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Old 10-04-2008, 11:23 PM   #1
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Angry 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.
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Old 10-05-2008, 12:02 AM   #2
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it doesnt help that we have **** for gasoline here in cali, so you end up having to run richer than most other people to stay safe ftl...
do you have a fuel pressure gauge?
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Old 10-05-2008, 12:04 AM   #3
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Fuel and boost tables:


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Old 10-05-2008, 12:05 AM   #4
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Some pics and the overall results





35000 cfm fan, simulates 80mph driving!
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Old 10-05-2008, 12:08 AM   #5
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Quote:
Originally Posted by 18psi View Post
it doesnt help that we have **** for gasoline here in cali, so you end up having to run richer than most other people to stay safe ftl...
do you have a fuel pressure gauge?
No, but I think I might be looking into getting one very soon.
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Old 10-05-2008, 12:09 AM   #6
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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
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Old 10-05-2008, 12:30 AM   #7
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Do you mind me being nosey and asking how much it cost to have it tuned at that shop? I'm thinking of getting mine done there too(after I deal with my state referee ticket).

Feel free to PM me if u like.
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Old 10-05-2008, 01:02 AM   #8
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sent you PM
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Old 10-05-2008, 10:41 AM   #9
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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. [email protected] 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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Old 10-05-2008, 11:41 AM   #10
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Sam, you are right on with the parts list. (goes to fill out sig...)
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Old 10-05-2008, 11:45 AM   #11
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test of new sig
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Old 10-05-2008, 12:33 PM   #12
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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.
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Old 10-05-2008, 01:21 PM   #13
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It's possible if he wasn't maintain fuel pressure, yet dropping it, he could be hitting those high DC% numbers. Aren't '99s notorious for dropping below 60psi?
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Old 10-05-2008, 03:29 PM   #14
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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.
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Old 10-05-2008, 04:27 PM   #15
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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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Old 10-05-2008, 04:27 PM   #16
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Quote:
Originally Posted by y8s View Post
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.
How the heck are you getting 250 rwhp at 9.5psi?? Very impressive.
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Old 10-05-2008, 05:06 PM   #17
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He has a bigger turbo - 2871, IIRC. Much more flow at lower boost levels.
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Old 10-05-2008, 05:25 PM   #18
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Quote:
Originally Posted by boileralum View Post
He has a bigger turbo - 2871, IIRC. Much more flow at lower boost levels.
I believe he has a T04 compressor none the less.. from his DIY page in sig:

Quote:
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)
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Old 10-05-2008, 05:28 PM   #19
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Quote:
Originally Posted by cueball1 View Post
+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.
search some of POPSTOY's posts on m.net, he went through a few different pumps until he found one that didn't drop pressure.
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Old 10-05-2008, 05:51 PM   #20
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Quote:
Originally Posted by elesjuan View Post
I believe he has a T04 compressor none the less.. from his DIY page in sig:
I obviously didn't RC - I knew it was bigger than the more common sizes though.
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