SD2 tuning

[278CIKILLER]

No problem.

[good2win22]

Been sitting here at work pondering on this...  It appears that when I get to 5100-5200 that's where the problem starts.  A little rise in KR and no advancement of RPM and I get out of the throttle.  Does this with both ignition systems installed.  The log on the WB is a bit erratic so it's hard to tell if there is a rich spike when this occurs.  If that was a definite, then I would lean towards blowing out the spark.  The no advancement in RPM is what is throwing a kink in my thoughts...  I have a hard time believing that I could be floating a valve but could I be collapsing a lifter?  All thoughts appreciated

[Pyro6]

I'll run this by you, it reminds me of when I was having problems with mine. Look at the alternator. I don't care if it's new, rebuilt etc....When I was making a pass, at 5000 rpm and 3280 ft give or take the car would just dive and wouldn't accelerate, it wouldn't shutoff though. I found that alt. output was ok but spikes were happening throwing a tantrum to the ECM. New rectifier bridge, stator, diode trio and brushes fixed it right up. Don't know if that's what your dealing with but I would want to eliminate it. Most modern alternator testers have a diode test feature.

[good2win22]

I'll run this by you, it reminds me of when I was having problems with mine. Look at the alternator. I don't care if it's new, rebuilt etc....When I was making a pass, at 5000 rpm and 3280 ft give or take the car would just dive and wouldn't accelerate, it wouldn't shutoff though. I found that alt. output was ok but spikes were happening throwing a tantrum to the ECM. New rectifier bridge, stator, diode trio and brushes fixed it right up. Don't know if that's what your dealing with but I would want to eliminate it. Most modern alternator testers have a diode test feature.

How did you identify the spikes?  Log?

[Steve Wood]

you can put your meter on AC volts and see what kinda AC is leaking out.

[Pyro6]

I was at my wits end with the trouble the car had, the only thing I didn't look at was the alternator. I took the alternator off and sent it out to the shop in Lancaster that rebuilds and supplies my shops starters/alternators. He load tested it with his bench system and it failed miserably. If I had the Sun tester I have today, I believe it would have failed the diode test. Since it was only breaking up at 5 grand, I figured his bench tester could best simulate that speed and load. The stator and rectifier bridge were shot. It would've show up if I would have disassembled and component tested it on the bench, but I wanted to see  dynamic breakdown.

[daveismissing]

You might be able to take a portable Am radio (if they still exist) and bring it near the alternator in question. Spikes like that tend to have a lot of high frequency content making ugly noises.
Comparison to an  identical know good one at the RPMs in question might tell you something.
 

[good2win22]

you can put your meter on AC volts and see what kinda AC is leaking out.

Hadn't thought of that. Still working so I'll give it a shot when I get home.

You might be able to take a portable Am radio (if they still exist) and bring it near the alternator in question. Spikes like that tend to have a lot of high frequency content making ugly noises.
Comparison to an  identical know good one at the RPMs in question might tell you something.

Haven't thought of that either. I have an hand held radio for emergencies that has am capabilities. I'll give that a shot as well when I get home.

[good2win22]

Not a single crazy thing going on with the alternator.  Had the wife helping with revving and me on the volt meter and old weather radio tuned to WBAP.


 Spoke with TA performance while at work and had these waiting for me when I got home. With my installed height and one .030" shim, spring open pressure or valve seated pressure will be 160#'s. Up from 135.  Plan to swap the springs tomorrow

[good2win22]

Big back story to the spring swap and I don't feel like typing.  Got the springs swapped but no test runs yet.  It's been a long day...

[good2win22]

Ran the back road test site before leaving for work. Still doing the same thing. Gets to 51-5200 rpm and stops accelerating.  Slight rise in KR but still below 1 degree. No rich spike on the log.


Been pondering what the exhaust pressure is driving the turbine. I don't have a sensor installed on the header. I wonder if the back pressure is too much at that rpm restricting further advancement of engine rpm. Not sure how to test this theory with a sensor or how to remedy it if it is in fact a problem.

[TexasT]

Fresh plugs?
Are you back to the fancy ignition or the stock stuff?
I've read that the fancy ignition needs a tighter gap on the plug(might be knocking the spark off with high volume coming into the cylinder).
I'm guessing the fuel pressure is steady and you have a fresh filter on there.

[nocooler]

Jason - pop the wastegate arm off and wire the gate open, then take it for a run. That should take some drive pressure off the turbo and determine if it's back pressure.


Check all the stupid stuff.

[good2win22]

Fresh plugs?
Are you back to the fancy ignition or the stock stuff?
I've read that the fancy ignition needs a tighter gap on the plug(might be knocking the spark off with high volume coming into the cylinder).
I'm guessing the fuel pressure is steady and you have a fresh filter on there.

Stock ignition still on car
Plugs are NGK 5671a-8. Have run the -9, -10,  and -11. Does it with all plugs
Fuel pressure steady, rises appropriately with boost, new filter and injector duty cycle is 51%

Jason - pop the wastegate arm off and wire the gate open, then take it for a run. That should take some drive pressure off the turbo and determine if it's back pressure.
Check all the stupid stuff.

That's exactly what I was going to do. What I don't know is what to do if it still happens. Bigger turbine a/r? Re shim the head gasket for lower compression? 


I also thought about making a run without the air filter

[gusszgs]

Exhaust plug somewhere? Do you run a cat converter? Can you open a dump?