Took car to dyno today, have fuel issues
10-04-2008, 10:23 PM
#1
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Took car to dyno today, have fuel issues
So, after having my FM II kit installed for almost a year, I finally took it to a dyno tuner (Church's Automotive in Long Beach) today. The guys were very thorough and tuned the car for a consistent AFR around 11.8 without the EBC connected. The car was developing about 6psi at 3200 rpm then slowly increasing to right around 9psi at redline. The tuner commented about how much fuel he had to add above 5500 rpm to prevent it from going lean.
When we were satisfied with that, we started tuning the EBC. Long story short, we were finally able to get the same range under control (max boost 14psi), but he said the 550cc injectors are running about 95% duty cycle. He said I might have some sort of fuel issue, and I might consider upgrading the fuel pump.
All of the posts here and on M.net talk about people upgrading the pumps, but they only refer to NAs and I have a 99. Any suggestions on what I can test or how I can confirm this is the problem?
Let me know what information you need and I can try to post it. As soon as I can find the cable for my digital camera, I will post some videos.
When we were satisfied with that, we started tuning the EBC. Long story short, we were finally able to get the same range under control (max boost 14psi), but he said the 550cc injectors are running about 95% duty cycle. He said I might have some sort of fuel issue, and I might consider upgrading the fuel pump.
All of the posts here and on M.net talk about people upgrading the pumps, but they only refer to NAs and I have a 99. Any suggestions on what I can test or how I can confirm this is the problem?
Let me know what information you need and I can try to post it. As soon as I can find the cable for my digital camera, I will post some videos.
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10-04-2008, 11:09 PM
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Hrm... can't seem to figure out how to embed the youtube video. Make sure you watch it on high quality or you can't see anything.
http://www.youtube.com/watch?v=7x6PUgVT3aI
http://www.youtube.com/watch?v=7x6PUgVT3aI
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).
10-05-2008, 09:41 AM
#9
With nothing in your signature, I have to assume that's a Hydra fuel table and a 2560? HINT HINT NOOB!
Dynapack compares similarly to a Dynojet, but I just did some searching and found sveral places that claim Churchs machine reads a little on the high side. 250whp@14psi on a '99 is about right... maybe a little low, but that's even weirder if Church's typically reads high. In any case, you should be nowhere near 95% duty cycle.
550's and the stock fuel pump should be good for a tick over 300whp. You may indeed have a fuel issue. An upgrade for the stock fuel pump is the Walbro190lph, no need for the HPmodel on a standalone car. A new fuel filter is good insurance too. I don't know how you'd check the health of the fuel pump on a returnless car, so it might be a good idea to spend the $100 for a new pump and filter. Pumps and filters at your local KragAutoPepVance.
And make it easy on us to give advice... fill out your signature please. I'm really interested to know what exhaust you're running if I got the rest of it right.
Dynapack compares similarly to a Dynojet, but I just did some searching and found sveral places that claim Churchs machine reads a little on the high side. 250whp@14psi on a '99 is about right... maybe a little low, but that's even weirder if Church's typically reads high. In any case, you should be nowhere near 95% duty cycle.
550's and the stock fuel pump should be good for a tick over 300whp. You may indeed have a fuel issue. An upgrade for the stock fuel pump is the Walbro190lph, no need for the HPmodel on a standalone car. A new fuel filter is good insurance too. I don't know how you'd check the health of the fuel pump on a returnless car, so it might be a good idea to spend the $100 for a new pump and filter. Pumps and filters at your local KragAutoPepVance.
And make it easy on us to give advice... fill out your signature please. I'm really interested to know what exhaust you're running if I got the rest of it right.
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10-05-2008, 11:33 AM
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Can we see some AFRs from (and I hope you did) the datalog you took for the run? 95% duty is way high.
Example: at 7000 rpm and 9.5 psi (250 rwhp) I'm at 68% on my 550s. That's at 12.2 AFR.
Example: at 7000 rpm and 9.5 psi (250 rwhp) I'm at 68% on my 550s. That's at 12.2 AFR.
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10-05-2008, 02:29 PM
#14
+1 for all the above. Your problems are likely a relatively cheap and easy fix. Walbro 190 pump and a new filter just in case. The pump is about a 15 minute fix your very 1st time. Just follow the directions in Mnet's garage. It's worth doing without a 2nd thought.
Log some full throttle pulls and see where the duty cycle is after the new pump and filter.
Log some full throttle pulls and see where the duty cycle is after the new pump and filter.
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10-05-2008, 03:27 PM
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will do. I didn't do a data log on the dyno because I didn't have my laptop connected. I might get around to doing it if I can break away from the house a little while later today. If nothing else, I think I am going to look for a new pump and filter. For the pump, can I get the same one that is rated for the NA miatas? That lightning motorsports place only has the NAs listed and Walbro doesn't show that they carry a version for the NBs.
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10-05-2008, 04:25 PM
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The Garrett GT25, p/n 705330-0002. aka the GT2876R.
Compressor: 0.70 A/R, 48 trim, TO4S (2.09/3.00 dia), 44 lbs flow.
Turbine: .86 A/R, 76 trim, NS111 (1.85/2.12 dia).
(I have since swapped in the -0001's .64 A/R turbine housing)
Compressor: 0.70 A/R, 48 trim, TO4S (2.09/3.00 dia), 44 lbs flow.
Turbine: .86 A/R, 76 trim, NS111 (1.85/2.12 dia).
(I have since swapped in the -0001's .64 A/R turbine housing)
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10-05-2008, 04:28 PM
#19
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+1 for all the above. Your problems are likely a relatively cheap and easy fix. Walbro 190 pump and a new filter just in case. The pump is about a 15 minute fix your very 1st time. Just follow the directions in Mnet's garage. It's worth doing without a 2nd thought.
Log some full throttle pulls and see where the duty cycle is after the new pump and filter.
Log some full throttle pulls and see where the duty cycle is after the new pump and filter.
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- I knew it was bigger than the more common sizes though.
