View Full Version : what causes power lost past 3,000 rpm?

08-07-2005, 03:14 PM
After messing around all week here we changed the spark plugs and gapped them to .028. We took the valve cover off and this time when we put th CAS we made sure it was sending spark at 15 degrees BTDC by watching the CAS send spark to the first coilpack as we turned the crank, it worked good.

So we put everything back together and the timing was off by 5 degrees. we put it back to 15 degrees BTDC by adjusting the CAS. the timing is now perfect. I can not make any boost what so ever in neutral, before i could hit 7 psi in neutral.

When i go for a drive though i'm still getting power loss, really bad at around 3,000 to 3,500 rpm.

What would be the likely culprits? I was thinking the ignitor might be sending insufficient spark while under boost causing this to happen. it is the only real thing i could think of. If it were just one coilpack the problem would be noticeable and i couldn't forsee all 4 coilpacks having issues.

Right now i have the fuel pump re-wired using 12 gauge wire to the batter and a 30 amp relay. still confused to why this is happening. we checked compression and it is pretty good, all around 150 psi level.

So once again what would cause a car to break up at that rpm level? there are no cel codes at all. redtop sr20det engine.

08-07-2005, 03:24 PM
just a quick note, the timing is nice, BUT the CAS is not in the middle like everywhere says it should be. is that still okay?

08-07-2005, 04:36 PM
My CAS is not in the middle of its adjustment range either when it is set at 15*BTDC(confirmed by a timing light the one time I got the car into timing mode and stabbing the CAS). The bolt is closer to the top of the notch on the CAS than in the middle like I hear it should be.

I never got a response when I asked if this is normal, but I'm guessing it is since my car runs fine and it is definitely 15* BTDC according to the dots on the CAS.

08-07-2005, 06:19 PM
I'm thinking the only things can be causing this issue would be:

#1 fuel injectors getting stuck
#2 ignitor not sending sufficient spark under load
#3 clogged fuel filter (i have a 2 month old mr gasket high flow fuel filter).
#4 bad fpr
#5 bad coilpacks

#6 and the one i'm giving serious thought to is the actuator i have on the turbo is screwd. If that were the case it would cause the boost to hesistate. a good bump could have hurt the diaphram and be leaking vacuum and boost. i'm thinking of upgrading to the HKS actuator.

I'm going to have a friend test my ignitor and coilpacks on his SR next weekend which will eliminate some things.

It can't be a huge boost leak i dont think though, you can't hear any air at all coming out, in the past i would hear it like no tomorrow.

I put a new coolant temp sensor in as well and its running wicked at idle and in neutral now, timing is very nice for a change. We tried driving the car with the knock sensor plugged in and with it not plugged in and there was no difference. It simply feels like its running out of fuel or out of spark.

I did have this code 21 that popped up a few days ago, i didn't think much of it since i took my ignitor out and then plucked it back in and the code went away, i also added an extra groud for the ignitor.

We took about 3 hours doing the timing today though. took the valve cover right off and sat there watching where the engine was sparking and such, it actually worked really good.

Which of the things above do you guys think it would most likely be? The vacuum used to be a steady -17 at idle, its now around -13 to -14. I'm thinking if the FPR or Actuator were hurt it would cause it to leak a tad. I hope i get this all figured out..

08-07-2005, 08:18 PM
If the vacuum reading at idle is that low, then you may have a leak in the piping or the ignition timing is severely retarded.