Thanks in advance for your help: I've run KOER and got the 33 Code for EGR. Because a little knowledge is a dangerous thing, I tested the voltage to the EGR sensor, and pulled a 5.2 volts. It should be higher, right? Now, I had a ground issue recently, one that killed my radio... fixed that at the cable, so I'm wondering if this voltage may be wrong (should be 12?) and that this low voltage could be from a blown PCM??? Also, I have not tested the sensor for resistance and any help in learning how to do that properly would be appreciated. The other code I pulled was a 25... haven't pursued that one yet.

thanks so much!

tony

 

33 EGR did not open/ respond during test or if memory code, did not open intermittently

First don't "shoot the messenger"
i.e. don't blame the sensor for reporting a problem, first see if there is a problem
Get a length of vacuum hose that fits in the EGR Valve
Put it on the EGR valve
Start engine
Suck on the other end of the vacuum hose
Engine should start to stumble as EGR Valve opens, if not, EGR valve is stuck, as reported by the EGR Sensor, remove and clean EGR Valve, test it before reinstalling to make sure its working, i.e. vacuum hose and suck on it

If EGR valve seems to work, engine stumbles when its pulled open and engine recovers with no vacuum(EGR closed)
Then test the EGR solenoid, follow the EGR Valve's vacuum line back to the EGR solenoid, check that this hose has no cracks/breaks
EGR solenoid is a 12volt vacuum valve controlled by the computer
Unplug its 2 wire connector, check that contacts are clean inside connector, and solenoid
The red wire on connector should have 12volt with key on
To test solenoid its easier to remove it, but you can use a 9v battery(or 12v) and touch + and - to the 2 terminals on the solenoid, polarity doesn't matter, as long as 1 terminal has + and the other - you should hear the solenoid "click" open, repeat a few times, if no "click" then replace it

EGR solenoid has another vacuum hose attached, follow it back to the Engines intake manifold, vacuum source, no cracks/breaks, it might go to a "T" hose connection, that OK, its connected to Vacuum Reservoir
Start engine, unhook this hose at EGR solenoid and make sure it has good vacuum present, should hold tight on your finger, and engine RPMs may go up when hose is open

The EGR Sensor runs on 5volts, same 5volts is used by TPS, Air Temp sensor, and ECT sensor, it comes from the computer, so if this 5v was the issue all 4 of these sensor would set codes
Its possible the EGR sensor is bad, just not the first thing to test


25 Knock sensor not tested (ignore if not pinging) - KS
This code should not be present on a vehicle with EGR system
Ford used Knock sensors OR EGR systems, but usually not both, but 1986 2.9l could have both

I would pull out the computer and open it up, have a look at circuit board for corrosion, also look at the 2 or 3 barrel capacitors that stick up, these had a tendency to leak or fail after 25+ years, under $5 to replace
Also unplugging the computer's large connector and plugging it back in CLEANS all the small pins/slots, if these get dirty they can lower voltage from sensors causing codes and issues

 

Ron,

I can't thank you enough for these clear instructions. I have removed the EGR, tested it with a mitey-vac. It moved, but I cleaned it out while I was there, and reinstalled. I checked the voltage at the EGR solenoid and got 12 volts. Initiated the voltage to the leads and got the click. After all that, I tested KOER and no more 33 code--now i get the 23 TPS sensor out of range. So, I decided to check my plugs, as I know my muffler needs replacing and I wondered if any backup exhaust had fouled them. Good color, no soot or hot spots. (I only took off two on the driver's bank, as I was found they were extremely tight... the pro shop of two years' back must've done this and that is disappointing.) About 20 miles ago, I had dropped some Seafoam in the tank to clean the injectors. Did about ten ounces in the ten gallons I figured I had.

At this point, with the 23 code, I'm not sure where to go except finish out your instructions and remove the computer. That same shop had put in one back two years ago... was a remanufacture, I believe. Figured it will be okay, but who knows? I'm leery of messing with the TPS, but if you have a good tip there, you know I'll listen.

As always, can't thank you enough, Ron.

Tony

 

TPS(throttle sensor) is the same as a volume control or light dimmer, a variable resistor
Has a 5volt and a ground wire, and then the 3rd center wire sends variable voltage back to the computer to show throttle plate position
Key on engine off
Use a sewing pin to pierce the insulation on the center wire
Ground the volt meter
Test the center wire voltage, should be 0.69 to 0.99, so under 1 volt
Open throttle manually and watch the voltage, should go up and be smooth, no jumping or dropping, at WOT(wide open throttle) you should see 4.5v to 4.7v
repeat the test a few times looking for drops or jumps in voltage, means TPS is bad, has dead spot or short

There is a screw adjustment on the throttle linkage, looks like an idle screw, its not, its the "anti-diesel" screw, lol, fuel injection can't use an idle screw, every one knows this
Anyway you can adjust this screw if TPS voltage is too high with throttle closed, turn it counter-clockwise a bit and voltage on center wire should drop down a bit, under 1volt is what computer expects to see with key on

People adjust this screw thinking its an idle screw, and it does act like one, but they screw up the TPS voltage without realizing it

The IAC Valve is what ALL fuel injected engines use to set cold and warm idle levels

 

Again, much thanks, Ron for the detailed approach instructions.

Ii have 1.2 volts on the KOEO TPS test. It does dial up smoothly. I saw that the anti-diesel screw doesn't even touch the linkage. I know this TP is about 25K miles old, as is the IAC. Also... I get the 23 code on a computer that I put in on a hunch. The original computer doesn't even show this code. I'm kinda stumped here. Any further suggestions, I will of course go that route. And as always, thank you.

tony

 

The old TPS units had slotted holes so you could adjust them once installed, new ones do not

First, are you sure the throttle plate is closed all the way?
Disconnect throttle cable and see
Remove TPS and see as well
Neither should hold the throttle plate open, even a little

The fact its not touching the anti-diesel screw is odd

You need to get the TPS voltage down under 1volt, with TPS off see what voltage it shows at the low end, should go down to at least .69v, you want .90-.99v
If TPS can't get below 1volt when its not bolted to the engine then I would replace it, that would be very odd failure for a TPS
If the TPS is holding it open, then you may need to drill out the TPS holes so you can adjust it

 

Thanks so much.

I have checked the TPS again. The screws were a bit loose, but not much wiggle room--and that includes the ability to ramp down the base-line voltage. I did manage to do that, and a pic is enclosed that I got it down from 1.2 to 1.1

The screws were a tad loose and I could move the tps just a little without much effort... but not much wiggle room. A shop had installed this TPS almost three years ago. My kicking issue had evolved over time, but I knew that I had to replace the main fuel pump and put it off as that. Anyway, I do have a spare TPS in my parts collection. I'm going to drive this for my job and revisit it this afternoon. I have it on my agenda to check the voltage to the oxygen sensor, but that's after I get this down.

As always, thanks so much. Your guidance is very much appreciated.

TPS voltage

 

Issue solved:

First, I want to say that I had a surgery which kept me away from the computer and pretty much everything else, but all is good now. I replaced the TFI and it solved the problem.

Thanks to you Ron, for your help. It helps in more ways than I can give words to.


Tony