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Odd qusetion...Need help in a major way....no power?

Old 04-23-07, 11:06 AM
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Exclamation Odd qusetion...Need help in a major way....no power?

So, Just had the first race of the year and it went like hell. The car runs well for about two laps and then looses a bit of power. Feels like it drops maybe 15 or 20 horsepower. Anyone have any idea about this. It is extreamly frustrating to pass 9 cars on the start (two wheels off in the grass down the straightaround corner one), pull out a 4 second lead only to get passed all back but one. It feels stong for about two laps or so, then power tappers off. Then when it cools off after a qualifying or practice, it is fine for two laps again. I also noticed it seems to bog a bit under high load corners. maybe that has something to do with it, I dont know.

Any help would be greatly apperciated cause I am pretty frustrated about this one. thanks everyone!
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Old 04-23-07, 11:52 AM
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Too hot of a spark plug heat range

Lack of fuel pressure after running awhile

No heat shield on carb

Excess oil temperature

Excess water temperature
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Old 04-23-07, 12:08 PM
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Originally Posted by speedturn
Too hot of a spark plug heat range

Lack of fuel pressure after running awhile

No heat shield on carb

Excess oil temperature

Excess water temperature
+1, also what car what class?
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Old 04-23-07, 01:53 PM
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it is 90 na....injected....ITS.

fuel pressure is good, it has an adjustable regulator on it...at about 45 pounds. temps are good...water never above 200 even at road america on a 90 degree day and oil never above 230 on synthetic.

I do not have a heat shild between the intake and exhaust manifold htough.....could this be making this big of a difference? Thanks guys, I really appericate your help.
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Old 04-23-07, 01:55 PM
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oh yeah...i am running the stock 3rd gen plug....that was what mazdacomp told me years ago.....no good?
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Old 04-23-07, 01:55 PM
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header is wrapped....
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Old 04-23-07, 02:29 PM
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What are the water temps before and after the power loss?
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Old 04-23-07, 02:57 PM
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ya know, I have never had a chance to think to look.....what a moron. the typical routine is warm up the car...get to grid...wait with the engine off....do a warm up lap....one or two green flag laps and power drops off. If I remember correctly, water heats up pretty quick, ussualy at temp before the warm up laps, and oil temp comes up before the green...i think.

I would lean towrds the assumption that it is not to hot....temp wise. But I am the one with the questions and you have the answers. My temps are always very safe, nothing to hot.

thanks!!!
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Old 04-23-07, 04:04 PM
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hows this sound....could the header be heating up the manifold right above it to the point that it is vaporising the fuel mix? Just throwing it out there...throw it back if im wrong.
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Old 04-23-07, 05:25 PM
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No. Ideally you want the fuel vaporized. The only thing the heat would do is reduce air density causing a power loss. However, your car is no different from any other ITS car as far as the manifold location and the header you're using. I never ran with wrap or a heatshield and never had a problem. Many others do the same thing and don't have a problem. The exhaust temps will achieve max levels immediately. It's not taking 3 laps for the header to get warm. It's not taking much longer than the warm up idle time to heat soak the manifold to near coolant temps either. Your problem lies somewhere else.

The ECU progressively pulls timing once the water temps cross 205*. I've experienced this before when running in a crowd for extended periods causing the temps to elevate. A couple degrees of timing makes a big difference in power. The ECU will pull about 3* between 205 and 215*. Enough to make a noticeable difference in power.

Further, what are a/f mixtures doing? 45 psi pressure on a completely stock S5 system is way too much for optimum power. To achieve good power you need to bleed pressure down well below stock, to the point atomization begins to suffer. The stock S5 setups runs far too fat at full load to make good power.

You need more info to make an informed estimate of what's going on.
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Old 04-23-07, 06:09 PM
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humm...when i had it on the dyno my af gauge was reading extreamly lean and the header would get red. It is basically your typical ITS engine...header...carbon seals. Nothing fancy. What timing do you run...i have about 23 degrees. I hear guys run more but I would like to error on the side of longevity somewhat.
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Old 04-24-07, 07:24 AM
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This may be a dumb question but: are you running a stock ECU?

When you were running lean on the dyno, were you running 45psi on the fuel?
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Old 04-24-07, 08:50 AM
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Yes..stock ecu. No, I added the adjustable pressure regulator after the dyno....It was lean totallly stock and the regualtor was the fix for that. I wasnt clear on that, thanks. She was stock pressure on the dyno. Thanks guys!!!
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Old 04-24-07, 02:02 PM
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You need to go back to the dyno. Simulate race conditions and see what happens.
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Old 04-24-07, 06:01 PM
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Originally Posted by C. Ludwig
You need to go back to the dyno. Simulate race conditions and see what happens.
yeah, dyno it cold. drive it around for a while, get it good and HOT and redyno.

or just dyno all day =)
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Old 04-25-07, 06:49 PM
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yeah the dyno is what im thinking.....

on another note, what timing do you guys run? I have heard 26* but that seems a little risk to me. I am a bit leary of breaking a carbon seal, seems that ignition up that high might go bad in a hurry. How wrong am I on this one....

Also, according to racing beat if you remove the thermostat completely and block off the bypass hole with a 1/2 pipe plug. I have a vary large alumium radiator so do you think that it may run cooler some other way....could the water be circulating too fast to be cooled to its maximum.

just a thought.
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Old 04-26-07, 06:32 AM
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Originally Posted by bean13
yeah the dyno is what im thinking.....

on another note, what timing do you guys run? I have heard 26* but that seems a little risk to me. I am a bit leary of breaking a carbon seal, seems that ignition up that high might go bad in a hurry. How wrong am I on this one....

Also, according to racing beat if you remove the thermostat completely and block off the bypass hole with a 1/2 pipe plug. I have a vary large alumium radiator so do you think that it may run cooler some other way....could the water be circulating too fast to be cooled to its maximum.

just a thought.

26* is about right. No danger of damage with an IT engine. This stuff needs to be sorted on the dyno as well. Keep feeding advance in until the power gain levels off then lock it in. Somewhere between 25-27* total advance at WOT is where you'll see max power. Keep in mind this is not idle advance it's total advance you'll see while under load.

As far as the the water pump, the common practice is to gut the thermostat and plug the bypass hole in the bottom of the waterpump. The gutted thermostat acts as a bit of a restrictor. Coolant flowing too fast is a wives tales really.
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Old 04-26-07, 07:02 AM
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are you sure you remove the thermostat completely??? i thought you just gut the thermostat.
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Old 04-26-07, 07:54 AM
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Since we are on the topic and ignition has come up, how about fuel pressure? If 25-27* is typically max power range what is normal fuel pressure range? I got max power on my ITS S4 motor at 30PSI but did not check timing (that's next dyno trip). Curious as to what other S4 motors see, I had heard PSI should be higher? I did runs from 25-45 PSI and saw about a 8 peak HP difference. Sound about right? At 30 PSI I had an AF of 13.6.
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Old 04-26-07, 09:12 AM
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I have a volt meter connected to my O2 sensor so we can monitor the exhaust gas while racing. If the sensor output starts dropping.... say from 0.6 volts to 0.3 volts, then the car is leaning out. Higher volts = richer, lower volts = leaner... typical generic O2 sensor output is usually between 0 and 1 volt. The actual reading is not as important as if and how it changes when you begin to loose power. If you get nearly no volts, then you have a bad O2 sensor.
I bought a digital panel mount 0 to 2 volts voltmeter on ebay for about 15 bucks like this one:
http://cgi.ebay.com/Brand-New-3-Red-...QQcmdZViewItem

This is a long shot but when we switched our car from the stock tank to the fuel cell, we no longer had the filter sock on the fuel pickup. We found that there is a filter screen inside the suction nipple of the stock GSL-SE fuel pump. After a few races, that screen plugged. To a much greater extent, we experienced the same full power for a couple laps then loss of power for the rest of the race. JLC racing in Kent, WA found that problem for us. We fixed it by cleaning the pump screeen and installing an inline filter in the upstream fuel line.
Good luck!
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Old 04-26-07, 09:13 AM
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that seems about right with what Ludwig told me before and he knows his stuff. With my S5 at stock fuel pressure the af gauge on mine went extreame lean and turned the header red....so I dont know. I am interested to see what is suggested!!!
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Old 04-26-07, 09:14 AM
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the tank problem is interesting....cant hurt to check that. Thanks alot!!!!!
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Old 04-26-07, 03:07 PM
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I've done dyno work with several S5 cars and they all needed less pressure than stock to get an adequate a/f ratio. Working in the stock fuel pressure range usually produces a/f ratios in the 11-12:1 range thru 5-8k rpm. Best power is well lean of that. The only way to drop the a/f ratio through the rpm range we are concerned with (5-8k rpm) with the stock ECU is to pull fuel pressure which causes a total enleanment across the board. No big deal. In my experience, and it's been the experience of others, you should not have to add pressure to an S5 setup to optimize fueling.

As a side note, when doing recent development work on our soon to be released IT legal S5 programmable ECU, we had to drop stock programmed injector on time over 30% in some places over 5k rpm to achieve a proper a/f ratio for best power. That gives you a good idea what you're up against. This same ECU netted almost 10 hp average across the useable rev range and nearly 18 at points past peak power but below the 8500 rpm shift point we use.

I have not worked with an S4 setup. I have heard they run lean and need more pressure. But that is anecdotal. The bottom line is that there is not a good way to guess at this stuff at the track. If you have a wideband setup you can get the a/f close but you still won't know what works best and what is really producing best power. You absolutely need a dyno to properly setup the system.

DYNO, DYNO, DYNO

To diagnose a problem like Bean is having you need onboard tools also. A fuel pressure gauge you can see in the cockpit and a wideband readout would help a lot. Obviously you should already have temp gauges.
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Old 04-26-07, 03:50 PM
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Originally Posted by bean13
that seems about right with what Ludwig told me before and he knows his stuff. With my S5 at stock fuel pressure the af gauge on mine went extreame lean and turned the header red....so I dont know. I am interested to see what is suggested!!!
i had a gsl-se once, that did what you're describing, in the morning it ran like a bat out of someplace warm (it wasnt THAT fast), but on the way home, by the time i got off the freeway, it would barely go 40....

culprit turned out to be an aftermarket fuel filter that had internally rusted.... new fuel filter, fixed the problem
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