Two trains of thought on replacing vacuum lines. Use what was there, or replace the small diameter "vinyl" hose with rubber. I went the first route. I found the "hard" vacuum lines at the local parts store, so I used that. Otherwise use a small good section of the hard line as an adapter to replacement rubber hose. Forget Ford.....$$$$$$

 

I will have to check that out. Different colors mean different thickness dont they or does that matter. How much roughly did it cost to replace them .

 

Different colors for ease of hooking up and tracing out where they go. I have about $30 USD in new vacuum lines both hard and rubber.

 

Sounds good I will try that tommorow, see what happens also see what the timeing looks like. Try and clean the IAC, Test TPS and go from their. Going hunting in a two weeks so want the truck to run good.

 

i have an 87 f150 5.0 efi and the IAC has always been the culprit for the surging idle. sometimes hard start or slow start. Idle will seem ok then almost die the idle back up. IAC affects idle or start only. My experience has been just go ahead a buy a new IAC. Cleaning the electrical solenoid plunger worked a few months at most. cleaning the valve part didnt do squat. I have nerver found the valve part stuck from the carbon black. I have replaced about 5 or 6 over the 22 years ive had the truck. original lasted about 5 years replacements including those from ford lasted about 2 to 3 years.

 

Thanks for the info that is what I am starting to suspect right know. I dont know much when it comes to the electrical and sensors.

 

well got all my supplies. going to try and clean the IAC no one had a gasket for it except ford and their were none in canada would have to be shipped from the U.S. would take over a week. So i will make my own. What is the best way to clean the IAC I got some kleen flow i am planning on taking it off and giving it a spray.

 

Well I got the IAC cleaned and wow it made a big difference and I also put some sea foam and cleaned the TB much better but not perfect when I hit the throttle the revs stay up for a sec then back down I think the TPS is wearing out. Does this sound right to anyone I did have a code for the TPS. And also the vacum lines need to be replaced. and when I was revving the motor I could not see The EGR move at all. How noticeable is it when it moves. any input would be great feel as though Iam moving closer to having it done. Also checked plenum gasket with propane and it seems good.

 

The parts guy at Auto Zone told he he ruined his injector seals by putting SeaFoam in his gas tank. He said it worked fine in the intake or added to oil if done per the instructions. Just dont put it in the gas. the injectros he ruined were on a $15000 race engine.
On my truck the EGR is hard to see move. It doesnt work at idle as I remember. engine needs to be about 2000 or more. I reach over on top of the throtle body and pull the throtle linkage to rev up the engine while looking at the egr shaft just below the rubber diaphram. Its had to see well at least for a short fat man. I even tryed putting a tee in the line to the vacuum hose on top of the egr and installing a vacuum gage. when the engine was reved the vacuum went to about 4 inches for a few seconds and then to about 0 to 1 inch for a little while. I could see the shaft and diaphram move. for a few seconds and then it looked like it stopped. when i idled down and reved back up it would repeat. My egr diaphram dont leak. I put a hand vacuum on the egr and pulled a 25 inch vacuum and it would hold it with no leakage.

 

Yeah I only put it in the throttle Body and dumped it in the oil. Will see what all the hype is about from napa the person their says they use it once a month in their gas. I still think it is my TPS giving me some trouble when I hit the gas it seems to go up ok but then come down sit a sec and come down again. I did have a code about the improper voltage for operating the TPS. Voltage is fine to the TPS but the resistance is low. So that is my next step.

 

Vancouver,you need to search this forum. If i remember correctly the TPS is located on the throttle body just below where the 2 big black air intake hoses connect. Mine has a 3 wire connector with a black, orange, and green wire. the resistance between the black and orange is about 3800 ohms and 700 ohms between green and black. on my 87 5.0 efi. MY haynes and chilton manual just says match mark when replacing. my sable manual syas you should have less than 1.0 volt between the signal wire and common. this seems inline with what i remember from searching these posts a while back. When you check ohms and say its low wher are you measuring and how? you need to be sure you have a good connection with your ohm meter. I unplugged my sensor to read the ohms but you need to be careful, if your probe is too big you can ruin the tps recepticale by spring open the pin recepticales. too loose and you will get a bad reading or erratic reading. If your connection is good, when you operate the throttle linkage the ohms reading between the green and black wire should go from 700 to 3600. Please bear in mind your ohms reading may be as much as 25% different. but the ohms should increase as you push on the gas peddle or move the linkage. if your sensor is bad you may see your ohms go away or get a high reading. the main thing is that the ohms change steady and dint jump around. when the engine is on, the computer put 5 volts between the black and orange wire. this should stay the same within 0.1 volt or less (4.9 to 5.1 volts).

 

I forgot to menion that resistance will usually be lower and lower temperatures.

 

yeah I have tested it. Would the TPS still give me wierd idle. Not as bad know that I cleaned the IAC. Kind of a miss or rough excelleration. When I ran the codes it also came up as TPS low current or something like that, could that really be anything else I checked and do have 5 volts steady going to the unit. Also when I shut off the motor I hear a hissing sound and I have no air conditioning. It sounds like it is coming from the drivers side their are a couple big tubes that have some canister type things on them and a silver type one as well. It kinda sits near the back but I think they have something to do with the EGR system.

 

the hissing sound could be a vacuum leak which can cause miss. TheTPS can too on the acceleration as the computer wont know where the throttle is.

If the TPS siganl is not right the computer dont know what speed to go to or how much more gas to feed the injectors to get there. If your 5.8 is similar to my 5.0 the big vacuum hose is probaly to the power brake booster, and the other one to the cruise control. yours may be different. on mine there are also fuel hoses and vacuum lines to the TAB, TAD, and EGR relays.

One other thing having 5 volts to the TPS doent mean its okay. you have to have voltage on the signal wire too. You could have voltage on the computer side of the connector but not on the TPS side. That low current reading might be saying the circuit is open or intermittent to the signal line. It could be the connector or a bad TPS. Which would be typical for a variable resistor or pot as most electronic folks call them. The TPS is a resistor (pot) with a wiper arm on it. The wiper arm is the signal to the computer. You say you tested the TPS but you dont say how or what you got. The TPS has three leads on it. you will get 5 volts aross 2 of them. with the engine idling if you leave one of your meter leads on any one of the 2 you read 5 volts on then move one meter lead to the 3rd lead on the TPS you should read a little less than 1 volt or a little more than 4.

Getting a voltage reading does not always mean current is flowing. Unplug the connector to your TPS and check the ohms while someone pushes on the gas pedal for you. You should read about 4K across 2 of the leads and it wont change when you push the gas pedal. Pick another combination of 2 leads, and as you push the gas pedal the resistance will increase from about 600 ohms to less than 4000.
Or it might decrease from less than 4000 to about 600. depending on which 2 you tested. the ohms should change smoothly without interruption or sudden increase,indicative of an open circuit. Have who ever is pushing the pedal push down slowly and ease back down as you watch the ohms.

 

Thanks yeah I have about .8v and when I test the ohms when running it does increase steady so maybe it is not the TPS but I did have a code for that. I have no cruise control. I think it is for the EGR. So the TPS does not control idle