Interesting Problems.

[FusionCola]

Hey guys! I finally got around to doing a compression check on my motor. They read 120, 120, 115, 120 cold. I couldn't get a warm reading because I couldn't get the thing to kick over. When it does run it runs really well and doesn't feel down on power or anything like that and also runs decent afr's from 11-12 throughout the powerband. Now I know the numbers are ridiculously low, but considering they were all within range of each other I'm thinking that my starter could 1) not be getting enough power, causing it to turn the motor over slower than need be for the compression checker (This could possibly explain why my starter will stall when cranking the motor) or 2) The starter is just bad. It could also be that the compression tester I was using was borrowed from a friend and wasn't in the best of shape, so it could have been leaking. When the starter stalls out the car hits a compression stroke and then the starter will freeze up and won't kick the motor over, it makes a wub sound. I'll try to get a video of it soon. The battery has been relocated to the back so I'm thinking that maybe it's suffering from an amp drop from the added amount of cable. I bought myself a new tester and will check probably tonight or tomorrow and will update the thread.

Nistune with a different tune on it is installed so I am also looking for a regular ca ecu so I can run the diagnostics on it and see if the new ecu will help with the problem. The nistune is tuned for a vg30 N62 maf. My car has a J30 maf. The nistune is also set up for 450cc DSM injectors and my car has 370cc injectors with the fuel pressure turned up to compensate (I know it's not the same, but I'm just trying to get the car running. I don't drive it.)

Things I have already messed with:
timing is dead on
CTS has been replaced with a new unit
No boost leaks
Possible vacuum leak at the iacv.

Any and all help is welcomed! Thanks in advance for the advice! I'm tired of turbo motors already

[boost_boy]

I would start with making sure your starting system is adequate enough to provide you with a good basis for checking your compression properly. Lastly, unless you have someone preofesionally setting up that Nistune system for you, your problems continue.

[FusionCola]

Figured out my starting issue, or at least one problem of many. I had an extra ground running from the intake manifold to the chassis. Along with another ground from the back of the motor to the chassis. Apparently this wasn't enough and the motor didn't have enough grounds. Threw an extra on the head to the strut tower just to try it and it kicks over normally now without the starter stalling/freezing. It also fired on the first attempt and continued to fire every attempt after that. My nistune was throwing a CAS code so I'm thinking my CAS could be bad. I need to play with it some more and get it running well enough to possibly get the car to a competent tuner. Currently the car is idling safely with safe, rich, AFR's, but if you touch the throttle it will try to bog down and die, at this point AFR's go straight lean as well. Something is amiss! Don't worry I'm not trying to drive it or move it. I'm just happy my car can finally move if the need arises. I'll keep you all updated.

More research and more tinkering for me! Yay.

[float_6969]

Do you have the big ground that goes from the intake manifold to the negative battery terminal?

[D_Stirls]

I wouldn't stress about those compression results, the main thing is that they are even and one or 2 aren't vastly different from the others. If the engine still feels strong and it's not using oil, poping dipsticks, blowing smoke then happy days.

FYI, when i tested my standard engine i got 165psi across the board. I have changed my cam intake cam and played with my cam timing and it now tests at 130psi across the board. There are so many things that can effect the scale of the number (i.e. tester calibrated off, cam timing, etc) that if the numbers are even enjoy that car and don't worry.

[float_6969]

And for comparison, my completely stock CA had 150psi of compression (+/- 3psi) and was burning oil and blowing dipsticks and filling catch cans like crazy. Compression tests are only a small part of the picture.

[FusionCola]

I'm not stressing about the compression. If the motor needs to be rebuilt, I have the time and money to do so. Float! I had no idea that the ground had to run to the negative battery terminal!!! I have my intake ground running to a bolt next to the windshield wiper motor... Oops

I'm still playing with the car and it seems to be doing better each time I get it to start, thankfully. Debating about saving up to tow the car to Autovaughn for a proper tune. I wish that there was a tuner closer to my location. Disbursement is supposed to be posted today so new parts should be arriving soon!

List so far:
-New hot pipes on intake side
-New couplers as mine are mismatched colors and look bad (not to mention the coupler coming off my turbo is a cut Hummer rad hose, lol.)
-Fix the rusty hole where my battery tray used to be
-pull interior/ kill sound deadenning
-Unjank my battery wiring
-New gaskets YAY!!!!