Major Program Problem

[Tannon]

I've been having this problem with my V6 turbo firebird for 6 months now. I can't floor the car or go anywhere over around 70-75% throttle. It goes into what seems like a "limp mode." Flooring the peddle does what it should for about one or two seconds, then it cuts the RPM to just below 3K with the throttle still 100%. While it's doing this the car sets off the P0300 code, so there is multiple cylinder misfire, and I cannot undergo normal acceleration until I let completely off the peddle again. I've got a log and my bin. Please give me some help, I've been stressed about this car for over 6 months.

The first log is a longer run. The second is a 15 second run that demonstrates my problem when I'm at 100% throttle and my RPM sits at a constant 3500.

http://turbov6camaro.com/images/bin

[devildog9999]

Can you give us some detail on the car? Motor, injector size, NA or forced induction?

[Tannon]

Sure thing. I don't have pictures but you can find all that information on my webpage.

http://www-personal.engin.umd.umich..../firebird.html

[viper04af]

he had some KR i got all i help him get it tuned and a little thing fuel in a cell or two but i can't figure out for anything what the problem is

[Chris@HPTuners]

looks like you have no boost to me. Are you losing spark under boost?

Chris...

[Tannon]

My boost gauge reads 6psi under heavy throttle. I haven't turned it up because I figured the problem would get worse. Is there an easy way to tell if I'm losing spark under boost?

[Chris@HPTuners]

your logs indicate that when the problem occurs you are showing vacuum, not boost. Remember the MAP value is absolute so 45 kPa (~6 PSI) is actually below atmospheric.

[viper04af]

check your wasgate maybe its sticking open or somthing ???

[Tannon]

Wastegate is fine. I have full confidence that this is a computer issue, otherwise it would just let me blow up my engine (or at least thats what it thinks will happen). I'm thinking about getting a stand alone engine management system to fix my problem once and for all. However these units also require a transmission controller for my 4L60E, and that's another 3K to drop on this car. Hopefully we can get my car working decent enough for me to max out the MAF or MAP and I will be happy for another year or so.

I thought that this would be a fuel problem. Would it have anything to do with the stock fuel pressure regulator? Or if it's a spark problem, do I need to hook my DIS-4 back up? (Took it off because the car doesn't want to start with it hooked up)

[Chris@HPTuners]

your MAP reading in the scan clearly shows you have no boost when the problem occurs. You need to find the cause of that problem. If you lower the boost level does the problem still occur?

Chris...

[Tannon]

Yes, the problem occurs at any boost level. It gets worse at higher PSI and slightly better at lower PSI than the 6 that I run. However, I understand that the MAP is showing vaccume when the problem occurs. But that can't mean anything because even though I am at 100% throttle, I am getting limited down to 3K RPM. My gauge doesn't even show boost until I'm at 4000 or so RPM.

Infact, I remember this exact cutoff problem when I ran nitrous instead of a turbo. At a 50HP shot it was fine, but when I beefed it up to 150 it would limit the RPM but still be using the nitrous because I was at 100% throttle.

[OneSlowGTP]

Try colder spark plugs, check wires / coilpacks. Log your per cyl airmass compare that to your RPM and when the problem occurs, sounds like it's not able to spark though the more dense air/fuel mass under load....

What cyl's are showing misfires?

Yes, the problem occurs at any boost level. It gets worse at higher PSI and slightly better at lower PSI than the 6 that I run. However, I understand that the MAP is showing vaccume when the problem occurs. But that can't mean anything because even though I am at 100% throttle, I am getting limited down to 3K RPM. My gauge doesn't even show boost until I'm at 4000 or so RPM.

Infact, I remember this exact cutoff problem when I ran nitrous instead of a turbo. At a 50HP shot it was fine, but when I beefed it up to 150 it would limit the RPM but still be using the nitrous because I was at 100% throttle.

[OneSlowGTP]

Autolite 103's should be the right heat range for your setup.

[viper04af]

what plugs are you using now? should have the above or TR6 @.035

[Tannon]

Right, I have the NGK TR6's, just put those in about a month ago. I'll set up a new log config with cyl airmass (if I can find it). I also need to set up one for misfires, didn't think I had any.

[Tannon]

So here's an update to my problem. I no longer read boost at the boost gauge and I can now floor it without a problem. It goes to the commanded shift point and shifts beautifly. I believe that it must be a wastegate issue, I've already gone through one. This internal wastegate junk doesn't work very well. Do I have to grab a whole new turbo for an external wastegate setup?

[viper04af]

So here's an update to my problem. I no longer read boost at the boost gauge and I can now floor it without a problem. It goes to the commanded shift point and shifts beautifly. I believe that it must be a wastegate issue, I've already gone through one. This internal wastegate junk doesn't work very well. Do I have to grab a whole new turbo for an external wastegate setup?

ummm weird

so to otook the boost gauge out and everything is fine?

[ravenp]

You no longer read boost? DOes that mean you're not feeling it either, i.e. the car pulls like it's na?

When the car went into limp mode, did you hear a 'whoosh' sound like you were losing pressure?