Fitech Wont pass Smog all the sudden

[wilcom]

What state? What were/are the emission rules for the 1970 in that state? Smog pump?
Is fitech new to the problem, did it pass emissions before fitech? Or fitech passed then didnt?
AI says:

Your engine is failing due to an extreme rich-running condition, meaning it is dumping massive amounts of unburned raw fuel into the exhaust.
A High Speed CO of 10.39% is extraordinarily high (normal running is usually under 1.0%), which indicates the FiTech system is completely flooding the cylinders under load. This massive excess of fuel prevents proper combustion, which is exactly why your Idle HC (2173 ppm) and High Speed HC (791 ppm) are spiking way past the legal limits.

Why Your FiTech is Flooding the Engine

• False Lean from an Exhaust Leak: This is the most common culprit on vintage 302 engines. If you have even a tiny exhaust leak near the headers, collector gaskets, or the O2 sensor bung, outside air gets sucked into the exhaust pipe. The FiTech O2 sensor reads this extra oxygen, falsely thinks the engine is starving for fuel, and forces the injectors to stay open.
• Incorrect Fuel Pressure: FiTech throttle bodies strictly require 58 PSI of fuel pressure. If you are using an frame-mounted inline pump without a baffled tank, or if your fuel pressure regulator is failing/stuck, high fuel pressure will bypass the ECU's control and force massive amounts of fuel through the injectors. [1, 2]
• Mismatched Engine Setup Parameters: If your handheld controller is programmed with the wrong engine displacement (e.g., set to a 350 or 400 cubic inch engine instead of your 302), or if the "Cam Selection" profile is set too aggressively (e.g., Selection 3 or 4 for a mild/stock cam), the base fuel map will be drastically over-enriching the mixture.
• Faulty Engine Coolant Temperature (ECT) Sensor: Look at your FiTech handheld while the engine is fully warmed up. If the ECT reading is stuck below 170°F (76°C), the system stays in "Warm-Up Enrichment" mode. This acts like a stuck mechanical choke on an old carburetor, constantly flooding the engine with fuel.
• Leaking Injector: A mechanical failure where one of the internal fuel injectors is physically stuck open or dripping will bypass all computer commands and pour raw fuel directly into the intake manifold. [1]

Immediate Troubleshooting Steps

1. Check Handheld Diagnostics: Plug in your FiTech handheld with the engine running. Look at the AFR (Air-Fuel Ratio) and Target AFR values. If your Target AFR is 14.7 but your actual AFR is reading incredibly lean (like 16.0+), yet you smell heavy fuel, your O2 sensor is being fooled by an exhaust leak. [1, 2]
2. Verify Fuel Pressure: Hook up a mechanical fuel gauge directly to the FiTech inlet loop to ensure it reads exactly 58 PSI under load, not higher.
3. Verify Basic Setup: Re-check your initial setup wizard on the handheld. Ensure the engine size is correctly scaled for a 302 and that your cam profile selection matches the vacuum characteristics of your engine.

To help pinpoint the exact setting or mechanical failure, what are your Target AFR and Actual AFR values on the handheld at idle, and what Cam Selection (1, 2, 3, or 4) did you choose during setup?


Non AI my second thought, buy an autolight 2200 carb, try that. But, do you smell fuel in the oil?

But really, why is fitech not helping you? Sounds like you have a lot to chase, my first thought get your fuel pressure down to 58psi.

thank you,

I have passed smog for 5 years in Nevada but since 2024 its been failing for high hydrocarbons.

You have come up with the same answers that I did. checked fuel pressure gauge ...63, new 02 sensor, new vacuum hoses, new pcv valve, FItech handheld basic setup correctly for CAM 2, 302, etc.. IAC is set to 6-7, AFR set to 14.7 (it bounces between 13.8 and 15.2) which is normal for RV Offroad CAM. Fitech says take the AFR down to 13.5- 13.8 to see if that helps due to cam overlap. I tried this and the left side exhaust pipe
Anyway since I rebuilt the engine back in 86 I figure that maybe the exhaust headders are leaking for for exhaust manifold gasket. hedders seem a bit rusted but otherwise visual inspection looks good. I think I will buy a smoke machine to test with.

Just talked with Alex at Fitech and he said to monitor the Trim and Learn settings and see what percentages they are reading. This could point more directly at exhaust leak or other issue to look for. Also he said to install a catalytic converter for sure!

 

[EPB72]

thank you,

I have passed smog for 5 years in Nevada but since 2024 its been failing for high hydrocarbons.

You have come up with the same answers that I did. checked fuel pressure gauge ...63, new 02 sensor, new vacuum hoses, new pcv valve, FItech handheld basic setup correctly for CAM 2, 302, etc.. IAC is set to 6-7, AFR set to 14.7 (it bounces between 13.8 and 15.2) which is normal for RV Offroad CAM. Fitech says take the AFR down to 13.5- 13.8 to see if that helps due to cam overlap. I tried this and the left side exhaust pipe
Anyway since I rebuilt the engine back in 86 I figure that maybe the exhaust headders are leaking for for exhaust manifold gasket. hedders seem a bit rusted but otherwise visual inspection looks good. I think I will buy a smoke machine to test with.

Just talked with Alex at Fitech and he said to monitor the Trim and Learn settings and see what percentages they are reading. This could point more directly at exhaust leak or other issue to look for. Also he said to install a catalytic converter for sure!

You can’t run a cat if your running at 10% CO , your current AFR readings are inaccurate as there is no way you can have 10% co and be close to 14.7 not possible .. to run a cat you need to be in fuel control and cycle between rich to lean at least a few cycles a second or the cat won’t last or even light off , at 10 % it will probably start glowing red and melt down ,,

Knowing fuel trim is a place to start , FItech provides that?? How is it shown % , block learned, integrator or a lambda # ?

HC usually is an ignition issue or lean misfire issue ,, But excessively rich condition will elevate HC as well, providing your engine is mechanically sound,,

 

[Broncobowsher]

One of the ways to reduce HC is a higher cylinder pressure. To get that, lower manifold vacuum. To get that run less timing. The smog era of 6° initial timing wasn't performance, it was to make more cylinder pressure to make the fuel burn off. As stated HC is typically a bad ignition system, or somewhat surprising to many a lean fuel mix. Where you don't have complete combustion because there is too much air in the way and some raw fuel goes out the tail pipe, raw fuel is HC.

Another question, how is the oil consumption? If the HC is a result of burning oil, there really isn't any fuel trim or ignition fix for that. Burning oil usually isn't really burning it, it is just passing it through the engine and sending it out the tail pipe. Oil is a hydrocarbon, HC.

High CO is only one thing, too rich. The oxygen available for combustion will bond with the hydrogen of the hydrocarbon first. Leaving a lack of oxygen to bond with the carbon, In that case you only get one oxygen per carbon, CO. Ideally there should be enough oxygen mixed with the fuel for two oxygen per carbon, CO2.

Then there is way too rich where there isn't even enough oxygen for the amount of fuel going through to even make CO, or even split the HC and burn off the hydrogen. And raw fuel comes out. This is also black smoke as some HC does burn off the hydrogen and you have black carbon leaving the engine.

No rule that there is only one problem as well.

 

[wilcom]

One of the ways to reduce HC is a higher cylinder pressure. To get that, lower manifold vacuum. To get that run less timing. The smog era of 6° initial timing wasn't performance, it was to make more cylinder pressure to make the fuel burn off. As stated HC is typically a bad ignition system, or somewhat surprising to many a lean fuel mix. Where you don't have complete combustion because there is too much air in the way and some raw fuel goes out the tail pipe, raw fuel is HC.

Another question, how is the oil consumption? If the HC is a result of burning oil, there really isn't any fuel trim or ignition fix for that. Burning oil usually isn't really burning it, it is just passing it through the engine and sending it out the tail pipe. Oil is a hydrocarbon, HC.

High CO is only one thing, too rich. The oxygen available for combustion will bond with the hydrogen of the hydrocarbon first. Leaving a lack of oxygen to bond with the carbon, In that case you only get one oxygen per carbon, CO. Ideally there should be enough oxygen mixed with the fuel for two oxygen per carbon, CO2.

Then there is way too rich where there isn't even enough oxygen for the amount of fuel going through to even make CO, or even split the HC and burn off the hydrogen. And raw fuel comes out. This is also black smoke as some HC does burn off the hydrogen and you have black carbon leaving the engine.

No rule that there is only one problem as well.

Thank you all.

This is the email that i sent to Fitech techs yesterday and have not heard back from them. Today I use my shop vac to push air into the exhaust and sprayed soapy water on the headdder collectors and head gasket and found both collectors and one side headder head gasket blowing bubbles....so there is my vacuum leaks!

Email;

1970Ford 302 engine with RV Offroad cam.

Settings Fitech 30003

302 Engine with dual exhaust
Set to CAM 2
AFR set to 14.7
IAC steps at idle bouncing 4-6

Don’t use any vacuum off of manifold just rear of Fitech for ported Distributor and PCV Valve.

Electronic Dist, 2-wire (timing 14 deg btdc) with 6AL MSD box. (8 deg factory and 6 more for CAM?)

External Bosch fuel pump. 62 psi on fluid gauge located 10” before carb line input.

This test was done with the vehicle stopped and foot on gas to run @ 800, 2200, 2900 RPM for 1.3 minutes each

Idle @800 RPM. Bouncing around from 774 to 854 (RV Cam?)
Map 38.5 to 41.
Vac -12.7 to -13.5
Coolant 174
AFR bouncing around from 14.5 to 15.8
AFR Trim -3.3 to 6.3
AFR Learn -23.2 to -26.6

@2200 RPM.
MAP 27.5 to 28.3
VAC -16.5 to 16.8
Coolant 170
AFR Trim .3 to 12.2
AFR Learn -24.2 to -25.8

@2900 RPM.
MAP 28.5 to 29.3
VAC -16.1 to 16.5
Coolant 170
AFR Trim -2.3 to 5.6
AFR Learn -2.3 to -29.1

In addition to the vacuum leaks I found, is the timing set correctly? I know the manual says 6-8 deg for stock but I was told to use 12-15 deg for RV offroad cam and electronic dist. Is this correct? For the smog test I had it set to 10 deg and got the high HC and HO failures...but again vacuum leaks.
Onice I fix the headder and collector gaskets I can start with 6 degrees of timing and go from there, but how will I know if that is buring the fuel properly......watch the AFR Learn %?

thanks again,

 

[DirtDonk]

Here's my input to some of what you sent to them:

Settings Fitech 30003

302 Engine with dual exhaust
Set to CAM 2
AFR set to 14.7
IAC steps at idle bouncing 4-6

Can't say it's always the case, and in yours it's been passing fine before, but generally most TBI systems end up needing a slightly richer than perfect stoich AFR.
Something along the lines of 14 to 13.5 instead of a perfect 14.7. Even for stock cams. For hi-po cams like yours, I would think even richer would be best.
But best for smog? Dunno...

Is this AFR at idle only? Or us ut set up to look for that throughout the range?

Don’t use any vacuum off of manifold just rear of Fitech for ported Distributor and PCV Valve.

Just so we're clear here, your PCV valve is pulling through the large port delivering full manifold vacuum, not ported. Correct?

This test was done with the vehicle stopped and foot on gas to run @ 800, 2200, 2900 RPM for 1.3 minutes each

Idle @800 RPM. Bouncing around from 774 to 854 (RV Cam?)
Map 38.5 to 41.
Vac -12.7 to -13.5
Coolant 174
AFR bouncing around from 14.5 to 15.8
AFR Trim -3.3 to 6.3
AFR Learn -23.2 to -26.6

That's very low for idle vacuum. Even with a cam, it's at the lower end. Maybe the cam is bigger than you think? Or maybe there is something else going on.
Have you checked idle vacuum at different ignition timing settings? Stock would be like 19-22 or so. Whereas a mild cam might take it to 17-18, and a performance cam would be in your range.
I would try for higher if you can. Don't know what that does to your smogs, but it's worth a check I think.

@2200 RPM.
MAP 27.5 to 28.3
VAC -16.5 to 16.8
Coolant 170
AFR Trim .3 to 12.2
AFR Learn -24.2 to -25.8

@2900 RPM.
MAP 28.5 to 29.3
VAC -16.1 to 16.5
Coolant 170
AFR Trim -2.3 to 5.6
AFR Learn -2.3 to -29.1

Glad you posted the numbers. Someone here should have some insight.

In addition to the vacuum leaks I found...

For the record, these are not actually "vacuum" leaks. They are leaks certainly, but they're exhaust leaks and are only messing with your O2 sensor readings, and not the mixture entering the intake. Well, not directly anyway, as they do mess with the ability of the computer to reach a consistent AFR that you're setting, because of the messed up 02 readings.
Not sure I worded that correctly, but wanted to at least touch on the subject of intake vs exhaust readings.

...is the timing set correctly? I know the manual says 6-8 deg for stock but I was told to use 12-15 deg for RV offroad cam and electronic dist. Is this correct?

Hard to say. The cylinder heads matter a lot, and each engine is different.
For performance, that's one thing. But for best emissions readings, that's another. I'm sure some of the other members have insight into that. I've got no experience with what ignition timing has what effect on readings, and at what rpm.

For the smog test I had it set to 10 deg and got the high HC and HO failures...but again vacuum leaks.

Fix the exhaust leaks first and foremost. Hopefully someone here can shed some light on whether or not you should dial back the timing even further, or advance it to where it runs best. Or somewhere in-between.

Onice I fix the headder and collector gaskets I can start with 6 degrees of timing and go from there, but how will I know if that is buring the fuel properly......watch the AFR Learn %?

I think you nailed it right there. Too bad we don't all have exhaust gas analyzers in our garage to test each and every setting change!
I don't suppose your smog check guy is your new best friend and lets you re-test for free? Kind of a long shot probably!

Good luck. Hopefully Fitech and other members here can clear this all up for you.

Paul

 

[73azbronco]

I'm going to harp again, you say 63psi, but what does fitech say it should be? Google says 58. An extra 5psi is an extra 11% of raw fuel into the cylinders, the fitech does not know about the extra fuel pressure, and it sure doen't know it without cat sensors, which as stated, you would be fouling at this level.

First step in diagnosing any EFI system on the planet, what is the fuel pressure.

Fix the pressure.

Fix the leaks

What camshaft does it have, 12 vacuum is like the lope-iest camshaft out there. Or you have intake leaks

 

[Broncobowsher]

Exhaust leaks will make it impossible for the EFI to tune. It isn't the exhaust leaking out that is the problem, it is the pulse creates a vacuum that pulls air in. That mixes with the exhaust and the sensor reads lean. More fuel is added. Exhaust must be sealed or there is no chance this will ever work.

 

[hunter1]

I'm going to harp again, you say 63psi, but what does fitech say it should be? Google says 58. An extra 5psi is an extra 11% of raw fuel into the cylinders, the fitech does not know about the extra fuel pressure, and it sure doen't know it without cat sensors, which as stated, you would be fouling at this level.

First step in diagnosing any EFI system on the planet, what is the fuel pressure.

Fix the pressure.

Fix the leaks

What camshaft does it have, 12 vacuum is like the lope-iest camshaft out there. Or you have intake leaks

The 400 HP Fitech internal regulator is at at 43 psi. Shouldn’t matter the what incoming pressure is, the extra should bypass to the return side.

 

[73azbronco]

Does he have an internal return style?

 

[hunter1]

Does he have an internal return style?

Yes, if incoming pressure is higher than the internal regulator it will bleed off to return. Been through all of this with mine.

 

[wilcom]

Thanks to all for your tech help and ideas...

Called Fitech and the fuel pressure is fine and I have a return to tank. Also found the big vacuum problem!!!! I decided to do a leak test so I blocked off the dirvers side exhaust pipe (I have dual exhaust and the O2 sensor in on the passanger side) and hooked my shop vac to blowing out and taped it to the passender side pipe and turned it on. I took a spray bottle of soapy water and sprayed around the old headers and found two small leaks on passenger side and both collectors had leaks. the collector leak on the passenger side was about 7" down stream where the O2 sensor was so there is the vacuum leak along with the header on that side that told the O2 sensor to add more fuel due to more air coming in thru the pipe.
My old headers are 36 years old so I took them off and put on some ceramic chrome plated headers from Toms Offroad. Now I have to figure a way tohok my exhuast pipes to them. I see James Duff has an adaptor kit to mate his his new dual exahust to Toms headers so I am going to order them and cut off the old flared ends on my pipes use the Duff ones to connect my pipes to the headers.
I also thought I would clean up the O2 sensor due to running the rick condition for so long. Anyone have a cleaner suggestion? I read that they are sensitve to cleaners and to use gas or sensor cleaner?
FYI, I took the plugs out to make it easier for removing the header bolts and I could see the Number 1 piston was at TDC and could see the top of the pistion was black with carbon buildup for the rich condition. I will try some Chevron Techron Concentrate Plus fuel system cleaner to see if it gets rid of it.

 

[serial car restorer]

In my experience, cleaning an O2 sensor is always a sketchy task. Given the issues you've had, I'd replace it.

 

[73azbronco]

Ditto, you don't clean O2 sensors, they need to be replaced.

 

[Broncobowsher]

And find good ones. Not the cheapest that 'interchange' Fought low quality wideband sensors on the daily driver. Spent the real money, got a good one from a real parts store, fixed many issues. That is the last time I am going to try off-brand O2 sensors.

 

[73azbronco]

buy a bosch

 

[Remos69]

What he said!