sethsuperpro

Hello, I'm a first time miata owner, I have a couple friends that have miatas and have just dove in and bought a 1999 NB with a clean T3 turbo set up. Unfortunately one of the cylinders has about 120psi compression and two have 140psi and the last one has 150psi, mind you the car has 180k miles but still should be nowhere this low. The car doesn't run it cranks fine and the last owner said he was able to start it a few months ago by pumping the gas. My friend ruled out the cam position sensor as an issues as he has multiple miatas and just swapped a functional sensor on mine. We also tried spraying starting fluid in the intake with no avail, just a few backfires. When we bought the car my buddy brought a camera to look into the cylinders, and the pistons don't appear to be burnt. I've assisted my friend in a headjob on his miata so I don't mind getting my hands greasy, I really would love to get some input on what my issue/issues might be. Thanks

sethsuperpro

Oh forgot to mention I also have spark.

technicalninja

Compression goes to **** with extended storage.
Those numbers wouldn't worry me AT ALL with it not starting for months.
You have more than enough compression to run it to temp.
Get it running and then drive it aggressively.
I would wire wastegate OPEN to reduce the possibility of destroying it under boost.

Just letting one idle to temp will not get the pistons/rings hot enough to "fix" weak compression.

I once had an aircooled VW we let sit a year and when it came time to re-start it had cylinders as low at 40 psi.
I thought it was gone...
After getting it started I drove it WFO. AT first it wouldn't go 50 mph and then it got better and better as I drove it further.
After 1 hour of ******* the turd the compression was back up above 100psi and we drove it a couple of more years.

You're not broken yet in my book.
Do not trust an aftermarket turbo car under boost until you've done a whole bunch of testing and verification.

If the fuel in the tank is more than 6 months old my first job would be changing that ****.
You need to verify fuel pressure as one of your first checks...

sethsuperpro

Alright thanks for tips, I appreciate it.