Car falls flat , exhaust?
06-20-2014, 08:33 AM
#21
Thread Starter
Will do. RIght where the car falls flat boost builds from 6 psi (it is a 6 psi pulley) slowly to 8 psi at redline.
EVERYTHING that could be the problem has been checked but two. I am going to install new plugs (the current ones are 3000 miles old) and recheck to make sure gap is not more than .032 to make sure I am not getting spark blowout. And then getting exhaust tested in two weeks when I get back from a short vacation.
I have basically ruled out coils (new) sensor readings (they are all within normal range), boost/vaccum leaks,cat plugged, belt slip, and anything else I can possibly think of besides valve float, plug gap and plugged muffler. I do not know how to diagnose valve float but I would find it quite odd at my power level.
06-20-2014, 11:52 AM
#22
Spark blow out and valve float are both very pronounced, and actually pretty similar in how they feel to the untrained, which is the engine misfiring. That condition is pretty easy to feel in the seat, where as just a flat line or drop in power yet engine still firing properly feels very different. Valve float and spark blow out feel very much like a soft rev limiter from ignition cut. Unless something is mechanically wrong with your valvetrain, you are not getting valve float with this set up guaranteed. Spark blow out is possible if your running to large a gap, and 0.32 is pushing it for FI. Id drop down to 25-28 just to be sure and eliminate this variable before moving on to the next. Increase it later once you figure out the problem.
06-20-2014, 02:08 PM
#23
Spark blow out and valve float are both very pronounced, and actually pretty similar in how they feel to the untrained, which is the engine misfiring. That condition is pretty easy to feel in the seat, where as just a flat line or drop in power yet engine still firing properly feels very different. Valve float and spark blow out feel very much like a soft rev limiter from ignition cut. Unless something is mechanically wrong with your valvetrain, you are not getting valve float with this set up guaranteed. Spark blow out is possible if your running to large a gap, and 0.32 is pushing it for FI. Id drop down to 25-28 just to be sure and eliminate this variable before moving on to the next. Increase it later once you figure out the problem.
psh, gap it way down.
06-20-2014, 03:43 PM
#24
Thread Starter
Originally Posted by s2000Junky' timestamp='1403293926' post='23211601
Spark blow out and valve float are both very pronounced, and actually pretty similar in how they feel to the untrained, which is the engine misfiring. That condition is pretty easy to feel in the seat, where as just a flat line or drop in power yet engine still firing properly feels very different. Valve float and spark blow out feel very much like a soft rev limiter from ignition cut. Unless something is mechanically wrong with your valvetrain, you are not getting valve float with this set up guaranteed. Spark blow out is possible if your running to large a gap, and 0.32 is pushing it for FI. Id drop down to 25-28 just to be sure and eliminate this variable before moving on to the next. Increase it later once you figure out the problem.
psh, gap it way down.
As far as what I feel when running it hard, I don't really feel anything like a soft rev limiter, it still climbs (rpm) and the car moves without any semi abrupt change, but you can see the line on the dyno. It is still accelerating, just not in an increasing arc I guess. Revs and rpms climb, but power tops out before redline.
06-20-2014, 05:41 PM
#25
Originally Posted by camuman' timestamp='1403302112' post='23211759
[quote name='s2000Junky' timestamp='1403293926' post='23211601']
Spark blow out and valve float are both very pronounced, and actually pretty similar in how they feel to the untrained, which is the engine misfiring. That condition is pretty easy to feel in the seat, where as just a flat line or drop in power yet engine still firing properly feels very different. Valve float and spark blow out feel very much like a soft rev limiter from ignition cut. Unless something is mechanically wrong with your valvetrain, you are not getting valve float with this set up guaranteed. Spark blow out is possible if your running to large a gap, and 0.32 is pushing it for FI. Id drop down to 25-28 just to be sure and eliminate this variable before moving on to the next. Increase it later once you figure out the problem.
Spark blow out and valve float are both very pronounced, and actually pretty similar in how they feel to the untrained, which is the engine misfiring. That condition is pretty easy to feel in the seat, where as just a flat line or drop in power yet engine still firing properly feels very different. Valve float and spark blow out feel very much like a soft rev limiter from ignition cut. Unless something is mechanically wrong with your valvetrain, you are not getting valve float with this set up guaranteed. Spark blow out is possible if your running to large a gap, and 0.32 is pushing it for FI. Id drop down to 25-28 just to be sure and eliminate this variable before moving on to the next. Increase it later once you figure out the problem.
psh, gap it way down.
As far as what I feel when running it hard, I don't really feel anything like a soft rev limiter, it still climbs (rpm) and the car moves without any semi abrupt change, but you can see the line on the dyno. It is still accelerating, just not in an increasing arc I guess. Revs and rpms climb, but power tops out before redline.
[/quote]
In my experience running to close a gap for your power level and you start creating a similar problem to what your trying to avoid, 0.32 is probably fine for your power but it would be on the upper range so I'm suggesting running it closer to the middle of an acceptable range for troubleshooting. But hearing your symptoms tells me its not spark blow out either. Belt slip would be the first guess, but since you said boost keeps climbing to redline that wouldn't obviously be it. It probably is a restriction in your exhaust, and my guess is its the high flow cat before anything else. I'm just not sure why the roots system would be more impaired by the same exhaust system that otherwise gets a centrifugal set up over 100whp more then yours before it starts seeing similar restrictions. Yeah the roots delivers a bit more heat which would surly aid in your symptom, just wouldn't think it would be the sol contributed, but isn't helping. Might be water/meth injection time.
06-23-2014, 07:28 AM
#26
Thread Starter
In my experience running to close a gap for your power level and you start creating a similar problem to what your trying to avoid, 0.32 is probably fine for your power but it would be on the upper range so I'm suggesting running it closer to the middle of an acceptable range for troubleshooting. But hearing your symptoms tells me its not spark blow out either. Belt slip would be the first guess, but since you said boost keeps climbing to redline that wouldn't obviously be it. It probably is a restriction in your exhaust, and my guess is its the high flow cat before anything else. I'm just not sure why the roots system would be more impaired by the same exhaust system that otherwise gets a centrifugal set up over 100whp more then yours before it starts seeing similar restrictions. Yeah the roots delivers a bit more heat which would surly aid in your symptom, just wouldn't think it would be the sol contributed, but isn't helping. Might be water/meth injection time.
I also pulled the cams once to do the retainer upgrade, but everything lined up nice when I put it back together, and it had the same problem both before the cam pulling and after. And I never had any codes after fiddling with cams.
06-23-2014, 09:05 AM
#27
Originally Posted by s2000Junky' timestamp='1403314893' post='23211976
In my experience running to close a gap for your power level and you start creating a similar problem to what your trying to avoid, 0.32 is probably fine for your power but it would be on the upper range so I'm suggesting running it closer to the middle of an acceptable range for troubleshooting. But hearing your symptoms tells me its not spark blow out either. Belt slip would be the first guess, but since you said boost keeps climbing to redline that wouldn't obviously be it. It probably is a restriction in your exhaust, and my guess is its the high flow cat before anything else. I'm just not sure why the roots system would be more impaired by the same exhaust system that otherwise gets a centrifugal set up over 100whp more then yours before it starts seeing similar restrictions. Yeah the roots delivers a bit more heat which would surly aid in your symptom, just wouldn't think it would be the sol contributed, but isn't helping. Might be water/meth injection time.
I also pulled the cams once to do the retainer upgrade, but everything lined up nice when I put it back together, and it had the same problem both before the cam pulling and after. And I never had any codes after fiddling with cams.
Last time I had a motor flat line prematurely it took a dump about two weeks after the dyno. Have you considered checking the comp and leak down to make sure everything is solid? Nothing worse then a blown motor and a brand new $800 cat back on the car.
06-23-2014, 09:33 AM
#28
Thread Starter
Originally Posted by vader1' timestamp='1403537316' post='23214348
[quote name='s2000Junky' timestamp='1403314893' post='23211976']
In my experience running to close a gap for your power level and you start creating a similar problem to what your trying to avoid, 0.32 is probably fine for your power but it would be on the upper range so I'm suggesting running it closer to the middle of an acceptable range for troubleshooting. But hearing your symptoms tells me its not spark blow out either. Belt slip would be the first guess, but since you said boost keeps climbing to redline that wouldn't obviously be it. It probably is a restriction in your exhaust, and my guess is its the high flow cat before anything else. I'm just not sure why the roots system would be more impaired by the same exhaust system that otherwise gets a centrifugal set up over 100whp more then yours before it starts seeing similar restrictions. Yeah the roots delivers a bit more heat which would surly aid in your symptom, just wouldn't think it would be the sol contributed, but isn't helping. Might be water/meth injection time.
In my experience running to close a gap for your power level and you start creating a similar problem to what your trying to avoid, 0.32 is probably fine for your power but it would be on the upper range so I'm suggesting running it closer to the middle of an acceptable range for troubleshooting. But hearing your symptoms tells me its not spark blow out either. Belt slip would be the first guess, but since you said boost keeps climbing to redline that wouldn't obviously be it. It probably is a restriction in your exhaust, and my guess is its the high flow cat before anything else. I'm just not sure why the roots system would be more impaired by the same exhaust system that otherwise gets a centrifugal set up over 100whp more then yours before it starts seeing similar restrictions. Yeah the roots delivers a bit more heat which would surly aid in your symptom, just wouldn't think it would be the sol contributed, but isn't helping. Might be water/meth injection time.
I also pulled the cams once to do the retainer upgrade, but everything lined up nice when I put it back together, and it had the same problem both before the cam pulling and after. And I never had any codes after fiddling with cams.
Last time I had a motor flat line prematurely it took a dump about two weeks after the dyno. Have you considered checking the comp and leak down to make sure everything is solid? Nothing worse then a blown motor and a brand new $800 cat back on the car.
[/quote]
Well I am checking the exhaust first but I did a leak down and compression test before doing my retainer upgrade last year and both were fine. And this was after it had flatlined at two different shops covering a period of a few years.
Curious to see what is does with a different exhaust, but I have to say, that better fix it because I would be totally stumped. Once it stops making power at about 6800-7000 it actually pulls fuel/duty cycle to maintain the same AFR at increasing RPM. The tuner points to that and says, "your exhaust is restricted."
06-23-2014, 12:13 PM
#29
Originally Posted by s2000Junky' timestamp='1403543105' post='23214492
[quote name='vader1' timestamp='1403537316' post='23214348']
[quote name='s2000Junky' timestamp='1403314893' post='23211976']
In my experience running to close a gap for your power level and you start creating a similar problem to what your trying to avoid, 0.32 is probably fine for your power but it would be on the upper range so I'm suggesting running it closer to the middle of an acceptable range for troubleshooting. But hearing your symptoms tells me its not spark blow out either. Belt slip would be the first guess, but since you said boost keeps climbing to redline that wouldn't obviously be it. It probably is a restriction in your exhaust, and my guess is its the high flow cat before anything else. I'm just not sure why the roots system would be more impaired by the same exhaust system that otherwise gets a centrifugal set up over 100whp more then yours before it starts seeing similar restrictions. Yeah the roots delivers a bit more heat which would surly aid in your symptom, just wouldn't think it would be the sol contributed, but isn't helping. Might be water/meth injection time.
[quote name='s2000Junky' timestamp='1403314893' post='23211976']
In my experience running to close a gap for your power level and you start creating a similar problem to what your trying to avoid, 0.32 is probably fine for your power but it would be on the upper range so I'm suggesting running it closer to the middle of an acceptable range for troubleshooting. But hearing your symptoms tells me its not spark blow out either. Belt slip would be the first guess, but since you said boost keeps climbing to redline that wouldn't obviously be it. It probably is a restriction in your exhaust, and my guess is its the high flow cat before anything else. I'm just not sure why the roots system would be more impaired by the same exhaust system that otherwise gets a centrifugal set up over 100whp more then yours before it starts seeing similar restrictions. Yeah the roots delivers a bit more heat which would surly aid in your symptom, just wouldn't think it would be the sol contributed, but isn't helping. Might be water/meth injection time.
I also pulled the cams once to do the retainer upgrade, but everything lined up nice when I put it back together, and it had the same problem both before the cam pulling and after. And I never had any codes after fiddling with cams.
Last time I had a motor flat line prematurely it took a dump about two weeks after the dyno. Have you considered checking the comp and leak down to make sure everything is solid? Nothing worse then a blown motor and a brand new $800 cat back on the car.
[/quote]
Well I am checking the exhaust first but I did a leak down and compression test before doing my retainer upgrade last year and both were fine. And this was after it had flatlined at two different shops covering a period of a few years.
Curious to see what is does with a different exhaust, but I have to say, that better fix it because I would be totally stumped. Once it stops making power at about 6800-7000 it actually pulls fuel/duty cycle to maintain the same AFR at increasing RPM. The tuner points to that and says, "your exhaust is restricted."
[/quote]
I'm not a roots expert, but knowing what I know about our exhaust efficiency, id guess the blower was past its, and just blowing hot air after 7k rpm. Its building boost but it isn't quality.
06-23-2014, 12:18 PM
#30
Thread Starter
This is why the problem drives me nuts. It is not the blower efficiency either. Same problem, two blowers. The new one is much more efficient than the first and pushing far less heat than the last. Same problem and happens at about the same power level, same rpm. And people with the same blowers have made more power. It is definitely something on MY car, but if it turns out not to be the exhaust then I pull what is left of my hair out. Both blowers were spun to max suggested blower speed at 9000 rpm, but this blower speed is 3000 rpm higher and still 20% more efficient at that speed.
Won't know for a couple weeks when I get back from vacation and visit this custom exhaust shop.
Thread
Thread Starter
Forum
Replies
Last Post