[rehoward]

I would like to remove the air pump and all air injection stuff from my 1989 LX convert. The car is old enough that it does not have to pass emission testing and removing extra junk in the cramped engine compartment is one of my goals.


So if I remove the air injection system will this affect the O2 sensor or confuse the ECU? Is there a correct way to go about this? Thanks.


Randy

 

[Dana W]

The only air pump I ever took off was in 1972, in the pre-cat days, but that was on a 360 V8 Jeep Renegade engine.. The only thing that changed was getting rid of a useless "V" belt, and a little less drag on the engine.

I don't even remember where the air was injected in my '88 5.0 LX. I bought the Mustang new and it's been a while. That was my 1st of four Mustangs. You may have to go to a plumbing supply store for some "pipe Plugs" to fill the holes in the exhaust manifolds. Those holes might have American standard tapered pipe threads, not straight bolt threads. Mine needed 3/8" plugs but that was the Jeep engine. The Jeep's air was injected directly into the tops of the iron exhaust headers. Can't imagine why I can remember even that. :grin:

 

[wbrockstar]

(** Special Note **)
For those retaining the catalytic converters, you CANNOT delete any portion of the smog (thermactor) system or your converters will clog and fail.In addition to this,if any part of the system is currently defective,its very important that you repair or replace that component,because if you don't,it'll cause the converters to clog & fail.

The following components make up the thermactor & egr system.
1) smog pump
2) tab/tad valves
3) hoses
4) tab/tad solenoids
5) crossover pipe & check valve
6) hpipe airtube pipe & check valve
7) egr valve
8) evp sensor
9) evr solenoid
10) vacuum hoses & check valve
11) Once the crossover pipe is removed,the cylinder heads thermactor passages can be plugged by using thermactor plug inserts or a 5/8 11 bolt.The passage inlets may require you to clean the hard carbon buildup from them enough so the inserts or bolts can be screwed in.One benefit of using the plug inserts vs bolts is the inside & outside of the insert has threads.The internal threads are used to mount accessories to the engine. Since both heads can be installed on either side of the block,not having these inserts would mean you'd have to install the correct head on each side of the block,meaning you would have to make sure that the end of each head without these inserts would have to be the end of the head that goes to the rear on each engine bank.Otherwise if you didnt pay attention to which end of the head went to the rear & you positioned a head on the driver side with the inserts not being in place on the end facing the front of the car,you wouldn't be able to mount the ac compressor and power steering pump & this heads thermactor passage would now be open to the atmosphere.

If you're removing all of the thermactor components,you dont have to do anything to the tab/tad solenoid wiring harnesses if you dont want to.The only thing that'll cause,by leaving them disconnected,is possibly the following codes (44/94/81/82) However these codes wont cause a check engine light & they also wont cause any driveability issues either.If these do show up,when you run a koeo/koer scan,these codes being present is equal to a code 11 (system pass code)
If you dont want codes 81 & 82 (solenoids) to pop up in a koeo/koer scan,you can buy some resistors & insert them into the tab/tad solenoid wiring harness plugs,but codes 44/94 will still be present,even after you add the resistors.You need (2) 75ohm 3watt resistors for these two solenoid harness plugs.Just bend the resistor wire ends into a 90° angle then insert the wire ends of 1 resistor into the tab solenoid harness plug pinouts & do the same with the other resistor into the tad solenoid harness plug pinouts.That will prevent codes 81 & 82 from popping up.If it was me,I would just leave the harnesses disconnected & ignore the codes above when they pop up,but the resistor trick is easy enough to do if you want those 2 codes gone.
The smog components are absolutely useless,if you are no longer running converters.If youre running an offroad hpipe, leaving the smog system components functioning,can possibly cause the o2 sensors to read lean because of the smog pump air thats still being dumped into the hpipe.

As far as the ecm & o2 sensors go,in how they relate to the smog components,the ecm uses the o2 sensors to test the operation/ function of the thermactor components.IOW - when the ecm wants to run a test to see if the smog components are working,it simply cycles the tab/tad solenoids on/off then looks for a change in o2 readings.Example:: lets say the ecm cycles the tab (bypass) solenoid On & the tad (diverter) solenoid Off,
smog pump air should pass through the bypass valve then through the diverter valve and on to the hpipe (catalytic converters) When this air reaches the o2 sensors,it causes the oxygen level to increase,which causes a lean condition then o2 sensor lean codes.So if the ecm ran the test above and it made the o2 sensor read lean,that tells the ecm the smog components are working properly.If the ecm ran the test above and it caused the o2 sensor to read rich or not change at all,that tells the ecm a smog component is suspect.
Hopefully that explains what the o2 sensors are used for,in relation to the smog system.

(Pipe Plug link)
https://lmr.com/item/LRS-6086AK/1979-95-Mustang-Cylinder-Head-Smog-Plugs-for-50L-58L

 

[rehoward]

As usual your comments are most appreciated wBrockstar. I have read that plugging a resistor of a specific ohm value into the disconnected leads will resolve error codes concerning the ECM. Do you know the values of the resistors regarding ohm value and wattage? Thanks for your help.


Randy

 

[wbrockstar]

As usual your comments are most appreciated wBrockstar. I have read that plugging a resistor of a specific ohm value into the disconnected leads will resolve error codes concerning the ECM. Do you know the values of the resistors regarding ohm value and wattage? Thanks for your help.


Randy

75ohm 3watts

 

[wbrockstar]

BTW- I dont know if youre removing any other parts related to the emissions system,but resistors can be used for those too.
Tab/Tad solenoids=(1) 75ohm 3watt
Canister purge=(1) 75ohm 3watt
Evr solenoid=(1) 75ohm 3watt
Evp sensor=(2) 3.9k ohm 1/2watt +
(1) 390ohm 1/2watt

If you use resistors on the evp sensor harness,follow the diagram below to make a resistors triangle.

 

[rehoward]

BTW- I dont know if youre removing any other parts related to the emissions system,but resistors can be used for those too.
Tab/Tad solenoids=(1) 75ohm 3watt
Canister purge=(1) 75ohm 3watt
Evr solenoid=(1) 75ohm 3watt
Evp sensor=(2) 3.9k ohm 1/2watt +
(1) 390ohm 1/2watt

If you use resistors on the evp sensor harness,follow the diagram below to make a resistors triangle.

Did you mean EVR solenoid or EGR solenoid? Do all of these connectors have just 2 terminals that you jump with the resistor or is it more involved than that? Don't understand the EVP resistance formula. Do I use 2 resistors for that? Are they used individually on separate circuits or maybe wired in series or parallel for one circuit? Thanks again for the help.
Randy

 

[wbrockstar]

Did you mean EVR solenoid or EGR solenoid? Do all of these connectors have just 2 terminals that you jump with the resistor or is it more involved than that? Don't understand the EVP resistance formula. Do I use 2 resistors for that? Are they used individually on separate circuits or maybe wired in series or parallel for one circuit? Thanks again for the help.
Randy

Yes,all but the EVP sensor use just two terminals.Jumping the harness plug terminals is exactly what you do.The EVP sensor will require three resistors in total & yes you'll be running them in series by making whats called a resistors triangle, which I'll explain more about below.........

EVR is basically short for EGR Vacuum Regulator solenoid.Its the single solenoid mounted above the dual tab/tad solenoids on the rear of the passenger strut tower.The solenoids & sensors discussed in previous posts & this one,except the EVP (EGR Valve Position) sensor,use a harness plug with two pinouts.For the resistor,hold onto it,then use pliers and bend each wire end into a 90° angle then insert each wire end into one of the harness plug pinouts and you're done. The resistor basically simulates the coils resistance which is what makes them work. Use this same technique for any of the other emissions solenoids/sensors/valves you've deleted that you don't want a code to pop up for.

For the EVP sensor,you bend each resistor wire end into a 90° angle then insert each wire end into the correct harness plug pinout,like shown in the diagram at the bottom of this post.The only difference is,youll be inserting a wire end from two separate resistors into each of the three harness plug pinouts on the evp sensor harness plug.The evp sensor is the only one out of all the emissions devices,that you'd delete,that requires this 3 resistor setup.
The other devices only require 1 resistor.If you don't wanna insert 1 resistor at a time on the evp harness plug,just set the resistors out on a table,form them into the shape of a triangle (matching how theyre layed out in the diagram below as far as ohm/watt value goes) twist the wire ends together at each intersecting point (3 of them) bend the wire ends into a 90° angle and insert each wire end pair into each harness plug pinout & you're done.

If you dont wanna mess with making the resistors triangle,you can use the following method instead to keep the cel from coming on.

1) Remove the EVP sensor from the EGR valve,leave the harness connected
2) Turn the key on/engine off
3) Backprobe the harness terminals as follows.
Connect the black multimeter lead to the black/white wire terminal
Connect the red multimeter lead to the brown/lt green wire terminal
4) Manually push the evp rod inwards until the meter reads any voltage value between
0.24-0.63 volts.
5) Once the voltage reading is between this range,hold the rod in that position,wrap some electrical tape around the sensor body & over the end of the evp rod,so that the rod stays in that position once you take your finger off of it.
6) Verify the rod hasnt moved any,with the meter,then pour some superglue on the rod where it meets the sensor body,let it set up/cure then remove the tape & check voltage with the meter again to make sure the rod is glued into the correct voltage range (0.24-0.63)
7) Reattach the sensor to the egr valve then reinstall the valve (unless youre gonna use a block off plate over the egr spacer holes where the egr valve is normally positioned)

The procedure above accomplishes the same thing as installing a resistors triangle or a egr delete plug.
You can leave the egr valve & evp sensor installed with the wiring harness plugged in or remove the evp sensor from the egr valve,remove the egr valve from the egr spacer & block the holes with a block off plate then ziptie the evp sensor to anything in the engine bay that'll prevent it from moving around.