Fox Xtremely high fuel consumption

[General karthief]

Some more useless 'old guy' stuff, to explain the 'side gap' done to spark plugs (or spark-o-lators as the VGG guy says) it's to uncover the spark. The thinking was more spark exposed to the mix makes for a bigger/better burn, similar to 'indexing' the plugs.
IIRC they did alot of 'tinkering' back when pro stock cars were real door slammers with factory 'style' engines and those 'engine secrets ' filtered down through the ages.
Just a street racers 'old wifes tail'.

 

[PonyGTrider]

Some more useless 'old guy' stuff, to explain the 'side gap' done to spark plugs (or spark-o-lators as the VGG guy says) it's to uncover the spark. The thinking was more spark exposed to the mix makes for a bigger/better burn, similar to 'indexing' the plugs.
IIRC they did alot of 'tinkering' back when pro stock cars were real door slammers with factory 'style' engines and those 'engine secrets ' filtered down through the ages.
Just a street racers 'old wifes tail'.

And I was buying that idea

 

[PonyGTrider]

At this point I will take apart the top end to fix the threads on the first hole of the head for the bolt that holds down the lower intake on the driver side. Some long time ago I pulled the threads so now is the time to fix it, no leaks but it is time.

Even I don’t see a potential vacuum leak it will be a good time to verify that.
After all of this conversation I’m trying to determinate why my fuel pressure is 39 psi with the vacuum hose hooked up to the pressure regulator. And why the fuel pressure drops ONLY 1psi from 40psi without vacuum hose to 39 with vacuum hose.
That suggests two things: ONE, There is a massive vacuum leak. Or TWO, there is no vacuum leak but those three cylinders with questionable low vacuum numbers are caused by the lower compression cylinders.

In any of these two events it is highly possible that my xtremely poor mileage is caused by over fueling because of too much fuel pressure during idle and partial load.
Tell me guys if that makes if conclusions are making some sense.
I know it has been a long post but it will well worth it.

Thank you all

 

[gkomo]

You mentioned you tried different ECUs, an A9L and A9P. Isn't the A9P for automatic cars and requires some rewiring for the O2 sensors? Did you do the wiring swaps/jumpers when switching ECUs? What ECU are you currently running?

Also, have you posted any pictures of the whole car in this thread anywhere? Curious what we are all talking about.

 

[AeroCoupe]

I will say that with 84 octane gas it may be blending a lot of ethanol into the mix. This will hide a rich mixture as alcohol will not show rich like gasoline does. Good video on how to read them:


View: https://www.youtube.com/watch?v=4oLMihA4ZrA&t=35s

What I am driving as it with the gas you have can you tell us how much ethanol (if any) is in the blend? @TOOLOW91 hit the head on the nail with the Autolite 3924's as they are an excellent plug. I run them in the Edelbrocks on the Coupe and the AFRs on the T-Bird.

 

[PonyGTrider]

You mentioned you tried different ECUs, an A9L and A9P. Isn't the A9P for automatic cars and requires some rewiring for the O2 sensors? Did you do the wiring swaps/jumpers when switching ECUs? What ECU are you currently running?

Also, have you posted any pictures of the whole car in this thread anywhere? Curious what we are all talking about.

That is correct, I run either one with no wiring modifications and they both run great. No hanging idle or any other issues with the A9P
And as far as where is this engine nested in, here it is…

 

[PonyGTrider]

I will say that with 84 octane gas it may be blending a lot of ethanol into the mix. This will hide a rich mixture as alcohol will not show rich like gasoline does. Good video on how to read them:


View: https://www.youtube.com/watch?v=4oLMihA4ZrA&t=35s

What I am driving as it with the gas you have can you tell us how much ethanol (if any) is in the blend? @TOOLOW91 hit the head on the nail with the Autolite 3924's as they are an excellent plug. I run them in the Edelbrocks on the Coupe and the AFRs on the T-Bird.

I’m not aware of what is in the fuel.
And as far as plugs it is unbelievable that I couldn’t find a set of 3924’s in the entire city not even in Autozone, so I’m using a set of NGK FR5-1 which are longer than the FR5’s

 

[AeroCoupe]

They can be a hard to find here in the states where I live so I usually order three sets at a time when I get down to one set left.

You need to find out what the blend is on your gasoline as it will really help with reading the plugs.

 

[gkomo]

That is correct, I run either one with no wiring modifications and they both run great. No hanging idle or any other issues with the A9P
And as far as where is this engine nested in, here it is…

Clean fox!

 

[FastDriver]

If this is a converted auto to manual trans car, you cannot wire up an A9P & A9L interchangeably, without harness modification. He was right to point out that the wiring harness needs to be modified to ensure the O2 sensors pin into the EEC correctly. You'll have to search that one, as I've never done it, but I know you can burn up an A9L if you just plug n play.

If it were a massive vacuum leak, you'd know by it refusing to idle down to normal... i.e. you might see 1500+ RPM. More likely, one of the hoses traced back from the FPR is leaking.

 

[nickyb]

I would like to.see photos of your engine from a few different sides.

 

[PonyGTrider]

They can be a hard to find here in the states where I live so I usually order three sets at a time when I get down to one set left.

You need to find out what the blend is on your gasoline as it will really help with reading the plugs.

Never had any issues finding them up until now

 

[Noobz347]

They can be a hard to find here in the states where I live so I usually order three sets at a time when I get down to one set left.

You need to find out what the blend is on your gasoline as it will really help with reading the plugs.

More than likely, it's the same as ours without the additive package.

If it were an ethanol blend the octane would higher.

My guess is that it's straight gas from a Texas refinery.

 

[PonyGTrider]

Ok guys I think I’m getting somewhere with these new findings.
So I removed the top end and found some interesting stuff.
Because my lower intake is held down by ARP studs it was a bit hard to get it loose from the back so had to remove all the studs but still I broke the seal and found some weird conditions.
Talking about massive vacuum leak??? Possible! The lower intake front end mating surface to the block you can see clearly the silicon beed broken as I lifted the intake so that means it was completely sealed. The rear part of the intake does not show that, instead they look like flat patches of contact against the block but it doesn’t look like a constant beed of contact. That opens the door for a major vacuum leak, but the stunning thing is that I sprayed carb cleaner and even I use propane back there and no hesitation or change in idle speed.
Please see the photos of the front and rear intake/block mating surface and tell me your opinion.
On the rear you can see the smears of silicon as I was spreading it with my finger.
Does it look like a potential massive vacuum leak to you???

 

[FastDriver]

I see good silicone squeeze on either the top or bottom side pretty much everywhere. I don't suspect it of leaking. I don't see any silicone on the lower-to-head gaskets, which I normally like to do, but the Felpro 1250s are usually fine. Nothing obvious here, to me.

 

[PonyGTrider]

I see good silicone squeeze on either the top or bottom side pretty much everywhere. I don't suspect it of leaking. I don't see any silicone on the lower-to-head gaskets, which I normally like to do, but the Felpro 1250s are usually fine. Nothing obvious here, to me.

The front looks there was a good bonding but I’m a bit suspicious of the rear.

I don’t know about you guys but just hate the cork gaskets and usually I toss them but this time I might use them with ultra-black RTV.

Also I had a couple of bad experiences of disintegration by the water port using the regular 1250’s, instead I love the 1250S-5 as they come out intact upon disassembly.

 

[gkomo]

I might be going off on a tangent here but i'm confused how you can pop in both A9L and A9P ECUs without doing anything and the car runs fine.

 

[gkomo]

Anyone use those china wall silicone gaskets? I remember the Infamous Project used them on one of his builds and didn't have an issue, at least if i recall correctly from a YouTube video.

 

[PonyGTrider]

I might be going off on a tangent here but i'm confused how you can pop in both A9L and A9P ECUs without doing anything and the car runs fine.

I don’t know what to tell you, the A9P is not such. That was given to me a an A9P but it has not a single label to prove it so probably it is a A9L, now I’m not sure.

 

[PonyGTrider]

Anyone use those china wall silicone gaskets? I remember the Infamous Project used them on one of his builds and didn't have an issue, at least if i recall correctly from a YouTube video.

I used those blue ones but one of them Got squeezed out and never used them again.
Now I’m thinking of using the cork ones with a coat of ultra black RTV hopefully I got better sealing