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Old 06-24-2008, 12:36 AM   #1
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Default Installed "new" injectors now running lean.

I installed a vishnu fuel rail and RC550 (high impedance) injectors. I'm running a link and previously was running 460cc injectors.

After installing and adjusting master fuel to 80 the car idled roughly and off the scale lean. Even if I adjust master fuel back to 100 where it previously was set it is still running leaner than it was with the 460s. I haven't touched injector offset yet, I assume it can't make that much difference.

Could a vacuum leak cause this? I'm pretty sure I've got a good seal at the injectors. When I was installing the FPR on to the rail I pinched the oring and tore a large chunck of it off. I've installed a new oring, but maybe there is a piece of it in the rail somewhere.

I'm guessing that the injectors are probably fucked.

God dammit!
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Old 06-24-2008, 01:46 AM   #2
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How are you seting the FPR? 80 psi? Isnt that a bit high? Is the vacum line for the FPR conected before or after the throttle body? Did you ahve the injectors flow tested?
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Old 06-24-2008, 01:50 AM   #3
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How are you seting the FPR? 80 psi? Isnt that a bit high? Is the vacum line for the FPR conected before or after the throttle body? Did you ahve the injectors flow tested?
The FPR I mention is the stock one bolted to the fuel rail. The setting of 80 is Master Fuel on the Link ECU. The injectors were supposed to have been recently cleaned, so I didn't get them flowed. Suppose I will have to now.
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Old 06-24-2008, 10:05 AM   #4
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Do you have a compressor? If so- here's what I did. Used some hose that fit snug over the injector feed end, put some fuel in the hose (don't fill it, just enough to feed the injector), then put the compressor on it at 40psi. Remember to keep the injector low so it's always got fuel. Then take a low amp 12v source (battery charger), put ground on one injector terminal, and then quickly tap the 12v+ to the other terminal. That'll reveal any major oddities in the injectors. Just make sure that you move the + quickly. If you hold it there too long you'll burn up the injector.
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Old 06-24-2008, 10:09 AM   #5
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I have a little rig I made with a half dead 9V to test injectors in the manner Rob has described. Most new "smart" battery chargers won't work.

Then the question becomes, did you put injectors in the car that you didn't service first?
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Old 06-24-2008, 11:14 AM   #6
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I have a little rig I made with a half dead 9V to test injectors in the manner Rob has described. Most new "smart" battery chargers won't work.

Then the question becomes, did you put injectors in the car that you didn't service first?
Bought them from a user here, they were supposed to have been serviced. Ya I know ...
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Old 06-24-2008, 11:15 AM   #7
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Thanks for the testing ideas guys.
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Old 06-24-2008, 11:30 AM   #8
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perhaps the RC's atomize the fuel better, allowing for more complete burn?
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Old 06-24-2008, 11:31 AM   #9
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Jay,

The injectors were serviced, and here is the report. If something is wrong with them, I will refund you and deal with Affordable Fuel Injection
Attached Thumbnails
Installed "new" injectors now running lean.-100_0589.jpg  
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Old 06-24-2008, 11:45 AM   #10
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Were the old injectors RX7/OE? I wouldn't assume anything. It's not going to hurt anything to move the master fuel around and change offset. I know there's a big difference between an RC 550 and an RX7 550. The difference between the two may not yield a logical result in your situation. If you get it idling right, then drive around out of boost and see what the AF looks like.
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Old 06-24-2008, 11:50 AM   #11
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Quote:
Originally Posted by Ben View Post
perhaps the RC's atomize the fuel better, allowing for more complete burn?
This is the reason I am switching from the RX7 460s. In my experience the RC injectors idle better. However the difference between the 460s and these 550s is very significant, like I'm only getting 75% of the fuel or so. Like I said if I leave master fuel at 100 with the 550s it idles Ok, but more lean than the RX7 injectors by a point or so. With master fuel at 100 and the 550s the car should be really rich.
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Old 06-24-2008, 11:57 AM   #12
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Quote:
Originally Posted by m2cupcar View Post
Were the old injectors RX7/OE? I wouldn't assume anything. It's not going to hurt anything to move the master fuel around and change offset. I know there's a big difference between an RC 550 and an RX7 550. The difference between the two may not yield a logical result in your situation. If you get it idling right, then drive around out of boost and see what the AF looks like.
Yes they were OE 460s.

Running an RC550 on a 1.6 Link should require master fuel of 80. (440/550). I ran my RX7 460s with a MF of 100 and a different offset (can't remember the number off hand). This is a pretty good indication that the RX7 injectors do flow in the neighborhood of 460cc.

I'll play with injector offset, but I don't have high hopes. I don't think it will compensate enough. I'd probably have to run MF a few points above 100 to get idle in the 15AFR range.

At this point I think I'll switch back the RX7 injectors, and see if the problem persists. If not then I'll look into having the RC's serviced.

It's just a pisser since I modified my harness already
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Old 06-25-2008, 11:26 AM   #13
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I've been owned by injector offset. Set injector offset from 30 to 85, and it idles like a dream with master fuel at the proper 80. Haven't driven it yet, but I would assume that the injectors are fine.

After posting this thread keinayo who originally sold me the injectors sent me a refund for them with out any prompting from me. Said if the injectors turned out to be bad for me to send them back at his cost and he'd deal with the company that cleaned them. If they turned out ok to send the refund back.

Needless to say I'm pretty impressed and will be sending the refund back once I confirm it'll do more than idle correctly.

So a big thanks to keinayo!

Jay
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Old 06-25-2008, 11:30 AM   #14
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Nice. Yoram is indeed a stand up dude.
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