Hey fellas, have been a long time, but life happened a bit but now i'm back and i'm back with a problem.

My car had been in my garage for 6 months because of a transmission problem. Last week we fixed that problem but another one accured.

Injector Duty goes %100 at around 7900-8000rpm and afr goes lean to 12.0-12.1 from 11.5.

Injectors are cleaned and tested. Precision 780CC.
Fuel pump have been replaced with a exact new one. Which is an Aeromotive 340LPH.
Fuel regulator have been check and replaced with a new one.

Setup has been the same for the last 2 years. Turbo is the same, boost is the same(16psi peak-15psi cont.), fuel has been the same, limitor has been the same(8600rpm), injector duty was around 80-82% back then at around rpm limit.

What can be the problem, i'm out of ideas, hope you fellas can help me out.

Thanks in advance...

 

Stock FPR? Have a gauge installed??

My guess is dropping pressure at high rpm

New fuel filter wouldnt be a bad idea

 

Oh yeah i forgot that new OEM fuel filter has been installed. It is an adjustable FPR with a gauge and it is set at 60psi as it has always been.

Tomorrow we'll rellocate the fuel pressure gauge to the inside of the car to see what happens in the high rpms. And even if so it is the case what can cause it? I'm afraid of the other possibility that if the pressure doesn't drop why this happens?

 

Same gas from 6 months ago?

if so then it's that the fuel has gone bad. drain and flush the system and refill with fresh fuel.

 

Done that too, i'm afraid...

 

We've been trying a lot of things that's why i forgot to mention in the original post.

Tomorrow we'll see if the fuel pressure drops at that point where duty cycle sits at 100%. My friend/tuner/mechanic was kind of busy today.

What has been done so far;

-Injectors have been tested and cleaned.
-Fuel rail was checked and cleaned.
-New adjustable FPR + New Fuel Pump
-New OEM Fuel Filter
-Fuel tank has been drained, flushed and new fuel have been filled.
-Return and feed lines have been checked but not throughly. We simply checked each line with pressured air if it was clogged.(Removed the piece at the head of the fuel rail and pumped air at the fuel pump feed line at the back seat for the feed line, and opened the fuel tank cap and pumped air at the end of the fuel regulator and saw it came out at the fuel tank cap for the return line.)
-Electrical wirings have been checked. Battery voltage is stable the and wirings at the fuel pump is good.(upgraded back then anyways, thicker ground cable,...etc.)

Can't think of anything else. Everything is the same, what can cause this ? :/

 

Something in the tune is causing the fuel injectors to raise their duty cycle. I.E. iat corrections, or the map sensor is seeing more boost. Hondas ecus run open loop at wot and do only what the ecu is programmed to do. It does not make corrections based on air flow like a maf based car would. Why the motor is running slightly lean even with more injector duty could be a number of reasons. The ecu could be adding more timing then before or the motor is less efficient due the the hotter temps outside possibly. It's too hard to say without comparing before and after datalogs.

 

What map sensor are you using?

 

@92cxturbo; i'll pass that info to my friend since he is my tuner. But, like i said, everything is the same before and after the malfunction.

@HyperHoHo1; i'm using an AEM 3,5 bar one.

 

New info;

Fuel pressure is steady. That leaves the injectors... How can sitting for 6 months(occational starts in the garage) can ruin injectors ?

And the thing is, injectors have been tested&cleaned in a Bosch Car Service. But i guess the test they were doing was at 2 Bar(around 30psi) and they can't perform the way they used to perform under 60psi pressure.

Btw, injectors were Precision 780CC Low Impedance ones. I was using them with resistor box. I won't recommend Precision injectors to anyone anymore i guess...

 

Easy way to check is to swap in some other injectors - maybe rc750 and then tweak your tune for that size (go a little richer wot), and take a pull.

Basically, a known good set of injectors should give you confirmation whether that's the cause.

 

Yeah, that's next in our to do list.

 

We haven't tried another set of injectors yet, we're looking for one that we can try, BUT(!), we've noticed a new symptom;

The AFR is sometimes 11.8 and sometimes 13.0 at WOT after VTEC and Full Boost. But the duty is always 100%. It is not fluctuating in one run, each run it is either 11.8 or 13.0.

Let me remind you that we've renewed the OEM fuel filter, fuel pump(which was a Aeromotive 340LPH and the BRAND new one is the same), new FPR, the fuel tank is flushed and new fuel have been put in, feed and return lines have been semi-checked via applying pressured air with each sides of the lines are open. Except for the injectors, anything fuel related has been checked. MAP sensor is good too, we've tested another one and it is the same. All other cabling has been checked too, they are rock solid. Electrical system is fine.

Fuel Pressure is steady too. 62psi at idle, and when at full boost it is 70psi and holding without fluctuation.

Now, before trying a new set of injectors, we'll make a new feedline from the tank. But, that made me think, if the AFR is changing this much(11.8 vs 13.0 is a lot) maybe the injectors are fine ? Do faulty injectors behave like this ? Can it be a clogged feedline or maybe an inside the ECU electrical failure ? Loosen, rusted soldering point, or something ? But, everything else is fine like a beast. I'll go crazy soon... :'(

 

Have you done a fuel pump volume check?

 

Your fuel pressure is disturbing. 15-16psi of boost only raises your fuel pressure 8psi? That's a problem. Do you not have a 1:1 regulator?
Why is your idle pressure so damn high? Check the vac source on the regulator, I suspect a leak which would explain the inconsistent AFRs.

 

Yea pressure should climb one psi for every psi of boost pressure... assuming you are using a 1:1 regulator.

Also 62psi is too high for base pressure, especially with the old Lucas/rochester style injectors. their maximum pressure ceiling is 75psi IIRC

Are you using e85 or standard e10 pump gas? when fuel sits it goes through all sorts of weird chemical changes and it aborobs moisture. the water suspended in the fuel can damage injectors due to corrosion of internal parts.

 

New info: With the current setup, we can't set the idle FP at or under 50psi at idle.

My FPR is a no-name ebay one i think(generally labeled as Tomei or Sard), the one i replaced earlier was the same BUT the car was OK until the transmission thing. As far as the pressure goes, my FIRST tuner set it to 60psi when the car was first built. He removed the vacuum line from the FPR and set it to 60psi and i never questioned it until now.

Anyways, today we're gonna replace it with a genuine AEM FPR to check. If everything is the same again with the genuine AEM FPR, i think only thing left to do is getting new set of injectors because i can't find another set to test with.

Reminder; my current injectors are Precision 780CC Low Impedance ones that i've been using since the built with a resistor box.

What would you recommend i get IF new regulator doesn't fix it ?

RC or ID ? I'm thinking of getting 1000cc in case i want to up the boost.

PS: I'm using regular pump gas 95octane(it is equivalent 93octane of your gas i believe) with a methanol kit(50/50 solution).

 

Your FP is definitely suspect and be advised a functioning FPR with change the FP more requiring the fuel table to be touched up.

I would always recommend ID over RC injectors. Just compare the age of the products. Old vs new tech.

 

Rc has high impedance injectors.

They been around a lot longer.

I would go with the people who have been in buisness longer with anything I buy when it comes to quality.

 

while rc is a well established company the new bosch ev14 based injectors are far superior in every aspect.

Higher fuel pressure capacity, better atomization, quicker response time, finer pulsewidth resolution, etc.

 

Hey guys, new info:

We tried new AEM FPR still the same issue. And we got a new symptom that we can reduce the FP at or under 70psi.

But the wierder thing is, we put STOCK FPR and it is still 70PSI. WTF ???

And even wierder is that injectors go 100% duty at 70PSI.

Can broken/faulty injectors can do that ?

Return and feed lines are PERFECT. What can cause this ?

We are going out of our minds fellas, only thing we haven't changed are injectors.

Everything else is cleaned, checked and/or replaced...

I'm out of my rope fellas, what can cause this ? Stock FP @ 70PSI ? WTFFFFF ??? (

 

Use the largest orifice included with the AEM FPR to reduce the FP at idle.

What is the FP under boost though?

 

It is irrelevant i believe because i've been using the car with the other regulator for 1.5 years without an issue. Stock FPR should reduce the pressure to stock pressure. Now we gonna put a stock fuel pump to check the pressure.

 

What are you using to check pressure?

 

The stock fpr cannot keep up with a high volume pump therfore the pressure rises. If you tried using the bigger orfice with the aem and cannot lower pressure you have a cloged return line.