EGR
Thread Starter
|
New User
Joined: Oct 2010
Posts: 13
Likes: 0
From: Seattle
EGR
Hey guys! I was hoping to get some input on how to troubleshoot my EGR system. I have an 86 f150 5.0 efi and I keep having stalling/crap idle/surging issues related to my EGR, I'm almost one step away from just deleting it. I'm hoping to get some insight on how to pinpoint which part of the EGR circuit is giving me issues (solenoid, EVP, EGR valve) so I don't waste a wad of cash replacing stuff that isn't broken.
So a while ago I had the same issue, removed everything and cleaned out the ports and valve and all that and I was more or less fine for a while. Now If I unplug the connector to the EVP the truck will at least idle well enough to get me home in traffic. I did put a vacuum pump on the top port and applied vacuum and it seems like it affects the idle, didn't kill the engine though. If I remove the EVP and blow air directly into the EGR valve with my mouth I am able to blow a little air through. I know one of the three are bad, just not sure which one, any help would be great thanks!
So a while ago I had the same issue, removed everything and cleaned out the ports and valve and all that and I was more or less fine for a while. Now If I unplug the connector to the EVP the truck will at least idle well enough to get me home in traffic. I did put a vacuum pump on the top port and applied vacuum and it seems like it affects the idle, didn't kill the engine though. If I remove the EVP and blow air directly into the EGR valve with my mouth I am able to blow a little air through. I know one of the three are bad, just not sure which one, any help would be great thanks!
Moderator
Joined: Jan 2001
Posts: 56,951
Likes: 2,718
From: Virginia
I would check the codes first. You may have a EGR code, and if you take a meter and measure the resistance of the EVP, it might narrow it down to that one component. It won't work right if the computer is given false info on the position of the valve. See if you get a code 31, 32, 33, 34, or 35.
Moderator
Joined: Nov 2007
Posts: 22,415
Likes: 92
From: Denver Metro Area, CO
Yes, pull the codes, that's the first place to start:
Fuel Injection Technical Library » How To Run a Self-Test
Post your results here, BUT make sure you tell us which codes come from each of:
KOEO
CM
KOER
Fuel Injection Technical Library » How To Run a Self-Test
Post your results here, BUT make sure you tell us which codes come from each of:
KOEO
CM
KOER
Senior User
Joined: Feb 2012
Posts: 177
Likes: 0
From: Grants Pass, OR
If the EGR is stuck closed you won't notice much.
If stuck open or the tube that connects to the manifold is leaking then you will have poor idle & stalling issues. The EGR should open up at about 1K RPM. So if things get better after 1K RPM the EGR system is a possible cause.
Remove the vacuum line and put a hand vacuum pump on the EGR. You should be able to hear the valve clunk open and closed as you apply vacuum and release. Can be done with your mouth and a piece of vacuum line on the EGR.
Warm up the engine and pull the vacuum line off of the EGR and put your finger on the end of the vacuum line. You should feel no vacuum. Rev the engine and you should feel the vacuum kick on at 1000-1500 RPM or so. (engine must be warmed up).
Another item to check: There is a vacuum line coupler that has come loose on me a couple of times. If so the engine will not idle well at all. Here is a picture of the location. May be covered with tape or loom material.
http://i608.photobucket.com/albums/t...150/Vacuum.jpg
As others have said run the self diagnostic / code read procedure.
I have a tutorial in my web page link below.
If stuck open or the tube that connects to the manifold is leaking then you will have poor idle & stalling issues. The EGR should open up at about 1K RPM. So if things get better after 1K RPM the EGR system is a possible cause.
Remove the vacuum line and put a hand vacuum pump on the EGR. You should be able to hear the valve clunk open and closed as you apply vacuum and release. Can be done with your mouth and a piece of vacuum line on the EGR.
Warm up the engine and pull the vacuum line off of the EGR and put your finger on the end of the vacuum line. You should feel no vacuum. Rev the engine and you should feel the vacuum kick on at 1000-1500 RPM or so. (engine must be warmed up).
Another item to check: There is a vacuum line coupler that has come loose on me a couple of times. If so the engine will not idle well at all. Here is a picture of the location. May be covered with tape or loom material.
http://i608.photobucket.com/albums/t...150/Vacuum.jpg
As others have said run the self diagnostic / code read procedure.
I have a tutorial in my web page link below.
Old School Hot Rodder
Joined: Feb 2006
Posts: 6,472
Likes: 11
From: Exmore, VA
Problem I have seen on the early (85-86) 5.0L is the two EGR control valves will chatter at idle. We chased this on Archion's 86 F-150 for almost a year. End result was surprising, it ended up being the TPS. Same thing you are seeing, disconnecting the EVP would smooth out the idle.
On these systems, the EGR is controlled by opening a vacuum valve and then bleeding air back into the line. As klricks mentioned, pull the vacuum line off the EGR, at idle there should be no vacuum. The EGR is controlled more by throttle position than rpm. TPS voltage needs to be right at 1.0 volt at closed throttle, EGR starts at about 1.1 volt.
Archion's problem was caused by an aftermarket TPS that would not get below 1.1 volt at minimum air setting. He replaced it with a Motorcraft one, problem solved.
On these systems, the EGR is controlled by opening a vacuum valve and then bleeding air back into the line. As klricks mentioned, pull the vacuum line off the EGR, at idle there should be no vacuum. The EGR is controlled more by throttle position than rpm. TPS voltage needs to be right at 1.0 volt at closed throttle, EGR starts at about 1.1 volt.
Archion's problem was caused by an aftermarket TPS that would not get below 1.1 volt at minimum air setting. He replaced it with a Motorcraft one, problem solved.
Thread Starter
|
New User
Joined: Oct 2010
Posts: 13
Likes: 0
From: Seattle
So I tried pulling the codes with a test light and had no luck. The light would be on with ign off. Switch to run and it would blink once and do sorta flicker for a second then just stay on...I think I'll try to pick up a real obd and try my luck with that tomorrow. Maybe I have another issue in the harness preventing me from pulling the codes though.
Yeah klricks, I have no vacuum at idle but once I rev the engine vacuum is present when it's warm, thanks for the link, looks helpful I'll check that out tonight.
85lebaron2, thanks man, I'll test the Tps see if maybe that's the issue.
Yeah klricks, I have no vacuum at idle but once I rev the engine vacuum is present when it's warm, thanks for the link, looks helpful I'll check that out tonight.
85lebaron2, thanks man, I'll test the Tps see if maybe that's the issue.
Moderator
Joined: Jan 2001
Posts: 56,951
Likes: 2,718
From: Virginia
Trending Topics
Thread Starter
|
New User
Joined: Oct 2010
Posts: 13
Likes: 0
From: Seattle
Ok got the codes, my test light was being finicky.. But after trying to count (or miscount) the blinks I just caved in and bought an obd1 scanner for 20 bucks, good decision I think ha. Alright so here's what I came up with
KOEO 31 67 (then just 31 the second time)
CM 63 31
KOER 8 41 31
I know my neutral position is outta adjustment..and everything else points to the TPS or EGR as far as I can tell aside from the o2 when it's running. So any suggestions on where to go from here?
KOEO 31 67 (then just 31 the second time)
CM 63 31
KOER 8 41 31
I know my neutral position is outta adjustment..and everything else points to the TPS or EGR as far as I can tell aside from the o2 when it's running. So any suggestions on where to go from here?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Moderator
Joined: Jan 2001
Posts: 56,951
Likes: 2,718
From: Virginia
This is what the guy in the book says;
When you get a code 31 during the KOEO, it indicates the egr positioning device is transmitting a voltage lower than the ECA expected to see. When the EGR is closed, the EVP sensor should be sending a approx 0.5v signal to terminal 27 of the computer. Code 31 is generated when the voltage at pin 27 is less than 0.2v during the KOEO test.
He says the first thing to do is try and generate a code 35 during the KOEO test by taking and unplugging the EVP plug and putting a jumper between the signal wire and the vref wire. This will throw 5v on the signal wire and should generate a code 35, which is the error code for the voltage being too high. If you get a code 35, that proves the connector, wiring and computer are good, and it may be the EVP sensor is bad.
To further check the EVP sensor, you can put vacuum on the egr valve and measure the voltage on the signal wire as it changes. It should smoothly go from around 0.5v to approx 4.8v.
When you get a code 31 during the KOEO, it indicates the egr positioning device is transmitting a voltage lower than the ECA expected to see. When the EGR is closed, the EVP sensor should be sending a approx 0.5v signal to terminal 27 of the computer. Code 31 is generated when the voltage at pin 27 is less than 0.2v during the KOEO test.
He says the first thing to do is try and generate a code 35 during the KOEO test by taking and unplugging the EVP plug and putting a jumper between the signal wire and the vref wire. This will throw 5v on the signal wire and should generate a code 35, which is the error code for the voltage being too high. If you get a code 35, that proves the connector, wiring and computer are good, and it may be the EVP sensor is bad.
To further check the EVP sensor, you can put vacuum on the egr valve and measure the voltage on the signal wire as it changes. It should smoothly go from around 0.5v to approx 4.8v.
Moderator
Joined: Jan 2001
Posts: 56,951
Likes: 2,718
From: Virginia
If it keeps giving a code 31, the book says to check to make sure you have vref voltage. Take a meter and put it on the vref wire, and the sig return wire(he says the vref is usually orange, and the sig return is usually black. I haven't been calling out the wire colors, I hope you have a diagram that shows the wire colors you should be looking for). You should get close to 5v between the vref and the sig return. If you do not get 5v, then go between the vref and ground over at the battery, and see if you get 5v. If you do, there must be something wrong with the sign return wire.
If you get 5v between the vref and the sig return wires, then put the meter between the vref and the EVP signal wire, it should be around 5v also. If not, repair the EVP signal wire.
If all the above checks out, he then says to go and unplug the computer and leave the EVP unplugged also. Then take ohm readings between pins 27 and 40, 46 and 60 on the large plug. You should get infinity readings. If you don't, one of these wires is shorted.
If all this checks out, he says replace the computer.
If you get 5v between the vref and the sig return wires, then put the meter between the vref and the EVP signal wire, it should be around 5v also. If not, repair the EVP signal wire.
If all the above checks out, he then says to go and unplug the computer and leave the EVP unplugged also. Then take ohm readings between pins 27 and 40, 46 and 60 on the large plug. You should get infinity readings. If you don't, one of these wires is shorted.
If all this checks out, he says replace the computer.
Thread
Thread Starter
Forum
Replies
Last Post
MeanMark87
1997 - 2003 F150
3
Jun 14, 2014 09:58 PM