Let me know what experience you guyz had w/ these (Good and Bad). Also I have a Straight stock JDM B20B in my 92 Hatch w/ custom 2.5 carsound performance cat all the way back to muffler and a stock open box intake. So not many mods. Would movin up the fuel preasure help or do anything at all? If so how much should i bump it up to? Last does anyone know what the max a stock fuel pump can put out? Mind that I have a 1992 Civic VX Hatch.

Thanks All

 

a adj. FPR will only help if you are experiencing a leaner mixture than you desire.

it is your call.

increasing your FP probly wont make any difference, except increasing your fuel consumption, and speeding up cat converter decay...

but others may have a different opinion.

better to spend your $ on an air filter upgrade...

HTH,

t..

 

PS i have had good experience with mine, and as i am going B20VTEC soon, it will be essential to setting optimum FP...

t..

 

That's what i figured......guess i'll buy it and put it on when the car getz dynoed....i want to dyno the car b4 i start added mods to it. I really do want the Integra Type-R AEM CAI and JDM 4-1 header. Those should help a lil. Thanks 4 takin the time to answer back


[Modified by jdm4life, 6:31 AM 9/18/2002]

 

i have the guage, its pretty cool. easy to install.
doenst do much tho. i feel a bit rice for puting it on for no reason.
my $.02

 

Well everyone is their own man or woman. I don't knock on anyone whatever floats their boat u know . So u have the gauge but not the FPR (fuel Pressure Regulator)?


[Modified by jdm4life, 7:32 AM 9/18/2002]

 

if you're throwing it on the dyno then go for it.

otherwise don't bother...

 

My B&M fuel gauge is stuck, i mounted it on the fuel rail and i guess the vibrations from the motor jammed the needle mechanisim. I've heard this happening to others aswell. My next fuel pressure gauge will be a liquid filled one.

 

go for a digital one that sits inside the cockpit

 

Uh, wait a minute. Increasing fuel pressure on a O2 feedback equipped car will the car leaner at WOT. Think about that for a second.

 

uh - i have waited a minute and thought about it for a second and -

no, Honda PGM-FI has WOT settings based on a open loop fuel map...

so increases in FP will --> increase in richness at WOT...

t..

 

and you run a motorsports business?!?!?

you must have a better explaination!!!

t..


[Modified by tinkerbell, 3:53 PM 9/24/2002]

 

Actually we do run a motorsports shop, that is why we have a little more information than the average person Here is a little info that may help you to understand a little about engine management. I wrote this previously in regards to OBDII but it applies here:

OBD2 is not THAT bad. It actually makes thing much easier to work on if you have the right tools. As to the ECU resetting itself when you turn off the car, this is incorrect. What it boils down to is short term and long term fuel trim and how the computer is compensating. This applies to OBD1 AND OBD2. Have you ever noticed that once you do mods that the rear of the car is covered with soot and running rich. Seems contradictory to everyone telling you that intake and exhaust mods lean the car out. Actually, both sides are right. When you do mods, the car is actually leaned out but, when driving around in closed loop mode, the computer will look at the short term fuel trim and notice that it is lean and will "ratchet" the long term fuel trim up. If it still sees lean on the short term trim, it will ratchet the long term fuel trim until it (STFT) is where it is supposed to be. On most Hondas, the computer can correct the fuel trim up to about 25% more air flow. After this, it cannot correct. What you end up with is correction of the low-throttle and engine-speeds by the factory ECU.
Now the trick part. What the computer learns in low-throttle and engine-speeds from LTFT it uses to modify the tables for Wide Open Throttle (Open-loop) even though the computer is not actually compensating as it was in Closed loop mode. To recap, what the computer learns from the LT and STFT it uses to generate a modifier for the WOT fuel maps. Since the computer has been seeing lean-lean-lean, it modifies the tables for a rich mixture. The problem is that the WOT tables are already rich so there car ends up way too rich. That explains the lean and rich syptoms that both sides describe.
Typically the mods that you do will lean the car out (make more power) but the computer will compensate for it within a few hours of driving. Something like a Apexi Super AFC works great for this. Use the AFC to trim the WOT settings only and let the ECU take care of the low-throttle and engine-speed settings. You can look at a dyno graph that has the effects on air-fuel ratio by resetting the ecu. Not much power difference but look at how much the ratio changes http://www.lightningmotorsports.com/images/ecureset.jpg Remember this happens in BOTH OBD1 AND OBD2. What is happening is the car has learned to add more fuel since it has been running lean while under O2 feedback control. Once the ECU is "reset", the computer goes back to the default settings which are actually too lean. If you dyno a day or so later, the A/F ratio will go back to rich.
Another illustration is a LS-turbo we had on the dyno. The dash mount A/F gauge was stuck on Rich. The car detonated horribly under even the slightest boost. Once strapped in and hooked to the Wide band we could see that it was actually running a 15:1 A/F ratio even though the gauge was stuck on rich. I pulled out my scan tool and did a quick check at the ECU. The LTFT showed -25%. What that means is the ECU was pulling 25% of the fuel out. Hmmm.. ECU is in open-loop, WOT, but is trying to pull fuel out. Why? Beacuse the O2 sensor was bad, the ECU thought the A/F was too rich, and consequently modified the WOT fuel maps to be lean, in this case 25% lean. Put a new O2 in and the A/F gauge started working correctly, ECU LTFTs went back to around 0, and the car showed 12.6 A/F ratio on the dyno with no detonation at WOT.
The main thing about OBD2 that makes it less applicable for really high performance is that it monitors all engine parameters more closely and this can cause problems for an all-out racer. If you go to really radical camshafts, you will get an engine misfire code from the ECU because OBD2 uses a crankshaft speed fluctuation sensor to detect engine misfires. You can still put cams in the car, just nothing radical enough to set the misfire. You will get a CEL if you remove the cat since OBD2 monitors the efficiency of the cats with the fore and aft sensors. Just go with a High-flow larger diameter cat and you won't have a problem. We have dyno'd some of the new V-8 Camaros and they have shown absolutely zero horsepower gains from removing the cats (using straight pipe) on a mildly modified car. What it comes down to is that you can't be a ham-fisted mechanic with OBD2, if you work within its parameters, it will not give you trouble. If you could see some of the data that you can get out of the newer OBD2 ECUs, you would understand why I am not totally against it. I have seen (and used) OBD2 programming software for the domestic cars, and that totally rules. You can turn off misfire, rear O2 sensors, and much more than I care to list. As Hondata and others work through this, you will be wanting to keep that OBD2 computer (much faster processing) as it will be able to do whatever you want no-matter how far you want to go.

If you have any furher questions or would like to discuss this further, please let me know.

Tom (sorry for the book)

[Modified by lightning, 4:47 PM 9/20/2002]


[Modified by lightning, 3:33 AM 9/21/2002]

 

you have completely failed to explain why an increase in fuel pressure will lead to leaner WOT A/F's

what the ECU does is open and close a pintle on an injector. The some Honda ECU's can correct the pulse width for LTFT requirements, this is calculated using the stock fuel pressure - the OBDII ECU does not measure fuel pressure. once you increase FP from 'stock' the pintles open same time (with LTFT adjustments) but will let MORE fuel past the pintle because it is under more pressure.

therefore being richer.

why the heck do people use an ajustable FPR if it is going to make it run LEANER?!?!?

adjusting FP is elementary to tuning an speed density type EFI system.

maybe as a shop owner you would be advocating the sale and dyno tuning of after-market fuel adjusters??

if i am wrong, and increasing fuel pressure will make an engine run leaner - please explain...

t..

 

That is corect.

Actually, ALL O2 feedback Honda ECUs correct pulse width for the LTFT requirements.

Correct, the ECU does indeed calculate based on it's "known" stock fuel pressure.

Correct, the pintles are open the same time but under higher pressure so more fuel flows. But, "with LTFT adjustments". You seem to understate the importance of that. That is one of the key points to this discussion. That is why I said "on O2 feedback" cars. On a speed-density car, IF you turn off the O2 sensor feedback, the car will indeed run richer ore leaner depending on where the FP is set, with no changes done by the ECU. That is one reason why most companies making true "race" chips will turn off the O2, to keep it from messing up the A/F. The ECU can really change the A/Fs depending on LTFTs.

Go back to the dyno graph and look at the A/F ratio. If putting mods on the car leans it out, explain how the A/F goes almost 3/4 point richer than stock with an intake and exhaust on the car. Under cruising, the car has learned lean so the LTFTs are way in the + range. Now when you go to WOT, the car remembers that it has been lean and applies a modifier to the WOT fuel table to make it richer, problem is, Honda has made it too rich to begin with, the car runs too rich. Once the ECU has been reset, the modifier "dissapears" and lo and behold the car runs leaner. We check the car on the dyno a few days later and somehow the A/Fs have gone "mysteriously" richer.

Most times, it is never adjusted and no one knows what they have done. Normally, they talk to their local "guru" who tells them exactly where it needs to be set, no testing or tuning needed.

That is correct. it dictates the base fuel curve for the car. It minimizes the amount of "extra" tuning required if adjusted correctly, you just need to watch the FTs to make sure the car is not working against you (which it usually is).

Actually I do advocate their use, but only if done correctly and not as dash and engine compartment decoration as is commonly the case.

If you have any illuminating explanations, please let me know. I am always open to new and improved information.

 

I don’t have any illuminating expalination as to why you initially failed to include such relevant and necessary clarification of your original comment, as you have so clearly proved that it is much more complicated than a simple one liner.

For the purposes of this thread and the question initially raised here, what you said was far to broad an approach to tuning and from some perspectives was un-true.

Once clarified, your original comment has a sound basis, particulary with regard to LTFT, although this concept may be slightly beyond the ‘average Joe’ on the street.

I am glad that you have provided such succinct information regarding LTFT and the effect of increasing FP as this will be good for any person who comes across this thread in the future.

t..

PS - yes, i think i may have underestimated the impact of LTFT, what is the MAX OBDII can trim the fuel?

 

I thought higher fuel pressure = more fuel, lower fuel pressure = less fuel

 

Jordo, come by the shop and we can have a little talk if you didn't quite get the gist of the post. TTYL

Tom

 

what psi do you have your fpr set at

 

Sorry if the information seemed to be a little vague. I admit I was a little lazy in quoting a previous topic. As to a simple one-liner response, I was trying to elicit some thinking on behalf of you (and others) as to the total interaction of fuel pressure and fuel management. The OE ECU can correct about +/- 25% via the LT fuel trims to try to get back to Stoich. That is why it is a problem with O2 feedback. If you adjust the fuel pressure up 10-20%, the ECU can still overcome that and can work against you. The OBDI ECUs seem to have a little more tolerance in repsect to fuel pressure. On OBD2s, the ECU will set a code for "fuel system too rich" if you get the FP too high, at levels OBDI would not have a problem with. Basically the ECU has predefined limits for all of the various sensor inputs ie. MAP, IAT, TPS, etc. If the value exceeds the predetermined one, you will get a CEL. OBD2 is definitely more strict in that respect.

 

So in laymens terms, how much tolerence would say a mild P28 (OBDI) programed ECU (say Kenji's for the other readers) have for an adjustable FPR? Very broad I know, but enlighten the crowd on the pros and cons of one of the more commonly used methods of "tuning" the mildly modified Hondas with mild OBD I ECU programs here...

I'd be inclined to take one of these ECU's to the dyno w/ wideband and lean it out 1 or 2 psi at WOT (since most run real rich) with a FPR...