100psi setting. Rockers need to be in place with the pushrods to apply their preload.

Otherwise throw another set of plugs and wires at it then retest.

I also assume cats not present - no collapsed exhaust?

[blkchevyz]

i might be wrong on the 20%, it was in the green on the gauge. its was a very inexpensive tool, and i struggled with it because input air pressure really changed what the readings where. you turn the pressure up till the leakdown reads 0... what ever it was, each cylinder were about the same.
i didnt hear any air leaking in the crankcase, intake or exhaust.

[GHuggins]

Directions on how to "normally" use a leak down tester.

Hook up air hose to tool. Set tool to whatever pressure you're going to test on - usually 100 psi but this won't show valve seat issues which is why I stated to start at 20 psi and crank it up slowly from there to 100psi. However for normal use - After achieving the 100psi on the tool setting (actually the 0 leak point on the secondary gauge) you then hook the tool up to the hose already installed in the plug hole after you make sure it doesn't have a schraeder valve in it. What the leak gauge goes to from there on the second gauge is your cylinder leakage percent...

Even though it won't show a valve seat issue, setting it to 100psi or 0 leak then hooking it up to the hose already installed in the cylinder is the most precise reading you can get. Otherwise cranking it up after the hose in the cylinder is hooked up skews the reading and makes it worthless as you can technically crank it up till it shows good. You're more so listening for the leak by starting at the lower setting and cranking it up from there and not going by the actual leak percentage doing it that way. All engines leak, just depends on how much and where it's going.

You also technically need to have that cylinder at tdc compression stroke for testing. Just watch out for engine spin as it will if the piston isn't perfect.

I was the go to drivability tech for nearly a decade at the steelership I worked at before getting sick and tired of it and getting into the AM

[blkchevyz]

8-29.hpl


there is a short wot run at the end.

[edcmat-l1]

Check the screen shots. Notice how only the B2 has these sharp downward spikes. It still looks like it has a light load miss.

In my experience these will misfire under light to moderate load and a lot of times actually pick up the cyl. under WOT.

I would get it in high gear at a lower RPM and speed and apply some throttle. It's more likely to miss aggressively in that scenario than under WOT.

[blkchevyz]

yeah that is where i notice it, at a higher load mid rpm, someone just asked for a wot.

so is that what a miss looks like on the o2 sensor? a sharp spike?

[edcmat-l1]

yeah that is where i notice it, at a higher load mid rpm, someone just asked for a wot.

so is that what a miss looks like on the o2 sensor? a sharp spike?

Sharp downward spikes. Especially when one O2 looks nice and smooth.

Footnote; sometimes the amount of pids and sample rate screws with the smoothness of the pattern.

[blkchevyz]

https://youtube.com/shorts/SpYemxoWIfM?feature=share

short video of it running with the valve covers off.

[GHuggins]

Stupid question, but where's the oil? Sure you got a good seal on the oil pickup?

[blkchevyz]

it was making its way up, i turned it off a few seconds later because it started spraying the headers with oil.