Back to the dyno today ... with race gas ... results inside
07-26-04, 05:59 AM
#16
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Just to give you guys an idea ...
I have been trying FOREVER to get myself a flat A/F curve and with no luck. Everyone who looks at my map says that it is because I have numbers all over the place and I am not supposed to just "plug in numbers" wherever I feel like it ... but that isn't how I do it. I do a dyno run, I look where it needs fuel and I add fuel. Where it doesn't need fuel, I take away fuel, pretty simple concept.
In the end, my fuel map looks like this:
Look at the circled area - how can those numbers be SO low ?
Now take a look at my latest dyno graph at 22psi
It appears to be VERY rich at that exact spot. What can possibly be causing this ? Just give me some hints to look for, I will try just about anything.
I have been trying FOREVER to get myself a flat A/F curve and with no luck. Everyone who looks at my map says that it is because I have numbers all over the place and I am not supposed to just "plug in numbers" wherever I feel like it ... but that isn't how I do it. I do a dyno run, I look where it needs fuel and I add fuel. Where it doesn't need fuel, I take away fuel, pretty simple concept.
In the end, my fuel map looks like this:
Look at the circled area - how can those numbers be SO low ?
Now take a look at my latest dyno graph at 22psi
It appears to be VERY rich at that exact spot. What can possibly be causing this ? Just give me some hints to look for, I will try just about anything.
07-26-04, 11:26 AM
#17
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You could be losing spark at that point, which would cause a very rich spot. Maybe you should look into the igition at that point. Possible needs a -/+ bump of a degree or two.
I think I remember someone else having this problem at a similar rpm with a GTE swap and a AEM EMS.
Just my $0.02
Oh and nice #'s. I'm looking at the SP63 as well when I get some cash. So its nice to have someone lead the way.
I think I remember someone else having this problem at a similar rpm with a GTE swap and a AEM EMS.
Just my $0.02
Oh and nice #'s. I'm looking at the SP63 as well when I get some cash. So its nice to have someone lead the way.
Last edited by qtb33; 07-26-04 at 11:27 AM.
07-27-04, 10:58 AM
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07-27-04, 03:50 PM
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Regarding the fuel problem that I posted above ...
I have 2 local tuners telling me that there are 2 totally different problems. The first one thinks that my problem is being caused by the butterfly in the stock NA intake manifold. I disconnected the vacuum line going to it way back when I first turbo-ed the car 10k miles ago, but he says it doesn't need the vacuum line to make changes because there is pressure inside the intake manifold. He thinks I should permanently mount the butterfly one way or the other and see if that makes a difference.
The second one thinks it is my fuel setup. My fuel setup is different than most ... I have 2 pumps, 2 feed lines, etc, but I don't have them T-ing together and I don't have a dual feed fuel rail. My setup has one feed line going to the rail and another feed line going to the fuel pressure regulator, then the return line from the rail going to the regulator and of course the return from the regulator back ... he suggests that I pull the feed line off of the regulator and T it together with the feed that goes to the rail, then run the return from the rail to the regulator and then back ...
I am about neutral on both. I can't see how either would make much of a difference, but I am curious if anyone else has had a similar experience or thinks I should try one or the other or both.
I have 2 local tuners telling me that there are 2 totally different problems. The first one thinks that my problem is being caused by the butterfly in the stock NA intake manifold. I disconnected the vacuum line going to it way back when I first turbo-ed the car 10k miles ago, but he says it doesn't need the vacuum line to make changes because there is pressure inside the intake manifold. He thinks I should permanently mount the butterfly one way or the other and see if that makes a difference.
The second one thinks it is my fuel setup. My fuel setup is different than most ... I have 2 pumps, 2 feed lines, etc, but I don't have them T-ing together and I don't have a dual feed fuel rail. My setup has one feed line going to the rail and another feed line going to the fuel pressure regulator, then the return line from the rail going to the regulator and of course the return from the regulator back ... he suggests that I pull the feed line off of the regulator and T it together with the feed that goes to the rail, then run the return from the rail to the regulator and then back ...
I am about neutral on both. I can't see how either would make much of a difference, but I am curious if anyone else has had a similar experience or thinks I should try one or the other or both.
07-27-04, 04:48 PM
#22
After thinking about it a bit, I think I agree that it may be worth trying the suggestion to rearrange your fuel lines. While you're certainly not fuel starved, I'm wondering if the regulator is actually doing it's job properly? If it can't siphon off the extra fuel to the fuel rail due to the direct feed from your fuel pump, it might cause the rich condition you're seeing. Seems like an easy thing to try at least...
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