Limp mode?

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Limp mode?

Blacktop
Hi all,
My ‘84 351w has a serious lack of power. It struggles to reach 65mph on a flat stretch of road and doesn’t want to rev. The slightest of inclines and I need to drop it down a gear. Could it be in limp mode? And if it is, how would I know? There’s no check engine light on. It’s a two barrel carb with computer control.

Thanks for any info,
Alan.
1984 F150 XLT short bed 4x4 351w 4speed manual
1980 F100 long bed 2wd 300-6 3speed manual project truck
🇬🇧UK based truck enthusiast🇬🇧
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Re: Limp mode?

BullnoseHunter02
Only 2 things that come to my mind are the injectors and the fuel pump. Its a carburated engine so i dont think its gonna have injectors on it. Plz correct me if i am wrong though. Im bettng its probibly an issue with your fuel pump.
Hunting for a Bullnose, single cab, 8 foot bed, decent shape with little to no rust! and under 10k in near or around the STL Mo area, (Illinois is a valid option aswell!)
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Re: Limp mode?

Blacktop
Thanks for the reply👍 I have a new fuel pump ready to go on. Also have a 4 barrel Holley and intake ready too but would prefer to fit that later when I junk all the smog, ignition and computer too.

Alan
1984 F150 XLT short bed 4x4 351w 4speed manual
1980 F100 long bed 2wd 300-6 3speed manual project truck
🇬🇧UK based truck enthusiast🇬🇧
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Re: Limp mode?

Gary Lewis
Administrator
In reply to this post by Blacktop
You said it is a computer-controlled 2bbl, and those can easily go into limp-home mode if the computer detects something it doesn't like.

The way to know is to pull the codes.  The EEC-IV Testing page explains how to do that: Electrical/EEC-IV Testing.  But if that doesn't make sense let me know.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Limp mode?

Blacktop
Thanks Gary, I’ll check it out 👍😊
1984 F150 XLT short bed 4x4 351w 4speed manual
1980 F100 long bed 2wd 300-6 3speed manual project truck
🇬🇧UK based truck enthusiast🇬🇧
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Re: Limp mode?

Ray Cecil
I thought the title of this thread was Pimp Mode, to which I thought Id offer my advice. Seeing that its Limp Mode, and I don't have ED issues yet, I still can't offer advice.
1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed


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Re: Limp mode?

Blacktop
😂😂😂
1984 F150 XLT short bed 4x4 351w 4speed manual
1980 F100 long bed 2wd 300-6 3speed manual project truck
🇬🇧UK based truck enthusiast🇬🇧
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Re: Limp mode?

Blacktop
Ive just ordered a digital obd 1 reader from ebay. The computer and carb will be going eventually but hopefully I can get it sorted for now👍
1984 F150 XLT short bed 4x4 351w 4speed manual
1980 F100 long bed 2wd 300-6 3speed manual project truck
🇬🇧UK based truck enthusiast🇬🇧
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Re: Limp mode?

vjsimone
No Engine Check Light until about 1988 on Trucks....
Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"
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Re: Limp mode?

Ray Cecil
vjsimone wrote
No Engine Check Light until about 1988 on Trucks....
I would have sworn my 86 efi 302 has a CEL or SES light.
1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed


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Re: Limp mode?

vjsimone
It has an "Extended Useful Life Indicator" Light?

http://www.garysgaragemahal.com/warning-indicators.html

Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"
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Re: Limp mode?

Gary Lewis
Administrator
Yes.  And initially it was called a Malfunction Indicator Light, and it did come about in '88.

Prior to that there was an Emissions light, and it functioned as explained here: http://www.garysgaragemahal.com/89-22-08-emissions-maintenance-warning-module.html
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Limp mode?

Ray Cecil
In reply to this post by vjsimone
vjsimone wrote
It has an "Extended Useful Life Indicator" Light?

http://www.garysgaragemahal.com/warning-indicators.html
I thought you were mocking me, but then I read the diagram...sure as shoot...there is an Extended Useful Life indicator....

I dont own the truck anymore, but I thought there was a warning light of some sort.
1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed


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Re: Limp mode?

Steve83
Banned User
In reply to this post by Blacktop
Blacktop wrote
Ive just ordered a digital obd 1 reader from ebay.
Try to cancel it.  These trucks are EEC-IV, and readers are extremely UNreliable on them.  It only takes a jumper wire & test light to get codes.  Click this, read the caption, and follow the relevant links in it:



Also...
Ford has no "limp mode".  It has HLOS & FMEM.  Neither causes the engine to run worse or with reduced power - both attempt to keep the engine running as well as possible for as long as possible.
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Re: Limp mode?

Ray Cecil
Steve83 wrote
 ........It only takes a jumper wire & test light to get codes.....
Maybe this is what I was thinking about. I do remember making a jumper and using a test light. Maybe this is the "CEL" I was thinking of.
1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed


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Re: Limp mode?

vjsimone
In reply to this post by Ray Cecil
The light in the Cab may have been labeled "Emissions", I believe it was in 1987.
Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"
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Re: Limp mode?

Steve83
Banned User
The EMISSIONS light (EUL/IMS) is different from the CEL.

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Re: Limp mode?

vjsimone
This post was updated on .
In reply to this post by Ray Cecil
1987


1988


Not to be confused with the “Engine Warning Indicator” in the 1987 – 88 – 89 - ….92 – etc.


Thanks Gary for helping me upload these.  
I hope it is only the second time you have told me how, and not more.
Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"
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Re: Limp mode?

grumpin
In reply to this post by Steve83
Steve83 wrote
Blacktop wrote
Ive just ordered a digital obd 1 reader from ebay.
Try to cancel it.  These trucks are EEC-IV, and readers are extremely UNreliable on them.  It only takes a jumper wire & test light to get codes.  Click this, read the caption, and follow the relevant links in it:
I have an Innova tester I use on my 1992 Bronco and it has worked well.

What do they do?
Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona
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Re: Limp mode?

Steve83
Banned User
grumpin wrote
What do they do?
Display spurious codes; often, codes that don't even apply to the vehicle.  Some also fail to display actual codes.  A jumper wire will never do either (when used as that caption describes).