View Full Version : Head retorque, power loss?

01-08-2006, 05:20 PM
So this is a 1993 MR2 turbo. Running the 3s-gte. I posted on the mr2oc but haven't recieved a response yet. I'm completely baffled and was hoping one of you might have some ideas.

So initially there was an issue after awhile with hitting higher levels of boost. I noticed on two seperate dyno's that there was coolant on the ground after my car left the dyno. I then had the mustang dyno hold the car at peak boost while I looked under teh car (18psi) and the moment the turbo spooled up, coolant began blowing out towards the ground from the overflow. They were ARP head studs and handn't been retorqued since they were installed with the new shortblock (about four thousand miles ago, two thousand of that, freeway driving.). Me and a good, and experienced friend of mine proceeded to take the IC piping off, TB off, wires and plugs, and the valve cover all off. Found the headstuds, retorqued them for good measure. 7/8 needed torquing. We put the valve cover back on, put the TB back on, IC piping, etc. Ran the car at boost with a catchcan for the coolant overflow. Dry as a whistle. Problem solved!

-- Before I go on, this is a good lesson that ARP studs DO need to be retorqued after about a thousand miles. DO NOT FORGET! Or you will be blowing coolant out when you boost and have to refill all the time... it's very annoying... -- I digress.

So, I felt it was time to test her out and see what she was doing. She had recently undergone a tune for about 305whp on pump gas. I pulled first lightly, maybe about 25%TP. pulled second with about 40%. And pushed 3rd with 80%. As I was pushing third, the car hit 18psi (target boost) but felt like she was doing maybe 200whp. The car shuttered a little bit, and didn't feel right at all. Almost as if she was misfiring. We datalogged the event on the EMS and everything looked fine. Our initial thought is maybe the spark plugs were going bad so we tested higher rpm's without boost in 1st gear. She did that just fine. Next step was to test 1st gear as I had been boost spiking as long as I had the new tune. The EMS was initiating fuel cut at the 3psi over mark. When I floored first, she held well at 18psi, minor spike to 20 caught by the EMS, but nothing more. She didn't pull very hard, and the car did the weird hesitation feeling again as well as backfired three times (not too abnormal when shifting, but very strange when driving spiritedly) and again sounded like it was violently misfiring.

It doesn't seem like a boost leak, she's reaching peak boost at the proper RPM's. However, I haven't counted that out yet. We rechecked all hoses and tightened everything back down, to no avail. What do you think? The one thing I should note, is the cams are HKS 264. The angle to get to the bottom right headstud was odd with the larger round section on the cam. The cam had to be rotated slightly in the direction the engine moves them. Of course, moving both. So I don't think that should've set my cam timing off since the machine moved the way it normally would. Also, it was about 1/4 circle turn, not much more/less than that. Any ideas would be helpful!

-- Note the car is heavily modified as well as using a Nemesis EMS.

01-09-2006, 07:39 AM
What plugs, with what gap, are you running?
Also, what are you using for an ignition? Does the Nemisis use stock dist? Or coil packs?