fuel pressure settings.

[rmoltis]

Way too much personal experience on all of the above , we just lost the developmental engine for Carolyn's racing Festiva at Pueblo Motorsports Park this last weekend. testing showed fuel pressure falling off at 7k rpm. A new pump fixed it, but the engine was already done.

Dang that sucks!
I hope that my advice wasn't perceived as festiva specific.
Rather I tried to give a general idea as to some of the variables to look at while considering if this original posters fuel pressure truly did or didn't need correction/adjustments.

My personal opinion to the original poster since he hasn't modified his exhaust manifold.
Is that his setup should be more than adequate since most of his power is made and focused within the original overall PowerBand of the engine.

But I would suggest he experiment with using a stock air box without holes drilled into it.
Since they are usually designed to flow air into the engine with less resistance.
I noticed it when I bored out an old air box hoping for an increase and instead I got a loss.

I would also say that with good emission like he posted.
His vehicle should be running close to optimum
Which is another good sign he may not need any extra fuel

But yet again this is just an opinion.
Data I'm sure would help solve the issue.

[Dragonhealer]

Was reading the ignition timing after full header back exhaust installation post and noticed his fuel pressure set to 42 psi. Not sure one can do this is a 1992 1.3. Anyone know how to get that much pressure in a '92? My regulator comes at 38 psi. I seem to start running out of gas above 5500 rpm. Can make it to 6000 and 6200, but can only make it to absolute limit of 6450 on a down hill grade. Suggestions?

New WIX filter, New 38 psi regulator, Replacement injectors cleaned by machine off the car (equal, smooth flow)
Strong mid range, using MSD and Hi Performance coil.


i218127

Back to basics, something is out of step. stock cam power peeks at 5400rpm, engine should run willingly to 7000rpm (fuel and ign, cut)

Or if you are passing through Tucson, stop by, we'll fix it !

[Dragonhealer]

I would also say that with good emission like he posted.
His vehicle should be running close to optimum
Which is another good sign he may not need any extra fuel

+1 ^

Are you running a stand alone ECU?

[i218127]

Fuel pressure

Is there anyone in the Palms Springs, San Bernardino, Riverside area that tunes Festivas?? I think I may be chasing my rear end on this for a while without some professional help. LA, San Diego?? Am kind of an invalid now and distance restricted.

i218127

[Advancedynamix]

Your best bet is Tucson. Ryal is a magician with these cars.

[Dragonhealer]

i218127,
I'm curious about your fuel pressure. is that reading key on, engine not running, F/P diagnostic grounded?
The reason I ask, is all the Festiva specific literature I have says this should be 36.3 psi, however every car I have checked ( that works properly ) shows 43psi on this test (+/- 1). Running on a worn engine, idle shows 35psi, snap WOT 32psi, snap closed from 3500rpm 42psi.
In my experience with EFI Festivas , (90-93 Miatas too), the open loop fueling (70% throttle or more) is plenty rich to start with, gets richer as the revs go up, and gets stupid rich by 7000rpm, like 9:1 AFR ! Please REMEMBER you can only check this sort of thing under load, NOT free revving!
I would like to help you sort this out,it is probably something simple but may be hard to identify. Rarely an ECU will be at fault, but it pays to go over all the basics first, again!

[Dragonhealer]

I agree Charlie. My issue is that the engine is running too cool to go into open loop so when I go wot it only richens slightly. I just need to get a smaller radiator.

Backwards, but yeah, the systems default is open loop, and always open loop past 70% throttle, but I wonder, how "too cool" is it running? Because the wax valve portion of the idle air bypass valve won't even close until 140 deg F, and if the ECU sees a large enough disparity, enough times, (it is comparing AFM/rpm/coolant and air temp/ O2/ and BARO curves) it will go into limp mode. OK, not exactly "limp", but a default running system to keep from damage in normal driving, it is supposed to set a check engine lamp, but often will not. Depending on what went wrong, it could have no apparent driving issues to extreme driving issues.

[gergorian]

Backwards, but yeah, the systems default is open loop, and always open loop past 70% throttle, but I wonder, how "too cool" is it running? Because the wax valve portion of the idle air bypass valve won't even close until 140 deg F, and if the ECU sees a large enough disparity, enough times, (it is comparing AFM/rpm/coolant and air temp/ O2/ and BARO curves) it will go into limp mode. OK, not exactly "limp", but a default running system to keep from damage in normal driving, it is supposed to set a check engine lamp, but often will not. Depending on what went wrong, it could have no apparent driving issues to extreme driving issues.

I have no Idle air. I removed it. But the more I have thought about it I think maybe the thermostat could be bad.

[Dragonhealer]

In the " They don't make them like they used to" department, we have had two new thermostats fail, full open!

[Movin]

41 PSI ? splitting hairs .
Humidity, baro pressure, temperature in the ECU and ?
each set up will need to be individually fine tuned.

[Dragonhealer]

41 PSI ? splitting hairs .
Humidity, baro pressure, temperature in the ECU and ?
each set up will need to be individually fine tuned.

True, variation in readings will be baro dependent, I'm at 2300 ft altitude, can't remember that of Palm Springs. But there is a world of difference between 39 and 43psi static regulated pressure, (not to mention the literature, which states 36.3, I think that is wrong). Running at idle, warmed up, there is a lot of variation car to car as the manifold depression (which controls the regulated pressure) is subject to so many variables. If OP is getting 39psi running, I would say his engine is in amazingly good health, but if his static pressure is 39psi I am wondering why.

[i218127]

Wow !! Didn't know I would get this much response. I'm still not sure what, if anything is the problem. My engine is still young having been refreshed out .002 (Like to know if anyone can tell me how big the engine is now). Runs strong to about 5500, and I mean strong !!! My friend thinks the engine needs more time to "loosen up" before we go bugs on it. I'm going to replace the Igniter(?) and see if that does anything. Not sure if bundling the MSD wiring next to the coil was a good idea. Not much room under the hood there. Anyone have any MSD wire routing ideas??? As Winston Churchill once said when Franklin Roosevelt burst in and caught him naked, "You see...I have nothing to hide".

i218127

[Dragonhealer]

Your friend is probably right. When we can, our engines go into a stock street car, with stock management, for 1200 normal in-town driving miles, before being put into there proper vehicle and dyno tuned....

[gergorian]

Wow !! Didn't know I would get this much response. I'm still not sure what, if anything is the problem. My engine is still young having been refreshed out .002 (Like to know if anyone can tell me how big the engine is now). Runs strong to about 5500, and I mean strong !!! My friend thinks the engine needs more time to "loosen up" before we go bugs on it. I'm going to replace the Igniter(?) and see if that does anything. Not sure if bundling the MSD wiring next to the coil was a good idea. Not much room under the hood there. Anyone have any MSD wire routing ideas??? As Winston Churchill once said when Franklin Roosevelt burst in and caught him naked, "You see...I have nothing to hide".

i218127

This is my engine bay as of 5 mins ago. I dont have an MSD box but I do have an MSD coil and Taylor plug wires.

[i218127]

Fuel Pressure

My engine doesn't look nearly that good. (In fact it looks pretty bad in comparison). But I did put in a new igniter and moved some of the wiring around. Think it may have been of some help. Ran up to 5700 clean in second, then stay there a sec, then took off to the rev limit. It could be slow to recognize the new capability (?). Don't want to push it too much, but will drive it for a while and see what happens. Engine is very strong. No knocks. ( I can't seem to make it knock) Just straight pull. Good torque. Got a little rubber in second. Was kind of shocked. (I may have been a little too aggressive between shifts. Don't want to break the thing !!) Thanks to everyone for all the help...I need it !!!!

i218127