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Discussion Starter · #1 ·
I took out my 720cc injectors and put in some that are supposed to be 1000cc. The a/f was then very lean across the board, near idle as well as under boost. So I had to turn the fuel settings UP for the new injectors. I'm using an AEM EMS to tune and FJO wideband to monitor a/f. I took out the plugs to verify the color agreed with what the FJO was telling me, and it did. I'm basically maxing out the 1000cc injectors at only 26psi with a small turbo (t60). I think my base fuel pressure is set to only 30 psi (normally I would know for sure, but my stupid gauge or sensor died). I was told 30 is too low and I may need to increase it to 45 psi. Is it normal for a/f to go lean like this if the fuel pressure is not increased, or do you think they sent me the wrong injectors?
 

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Discussion Starter · #3 ·
I believe I measured 30 psi with the fuel pumps on and the engine off last time my gauge worked. I've been running the same psi for many years no problem. Never heard of anyone running it so much higher, unless they were trying to push small injectors to their limits.
 
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^^^Thats not what Wreckless means.

Are you measuring 30psi with the vacuum line attached to the FPR or with it disconnected? For example, with my vacuum line off I have mine set to around 44psi.
 

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Discussion Starter · #5 ·
Well, with the engine off, it would be the same as if the vacuum line were unplugged, wouldn't it? Maybe I'll just run to the store and buy a cheap fuel gauge for now... I guess it's even possible that one of my fuel pumps or lines is messed up, but I doubt it.

30psi is what I remember, and I know it's not more than 35psi. Is that definitely too low? From what I was told, big injectors just need higher fuel pressure. I never heard that before... is that true? ~30psi is the most I've ever run for base pressure, and I've been running 33psi+ boost w/many different turbos for years. Never had a problem.

The new injectors I put in are Precision, PFU 041-0950. Here is a pic I took of them: http://www.paulmendelson.com/temp/injectors.jpg. Assuming the box they were in is correct, it sounds like these are indeed 1000cc injectors after doing some quick research on the net.
 
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Well, with the engine off, it would be the same as if the vacuum line were unplugged, wouldn't it? Maybe I'll just run to the store and buy a cheap fuel gauge for now... I guess it's even possible that one of my fuel pumps or lines is messed up, but I doubt it.
My bad, that works as well. Yea, 30-35psi is too low with the vacuum line off. Did you make sure to go into the AEM wizard and set up the EMS for the new injectors?
 

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Discussion Starter · #8 ·
Ok, thanks Taimur; maybe I'll turn it up to 42-45 psi and give it a shot. BlueSteel - Good question. I think I did do that initially, but come to think of it, I think I switched to a different map and forgot to do it again... lol, maybe that's part of the problem. I'm going to have to buy a new fuel pressure gauge or sensor before I mess with it again... I tried turning up the fuel pressure blindly and the afr is not changing how I expected.
 

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Discussion Starter · #9 · (Edited)
Wow it looks like I was way off on the fuel pressure lol... I just got a mini fuel pressure gauge and hooked it up in my engine bay. It's reading 60psi with the engine on or off! I loosened the adjustment screw on top of the FPR all the way, and the pressure is still 60psi. I then tried tightening it... the fuel pressure didn't change at all until the screw was about 80% tight, then the fuel pressure started going up like normal. What the heck? Is my FPR broken? Or maybe my return line is clogged/pinched? I assume the fuel pressure is not going up with the boost how it should - perhaps not until higher boost - so this would definitely explain my weird tuning issues I've been having.
 
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^^^Yea, it sounds like you have some issues there. I've had 1 FPR go bad on me and the outcome was absolutely no fuel pressure. The car died and would not start. Luckily, I had a spare
 
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