New injectors
Racer
Joined: Oct 2006
Posts: 438
Likes: 14
From: Tucson/Santa Paula AZ/CA
2017 C4 of Year Finalist
You need to check the supply line (to verify your check valve and pulsator in the tank are good) and the return line to see if the FPR is holding pressure. If you pressurize the rails and have someone else pinch off the supply hose back near the tank, you can determine if any injectors are leaking or if the check valve is defective.
I would NOT worry about a lean condition unless you have data scans and you actually know that you have a lean condition.
My Bosch III's are working great! The engine is smoother and pulls harder than it ever did with the Multechs. I had one definitely defective injector when hot and two others that were marginal when hot. My BLM's are 134-138 and my O2 sensor counts rollover quite regularly Rich/Lean Rich/Lean transitions are an indication of good AFR and there is LOTS of adjustment built into the ECM (0-255) for BLMs
I have adjusted my fuel pressure to 39 at idle, 48 psi WFO and 49 psi ignition on engine off. I am not concerned at all about running too lean. Won't happen.
Team Owner
Joined: Jul 2004
Posts: 28,430
Likes: 3,280
From: Hartford WI
I don't claim to know but I have the HSR one and the Kirban one and neither would hold pressure as long as the stock FPR. I called all around and got the same answer.
Racer
Joined: Feb 2009
Posts: 486
Likes: 3
From: el cajon ca
I see, well clambing the return line is a good idea and I would do it tomorrow to see What's up, thanks for the help
Racer
Joined: Feb 2009
Posts: 486
Likes: 3
From: el cajon ca
That's sound good and I will first do it tomorrow, thanks, and yah I have a wide band installed in my car and also I have also aldl cable and tuner pro so when I say it's running RICH I mean it, the wide band shows rich the first 3 min of cold start (11 to 12.5:1) on open loop and then it bounces between 14 to 15.9:1 in closed loop and its like 10.5 on WOT, and when I scan it the blm is 116 on idle so all that tell me it's rich, but I don't know if its from the 24lb injectors and it's just need to be tuned or I have a leaky injector! I kind of think that it would be a leaky injector #7 and that would explain why the O2 was leaning the mixture when it was mounted on tube#7!!
Racer
Joined: Oct 2006
Posts: 438
Likes: 14
From: Tucson/Santa Paula AZ/CA
2017 C4 of Year Finalist
Ricky,
Your 116 BLM sounds like 24# injectors and your AFR is right in line. Does the engine start and run smoothly? You don't have excessive "spark knocK" counts?
Your 116 BLM sounds like 24# injectors and your AFR is right in line. Does the engine start and run smoothly? You don't have excessive "spark knocK" counts?
Racer
Joined: Feb 2009
Posts: 486
Likes: 3
From: el cajon ca
the engine starts and run ok, finaly today i was able to check the pressure on the supplying line right before it conects to the fuel rails, when i open the ignetion, it shows 80 psi, and after like 15 seconds it goes down to 70 and it keeps going down till it gets 55 and stays there for like half an hour, after that i dissconected the gauge after i became sure that i have at least one leaky injector, because when i messured the pressure using the fitting at the rail, after the half hour it was almost at 10 psi!!!
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Racer
Joined: Oct 2006
Posts: 438
Likes: 14
From: Tucson/Santa Paula AZ/CA
2017 C4 of Year Finalist
the engine starts and run ok, finaly today i was able to check the pressure on the supplying line right before it conects to the fuel rails, when i open the ignetion, it shows 80 psi, and after like 15 seconds it goes down to 70 and it keeps going down till it gets 55 and stays there for like half an hour, after that i dissconected the gauge after i became sure that i have at least one leaky injector, because when i messured the pressure using the fitting at the rail, after the half hour it was almost at 10 psi!!!
Connect the fuel pressure gauge at the fuel rail.
1. Ignition ON, engine off at least twice with 15 seconds of OFF time
between ON events. Leave the ignition ON at least 5 seconds.
Record the fuel pressure at the rail.
2. Determine how long the pressure at the rail stays above 35psi
3. If the rail pressure drops off quickly (seconds), do the same
test as #1 again with the return hose pinched off either below the
A/C compressor or back at the tank(the hoses are easy to access
if you remove your fuel door and rubber grommet). If the pressure
still drops quickly........
4. Pressurize the fuel rail as in #1 above but as soon as you have
pressure in the rail, have someone pinch off the SUPPLY hose at the
tank or under the A/C compressor. This will verify the check valve
in the fuel pump is good (if the pressure holds with the supply hose
pinched, you have a defective fuel pump check valve).
If you can NEVER maintain pressure above 35psi for 20 minutes, you have a leaky injector. I'm betting on a FPR or fuel pump problem.
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
You said you’re running Bosch 24# injectors. If they are the black ones 155-703 then they are 24# @ 43.5 the blue Bosch 155-715 also rated at 24lb’s have a tendency to run higher, around 26.5lb on gas that’s why guys like them. Just a thought. Might want to retune a little if you’re running the blue 715’s
Instructor
Joined: May 2001
Posts: 186
Likes: 0
From: Midwest
Fuel injectors are manufacturer rated for static flow, meaning that they will flow at a given volume, at a given pressure, for a given time at full flow, no pintle, disc or whatever installed. However, the dynamic flow, with valving action, changes from various manufacturers and valving styles, such as pintle Vs disc, at different pulse rates, affecting "dash gasmilage". The only accurate way to compare is the old fashioned method, number of miles divided by the number of gallons.
Last edited by dynocar; Jul 16, 2011 at 10:09 PM.
Racer
Joined: Feb 2009
Posts: 486
Likes: 3
From: el cajon ca
If you change from the stock fuel pressure and/or to a different brand or flow rate of an injector, you can no longer use the "dash gasmilage" for miles per gallon. The "dash gasmilage" is calibrated to a specific factory injector's dynamic fuel flow using the injector's pressure differential, pulse width, RPM and MPH to calculate MPG. Any change from the dynamic flow of the factory injectors renders this computation in error. Example, if we change from a 20 to a 40 lb/hr injector, our "dash gasmilage" would approx double.
Fuel injectors are manufacturer rated for static flow, meaning that they will flow at a given volume, at a given pressure, for a given time at full flow, no pintle, disc or whatever installed. However, the dynamic flow, with valving action, changes from various manufacturers and valving styles, such as pintle Vs disc, at different pulse rates, affecting "dash gasmilage". The only accurate way to compare is the old fashioned method, number of miles divided by the number of gallons.
Fuel injectors are manufacturer rated for static flow, meaning that they will flow at a given volume, at a given pressure, for a given time at full flow, no pintle, disc or whatever installed. However, the dynamic flow, with valving action, changes from various manufacturers and valving styles, such as pintle Vs disc, at different pulse rates, affecting "dash gasmilage". The only accurate way to compare is the old fashioned method, number of miles divided by the number of gallons.
