I have had throttle hesitation for a little while and to try to determine the problem I just installed B&M FPG. I changed my fuel filter before installing the guage and noticed the fuel was practically black. My fuel pressure stays at around 32 at idle with a p30 ecu and B16a, but jumps to 40 when you open the throttle body. When I shut off my car off sometimes my guage loses all pressure and drops to 0 psi after 5-10 minutes. This is not right. Any suggestions?

 

Why would you expect the fuel system hold pressure when the car is not running?

 

No, it is running, just hesitating quite frequently in lower throttle body ranges. It maintains 32 psi approximately when running, and you can hear the fuel pump running, but I think the fuel pressure drop when the car is off might have something to do with why my performance is being affected. Leaky vacuum?

 

WTF? lol. ofcourse the fuel pressure will drop to zero if the car is off. somethimes it drops right away, sometimes it takes a few mintutes to drop

 

 

Actually. there is a check valve in the fuel pump that is supposed to maintain fuel pressure when the car is off on some cars. It doesn't have anything to do with your cars problem, though. The pressure should rise when the pressure in the manifold rises (like when you womp on the gas), this is normal. What does the fuel pressure do when you are driving?

-Scott Tucker


Modified by AutoEng2002Si at 2:47 AM 1/5/2006

 

Do you have any CELs (check engine light)? What do you spark plugs look like?

 

Thank you for your help guys. I do not have any check engine lights, although I did have one come on in high rpms in 4th gear, however when the vehicle shut off it disappeared. I think it is stored in the ecu, and I tried to jump the blue connector under neath the glove box with a paper clip to see the code, but nothing shows up.....I am not able to check the fuel pressure while driving because my guage is on my fuel filter. I checked the spark plugs(iridium, installed few months ago) to see they appear to be a little white. I read my haines manual for the D16A6 motor which is supposed to be in my CRX. It says when a spark plug is running hot like that that you may be getting lean fuel, or an intake manifold vacuum leak. Also, when the vehicle is warm, I turn it on sometimes and it will either stall out, or the idle will drop to like 100 rpms for a few seconds before it goes back up again. I also read in the haines manual that if it starts but stops immediately that it may be:
1. Insufficient fuel reaching the carbureator or fuel injector(s)
2. Vacuum leak at the gasket between the intake manifold/plenum and throttle body.

So I have concluded that my problem is either fuel related or an intake manifold leak. Since I installed a skunk2 manifold and a hondata heatshield, maybe something is leaking there. My fuel filter had black fuel in it, but I do not think it was clogged when I replaced it. Fuel coming from the tank looks fine.
I also think I hear a slight whistle sometimes at lower rpms when accelerating.....Did I just solve my problem myself? Is it a manifold air leak?

Oh and not all of us are qualified mechanics, but we try our best with the small amount of knowledge and money that we have. I am sorry I did not know the fuel pressure was not supposed to drop to 0 when the vehicle is off.

 

The whistle that you hear at low RPM is normal; it is typically caused by the throttle plate.

If you had a vacuum leak, you would typically have an erratic or high idle.

I would check the cam and ignition timing. I would guess that your problem is most likely spark related. You may also need a new fuel filter if the fuel is black.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B16aSir2 &raquo;</TD></TR><TR><TD CLASS="quote">I have had throttle hesitation for a little while and to try to determine the problem I just installed B&M FPG. I changed my fuel filter before installing the guage and noticed the fuel was practically black. My fuel pressure stays at around 32 at idle with a p30 ecu and B16a, but jumps to 40 when you open the throttle body. When I shut off my car off sometimes my guage loses all pressure and drops to 0 psi after 5-10 minutes. This is not right. Any suggestions?</TD></TR></TABLE>

honda spec s is 43 psi without vaccum
so at idle 32-38

your fuel system is normal but i recommend bumping it up to at least 45psi
most of the cars we check (with stock fpr) r around 45-55

all fuel system should hold pressure after shuting engine off..........
4 at least 1 min........

please bump my 4 sale thread

 

Thank you once again guys for all your help, all these little suggestions help. I am going to have the cam and ignition timing checked today.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B16aSir2 &raquo;</TD></TR><TR><TD CLASS="quote"> I checked the spark plugs(iridium, installed few months ago) to see they appear to be a little white.

</TD></TR></TABLE>

Did this problem crop up after you installed the iridium plugs or before? If it started before installing them then it is pretty safe to say that they are not the cause . . . but if it started doing it after you installed them, even if it was a month or more after, put the right plugs back into it. Your car's ignition system was not designed to handle either iridium or platinum plugs and they can lead to fouling. If your car came with copper-core plugs - stick with them, the engineers at Honda are pretty smart.

My second question is about the problem itself. You have given a better description than most of the new guys on this board and don't worry about not knowing something, If I come across as trying to flame you it just means I didn't think through what I wrote too carefully.

So . . . when did this problems start? A few months ago? Weeks? days? years?
Did it start happening when the weather started getting cold?
Did you notice anything else happen to the car around the same time, even if you think it is totally unrelated?
Did this crop up after installing any aftermarket performance parts (or even any aftermarket replacement parts such as a non-OEM Honda fuel filter)?

When you are driving, at what load and RPM does the problem happen? By this I mean does the car hessitate at, say, 2500 rpm when the gas pedal is depressed half way or, 'It only hessitates at WOT (wide open throttle) when I have the accelerator pedal all the way to the floor and am trying to get onto the freeway'

The darkness of your gasoline has me a little concerned but not too much. It may be the detergents in the oil holding dirt in suspension. This is true of motor oil also. Black motor oil just means its doing it's job. The detergents are latching onto microscopic dirt particles and holding them in suspension so they can be filtered out. Otherwise that black crap would be accumulating on the inside of your engine and form sludge and varnish. Another thing (sorry, straying off topic) always shake your quarts of oil before pouring it into the engine. Many of the additives in the oil are not oil soluble and are denser than oil so they collect at the bottom of the bottle. If you don't shake it they may sit there and not get into your engine when you pour it in.

The more specifics you give, the more the people on this board can help you.

-Scott Tucker


Modified by AutoEng2002Si at 4:33 PM 1/5/2006

 

do you smell fuel? check for leaks ...did you put the copper crush washers on the bolts when you changed the fuel filter?

 

Wow, pretty in depth reply Scott. I will do my best to give the necessary information.

1. You experience the hesitation when pressing the gas pedal 1/16 to 1/2. Making it very difficult to shift gears at lower rpms and keep momentum.(Causing poor drivability)
2. I started experiencing this problem actually on my old motor(D16A6) when I installed Venom injectors, an aem fuel rail and pressure regulator, and a venom fuel pump(which I still have in the car). Except it was not only hesitatiing, but actually losing rpms upon giving it throttle like it was being flooded with fuel, then it would finally lean out upon WOT. Generally this problem would occur in 2nd gear taking right turns. I took it to honda and they said the injectors were oversized, so I went to the junk yard and swapped them and it ran a little better but not quite perfect. I also had a small leak by one of my injectors before the swap so that was probably why it still wasn't perfect.
3. I finally got tired of my grinding transmission and SOHC's general lack of power, so I decided to upgrade to a B16a SiR2 motor. I went to http://www.raceup.com which is located in Miami(I live in West Palm Beach) and had my engine swapped. When I picked up the car the mechanic explained to me that he kept the OBD-O system and installed the PWO computer. When I had the motor put in, I had the clutch, water pump and timing belt replaced. I started to drive it home, and about 60 miles later, I was leaving a toll plaza, and once again, at 1/16 to 1/2 throttle my car was hardly going anywhere, like I was running off 2 cylinders. And it would make this noise like it was struggling to go but not getting enough fuel. I immediately pulled over and checked the ignition cables, spark plugs, and cap n rotor to find nothing distressing. But instead of making the long drive back down to raceup I decided that it might be a simple spark problem and I would let a mechanic look at it where I lived. DUMB IDEA! No one figured out ****. Japtrix(japanese performance shop) drove it around with the wideband hooked up and got correct readings from the 02 sensor. However they said that it might be that the engine is designed to run with 2 02 sensors and a different computer so try to unplug the 02 sensor and run in open loop. I did that, even though performance wasn't quite as good, and gas mileage was horrible, I didn't experience that awful hesitation. The wierdest part is that there was no CEL for the 02 sensor but whatever, problem solved.
4. To try and get my vehicle functioning the way it should be I decided to find someone that could rewire to OBD-I and put the correct P30 computer in. I found a guy, he changed the computer harness, the engine harness, the injectors, the distributor, the 02 sensor, and of course the ecu. Now I experience the problem again, no CELS, and the problem is not as severe. When giving the vehicle 1/16 to 1/2 throttle you can just feel it lacking it's power. Not losing rpms like the SOHC or stuttering like the other computer. I unplug my 02 sensor to see if that works like the other computer, get a CEL, and the problem is still not fixed.

Here is a full list of all symptons I am currently experiencing:
1. Hesitation at 1/16 to 1/2 throttle(75% of the time) The hesitation is always at the lower end of the gears, sometimes extending up to 5000 rpms. Vtec kicks in at 5900 and never experience this problem once in Vtec.
2. After popping vtec the idle can change from 1000 to 1200 or even 1500 rpms for a period of time.
3. Occassionally when the car has went down the street to the gas station, or a little further to a friend's house, it will have a hard time starting back up. It will start up, then shut off immediately, then upon turning the starter again, it cranks and cranks and cranks and cranks then fires at about 50 rpms and slowly crawls back up to 1000.
4. The fans don't kick on like they are supposed to. When I turn on the ac they both come on, but otherwise they don't. This problem has been happening ever since the engine swap. I think it is the thermal fan switch, but I haven't had it checked yet. Right now I just have the radiator fan wired to a switch that I flip on when I get in the car.
5. I have a very small head gasket leak in the front left corner in front of the distributor. I lose about 1 quart every 2-3 weeks from it. Should not be affecting overall performance.
6. Spark plugs(denzo iridiums installed by japtrix) are a little white on the ends signifying that they are running a little hotter than usual.
7. When I turn the key to the on positition, where you are supposed to hear the fuel pump kick on for 2 seconds before you start the car.....My fuel pump just keeps running. This just started happening after the new rewiring.
8. I have got a CEL in 4th gear twice, once after redlining it, and once around vtec. When I shut the car off, it went away. I tried to jump the blue connector underneath the glove box to see the code, but that self diagnostic method doesn't seem to be working right. My CEL never flashes or anything.

What I have done to attempt to remedy this problem since I had the engine swapped:
1. OEM main fuel relay.
2. Standard fuel filter.
3. Magnecor spark plug wires purchased from Honda.
4. Denzo Iridium spark plugs.
5. Distributor cap and rotor.
6. O2 sensor(bausch).
7. Had timing and tps sensor checked.
8. Replaced the CTS(coolant temperature sensor)

Mods to this engine:
1. Venom fuel pump.
2. Denzo Iridium spark plugs.
3. Magnecor spark plug wires.
4. Aem hybrid cold air intake system.
5. 4-2-1 headers.
6. Tanabe Hyper Medallion Full Cat-Back.
7. Stage 2 Port and Polish on the head as well as Ferrera valvetrain.(2000 Civic Si head - I know not JDM, I am still pissed about that)
8. B&M fuel pressure guage.
9. Skunk2 Intake Manifold.
10. Hondata heatshield.

I have been struggling with this problem of poor driveability for a year now. I just want to get the engine running like it should. I tired of embarrasing myself by running WOT everywhere. If there is anything that clicks in your head, please let me know.

 

Is the ECU they put in it tuneable and has it been tuned? If it has somebody needs to check their work. It sound it is either lean or way rich at the low load/low rpm portions of the main fuel map(s) (or they forgot to tune the ignition map - not likely). Personally if it was my shop fixing it, the first thing I would do is install an air/fuel analyzer in it, go out and duplicate the problem to see if it was lean or rich. Then I would go about fixing it. Without the car actually being in front of me I can't really be of much more help. Have you checked the TPS?

Good info on your car by the way, I had not idea fom the original post that the car was that extesively modified. Cut and paste that into your notepad so you can use it in future posts when you need it.

-Scott

 

sounds like a tps issue. If your tps is off, then it will giv eyou a problem like you are describing.

 

I do not believe the computer was modded. From what I understand it is a stock p30 ecu. So all fuel and ignition curves should be factory. I think this could be a tps issue as well. Whatever it is it has made me very aggravated for a long time. And I have wasted a lot of money on it. I am taking it to A1 Japanese to see if they can figure it out. I think the next step would be to get a good fuel/air analyzer like you suggested. So that way I can make sure that is the issue. Which air/fuel analyzer is good to get? Is there somewhere I can purchase this moderately cheap?

I want to ultimately get the computer chipped and tuned somewhere to increase overall powerband as well as lower the point at which vtec kicks in. Do you know of a good safe computer tuning system to use? And if I had it installed would they be able to find and eliminate my problem through dyno-tuning? Because this is gonna be my next step. Even though it will be costly, if it fixes the problem, then it will be worth it.

I know this is a little off-topic but I am getting a spoon sports throttle body for the car(don't ask why I am getting this and not getting the problem fixed) and it has a new tps sensor and map sensor on it. Does the new tps need to be set? If so is there a way I can do this myself?

Btw....Thank you for all your help Scott, I didn't know you had your own shop. It is cool that I can come on here and actually had a real mechanic give me a little advice.

 

Ok, I have now received the CEL in 3rd gear as well for a total of 4 times in the last couple weeks. It always comes on during Vtec(after 6000 rpms). It disappears when I shut the car off. Wtf? I tried to jump the blue connector and I get nothing.

 

If the computer is stock, based on the mods to your engine the tune is going to be off. Every mod you make changes the fuel and ignition requirments but with a stock ECU the maps stay the same. Even on OBD2 cars that have mixture adaptations they can not make infinite adjustments and they just shift the whole map richer or leaner anyway. I would recommend going to a stand alone ECU. If you can afford it get one of the better ones like those from AEM ($2000 grand, yikes!) or Accel ($1500) or many others. I have no experience with ECUs using crome or uberdata so I can't comment on them but they are a hell of a lot cheaper and free.

-Scott

P.S.: I don't own my own shop (I used to though). Although I worked as a mechanic for 14 years and and automotive engineer for 4. Of course all those years as a mechanic I was doing high perf projects too.