fuel pressure regulator
 

Does anyone know any home tuning tips??
I've heard of the one about pulling the vacuum hose off the fuel
pressure regulator and plugging it to get high pressure constantly
"interstellaroverdrive_420" <interstellaroverdrive_420@yahoo.com>

I have done this to both a 92 DX 1.8 L and my 2001 LX 2.0 with no
increase in fuel economy . However when you keep to the posted speed
limits i found that milage did improve slightly .I would do this if you
haven't put on a CAI intake and freed up the exhaust .
What this does is trick the computer. Under normal partial throttle
the computer uses 37psi to the injectors ,when you go to wide open
throttle the vac. switch open the regulator to atmosphere allowing the
pressure to increase to 42 psi . If you have the stock intake this is OK
but when you add a CAI and free up the exhaust this leads to a lean
condition under partial throttle .
To prevent this you can use this trick to allow more fuel in at
partial throttle . there is a slight trade off , the engine runs
slightly rich at idle . I found that using a spark plug one heat range
colder helped in this as well as 92 octane fuel .
Hope this helps . Malcolm Cole

Some home tuning tip ideas.
(I haven't had a chance to test any of these, so you're on your own. You can easily damage your engine by testing these ideas)

1) Remove any silencers/restrictions in the intake piping

2) Advance the intake and/or exhaust cams

3) Advance the base ignition timing, if possible. Big gains can be seen here, but it's dangerous!



I have some more ideas but I need to order a factory shop manual before I even suggest them. Does anyone know if this manual is available and if so, how much?

As far as the FPR mod that you mention, I don't believe that doing that would result in any differences at all. During idle and cruise, the computer adds and deletes fuel, in order to make the o2 sensor cycle from lean to rich, so the fuel pressure really doesn't matter, they just use a lower pressure to reduce emissions and improve idle quality. And if the solenoid closes off the vacuum source at WOT, then removing the hose will do nothing at WOT! But to be honest, I haven't looked at the system enough to know for certain.

Jason

How would I advance cams without adjustable cam sprokets? Make timing belt jump a tooth? How would I adjust ignition timing on distributorless ignition system with ecu constantly changing advance at different engine loads?
As for running "lean" with high flow intake-that shouldn't happen at all=naturally aspirated engine will not suck more air at intake strocke-just to displace volume inside cylinder. Power gains are realized because of less restriction of cotton filters. Its wrong to say that engine sucks in more air through them.
Alex

That's exactly what adjustable cam sprockets allow you to do, except you don't have to loosen the timing belt everytime that you want to make a change, and you can get better resolution with the adj gears.


The ECU has to have a reference point. Just find this reference point, hope that it's adjustable and adjust it. For example, on my mirage (also a distributorless system) the base timing@idle should be set to +5 degrees. If you add 5 degrees of timing to that and make the base timing@idle equal to +10 degrees, then the actual timing will be 5 more degrees then what the ECU is trying to set it at or thinks it is at. Careful with this though, it's easy to go overboard and damage your engine, and you should probably use a higher octane gas. Also, as I said before, I don't know if the timing is even adjustable in this way, I need a manual to find out, and I wouldn't try an additional 5 degrees without gauges to monitor what's going on.


The restriction is less so you make it easier for the engine to breath. A side effect is that you do get more air sucked in. More air equals more power.

Jason