Bad TFI ignition module?

88 XLT Ranger · Apr 13, 2018

I been trying to figure this issue out my 2.9l is a pain in the Azzz to start when cold. I have to put the throttle to the floor the starter spins until it starts real slow RPM's than picks up. Once it starts its rough like a miss once warmed up runs smoother. I get on the road 35-65mph its like its dropping a cylinder and picking it up off and on. Could this be the TFI? its stalls once in a while as well but fires right back up its a new Motorcraft I bought from Oreilly Auto Parts last year. I have my original Motorcraft TFI I had tested it passed good maybe put that back on?

I thought it was a plugged injector I added Red Line fuel system cleaner still the same. It feels like an ignition issue all the plugs look good no fouling all look to be firing good. I checked the fuel pressure its good no issues there

88 XLT Ranger · Apr 14, 2018

No Help? I thought this was the best place for help or ideas of that my solve the issue? I will figure this out myself I guess first change the TFI and test the ETC see if its bad. I did solve my last issue popping misfire as it was a bad intake lifter on number 3 cylinder. After changing $500 in parts I got pissed popped the valve covers off found number 3 cylinder intake rocker not moving thus lifter issue. I did the same this time around but all are good. I don't mean to sound bitter but I am sick of this pice of ----- Ford and its on going issues

I was thinking maybe someone had the same issue or an idea where to start. I don't have time to sit on my fingers waiting day's or weeks :icon_confused:

RonD · Apr 14, 2018

A fuel injected engine should NOT start if you press gas pedal to the floor and hold it there

All Fuel injection computers have a "Clear Flooded Engine" routine
Key on
RPMs at 0
TPS(throttle position sensor) above 4.5volts(gas pedal to the floor)
If these 3 things are correct then computer will shut off fuel injector pulses, for "Clear Flooded Engine" routine

If TPS voltage drops below 4.5v or RPMs go above 400 then computer will start injectors again

But while those 3 things are "true" engine will just crank.
I use this every morning to start my high mile 4.0l, lol, get oil pumped around engine before starting

If your MPG hasn't dropped recently then probably not a stuck open injector flooding engine.

But could be leaking Fuel Pressure Regulator(FPR), FPR has a vacuum line attached, remove it and check it for gasoline, shouldn't find any.

Next free test, cycle key on and off 3 times before trying to start engine.
This Primes the fuel system 3 times to build up any lost pressure.

1988 might still use a ballast resistor, but I don't think so.
But just to test run a jumper wire from battery positive to coil +, "hot wire" spark

Also check battery voltage, should be 12.3v or higher with key off
Under that will cause problems, old battery
Then test it while cranking engine, should stay above 9.8volts, if it gets lower than that then spark and computer can be marginal, so no start
Lower than 10volts can be starter motor drawing too many amps, or older battery cables or older battery

88 XLT Ranger · Apr 14, 2018

RonD said:
A fuel injected engine should NOT start if you press gas pedal to the floor and hold it there

All Fuel injection computers have a "Clear Flooded Engine" routine
Key on
RPMs at 0
TPS(throttle position sensor) above 4.5volts(gas pedal to the floor)
If these 3 things are correct then computer will shut off fuel injector pulses, for "Clear Flooded Engine" routine

If TPS voltage drops below 4.5v or RPMs go above 400 then computer will start injectors again

But while those 3 things are "true" engine will just crank.
I use this every morning to start my high mile 4.0l, lol, get oil pumped around engine before starting

If your MPG hasn't dropped recently then probably not a stuck open injector flooding engine.

But could be leaking Fuel Pressure Regulator(FPR), FPR has a vacuum line attached, remove it and check it for gasoline, shouldn't find any.

Next free test, cycle key on and off 3 times before trying to start engine.
This Primes the fuel system 3 times to build up any lost pressure.

1988 might still use a ballast resistor, but I don't think so.
But just to test run a jumper wire from battery positive to coil +, "hot wire" spark

Also check battery voltage, should be 12.3v or higher with key off
Under that will cause problems, old battery
Then test it while cranking engine, should stay above 9.8volts, if it gets lower than that then spark and computer can be marginal, so no start
Lower than 10volts can be starter motor drawing too many amps, or older battery cables or older battery

Ron thank you for helping I appreciate that very much. The way I have been starting this truck or the only way it will only start. I turn it over it tryes to start if I do it again it floods the engine. I seen it drip out the exhaust before the cats there clamped on. I now let it turn over it tryes to fire up I than put my foot to the floor it turns over a lot than it will start real slow RPM's than starts I let off quick as its full throttle. The truck turns over slow when cold once it fires up after 5 min warmed up it fires up quick on its own

I did check the FPR I even put a clear line in the vacume line to see if fuel is there I see none. I will check the battery again and do the cycle key as you say. I got a battery charger hook it up see if it fires up after cycle key

RonD · Apr 14, 2018

After engine is warmed up try using Clear Flooded Engine routine to see if you have leaking injectors.

There are only two ways gasoline can get into the engine, injectors or FPR Vacuum line

If engine fires with gas pedal to the floor then you have a leaking injector, FPRs been cleared.

You can find out which one by unhooking coil wire from distributor, so no start
Then crank engine over a few times with gas pedal to the floor
Now pull out the spark plugs
WET TIP spark plug has the leaking injector

88 XLT Ranger · Apr 14, 2018

RonD said:
After engine is warmed up try using Clear Flooded Engine routine to see if you have leaking injectors.

There are only two ways gasoline can get into the engine, injectors or FPR Vacuum line

If engine fires with gas pedal to the floor then you have a leaking injector, FPRs been cleared.

You can find out which one by unhooking coil wire from distributor, so no start
Then crank engine over a few times with gas pedal to the floor
Now pull out the spark plugs
WET TIP spark plug has the leaking injector

Thanks again Ron :icon_thumby:

The battery was 12.35 engine off cold I put the charger on it let it get to 15.75. I did the cycle key than the first try it almost fired up second time it fired up on its own. I need a stronger battery I got that Lucas stabilizer in it thick oil cold. I pulled the coil wire tuned it over a few time pulled the plugs. All looked good but number 3 cylinder wet its a new Napa injector I changed just last year. I put the plugs back in fired it up still running crappy RPM's jumping up and down. I noticed I forgot to put number 2 cylinder wire back on I put it back no change in pitch or running of the engine. I pulled the plug it was fouled. I put my new E3 spark plug in now it runs smooth no quick RPM change took it on the road power is back to normal. That Autolite Platnum plug was fireing off and on that is why it was getting power and losing it off and on

I had the plugs out a few times they alway's looked good kinda brownish on the electrode but dry. I tried Red Line fuel system cleaner it ran a little smoother maybe the new injector has something in it. Is there some other injector cleaner that might work and not distroy the cataletic converters?

RonD · Apr 15, 2018

Car battery at 15.75 volts is NOT a good thing, lol

After sitting overnight, 5+ hours, a new battery should be 12.8-13.0 volts
3 years old would be 12.5volt
5/6 years old 12.3volt and time to shop for battery sale

Fuel injectors have small screen filters in them.
Fuel filter will clean any debris out of the gasoline but the injector rails can get build up.
Injector cleaner can loose this up and cause it to clog the screens in the injectors.
Not saying thats whats happening, just saying it can happen if system has not been clean in a long time and you give it multiple treatments.

You can disable the coil on a cold engine
Then crank engine over a few times, do not touch the gas pedal
Then pull out spark plugs on one bank and have a look at the tips, all should be WET with fuel, equally WET, as you are running Batch Fire Injection in an '88
If you have one with a drier tip then that injector may be clogged

88 XLT Ranger · Apr 17, 2018

RonD said:
Car battery at 15.75 volts is NOT a good thing, lol

After sitting overnight, 5+ hours, a new battery should be 12.8-13.0 volts
3 years old would be 12.5volt
5/6 years old 12.3volt and time to shop for battery sale

Fuel injectors have small screen filters in them.
Fuel filter will clean any debris out of the gasoline but the injector rails can get build up.
Injector cleaner can loose this up and cause it to clog the screens in the injectors.
Not saying thats whats happening, just saying it can happen if system has not been clean in a long time and you give it multiple treatments.

You can disable the coil on a cold engine
Then crank engine over a few times, do not touch the gas pedal
Then pull out spark plugs on one bank and have a look at the tips, all should be WET with fuel, equally WET, as you are running Batch Fire Injection in an '88
If you have one with a drier tip then that injector may be clogged

Thank you for the info Ron

Its in the 50's cold temp here I had a hell of a time getting it started. I kept cleaning drying number 3 spark plug with my foot to the floor it finaly started. Would it work if I disconect the injector wire on number 3 just to get it started? It starts fine all day as long as the engine is warm. I got a set of fuel injectors from a 1989 3.8 V6 SC Cougar not sure if one of those can be used. I am kinda pissed that new Napa injector leaking I don't have the funds to buy another one yet. My poor starter is taking a beating

RonD · Apr 18, 2018

If an injector is leaking then it leaks 24/7, when ever there is fuel pressure, so doesn't need electric contact and disconnecting it wouldn't change anything.
You could test its wiring
With key on Red wire will have 12volts, other wire you would OHM to Ground, it should NOT be Low OHMs
Or if using a test light hook it to battery positive and then the "other" wire, not the Red one, it should not light up

You can check the wiring connector on the 3.8l injectors, if they match up then you could use one, assuming same length
The # rating shouldn't matter too much for 1 injector in a Batch Fire setup

88 XLT Ranger · Apr 18, 2018

RonD said:
If an injector is leaking then it leaks 24/7, when ever there is fuel pressure, so doesn't need electric contact and disconnecting it wouldn't change anything.
You could test its wiring
With key on Red wire will have 12volts, other wire you would OHM to Ground, it should NOT be Low OHMs
Or if using a test light hook it to battery positive and then the "other" wire, not the Red one, it should not light up

You can check the wiring connector on the 3.8l injectors, if they match up then you could use one, assuming same length
The # rating shouldn't matter too much for 1 injector in a Batch Fire setup

Ron

I got the idea to disconnect the FPR vacuum line let it warm up and do the clear flooded try. One my first start up cold before doing that I tuned it over wouldn't fire up. I did the clear flooded try it still wouldn't fire up. I let off the gas tried it again it fired up. I let it warm up disconnected the coil wire did the clear flooded try. I pulled number 3 plug its dry I did it twice plug still dry. I don't get this ordeal first its wet yesterday now dry. I did it once with the FPR vacuum line disconnected no change still dry. It still starts on the clear flooded way. It turns over a lot before firing maybe the throttle cable is stretched not shutting the injectors off all the way? it runs great its just this cold start up issue

RonD · Apr 18, 2018

You could do the "throttle cable mod", very easy fix, and take that off the table.

Doesn't read like there is a leaky injector now

88 XLT Ranger · Apr 19, 2018

RonD said:
You could do the "throttle cable mod", very easy fix, and take that off the table.

Doesn't read like there is a leaky injector now

Ron

Is there a link to the throttle cable mod? I got dial up internet service the search don't seam to want to open anything. I talked with an old guy here in town I mean old auto mechanic retired from 1970. He said the issue I had with the Autolite Platnum plug failing off and on in number 2 cylinder. His thought was weak firing on other cylindars thus hard to start. He said to buy a new set of regular Motorcraft spark plugs. He said Autolite quality is bad now day's. I do appreciate your time and effort in helping me on this issue

Bad TFI ignition module?

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