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I recently decided to modernize the fuel system and bought and installed the following:
- FFE primary rail with flow matched Bosch 650cc injectors (Blue sleeves w/o-rings)
- Rewired the injector clips to put in pigtails for the new injectors
- Full braided hoses in the engine bay (from hard feed line > secondary rail > primary rail > FPR > hard return line)
- Fuel Pressure gauge on the FPR
New Problem
1) The car starts fine, however runs rich (I'm seeing AFRs in the high 10's to mid 11s) and the car stalls out if I don't maintain the RPMs at around 2K. The injector duty seems to be around the 10% mark at idle and 15% around 2K RPM. Question: Is this normal behavior as I've went to bigger injectors and not adjusted anything in the ECU?
2) The setup no longer holds fuel pressure after the pumps prime or the engine is shut off/stalls. Previous to the new setup, the car would prime the pump and fuel pressure would go to ~35psi, then it would drop slowly back down over 5-10 minutes. However now following prime or shut off, the fuel pressure drops to zero almost immediately. Question: Is this normal behavior or is it possible I have a leak somewhere? No leaks are visible at the fuel lines.
Video
Here is a video of the car being started up and stalling out. You can also hear buzzing at the FPR after the fuel pressure goes back down to zero (as if something is leaking someplace):
My suspicion:
I have a feeling there is a problem at the new rail/injectors, which might be leaking fuel into the engine causing her to run rich. It might also be a problem with the FPR or maybe a wiring issue with an injector that fires more than it should.
I'm also not certain if I installed the primary rail or injector sleeves correctly, so wanted to validate with the forum before pulling things apart.
You will definitely need to set up the PFC for the larger primary injectors. You went from 550cc to 650cc.
The FPR is what maintains line pressure. Either you have a leak somewhere in the system or the FPR isn't holding pressure. It's possible an O-ring for one of the injectors is leaking.
Also test all your fuel pressure stuff with the jumper in the engine bay instead of trying to troubleshoot it while the car is on and running. This will also help you figure out if you've got an issue with vacuum on the FPR and be able to smell or see any kind of leaks while having the upper manifold out of the way.
I would check with the FFE instructions from their website and make sure you got the right combo of injector size + adapter fittings as well as using the two-oring method instead of the single o-rings that tend to come with the Bosch EV14 type injectors.
New Problem
1) The car starts fine, however runs rich (I'm seeing AFRs in the high 10's to mid 11s) and the car stalls out if I don't maintain the RPMs at around 2K. The injector duty seems to be around the 10% mark at idle and 15% around 2K RPM. Question: Is this normal behavior as I've went to bigger injectors and not adjusted anything in the ECU?
The primary injector change is why your AFR's are different. You went up 18% in fuel injector flow capacity with no fuel map changes. If you previously idled at 13.0 AFR, you would now be at 11.0 AFR without the change in deadtimes between the two injectors; Deadtimes could account for another 5-10% depending on the design of the injector.
Originally Posted by telram
2) The setup no longer holds fuel pressure after the pumps prime or the engine is shut off/stalls. Previous to the new setup, the car would prime the pump and fuel pressure would go to ~35psi, then it would drop slowly back down over 5-10 minutes. However now following prime or shut off, the fuel pressure drops to zero almost immediately. Question: Is this normal behavior or is it possible I have a leak somewhere? No leaks are visible at the fuel lines.
This could be a leak or the check valve in the pump could be bad. This is not necessarily a bad thing, you can still start your car like this; Just make sure you don't have any leaks!
Thanks a lot for all the responses. I'm back at it with an update and a couple more videos.
Originally Posted by Darkning
I would check with the FFE instructions from their website and make sure you got the right combo of injector size + adapter fittings as well as using the two-oring method instead of the single o-rings that tend to come with the Bosch EV14 type injectors.
I followed the FFE instructions and did the following, but just to be safe here is what I did:
1) Used the blue sleeves (pictured) which I got from IR Performance with the EV14 injectors
2) I left the top o-ring as is on the bosch injector and just pushed it into FFE primary rail
3) I removed the bottom green o-ring on the injector and replaced with 2 of the smaller injectors
Originally Posted by Copeland
The primary injector change is why your AFR's are different. You went up 18% in fuel injector flow capacity with no fuel map changes. If you previously idled at 13.0 AFR, you would now be at 11.0 AFR without the change in deadtimes between the two injectors; Deadtimes could account for another 5-10% depending on the design of the injector.
Makes sense, so I guess that is good to hear.
Originally Posted by Copeland
This could be a leak or the check valve in the pump could be bad. This is not necessarily a bad thing, you can still start your car like this; Just make sure you don't have any leaks!
Agreed, but it could also be a problem with the FPR too.
Here is what I'm seeing when I prime the pump when I go to key on:
So tonight I decided to do the fuel pump wiring mod, using a 30A relay and 10 gauge wiring direct from the battery. I decided this was the right time to do it since the car will be going to the Dyno for a tune in the next couple weeks.
Now with the upgraded wiring, the pump seems to be getting a lot more amperage (higher peak fuel pressure +15psi) and the system seems to be having a much harder time maintaining fuel pressure (fuel pressure bleeds off petty quickly).
So now, I'm wondering if I should troubleshoot this further (to determine if I have an issue at the FPR or the pump) and if so, how I should go about it?
So a key-on prime won't be constant (except for about 5s) after you turn the key on, it will lose pressure because it doesn't keep the pumps going for longer than that. Unless you've sent power to your relay (or the pump for that matter) from an ACC/Ignition signal instead of factory wiring. You'll need to go to the jumper box under the hood and jump the F/P and GND pins with a paper clip or piece of wire to get the pump to consistently run and pump fuel through the loop for as long as you need to troubleshoot.
With all that said, it definitely looks like the gauge is losing pressure much faster than a natural, gradual loss of pressure. My setup definitely loses pressure quicker than 5-10 minutes, maybe closer to 1-2. Are you sure that the fuel isn't leaking somewhere else in the lines? If not, the FPR may have failed on you.
It's not important that you hold fuel pressure with the fuel pump off, so I wouldn't bother trying to fix it. If you don't have external leaks, just drive it and enjoy it.
If you want to rule out the pump or a FPR for a pressure leak, you could cap off the return line to the tank. Probably just use a bolt and hose clamp to stop up the line.
Key on to run the pump to pressurize the system. If the pressure holds, you have a solid system with no leaks and the FPR is probably the culprit for not holding pressure with the fuel pump off. If it leaks down, you know you have a leak inside the tank on the fuel pump outlet side or something like that.
If the FPR doesn't maintain pressure with the fuel pump off I don't know how big of a deal that is, I don't think it is. If you have a leak at the fuel pump, that could be a problem since you would be losing volume from the pump which could result in a pressure drop at high demand.
So I used a jumper to keep the fuel pump running and the pressure holds pretty nicely when the pump is running. I'm not sure if the pressure is higher (because of the upgraded wiring) than what the car was set to on the previous tune.
I don't see or smell any leaks at this stage, so maybe the check valve at the pump has just gone bad. The car starts without too much fuss consistently.
Update:
I then went on to tweak the injector setting in the PFC using my commander. I changed the injectors to 650cc and reduced the injector pulse too for the primary injectors.I did expect this would lean out the car, but it did not.
I basically, followed the instruction on Page 26 of the PFC here
The car still runs rich and will stalls out as soon as the RPMs drop below 1500rpm. When it does stall I can hear a loud buzzing noise.
I thought the noise was from the FPR as the pressure was dropping on the gauge, but in fact the noise is coming from the area near the firewall. I haven't been able to figure out what the noise is (maybe an injector, or a boost solenoid). There are no visible leaks anywhere, and as soon as I go to key off the buzzing noise goes away and does not reappear when I go back to ACC or ON.
Things to address:
1) Car running rich: At this stage, should I try anything else to lean the car out (lower base pressure or PFC adjustments)? Alternatively, I can just wait to take her to the tuner.
2) Buzzing noise: Should I invest more time to try to figure out what the source of the noise is and if it is related to the rich condition?
Buzzing is going to be the ISC - idle control solenoid. Search around on that, I THINK if the TPS is set wrong it will buzz. Could also be dirty/stuck.
If you have more fuel pressure than stock that will richen the mixture up even more. You probably are best served adjusting the FPR to stock pressure.
07-20-19, 07:30 AM
Need advice on fuel system problem (Video)
