In the last couple of events I have done, I have developed an issue with my throttle. This is on an ITC/H5 Civic Dx HB. If I get on the gas really hard (floor it), it likes to fall on its face. If I ease into it (feather it), then there is generally no issues. I have learned to deal with this, but would like to get the problem fixed before my next race. Has anyone had or heard of this issue in the past? I've tried changing throttle bodies, made sure that the timing is set correctly, and have tried other ECUs and nothing has helped. Any and all help would be greatly appreciated.
Thanks,
Sam

 

don't these cars have issues with the fuel pump pickup getting uncovered under hard cornering/acceleration? are you having this problem with a full tank of gas? if it isn't fuel starve you'll have to do some more testing.

my guesses would be a fuel pump that isn't up to snuff, or a poor ignition system, be it plugs, wires, or cap/rotor. i had a problem with Autozone cap/rotors once where they would wear out prematurely. full throttle under heavy load would make the motor fall on it's face. gently rolling into the throttle didn't show the same symptoms, neither did revving it out of gear. hth

good luck!

nate

 

Ignition system was just completely replaced. Problem occurs regardless of the amount of fuel in the tank and happens in straight aways as well as corners. Was thinking it might be something fuel pump related, how could I check this? I have a fuel pressure gauge on the return line, so maybe I could clamp this shut and see if the pressure doubles to assure that I am getting the proper volume? Could it be a volume issue in that I am getting the proper fuel pressure at idle but there isn't enough volume for when the throttle is wide open and the second injector kicks in?
Thanks again,
Sam

 

you need to check the fuel pressure AND delivery rate (l/m) and make sure they are up to spec. your shop manual should have the procedures for checking both of these

does this car use a flap type AFM?

 

Please define AFM. I am still new to working on cars and still learning the lingo. I do have the factory service manual so I can figure out the specs as far as fuel pressure and delivery rate.
Thanks for the help,
Sam

 

I had a similar problem with one of my old RX-7s.

It was the fuel system - the pump was not delivering the requried volume/flow.

Did this problem appear before or after the ignition was replaced?

 

It appeared after the ignition system was replaced. My fuel pressure regulator had stopped working and was dumping all the extra fuel down into the IM and was causing the car to only run on three cylinders. I didn't find that the problem was the fuel pressure regulator until after I had replaced plugs, wires, distributor cap, rotor button and even tried a different distributor. Upon replacing the fuel pressure regulator and the ignition system, this problem appeared.
Sam

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H5Civic &raquo;</TD></TR><TR><TD CLASS="quote">Please define AFM. </TD></TR></TABLE>

sorry about that. Air Flow Meter. The flap type ones were common for a while and when they get old the carbon track (like a potentiometer) wears out and causes drivability issues

 

I believe that you are talking the round metal disk in the throttle body which is controlled by the throttle. At idle it almost all the way closed and as the throttle is openned, this opens as well to allow more air into the throttle body to mix w/ the fuel. The top one has been removed as it is basically only used for the choke and is not needed for racing applications. As far as I can tell, the lower one is still in good shape. I just replaced throttle bodies about three weeks ago and when I inspected the one I put on I didn't see any wear issues. I am leaning toward replacing the fuel pump in the tank as I believe that it may be going bad and therefore when I hold the throttle wide open there is not enough volume/flow to support the second injector and therefore the engine is falling on its face. Thanks for the help.
Sam

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H5Civic &raquo;</TD></TR><TR><TD CLASS="quote"> I didn't find that the problem was the fuel pressure regulator until after I had replaced plugs, wires, distributor cap, rotor button and even tried a different distributor. Upon replacing the fuel pressure regulator and the ignition system, this problem appeared.
Sam</TD></TR></TABLE>

Ummm... start there. maybe the FPR was defective..??

 

I don't believe the FPR (Mallory Ignitions aftermarket FPR) to be defective, as my fuel pressure gauge is in the return line and I was able to adjust the pressure to factory specs. Also, if the FPR had been defective, it would have started dumping the extra fuel in the intake again and causing the car to only run on three cylinders. I've also tried another throttle body w/ a stock FPR which worked fine when it was removed from the car it was on, and this throttle issue still persisted. I'm planning on replacing the fuel pump hopefully this weekend, though I am not looking forward to removing the fuel tank to do it. Thanks for the help.
Sam

 

i had the exact same problem with my b16 crx. if you ease on the throttle and bring it to 2k-3k can you floor it without it bogging. for me my problem was my msd coil. i replaced factory coil and it went away. it is something easy to test i would test it before i did a fuel pump