Engine runs very rough?

Most likely the TFI Module located left rear engine bay. see diagram below. Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

Thank you so much I will replace this today! I appreciate your help.

Let me know how it goes. This guide can help as well.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Please run down this guide and report back.

Replaced the TFI module. It has done the trick. Truck is running great now. It seems to be getting better gas mileage although not sure yet. The smell of gas is considerable less at the exhaust.

Thanks so much Doc!

Your Welcome hope that does it come again when needed.

My truck acts up from time to time. When it acts up i loose power,check engine light comes on,some times wont start and fuel pump keeps running. It has a 5.8L with dual tanks. I have pulled codes in the past,and replaced the O2 sensor,M.A.P sensor,fuel pump regulator,temp sensor ,T.P.S sensor. When truck runs right it runs fine...when acts up Has no power. It does not always act up seems to have a mind of its on regardless of temperature or length of time between drive cycles.

Usually the intermittent like this is the ignition module, If a fuel pump keeps running replace the relay in the under hood power distribution center. You need to get an OBD-1 code reader to see what the computer sees wrong when it isn't running right

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

I got a 1992 f-150 we replaced the stock 302 motor which had a 154 firing order with a H.O 302 motor that has a 137 firing order now the truck runs rough idles real bad runs very rich and top speed is about 60 mph at 2800 rpm ive replace all the sensors on the motor can you please help me

You may need to use a computer for a HO engine to make it run right.Is the chek engine light on? if so what codes is it throwing?

Thanks The code i've got are 41 25 23 33 21 I did put on the truck 302 induction system so all my wires an cable would line back up also the smog pump has been removed and this motor has not got mass air system on it thyank you Tim sheppard Williamsburg Va

what computer are you using.... ?

mustang computer

So this isnt just an engine swap, you took the entire harness and comp out of a mustang and put it in a truck?
Double check all grounds. th ecodes may not match up to your truck.. what year mustang?

no I just swapped motors pulled computer put truck induction on mustang motor and used truck wire harness 1988 motor

there is'nt any chance you could call 757 253 1429 is it ?

updated 2-5-09

Thanks for the help the codes i've got are 41 25 23 33 21 iv'e also removed the smog pump an put the truck induction system on the mustang 5.0 so all the wires and cables lineds up

Have you tried the trucks original computer?

yes

Did it act exactly the same? I just want to be sure, this comp is from a 92 truck, if so the codes are defined as follows
21- coolant sensor out of range
23-TPS out of range
25-Knock not sensed during dynamic response test
33- EGR not opening
41- No HEGO (o2 sensor) switching.

You should double check all grounds to be sure , most of the engine sensors share grounds, that may be why the TPS, Knock Sensor,EGR and Coolant sensor and o2 are having a problem

yes iv'e checked all gounds an replaced all sensors I was told that the comp has gone in limp mode and maybe the h. o motor comp won't work right because its out of a car not a truck tat maybe I should get a comp from a 5.8 which has the same firing order as the 5.0 HO motor Get it from the same year 1992 too tell you the truth i've about had with this truck ive spend around 450.00 on sensers and other elec parts tring to get it right an nothing seems to be working

I hear ya, for some reason Fords really dont like when you swap stuff around. Check theTPS and the Coolant sensor to see if they both have good ground and 1 of the wires on each sensor should be a 5 volt reference to the computer. Use a meter to test the continuity to ground on the wires.The ca/ truck thing may be accurate info as well, to verify this you would need the schematics for both computer plugs to compare them

i have a 1991 Ford F-150 Supercab, 5.8 EFI V8, E40D Auto Trans, dual tanks, 129,000 miles. I posted a question before, but I am still having problems with my truck. I have replaced the rear fuel pump, totally bypassed the front tank, lines and all, replaced the fuel pressure regulator, fuel pump relay, another relay in same area as fuel pump relay, changed the transmission filter and fluid, and even had codes pulled, of which at first it pulled 12 codes, shop cleared those, and redrove and pulled 18 more codes. the shop said all my codes related to a bad ground somewhere. i have checked all the grounds that I could find under the hood and along the frame. loosened them and cleaned them and retightened them. I'm still having problems with my truck not running properly. In drive it acts like it's cutting off and restarting itself, every so often the voltage will drop during this but not all the time. At idle, the truck just runs like it is misfiring/skipping. Now, if I drive the truck for more than 30-45 minutes there are strong exhaust fumes present and the truck won't restart for about 30 minutes if I cut it off. I'm to the point where I am thinking of starting to replace sensors one at a time, once a month, because I can't afford to do them all at once. That and the injectors. fuel system is up to par on pressure. all my vaccuum lines are connected properly and none are leaking. truck is costing me more to repair than to buy. Am I missing something simple?

When was the last tune up done.

i did a tune up back in october... its been less than 2000 miles since. my truck just keeps getting worse and worse. tune up didn't help anything by the way, and when i did the tune up i replaced all spark plugs gapped to specs, wires, cap and rotor. it ran a little better after i changed the oil, but only for about 20 miles or so. tune up was the first thing i suspected. i read another forum article and checked my MAP sensor, and i know its bad. truck idles much smoother with MAP sensor vaccuum detached but i don't know whether i should really run without it connected or not. i know catalytic converter isn't helping matters as its poorly clogged, but that is another $130 i don't have right now. i just spent $130 replacing fuel pump with brand new with no improvement. as i said, front tank is completely bypassed so i didn't replace both, just the rear. i'm going to replace MAP sensor and coolant temp. sensor in next 3 weeks and am hoping that helps some, but i still think i'm missing something simple.

well, guess what.. all along it was something simple. i changed out my MAP sensor and now the truck idles just fine. its amazing how something so simple can often be the last thing you check! i recommend that if anyone else is having similar ford issues like i was having, you check your MAP sensor first before spending more money than necessary. a MAP sensor runs about $50 for a truck like mine and takes about 5 minutes to change out.

Good job! The shop didn't zero in on the disconnected MAP sensor and flag that as a possible issue?

actually, there is still more wrong with it than just the MAP sensor, so now i am back to square one again. i plan on doing soething with the catalytic converter, and then valve cover gaskets and intake gasket. i'm planning on replacing most of my sensors after the catalytic converter is fixed. hopefully by then i can figure out what is wrong with the poor thing. besides the fact that its ford mind you. actually it has its good days and its bad days. today was a good day, tomorrow.. well we'll see.

Only a ford?! I'm offended! Ford's are the BOMB! :wink: (their trucks at least)

Actually my real baby is a cherry (almost :roll: ) 1970 Chevy CST/10 pickup. That's a real truck... with still plenty of power at 130mph.

actually i'll take a ford truck over any other truck. it's just this one particular truck has given me nothing but grief since i bought it. i've driven many ford trucks, most of them 450 or 550 diesel duallys, and all in excellent running condition. this one just has problems. but considering it is 17 years old and most everything in it is still factory stock, what can i expect. i just wish i could figure out what is wrong with the dang thing and get it fixed properly without having to spend more than what i paid for it. i finally took it to the shop for the exhaust system. i never realized that it had 2 catalytic converters and no muffler on it. well, that is getting fixed as we speak. once that is done, then i can concentrate on the valve cover gaskets and intake gaskets and idle air control valve, and go from there.

My first vehicle was a ford truck... a '72. Since then i've owned more fords than any other make, and more ford trucks for that matter. I've never had anything really go wrong with any of them.

The OBD1 system is pretty good. I think the weak part of the whole system is the various sensors that seem pretty fragile to me. They need a lot of attention. That and the little plastic vacuum hoses that ford used at that time. Those are cheezy and they crack so easily.

Other than that the actual mechanical components are more or less tried and true, the wiring seems to be well routed and protected. Good vehicles.

ok... so now i've gotten the exhaust fixed. my cats were fairly clogged, and my truck is running more consistent now. but it still has that irritating little loss of power hiccup that it has had since i got it. i changed out the idle air control valve, with no real noticeable change in performance. i'm still planning on doing the valve cover gaskets, but i'm beginning to wonder if there is a ground i have missed somewhere. or if something else might be causing a power loss. when driving, you can watch the rpms drop and jump back up, and sometimes the voltage will drop also, but not all the time. so what's the simplist thing i can check that i haven't looked into already? or did i just happen to get lucky in my unluckiness and get the one bad ford truck out of hundreds of good ones?

That's interesting. I remember a 1991 f150 having rpm surges on the highway. It turns out that the torque converter was kicking in and out causing the rpms to go up and down. How often does your truck do this? Is it in high gear, or does it do this all the time... in park at idle too?

it does the rpm thing all the time, park, drive, neutral, less so when you're running about 55-65 mph. i changed out the IACV (idle air control valve) and now the dang thing is sucking gas like a drunk sucks booze, and slam-shifts into gear. i'm going to put the old IACV back on and see if it changes that, but i think my truck is just haunted. unfortunately i can't afford to get another one right now, and i need to keep this one running.

A mal adjusted throttle position sensor will cause wierd shifts and bad fuel economy. At closed throttle it should read almost exactly 0.94 volts. Two or more decimal points either way will cause horrible driving conditions.

My [url=http://www.carpartswholesale.com/cpw/ford~f150_pickup~parts.html]ford f150[/url] is bad, is there an expert mechanic that can help? :(

Are you looking for someone to look at it and repair it, or are you looking for diagnostic advice?

When I start the truck cold it starts hard and runs rough until it warms up then it runs great.

what i would be doing is checking the engine temperature sensor, and record down the temperature of the air and the resistance value of the ect.

is it within specs?

check the IAT. they both should have very similar resistance values.

Truck starts and runs pretty good at idle, as soon as it warms up it starts running rough and dies. When you step on the gas it falls on its face and does nothing.

First, has your truck been tuned up lately? Air filter, plugs, wires, etc.? Check your fuel pressure under a load with the engine at operating temp. You may have a clogged screen at the pump or a clogged fuel filter. (Also water in the gas)

Also, sometimes when a coil goes bad, it will do so when the engine warms up and the underhood temps get high. You can check for this with a spark checker. But you want to warm the engine up, remove one wire at a time and use the spark check while reving the engine up to the point it wants to stall (if it stalls). Your spark should be a bright white/blue with a strong snap to it.

i think on these trucks it has 2 fuel pumps 1 in tank 1 on rail make sure both are working