95 S14 running issues before tune. KA-T

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onepointone
Posts: 6
Joined: Fri Jul 09, 2010 8:23 pm
Car: '95 S14 - KA-T

Post

I have searched around and found some similar stuff, but couldnt find anything exaclty like what I am dealing with.

I bought a 95 S14 off of a co-worker of mine that he attempted to turbo. Two cylinders were low on compression along with some other issues that I sorted out. I am at the point now where I am ready to have it tuned, but am not really sure its running correctly.

The car is a KA-T with a nistune setup in the ecu. Related stuff is SR injectors, stock MAF (switching to z32 before the tune), recently replaced distributor since I broke the one that came with the car, crower cams, 255 fuel pump, and misc other stuff, but that should be the main things related to the concern.

The vehicle idles decently right now, but when you rev the engine with the TPS plugged it in revs like crap. If you slowly increase RPM you can get it to 3500 - 4000, if you stomp the accelerator, it goes to 2000 rpms and stops. If you unplug the TPS, you can rev it to pretty much red line without much drama. I spoke with the guy that loaded the base map on the nistune when the previous owner had it previously to getting to this point. He said it was for NA, stock MAF with SR injectors, and that the car should idle, but told me not to boost it. The TPS was out of adjustment, I was able to get it back into spec per a how-to on here. When setting the timing (at 20btdc), I was having trouble getting a good signal to the timing light from cylinder 1. Cylinders 2 and 4 gave the timing light a good signal and cylinder 3 was decent, but there were some spots that seemed to skip a flash every now and then. I used a different timing light and was able to get a decent signal on cylinder 1, but it wasnt perfect. I got the timing in, but I am curious if I bought a bad distributor? There is a new cap, rotor, and plug wires on there, and I know the plugs arent fouled. When I rev it with the TPS plugged in it just sounds like the ignition is breaking up, but I guess there is a possibility its fuel related. It just doesnt explain why I can rev it with the TPS unplugged.

When I try to drive the car, I cant get it over 1800 - 2000 RPMs, but can get it up to about 35 mph by short shifting it and being easy on the throttle. I did this with the TPS plugged it to check for DTCs. It did have a coolant temp and iat codes that I sorted out and they didnt come back. I unplugged the battery for a while and drove it again and it didnt make much difference. If I drive it with the TPS unplugged it drives better, but like crap if the turbo starts making any kind of positive pressure.

Any ideas? Its been a fun project so far, just ready to get this thing tuned and going.

If any of you are interested, here are some pictures of the project so far.
http://www.facebook.com/album.php?aid=2 ... 6a02c1bf41

Thanks for the help. :dblthumb:


indomiekid1
Posts: 147
Joined: Tue May 25, 2010 6:21 pm
Car: S14.
Location: Austin,TX

Post

car looks good, bet you are ready to have it boosted. i'm guessing there was a rebuild done on the motor right?
why were two cylinders low on compression?

onepointone
Posts: 6
Joined: Fri Jul 09, 2010 8:23 pm
Car: '95 S14 - KA-T

Post

yea, the rebuild was part of the problem. a machine shop had put in some new exhaust valves for the previous owner. the cut the new valve seats, but didnt around for the increased valve height, so when the cams were bolted in, all of the valve clearances were way too tight. there were two valves that were less than .0015" when spec is .013 - .016. The motor was rebuilt with eagle rods, cp pistons, new bearings, the crower cams, ect.

A guy on the another forum said to check the maf, did that and it checked out ok per the fsm. I also double checked the TPS and it checked out ok too.

anyone?

indomiekid1
Posts: 147
Joined: Tue May 25, 2010 6:21 pm
Car: S14.
Location: Austin,TX

Post

damn that sucks.
s*** it seems like you have checked a lot of things already.


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