Thread: Spark plugs gap getting hit shut?

Yesterday I was taking my car out to do some data logging. I just installed a z32 maf and 370cc injectors into my VE with bolt ons. I was running a calum base map for a sr20de+t with 370's and z32 maf, there for my timing was safe and the car was running rich at WOT. I was driving to the place where I do my street tuning and all of a sudden the car starts to spudder and I heard some clicking in the head. I pull over and turn off the car, restart it and the ticking is gone, but the car feels like it is running on 3 1/2 cyl's.

I drive the car home with it spuddering like this, and pull the spark plugs. Cyl #1 plug gap was closed and the plug looks like it was hit.


All of the other spark plugs are fine. I replaced the plug and the motor did not bend a plug again but it still runs like it is missing a half cyl. The car runs the same weather the spark plug wire for cyl #1 is plugged into the dizzy or not.

I pulled the valve cover off, set the motor to TDC and everything looks fine in the head upon visual inspection. When i pulled all of the spark plugs and looked down to the pistons there seemed to be alot of carbon build up on all of the pistons. Could this have caused a detonation in cyl #1?

I pulled the header off and the exhaust valves do not look damaged.

I put a long rod down all the cyl through the spark plug hole and hit the rod againt the piston to see if the bearings had any play. Everything seemed to check out here.

Next on my list is to do a compression check, and to pull the intake manifold off the visually inspect the intake valves.

I'm betting you'll find compression failure on that cylinder if a new spark plug didn't solve the problem. That looks like detonation damage to me, although it could be a rare case of pre-ignition if it happened that suddenly.

Have you checked the tb screws?

it certainly feels like there is a lack of compression in cyl #1. when i turn the motor over by hand. Cyl #1 feels like it compresses easier.



Yes, they are both still in tacked.

If indeed the screw fell off,it sometimes gets caught between the valve and valve seat. You can take off the vc and check the valve spring to see if anyone of them is compressed.

Nevermind that post then^^^^^

Looks like something got injested. Really the only way that could happen. Ive seen and heard detonation on an n/a motor and its very unlikely that it did that to the plug. Ive seen a starting tune on a ve that had way too much timing and was running a 14.7-14.9:1 a/f past 6k and nothing like that happened. Matter fact it didnt cause any damage. Its very hard to get enough detonation to do that on an n/a motor especially with a de-t basemap, lol.

Looks more like mechanical damage than detonation.

Look for other possibilities that something else may have been sucked up through the intake.

Pressurize the cylinder listen for an audible leak,, I'd really focus on the intake. Whee on the tip was it hit? Just inone spot are or few spots?

I have seen ve's start up on much worse tunes and never seen any damage.

I just dont see what else my motor could of sucked up. I run a filter 100% of the time, no peaces of the MAF or IAT, intake mani gaskets had no peaces missing were missing.

I will get to that once the motor is out and I can get it to someones house with an air compressor.

The plug looks like it was hit multiple times, and i defiantly heard something hitting in the head multiple times. The plug is hit all around not just on the crown. Pritty much every part of the plug that would be visible in the cyl is hit multiple times.

Im waiting on an engine hoist to pull the motor and a truck to go pick up a DE the throw in the car for now.