Notices
1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

p1120 p1121

 
  #1  
Old 12-28-2004, 08:22 PM
fordgta
fordgta is offline
Freshman User
Thread Starter
Join Date: Dec 2004
Location: MIchigan
Posts: 36
fordgta is starting off with a positive reputation.
p1120 p1121

These r ths codes im gettin off the datalink. ive replaced the tps sensor and the mass airflow also. The truck is a 96 5.8, it runs crappy....the only way i can describe it is a chug chug chug. Ive replaced the coil, distributor, cap+rotor,fresh plugs and wires. air filter to na avail........please help. Im kinda thinkin the catalytic converter is clogged. but why would the code keep coming back. And ive had the code cleared also. so thats not why.....ne1 know???????? thanks in advance
 
  #2  
Old 12-28-2004, 09:56 PM
IB Tim's Avatar
IB Tim
IB Tim is online now
Site Administrator
Join Date: Jan 2003
Location: 3rd Rock
Posts: 149,572
IB Tim has a superb reputationIB Tim has a superb reputationIB Tim has a superb reputationIB Tim has a superb reputationIB Tim has a superb reputationIB Tim has a superb reputationIB Tim has a superb reputationIB Tim has a superb reputationIB Tim has a superb reputationIB Tim has a superb reputationIB Tim has a superb reputation
Welcome to the only family Ford Truck site, on the net. The members in these forums are very knowledgeable about trucks; they will eagerly help you…with your question. If you have a minute check out the Guidelines, it will help you to navigate through FTE.
Enjoy FTE
 
  #3  
Old 12-28-2004, 10:13 PM
mike L
mike L is offline
Posting Guru
Join Date: Jul 2004
Location: va
Posts: 1,506
mike L is starting off with a positive reputation.
Welcome to FTE. See a list of codes at http://www.troublecodes.net/Ford/eec-vobd2.shtml . Did you test the wiring to each sensor? I'm just guessing but hows the fuel pressure? Do you have two fuel tanks?
 
  #4  
Old 12-29-2004, 09:40 AM
fefarms
fefarms is offline
Elder User
Join Date: Sep 2004
Posts: 941
fefarms is gaining momentum as a positive member of FTE.fefarms is gaining momentum as a positive member of FTE.
P1120 = TPS out of range, too low
P1121 = TPS inconsistent with MAF sensor

The TPS is giving the computer a reading of less than 0.5 volts, probably all the time. The computer sees this unreasonable value with the engine stopped (code P1120), and then sees the engine gobbling air (as measured by the MAF), but sees the throttle as being closed as sensed by the TPS (P1121). The TPS is not a primary sensor -- the computer uses the MAF sensor to determine the amount of air being ingested, and in turn the amount of fuel to inject. The TPS is there to fine-tune the transitions between idle, part-throttle cruise, and WOT. The truck will run without it, just not as well.

The codes can be caused by: a TPS that is broken, open circuit in VREF going to TPS, or a short circuit to ground in the TPS sense wire going back to the computer.

Use a voltmeter to probe the between the TPS sense wire and ground. With the key on, but the engine not running, measure the voltage. Should be about 0.9 volts with the throttle closed, should increase smoothly to about 4.5 volts at WOT.
 
  #5  
Old 12-29-2004, 10:27 AM
fordgta
fordgta is offline
Freshman User
Thread Starter
Join Date: Dec 2004
Location: MIchigan
Posts: 36
fordgta is starting off with a positive reputation.
well heres what i did. i unplugged the tps connector and checked the voltage on all three male connectors. the only one that had voltage was the red or live wire, it was 4.5 . The green wire has a very minute reading of .25 of a volt and nothing on the black wire. None of these changed while i opened the throttle by hand.................to mike L yes it does have two tanks , no i havent checked fuel pressure. but switching between tanks doesnt seem to be a problem, if that helps.....what should i do next.....thanks for your time helping me by the way
 

Last edited by fordgta; 12-29-2004 at 11:01 AM.
  #6  
Old 12-29-2004, 01:39 PM
fefarms
fefarms is offline
Elder User
Join Date: Sep 2004
Posts: 941
fefarms is gaining momentum as a positive member of FTE.fefarms is gaining momentum as a positive member of FTE.
Let's divide the TPS connector into "harness end" and "sensor end". Male and female get confusing -- are we talking about the plastic connector shell or the copper conductive elements?

If you disconnect the TPS connector, turn the key on, and probe the harness end, you should see 4 to 5 volts on VREF, and neglible voltage on the other two. It appears that you are getting this, though that 0.25 volts seems a little suspicious. It will not matter what you do with the throttle with the connector disconnected.

Turn the key off, and make the following tests:

Disconnect the TPS connector. Set the meter on "ohms". Probe between VREF on the HARNESS end and a convenient ground. The resistance should be fairly high >0.5 megohms. Probe between the sense line and ground. It should also be a fairly high resistance 0.5 to 1.0 megohms. Probe between SIGRTN and ground. This should be a low resistance -- maybe 1.5 ohms but certainly less than 10 ohms.

Now probe between different pairs of connections on the SENSOR end of the (disconnected) TPS connector. The throttle should be closed. The key should be off. VREF to SIGRTN should be about 4K ohm. TPS sense to SIGRTN should be about 1K ohm. TPS sense to VREF should be about 3.5K ohm. If you open the throttle, the resistance between TPS sense and VREF should go down, and the resistance between TPS sense and SIGRTN should go up.
 
  #7  
Old 12-29-2004, 03:55 PM
fordgta
fordgta is offline
Freshman User
Thread Starter
Join Date: Dec 2004
Location: MIchigan
Posts: 36
fordgta is starting off with a positive reputation.
apologise for being unknowledgable...but couild you explain VREF SIGRTN and TPS sense. I see red green and black wires . Harness side, sensor side i understand. Is vref red? is sigrtn green? is sense black?. sorry but ive never dealt with this kinda problem before i dont really know the language.
 
  #8  
Old 12-29-2004, 03:59 PM
mike L
mike L is offline
Posting Guru
Join Date: Jul 2004
Location: va
Posts: 1,506
mike L is starting off with a positive reputation.
tps wire colors for 87 to 89

signal return wire is black- white stripe
vref is orange
tp signal is dark green

sorry for your trucks its

1996 5.8

signal return wire is gray with a red stripe
vref is brown -white stripe
tp signal is gray -white stripe
 

Last edited by mike L; 12-29-2004 at 04:10 PM.
  #9  
Old 12-29-2004, 04:08 PM
fordgta
fordgta is offline
Freshman User
Thread Starter
Join Date: Dec 2004
Location: MIchigan
Posts: 36
fordgta is starting off with a positive reputation.
well i dont know what i did but i think the problem lies on the harness side. The little pocket meter i just got measures in 1x and in 10X. in 1x the harness side read 0, 0, and the green(on sensor side) or grey and white read 40
 

Last edited by fordgta; 12-29-2004 at 04:22 PM.
  #10  
Old 12-29-2004, 04:23 PM
mike L
mike L is offline
Posting Guru
Join Date: Jul 2004
Location: va
Posts: 1,506
mike L is starting off with a positive reputation.
pocket volt meters

Originally Posted by fordgta
well i dont know what i did but i think the problem lies on the harness side. The little pocket meter i just got measures in 1x and in 10X. in 1x the harness side read 0, 0, and the green wire (signal) read 40
I have the same volt meter. You need the 12 dvc or direct current volt setting or 12x. Use the 10x on your meter for now which stands for 10 direct current volts. Cars and trucks run on 12 volts, need key on not running. Look for the scale on your meter that reads 0 volts to 10 volts max. did you get 4 ? So the green wire reads 40 which means 4 volts? Or was that 40 ohms with key out and battery ground unhook.
 
  #11  
Old 12-29-2004, 04:35 PM
fordgta
fordgta is offline
Freshman User
Thread Starter
Join Date: Dec 2004
Location: MIchigan
Posts: 36
fordgta is starting off with a positive reputation.
Originally Posted by mike L
I have the same volt meter. You need the 12 dvc or direct current volt setting or 12x. Use the 10x on your meter for now which stands for 10 direct current volts. Cars and trucks run on 12 volts, need key on not running. Look for the scale on your meter that reads 0 volts to 10 volts max. did you get 4 ? So the green wire reads 40 which means 4 volts? Or was that 40 ohms with key out and battery ground unhook.
it was in 1x ohms so it was reading 40 ohms........although battery ground washooked up should i unhook?
 
  #12  
Old 12-29-2004, 04:42 PM
mike L
mike L is offline
Posting Guru
Join Date: Jul 2004
Location: va
Posts: 1,506
mike L is starting off with a positive reputation.
reading ohms

When reading in ohms you need to unhook the battery ground and remove the truck key or you will blow your fuse in your meter. I did it twice, you got lucky this time 1x is 1000 ohms thats the one you need to use try testing again.
 

Last edited by mike L; 12-29-2004 at 04:45 PM.
  #13  
Old 12-29-2004, 04:44 PM
fordgta
fordgta is offline
Freshman User
Thread Starter
Join Date: Dec 2004
Location: MIchigan
Posts: 36
fordgta is starting off with a positive reputation.
oops thanks,,,,,brown and white 4 volts with key on .........also will unhooking the battery clear the codes or is that in 1995 and later wehicles?????
 

Last edited by fordgta; 12-29-2004 at 04:47 PM.
  #14  
Old 12-29-2004, 04:58 PM
mike L
mike L is offline
Posting Guru
Join Date: Jul 2004
Location: va
Posts: 1,506
mike L is starting off with a positive reputation.
i'm pretty sure it will remove just the the memery codes, but just run it for a while and they should show up again. Is your engine light on? if so you wont loose the codes until you fix the problem. Checking the voltage and ohms on the tps should help. I can clear codes on my 87 by unhooking the battery.
 
  #15  
Old 12-29-2004, 05:08 PM
fordgta
fordgta is offline
Freshman User
Thread Starter
Join Date: Dec 2004
Location: MIchigan
Posts: 36
fordgta is starting off with a positive reputation.
well the check engine light is not on at this moment like you said it takes a while for them to show up after the battery has been disconnected or they get cleared at autozone. replacing the mass airflow sensor and the tps sensor didnt keep the same codes from coming back. p1120 and p1121. what should i do next?
 

Last edited by fordgta; 12-29-2004 at 05:10 PM.

Thread Tools
Search this Thread
Quick Reply: p1120 p1121


Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.