1997 v8 runs like garbage

[Explodemylifepls]

I tested both the iat and cts via checking the readings on the scanner and unplugging both. Neither made a difference. Checked fuel pressure at a steady 30 psi, thought I saw some yucky crap come out the bleeder. Tried unhooking the ground for a minute and then driving it again. Seems difficult to replicate the issue now even though the idle is still not perfect it won't bog as much and seems to be leveling out the fuel trims as I watched it them though the scanner while driving it. Not sure if it actually make a difference.

Only thing that made any difference in how it runs when it starts running poorly is unplugging maf or IAT. Tried cleaning maf, sits at 7 g/s at idle according to scanner.

 

[Mbrooks420]

30 is a little low. Probably time for a pump.

 

[Explodemylifepls]

I installed a new fuel pump Yesterday, it initially seemed to help. After driving it to work today the issue comes back, same rich code, barely runs at low RPM/low throttle input (<2/3 throttle). Still getting fluctuating o2 readings at idle, that level out if I get on it so it goes into closed(?) loop.

Im not 100% but there may be a correlation with the engine vey getting nice and heat soaked and this problem im having. I've ordered two new ignition coils to swap out to see if it changes anything. If that makes no difference maybe the PCM?

The pump I installed is a QFS 265lph, overkill but it should be getting plenty of fuel.

 

[Stynx]

Did you ever check around for vacuum leaks?

 

[Explodemylifepls]

I just went and sprayed a bunch of ether around intake and vacuum connections, no change.

 

[Mbrooks420]

I’d have used a factory style pump. More isn’t really better. What’s your fuel pressure when you’re having the issue.

 

[Explodemylifepls]

It idles around 40 and increases with increased vacuum load. I didn't drive it enough to very replicating the issue but it was already hot and idling rough. I do not think it's a fuel pressure issue

The larger pump is for the future when i engineer an upgrade to turbocharged air induction and roof-mount red dot agricultural AC unit

 

[CDW6212R]

For the return style Fords, the normal pressure is in the 35psi range, and with the FPR vacuum hose of, it should see 42psi or close to that.

The bigger pump might add some extra heat to the fuel depending on how hard it circulates through the system. Keep an eye on the pressure and be sure it doesn't go to high(which would point to an extra restriction that doesn't let it return to the tank fast enough).

 

[Stynx]

I just went and sprayed a bunch of ether around intake and vacuum connections, no change.

Eh, it was worth a shot. At least you know it's probably not.

 

[Explodemylifepls]

Well the new coil made it idle better but still the issue persists. If I cycle between open loop and closed loop it sometimes will drive fine but usually has problems at low throttle inputs low rpm still

I press the accelerator pedal from an idle after cutting the throttle or coming to a stop and it does not fire at all for a second before taking off.

 

[C420sailor]

You getting smooth readings from your TPS?

It’s a a stretch, but without an accurate TPS signal, you can get off idle hesitation like that

 

[Explodemylifepls]

I messed with it a bit and according to the scanner I can only get 93% throttle input.

I reset the pcm again and have been driving it for a bit now with a rough idle but has been running ok. Has a vacuum leak type sound that comes and goes can't pinpoint it but idles rough regardless. Have not been able to replicate the previous issue yet I've been driving it around for a bit now.

 

[C420sailor]

As long as you’re getting smooth readings throughout the range, no dead spots, it should be okay.

Reason I ask is that the PCM uses that for ‘accelerator pump’ type functionality. When it detects a rapid opening of the throttle, it leads with some additional fuel to keep the mixture from going lean. Without that, it can lead to a hiccup when you step on the gas.

But so can many other things.

 

[Mbrooks420]

You can potentially pull some slack out of your throttle cable and get it closer to 100. Usually just a takes a zip tie at the top of the pedal to take up the stretch.

 

[410Fortune]

I used pinch on fishing weights

 

[Explodemylifepls]

Drive it till the issue came back, disconnect ground, reconnect, problem is gone..

TPS reads smooth but only to 93%, even when tb is 100% open.

Battery voltage fluctuates between 13.x and 14.1%

 

[Explodemylifepls]

Is this "modulemadness" eBay seller an ok place to get a "programmed rebuilt" config # matching ecu?? Im having questions about where is a reliable place to get.

Why I think it's the pcm?? Well the issue goes away when I pull the ground for a minute and reset only to come back after driving for a while, but even after resetting its still not right the issue is just not as prevalent, or acts differently. (There's a noticeable power spike in the 3k rpm ish area.)

Also is the superior 2-3 accumulator ok to use, or should I get a stock style rubber bonded one? Also I need a new vb gasket to do the accumulator job right?

 

[Turdle]

What is your minimum tps voltage? Measure with voltmeter

 

[Explodemylifepls]

Not sure. Battery voltage voltage on the scanner will drop down to 12.8 with the ac and everything on, and I found a vacuum leak at what I can assume is the pcv valve, can't spray ether down there but with the noise it's obvious.

I think both the voltage drops and vacuum leaks are contributing or causing separate issues.

 

[Turdle]

Tps voltage at idle ( minimum) should be <1 v. .9 is ideal. Should rise smoothly to 4.75 v . Use a multimeter. The scanner is not quick enough to show the spikes.