300-6
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300-6
I am rebuilding the 300-6 in my 1992 f150. I want to get rid of all the emissions stuff like the air tubes frOm the exhaust manifolds to the catilatic converter. Is this possible or am I stuck with them?
Lead Driver
Joined: Sep 2006
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Your in the wrong forum for the year but you could remove those but there might be cold starting issues.
The air pump control solenoids does diverison of the pump air.
When cold starting, the pump injects air into the exhaust manifold to help burn and heat the cats.
Then after a short time the pump air is diverted to the cats to help them heat up.
If you have emmsisions inspection, a CEL lamp might fail you because when you remove these items you could get codes because the EEC is expecting the hardware to be there.
Also the EGR operation will still be attempted because the program does not know it's missing. If the proper response is not there another code would be set.
So the answer is yes and no depending on what your situation is.
If a visual inspection is made you would still fail requardless of operation.
Good luck.
The air pump control solenoids does diverison of the pump air.
When cold starting, the pump injects air into the exhaust manifold to help burn and heat the cats.
Then after a short time the pump air is diverted to the cats to help them heat up.
If you have emmsisions inspection, a CEL lamp might fail you because when you remove these items you could get codes because the EEC is expecting the hardware to be there.
Also the EGR operation will still be attempted because the program does not know it's missing. If the proper response is not there another code would be set.
So the answer is yes and no depending on what your situation is.
If a visual inspection is made you would still fail requardless of operation.
Good luck.
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Since you have an EFI motor, you'd best just put it back the way it came. PCV and evap are important to keep intact. As per prior post, the air and egr will also cause trouble if they go missing, requiring more fiddling and questionable results. As for power to be gained by removing properly working emissions stuff, very little, if any, is to be found.
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I had the egr on my truck clamped off when I put headers on my I-6 because it didn't have the connection. My cats are also hollow, but I have put a cold air intake in it to equal out the flow. I don't seem to have any cold starting/running problems
Lead Driver
Joined: Feb 2003
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From: Oak Harbor, OH
Here's the down side, on an EMISSIONS error the computer may or may not set the CEL, but it WILL run in open loop mode and not take information from the O2 sensors. So you'll wind up running full rich all the time. The EFI system was designed to make the most power with them so I'd leave them intact.
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Fleet Mechanic
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From: New York
Are you sure about this? I may have to move up the A/F meter install to see if mine is indeed running in open loop.
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Lead Driver
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I don't know who were talking to here but all need to understand EFI uses OX sensor/s to keep normal A/F ratios in the 14 to 1 range.
If the sensors are disconnected or in operable for any reason the motor is run of fixed 'rich' fuel tables in the 11 to 12 to 1 range.
This is the same table the PCM goes to when the throttle is about 7/8 or more open so enough fuel is supplied for a call to full power.
The TPS position or loss of OX signals tells the PCM to ignor the OX sensors and go to this table.
Loss of OX sensor function:
This is a built in safety function to protect the motor from overheating.
The same protection is built into all EFI systems.
Those systems classed as OBDII can be looked at with a good scanner that can read live data.
You look at the long and short term fuel trims tables and even the output of the OX sensors.
There is no guessing about it
EEC systems take a bit more work to look at.
Good luck.
If the sensors are disconnected or in operable for any reason the motor is run of fixed 'rich' fuel tables in the 11 to 12 to 1 range.
This is the same table the PCM goes to when the throttle is about 7/8 or more open so enough fuel is supplied for a call to full power.
The TPS position or loss of OX signals tells the PCM to ignor the OX sensors and go to this table.
Loss of OX sensor function:
This is a built in safety function to protect the motor from overheating.
The same protection is built into all EFI systems.
Those systems classed as OBDII can be looked at with a good scanner that can read live data.
You look at the long and short term fuel trims tables and even the output of the OX sensors.
There is no guessing about it
EEC systems take a bit more work to look at.
Good luck.
Fleet Mechanic
Joined: Nov 2011
Posts: 1,823
Likes: 43
From: New York
I don't know who were talking to here but all need to understand EFI uses OX sensor/s to keep normal A/F ratios in the 14 to 1 range.
If the sensors are disconnected or in operable for any reason the motor is run of fixed 'rich' fuel tables in the 11 to 12 to 1 range.
If the sensors are disconnected or in operable for any reason the motor is run of fixed 'rich' fuel tables in the 11 to 12 to 1 range.
The above experience is why I question the statement regarding forced open loop operation if the smog pump and related electronics are removed.
Lead Driver
Joined: Sep 2006
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DP, Your totally misunderstanding what you quoted me in the box.
Read it again.
My statement is based on "only' the OX sensors not on all the sensors you are mentioning.
The EEC expects input from the OX sensors on all models.
They are directly wired to the EEC.
If they are not operable, FI cannot be controlled so the program goes open loop to fixed tables.
The VSS, EGR, ACT, BOO have nothing to do with the OX sensors.
That is why you saw closed loop operations.
I fail to see how you associated them with what explained.
Good luck.
Read it again.
My statement is based on "only' the OX sensors not on all the sensors you are mentioning.
The EEC expects input from the OX sensors on all models.
They are directly wired to the EEC.
If they are not operable, FI cannot be controlled so the program goes open loop to fixed tables.
The VSS, EGR, ACT, BOO have nothing to do with the OX sensors.
That is why you saw closed loop operations.
I fail to see how you associated them with what explained.
Good luck.
Lead Driver
Joined: Feb 2003
Posts: 8,140
Likes: 4
From: Oak Harbor, OH
Fairly certain. Every car I've ever owned that had EFI and a failed/failing emissions part got horrible gas mileage and puked fuel out the tailpipe, when we'd repair the emissions system it'd run perfectly.
Fleet Mechanic
Joined: Nov 2011
Posts: 1,823
Likes: 43
From: New York
The context of this thread is primarily about removing the smog pump and associated plumbing/solenoids/etc. I don't read where anyone was suggesting to remove the O2 sensor. Clearly removing THAT sensor will not allow the PCM to go into closed-loop, as the O2 sensor is the sole sensor which allows for closed-loop operation. I would hope anyone taking a wrench to their car would know that much, but perhaps I assume too much.
Admittedly my response was as much a response to pfogle's comments. I think he's taking far too broad a brush to an "emissions CEL" but I'll wait until I have data to confirm/refute his claim.
Admittedly my response was as much a response to pfogle's comments. I think he's taking far too broad a brush to an "emissions CEL" but I'll wait until I have data to confirm/refute his claim.
Lead Driver
Joined: Sep 2006
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Well lets respectfully put it this way.
When you reply with a "not true" statement and that quote, I have to take exception to it because you are not being correct is doing so..
Trying to back yard engineer a system takes full understanding the original poster does not have, or he would not be here asking the question.
He will find out by the time it's all done.
Good luck.
When you reply with a "not true" statement and that quote, I have to take exception to it because you are not being correct is doing so..
Trying to back yard engineer a system takes full understanding the original poster does not have, or he would not be here asking the question.
He will find out by the time it's all done.
Good luck.
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