mzoomora

iTrader: (36)

I just did a compression test on my Z, and the results seemed pretty good. All of them were 150 on the first turn, then built up to 180 on the third. All of the cylinders were almost identical. All of the plugs were clean, although they did show they were rich.
The car was dynoed in the spring, did 320 through the exhaust, 330 with the cutout open. The A/F was pretty good also at WOT, cant remeber how much timing or anything like that. They did say that their dyno usually reads low about 10-20hp, but that still leaves more HP on the table. It idles like ****, worse than it probably should with the cam it has. I dont really drive the car much, so I havent noticed any oil being used or coolant loss, but like I said the plugs were clean.
Details of the car- 36k miles, MTI R1 cam (232/236 .575/.578 114), 918's, SLP LT's, ORY, SLP cat back, lid, bellows, LS6 intake, ported TB and MAF, thats about it.
I am thinking about doing a leakdown soon, but was wondering what ideas you guys might have. No codes are thrown, but the low rpm missfires were deleted anyway.
What next?

BLKWS.6

Rich plugs indicate weak ignition imho or incorrect plug-gap.

OHM out your plug wires with a volt meter, should be less than 15 ohms.
Check plug gaps
Change fuel filter and air filter (doubt thats the issue, but its probably time, huh?)

LS1-450

iTrader: (33)

Why does it idle like ****? Low RPM missfires deleted? What else is deleted; MAP sensor or TPS codes? Sounds like either an intake leak or a bad tune....maybe both. MAP sensor issues can cause a number of problems including idle, rich idle, & TPS codes.

Should also mention that 320 or 330 is way low for your set up if your describing your LS1. I would re-check your combustion chamber pressures/leak down test.

BLKWS.6

+1, I was thinking just what I would do for my 5.0, these things have sensors and I keep forgetting, lol.

mzoomora

iTrader: (36)

New wires, and they checked out fine.
I changed all the filters when I got it in the spring, so they are all okay.
Plugs are gapped according to specs. I was also thinking maybe a bad coil or something in the ignition, dont know.
I had a tuner on this site check out my tune, and he adjusted a few things so it should be fine. That along with the tune I paid for.
It has new Bosch 13111 O2's, and they are checking out fine.
The low speed misfires are deleted because of the cam, and the rear 02 codes, the MAF and tps codes are still in there.
As far as intake leaks, I had the intake off to change from a ls1 to ls6, and the driveability was there before and after. I may just pull it again anyway just to check it out. I have a set of heads I was going to install, and maybe a different cam, just concerned if the short block is good.

mzoomora

iTrader: (36)

Oh yeah, it did have a bad MAP and was replaced right after I got the car, no MAP codes since. It reads fine and the TPS tracks normally also.

LS1-450

iTrader: (33)

OK, if there are no MAP codes, then there is no leak or none to worry about. Sounds like another leak down test may reveal the problem. BTW, after losing 5 & 7 on my previous block, my car made 326 RWHP on 6 cylinders. Difference being that I have bigger heads. Never the less, you should be in the above mid to high 300's cam only (no heads) & maybe better.

BLKWS.6

Take a vacuum reading. Look for fluctuations which could indicate a valve-spring issue and make sure you have the right amt of vacuum.