Hi guys, I am about to start the car and before I do so I would like to know how to adjust the Comptech Fuel Pressure Regulator.

I realize that once I loosen the 13mm bolt I can use 5/32 HEX KEY to adjust it up or down.

1) Which way is leaner and which way is more rich?
2) Before I start the car should I bottom out the hex screw and then go up a certain amount of turns?


Please let me know ASAP guys if possible.

 

Down is richer, up is leaner. Average post height for base 5-6psi is about 6-7 threads showing above the lock nut. You need a fuel pressure gauge at min, idle pressure to be safe should be set 55-60psi at stock boost. A wideband to check your afr is really what you should have though.

 

I have the wideband so I can check as soon as I start it up. I assume 14-15 afr at idle cruise is okay and 12.5 in boost right?

 

idle is usually around 14.7 but can vary anywhere from 14-15.5.

On the FPR, counterclockwise is lower pressure...leaner. clockwise is more pressure...richer.

The air pump working at start-up and warm-up makes it go a little higher than that, though...mine can go into the 16s at idle when cold. On a warm engine, idle should be right in the stoich ratio of 14.7-14.8. The FPR adjustment range where it does that is quite wide, though. You need to set the FPR so that at full boost you are not rich and not lean...12.5 is probably too aggressive, esp in the summer...I'd shoot for mid to high 11s in the high range, but at full redline it tends to richen up more than that.

You really should get a fuel pressure gauge...it should be at 50psi at atmospheric pressure ( hose disconnected from FPR...no vac, no boost) for an AP1 and 58psi for an AP2. I use a B&M one I got from Amazon and put it on when going to the dyno...it is like a 5 minute process to install/remove...and the gauge is like $40.

 

yes, and you will be in the low 11's pre vtec to keep in that 12-12.5 range above. Its compromising, but if you have a vafc you can lean that area out and run a little richer up top if you like. But at stock boost 12-12.5 is plenty safe with this kit, even seeing that vtec transition spike in the low 13's is fine and normal. You just need to set your fpr so that your not running excessively lean at the top end where your creating too much heat, and not excessively rich down low where you can fuel wash your motor or create predetonation. You should not be in the 10's at all anywhere in the rpms. You have to find the right balance, becuase unfortunately the fpr isn't perfectly calibrated solely to offer the best fuel curve. This is why us old schoolers used a vafc and why all the new CT and SOS kits now incorporate the new FVM box which does the same thing but without the adjustment.

 

What is this fbm box and what would it replace on the ct kit?

Can it be used?

 

yes, it can be used.

the stock ESM just clamps voltage from the MAP sensor.

The FVM does some trim on the fuel maps, changes the VTEC transition, and clamps the MAP sensor voltage. It would replace the FVM. It's also easier to install as the SOS version has a wiring harness.

An adjustable VAFC is better, but the FVM is set up well for the 6psi kits. It does still run rich down low, spike to the low 13s at 6000-6500, and almost perfect up high.

 

Little update, I am seeing the following....

Idle: 14.7 AFR
Cruise: 14-16 AFR
Full Throttle:
2k RPM - 6k, 12 AFR
6k - 6200 rpm 11AFR (Spike)
6200 - 8000rpm......... 13.1


I am very happy with it now. Would like to leave it as is. I am running 7psi.
Should I keep adjusting AFR till 12.5 or keep it at 13.1?

 

Keep adjusting til you get to the mid 12s at the top end. That's where the ratio seems to be important.

So everything running good? Any hiccups? How's it feel?

 

Feels great, above 3k rpm is where I already feel power. Last night my friend with FD complemented how it picks up faster pre vtec. Past 6500 it really moves. This is with 120k mile clutch and surprisingly no slippage that I can see... YET

I turned FPR another 360 degrees to richin things up. It seems to be in 11.8s below vtec and 13.1 in vtec. Sigh, really don't want to get rid of that bottom end power by making it all sorts of rich, but I guess I have to to get it to 12.5.

I also need to throw boost gauge in and step colder plugs. So far I've been running stocks.