how do you determine if the fuel injectors are working like they should

[greaseyfingers]

I think either my fuel injectors, or ignition module are causing my 87 Ranger 4x4, 2.9 engine to run rough..

It runs rough either cold or warm..

I've replaced all the sensors, except for the ignition module.

I've put a 89 Ranger computer in, thus eliminating the EGR system.

Have installed new spark plugs and wires.

Replaced fuel filter, fuel pressure indicates 34 lbs. at idle and a little over 40 lbs. at higher RPM's.

I've got good spark, all electrical grounds are good, engine has good compression.

There aren't any vacuum leaks, anywhere.

I added three 12 ounce bottles of Techron to the gas tank and it's still running rough.

Can a ignition module cause it to run rough when it's cold or warm?

I've read in other posts that a ignition module usually fails when the engine is warm and the engine will stop and start again when it's cooled off.

The engine doesn't stop or anything when it's warm, it just runs rough either cold or warm, like I've already mentioned.

Anyone have any ideas to figure this out, as to what's causing this problem?

The only two things I haven't replaced, yet, are the fuel injectors or the ignition module?

The three 12 ounce bottles of Techron added to the gas tank, should clean up the engine's fuel injectors, if that was the problem. Shouldn't it?

 

[piotrsko]

best I can say is: if you got no codes, AND the timing advances when you increase RPM to no more than about 40 degrees, then the TFI is probably working. Injectors by themselves will lead to a miss or an overly rich condition. My problems were caused by an air in fuel problem and a clogged cat. check the tail pipe for deposits/color

 

[greaseyfingers]

best I can say is: if you got no codes, AND the timing advances when you increase RPM to no more than about 40 degrees, then the TFI is probably working. Injectors by themselves will lead to a miss or an overly rich condition. My problems were caused by an air in fuel problem and a clogged cat. check the tail pipe for deposits/color

It's got dual exhaust and no cat.

 

[low_five]

low compression in one cylinder will cause it to run bad. bent valve or other valve problem too. youve probaly checked the spark plugs, but one could be bad. might want to try a new set.

 

[low_five]

also, if the problem is one particular cylinder, get the engine up and idling, and pull one plug at a time. the one that causes the least difference is the bad cylinder. also, double and triple check that the plug wires are in the correct spots.

good luck.

 

[Spitfire1975]

... also, double and triple check that the plug wires are in the correct spots.

Could you clarify this a little? Always thought plug wires were pretty straight forward, but you have me wondering.

 

[UrbanRedneckKid]

Does "all the sensors" include the coolant temp sensor?
Some engines have 2, one for the gauge(1wire), one for the ecu(2-3wire).

If not, just change it, it's only 12 bucks, and usually causes issues like you have.

 

[greaseyfingers]

I just read this interesting information telling about troubleshooting a ford ignition module, on another website, which I am posting here for you to read, if you'd like to, as it says, a ford ignition module can also cause a bad miss on an erratic basis, which mine seems to be doing, unless it's my Ranger's fuel injectors, instead, causing this problem.

I think I'll change my Ranger's ignition module, today, weather permitting and see if that cure's my engine's rough running problem.

The information that I was referring to, as mentioned, regarding a ford ignition module is right below this sentence, if you're interested in reading it and seeing what you're thoughts are about this info.

Troubleshooting a Ford Ignition Module

Introduction
Ford used the TFI ignition module (thick film ignition) on vehicles from 1983 through the mid-1990s only. The vehicles that used this module had a conventional hall-effect distributor with a separate coil. The TFI module was located on a flat area on the base of the distributor. On some trucks and cars in the 1990s, the module was located on the radiator support housing within a heat sink. It contains solid state components encased in a thick clear electrolytic film. Its primary purpose is to send the hall-effect signal indicating top dead center on the number one cylinder to the electronic engine control (EEC-IV).

The computer then takes the signal and the pulse rate and determines the rpm. The computer sends a signal to the control module when to fire the coil. The control module automatically controls the dwell for sufficient saturation of the coil windings to give the proper spark duration given the rpm in real time without creating undue heat. It also monitors irregular or missed firing counts and will set a code if a failure is imminent.

However, this does not always work properly. There have been many problems with this system, stemming from heat saturation, cracking and a myriad of problems after a period of service.

Failure
The modules will fail once they have absorbed too much heat or cause other problems. When this happens the vehicle will stall and take a period of time for a successful restart, after the heat has dissipated. It can also cause a bad miss on an erratic basis.

Diagnosing the Module
If ignition problems are experienced, the first thing to do is to install a timing light and watch for an irregular spark. If there is, check the plugs. If the plugs are alright, the module should be replaced. They are not expensive, however, they require a small special tool to remove the torx screws in the module housing. If there was no misfire, but the vehicle is hard to start or stalls, the module should be inspected and replaced if found to be faulty.

The module should be removed and checked for cracking around the torx screw mounting surface. There should be a thick film of dielectric grease on the back metal side of the module. This layer of grease keeps the heat off of the module. If the module looks OK but the grease is depleted, it should be replaced and the module can be tried again by using the timing light for steady spark.

The PIP signal should also be checked. The top wire on the connector is used to check for PIP. Use a voltmeter and look for pulsing with the engine running. The pulsing means the wire from the computer to the ignition control module is good and the computer is working. If it is working, the module is bad. If no pulsing is noted, check the third terminal down for pulses to the computer. It would be wise to replace these modules every 30,000 miles as a preventative maintenance procedure considering the amount of failures and the relatively low cost versus the aggravation should a failure occur. The modules have never been modified so the new will only last as long as the old one.

 

[greaseyfingers]

Does "all the sensors" include the coolant temp sensor?
Some engines have 2, one for the gauge(1wire), one for the ecu(2-3wire).

If not, just change it, it's only 12 bucks, and usually causes issues like you have.

yes, I've already replaced the coolant temp sensor, along with all the other sensors on my Ranger, including the oxygen sensor, too.

I've pulled the plug wires off the distributor, one at a time, and it seems to be running about the same on all of the cylinders, but it's running rough and seems like it misses erraticly.

 

[UrbanRedneckKid]

Well then, If the TFI module is all that's left... just change it. Get one from your local store and if that fixes it, order an Accel one, and keep the other new one for a spare.

There is a way to test the injectors, but I would have no idea on where to find the test specs. You need a fuel pressure tester/gauge, and measure the pressure drop, with each injector individually.

Also, you did the fuel pressure check, but did you do a flow test?

 

[greaseyfingers]

Well then, If the TFI module is all that's left... just change it. Get one from your local store and if that fixes it, order an Accel one, and keep the other new one for a spare.

There is a way to test the injectors, but I would have no idea on where to find the test specs. You need a fuel pressure tester/gauge, and measure the pressure drop, with each injector individually.

Also, you did the fuel pressure check, but did you do a flow test?

How do you go about doing the fow test?

 

[UrbanRedneckKid]

How do you go about doing the fow test?

Well... I don't know what the spec is, but you put a hose on the test port on the fuel rail, run that hose into a container. Jump the fuel pump relay, and see how much(?spec) fuel comes out in so much time(?spec).

Simple test to perform, but you need the specifications for it.

 

[Spitfire1975]

It's got dual exhaust and no cat.

The truck wants a cat.

That being said, I was getting a miss and rough idle and replaced everything as well. The one thing that made the largest difference where the idle and miss was concerned was replacing the normal spark plugs with the double platinums and replacing the high pressure fuel pump.

 

[piotrsko]

fuel flow spec is 1/2 litre (.56) per minute flow @ 45 psi

from all data

and just FYI: on the 1 st gens, the TFI is installed with 5.5mm hex head screws needs a socket ground down to fit the hole.

 

[dangerbird92]

i have your fix

ok i traded my bronco II that had a shit brick of a 2.8 ford a 1989 ford ranger that ran ruff bad like what your sayin yours is so i checked everything spark gas everything i even compresion tested it it was all good so i figured i would start it up let it run an start pulling injetor wires i pulled the first one ran the same like shit so i pulled another one an it died so i pulled the injector an changed it an it turned out to be two injectors so i changed them an it fired right up no problem havent had a problem ever since you can pick up injectors at any junk yard that has rangers