Surging at idle issue.
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Cross-Country
Joined: Feb 2013
Posts: 85
Likes: 3
From: Gibsonville,NC
Surging at idle issue.
Hello all, I’ve got an 86’ F-150, 302 automatic with EFI. I’ve been having an intermittent issue with it surging at idle, but only after idling for a few minutes. It never does it at start up, but it will usually choke itself out & I’ll have to crank it 2 or 3 times before it will run. I have R&R the idle control valve, both sending units, new MAP sensor & pulled & thoroughly cleaned the throttle body. This helped for a week or so & now it’s back. Do you guys have any advice on what I need to check next? I’m at a loss. Thank you in advance for any help.
Lead Driver
Joined: Nov 2013
Posts: 7,180
Likes: 1,174
Please define “this”.
You posted a long list of things you did. Was this all done at once, or individually for each item? Something seemed to have improved the situation, at least temporarily. If you know a particular item helped, that’s the one I’d revisit.
For future troubleshooting, it’s best if you only make one change at a time whenever possible. It’s much easier to interpret the results that way.
You posted a long list of things you did. Was this all done at once, or individually for each item? Something seemed to have improved the situation, at least temporarily. If you know a particular item helped, that’s the one I’d revisit.
For future troubleshooting, it’s best if you only make one change at a time whenever possible. It’s much easier to interpret the results that way.
FTE Legend
Joined: Nov 2015
Posts: 30,940
Likes: 4,125
From: Angier, NC
First I would do on any computer controlled motor is pull codes to see what it has to say is wrong.
What "both sending units" are they you talk of?
Have you checked the out put of the TPS?
Take a fuel psi reading on the rail?
But first pull codes
Dave ----
What "both sending units" are they you talk of?
Have you checked the out put of the TPS?
Take a fuel psi reading on the rail?
But first pull codes
Dave ----
Thread Starter
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Cross-Country
Joined: Feb 2013
Posts: 85
Likes: 3
From: Gibsonville,NC
To clarify;
Just to clarify my OP.
1. All of these changes were done separately, over the last 6-8 months.
2. Fuzzface, I meat to say Both fuel sending units were removed & replaced.
3. kr98664, This helped for a week or so & now it’s back. I’m referring to each of these improvements, after they were installed. IAC valve, MAP sensor & throttle body cleaning respectively, and the fact that the surging issue came back anyway. All were done separately over a 6-8 month period. The fuel sending units were replaced separately & they were the first thing I did, I was trying to fix my inoperative fuel gauge to no avail.
4. Pulled codes KOEO and got 31, 10, 22, 64. Did not pull codes for KOER since I never received a pass code of 11 or 111.
1. All of these changes were done separately, over the last 6-8 months.
2. Fuzzface, I meat to say Both fuel sending units were removed & replaced.
3. kr98664, This helped for a week or so & now it’s back. I’m referring to each of these improvements, after they were installed. IAC valve, MAP sensor & throttle body cleaning respectively, and the fact that the surging issue came back anyway. All were done separately over a 6-8 month period. The fuel sending units were replaced separately & they were the first thing I did, I was trying to fix my inoperative fuel gauge to no avail.
4. Pulled codes KOEO and got 31, 10, 22, 64. Did not pull codes for KOER since I never received a pass code of 11 or 111.
Moderator
Joined: Jan 2001
Posts: 56,997
Likes: 2,744
From: Virginia
With the engine fully warmed up (take it for a short drive) let it sit there and idle, and while it's idling, unplug the idle air control valve connector. What does the engine do when you unplug it? Does it stall? It does nothing and keep idling?
By now these trucks are old enough that people touch the "untouchable" idle screw. You probably need to adjust it, or at least check it by unplugging the idle control valve and see what happens. If this screw is turned too far in, that is too much air going through the throttle valve, and it also puts the throttle position sensor beyond 1 volt at idle, which confuses the computer.
By now these trucks are old enough that people touch the "untouchable" idle screw. You probably need to adjust it, or at least check it by unplugging the idle control valve and see what happens. If this screw is turned too far in, that is too much air going through the throttle valve, and it also puts the throttle position sensor beyond 1 volt at idle, which confuses the computer.
Cargo Master
Joined: Sep 2006
Posts: 2,120
Likes: 390
From: Evansville, Indiana
Check for 5v reference at the MAP (easiest to get to)
Post Fiend
Joined: Feb 2008
Posts: 5,831
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From: St Albert, Alberta
This sounds like an EGR/Vacuum leak issue. meter out the EGR position sensor to verify it's operating. Yes, you have a code for it but meter out the sensor regardless, with the age of these trucks you should meter out sensors to verify that is what has failed and to rule out any potential wiring issues.
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Cargo Master
Joined: Sep 2006
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From: Evansville, Indiana
@Big-Dawg you have put a lot of time, effort and parts into your '86. I would like to recommend that you buy one more part,
. This book, to me, is the EEC-IV Bible. Costs less than most of the parts you've thrown at the truck.
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Joined: Jan 2001
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From: Virginia
@Big-Dawg you have put a lot of time, effort and parts into your '86. I would like to recommend that you buy one more part, Ben Watson's book. This book, to me, is the EEC-IV Bible. Costs less than most of the parts you've thrown at the truck.
Thread Starter
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Cross-Country
Joined: Feb 2013
Posts: 85
Likes: 3
From: Gibsonville,NC
Update on surging idle
Ok guys, I just received about 4 boxes of parts to throw on my F-150. I was excited & (the wife was playing 20 questions) but she knows a 35 yr old truck almost always needs something. Anyway, I ordered a new EGR valve, EGR valve position sensor, EGR pigtail, TPS, Air intake/charge temp sensor & pigtail. To top it off I got a Chilton manual just for good measure. I removed the negative battery cable (to clear any stored codes) then replaced EGR & EGR sensor first, then TPS & lastly the Intake air charge temp sensor. When I buttoned everything up & cranked it, it ran very smooth, didn’t die after idling down. YES! I plan to road test it today, fingers crossed it stays smooth. Thanks for all the help, even though I took the expensive route.
Lead Driver
Joined: Jun 2013
Posts: 5,670
Likes: 1,161
From: Tolland, CT
Big-Dawg, Not sure you've seen this, but this site has a ton of info,
EFI - Gary's Garagemahal (the Bullnose bible)
EFI - Gary's Garagemahal (the Bullnose bible)
Thread Starter
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Cross-Country
Joined: Feb 2013
Posts: 85
Likes: 3
From: Gibsonville,NC
New update
Hello all, I was proud of myself with the installation of my new parts until the next morning. Cranked the truck numerous times & it would die each time. I could give it gas & it struggled to idle with each crank. Decided to preform Gary’s suggestion with the idle screw adjustment & problem solved. It’s currently idling at 7k rpms. Thanks for the advice with this so far.
Today I re-ran my code reader, just to see what codes disappeared and if any new codes showed up. I ran the KOEO test after getting engine up to temp. This is what I got & in this order. Code 11,10,64,31. I found out from the Innova manual that the code 10 serves as an indication that the PCM has completed the first part of the KOEO test & the next codes displayed are Continuous memory codes. So it looks like I still need to find out what’s up with the voltage to the IAT & EGR. Thankfully the surging issue has disappeared, but it’s still not running 100% yet. Anyone care to explain how to chase down a low voltage reading/ground issue? 😂Thanks again!!
Today I re-ran my code reader, just to see what codes disappeared and if any new codes showed up. I ran the KOEO test after getting engine up to temp. This is what I got & in this order. Code 11,10,64,31. I found out from the Innova manual that the code 10 serves as an indication that the PCM has completed the first part of the KOEO test & the next codes displayed are Continuous memory codes. So it looks like I still need to find out what’s up with the voltage to the IAT & EGR. Thankfully the surging issue has disappeared, but it’s still not running 100% yet. Anyone care to explain how to chase down a low voltage reading/ground issue? 😂Thanks again!!
Last edited by Big-Dawg; Jun 6, 2021 at 11:52 AM. Reason: Adding an after thought.
FTE Legend
Joined: Nov 2015
Posts: 30,940
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From: Angier, NC
I would be more worried about that 7K idle 
I am guessing it's at 700 RPM
I dont know much about the EFI's but I would be guessing you need to see if the voltage is the same back at the PCM and if so then guessing bad PCM, if not then the wiring needs looking at.
Dave ----
I am guessing it's at 700 RPM
I dont know much about the EFI's but I would be guessing you need to see if the voltage is the same back at the PCM and if so then guessing bad PCM, if not then the wiring needs looking at.
Dave ----
Moderator
Joined: Jan 2001
Posts: 56,997
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From: Virginia
That "10" is really just a seperation pulse to separate the actual codes it's getting now with the memory codes it has stored. All those codes you got after the "10" are just memory codes that are gone now. Take the battery cable off to erase them, and then drive it some and see what comes back. It looked around at the moment you pulled the codes and saw nothing, that is where the 11 came from.
Thread Starter
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Cross-Country
Joined: Feb 2013
Posts: 85
Likes: 3
From: Gibsonville,NC
Reply
I would be more worried about that 7K idle
I am guessing it's at 700 RPM
I dont know much about the EFI's but I would be guessing you need to see if the voltage is the same back at the PCM and if so then guessing bad PCM, if not then the wiring needs looking at.
Dave ----
I am guessing it's at 700 RPM
I dont know much about the EFI's but I would be guessing you need to see if the voltage is the same back at the PCM and if so then guessing bad PCM, if not then the wiring needs looking at.
Dave ----