Ford 2.3L I4 SFI (89 Mustang LX)- help!

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Gah, I was halfway through typing this and the net crapped out on me.

Hey all. I got a problem here that's stumped me, but I;ve narrowed it down as much as I can. Hopefully, as it has been in the past, I can call upon the collective wisdom of the forum to point me in the right direction. Without further ado, on to the problem.

1989 Ford Mustang LX Convertible
2.3L 4 sylinder SFI engine (140)
A4LD Tranny (Automatic with overdrive)

Symptoms: Car was being driven to work. About 7 miles into the drive, I noticed the car start to run really rough, and upon turning into a parking lot and stopping, it died. Takes a bit of cranking to start, and required constant gas pedal action to stay alive. Nothing was done differently or changed before this. (Of course not, that would have made this one easy. *groan*)

Work done:
New spark plugs, wires, distributor cap and rotor. Used boot grease (silicone dilectric), anti-sieze, the whole nine yards of textbook plug maintenence.

Father adjusted the choke so I didn't have to keep giving it gas to idle.
* Noticed soot coming out tailpipe.

Replaced dryrotted hose to MAP sensor

Noticed timing was off a bit.
Timing fixed and new belt installed. Checked with a light, everything's spot on, exactly where it should be.

Replaced worn (cracked) serpentine belt. (Belt for Water pump, alternator, etc.)

Replaced fuel filter.

Each thing seemed to improve the problem by a fraction, but it's still very there. I can stand on the gas pedal and there's extremely little power to it. The car no longer dies on idle or while shifting gears.

Examining the spark plugs, it seems cylinders 1 and 4 are running extremely lean (i.e. no fuel) and 2 + 3 are getting fuel, perhaps even running rich. After talking it over with a couple of people, the idea is that it may be rust in the fuel rail, clogging it and perhaps the fuel injectors as well.

Now it's your turn. Ideas?

Any help is greatly appreciated, and if you require any more information, don't be afraid to ask. I might be able to get pics and/or audio up. Perhaps video if I feel saucy. Whatever would help the most.

posted by  digital_shad0w

lets look at a few things first

1. Is the ECM throwing trouble codes?
2. Timing marks aligned @ #1 cylinder set @ TDC before belt replacemet (should be OK if car was running well for 1st 7 miles or so)
3. All vacume hoses installed and in good shape
4. Vacume leaks @ fuel injector o-rings, intake manifold or throttle body?
5. Fuel filter installed with flow arrow pointed toward engine?

A noid light can be used to determine if the fuel injectors are getting the signal to fire from the ECM

If the first few items or so are good, I would install a test gage @ the test port on the fuel rail and check fuel pressure (Key-on, engine off should be on most cars with multi - port injection 35 psig-45 psig., Key on, engine running should be 30 psig- 40 psig, key on, engine running, vacume hose disconnected from regulator should be 35-45 psig) What you are trying to find is a weak fuel pump, a blocked fuel line

posted by  tbaxleyjr

There's no check engine light (never has been, kind of wierd.). Should I try hooking a voltimeter up and seeing if there are any signals and my light just won't come on?

Timing marks are good.

Hopefully tomorrow I'll hook up a fuel rail test gauge. I'm hoping it's the fuel pump or the lines, I really don't feel like trying to hunt down a fuel rail and (possibly) injectors :banghead:

Thanks for the help.

posted by  digital_shad0w

I have one thing to suggest: Oxygen Sensor. It sounds a lot like it.

posted by  DodgeRida67

That reminds me, my brother in law pointed this out to me, but I'm not sure if it's true. He had a mustang in the same year range, and he unplugged the oxygen sensor. Nothing changed. He said the car should have died as soon as he yanked it. I don't know much about sensors, does this sound right?

posted by  digital_shad0w

The Oxygen Sensor (OS) detects the air/fuel ratio in the exhaust so it can be adjusted. Probably is why you saw black coming out your tailpipe. I guess you ment black smoke?

posted by  DodgeRida67

NO, it doesn't. Your left rear tire should have gone flat,also. :doh:

posted by  lectroid

No smoke, but after it's been running for a little bit, you can look on the ground under the tailpipe and there's a pretty clear circle of black residue. I'm at work right now, but when i get home I'll try to get some pics of it to make things clearer.

posted by  digital_shad0w

I know what you mean now. What that is, is, the carbon "soot" in the exhaust system washing out from the steam and water when an engine is cold and warming up.

posted by  DodgeRida67

couldnt hurt to go ahead and interrogate the ECM anyway and see what it has to tell you

O2 sensors and coolant temp sensors cause screwy things when they malfunction

posted by  tbaxleyjr

Alright guys, I got some trouble codes for you to digest.

KOEO: 23 (23 (or): Closed throttle TP (Throttle Position) sensor voltage out of range. Suspect TP sensor.")

Continuous: None

KOER: 23 (23 (or): Closed throttle TP (Throttle Position) sensor voltage out of range. Suspect TP sensor." )
13 (13 (r): PCM could not lower idle speed below normal idle during KOER low rpm idle check. Suspect Idle Bypass valve problems) Also, from haynes manual: Normal Idle not within specified range.

I haven't done a cylinder balance test yet, I plan to do that tomorrow.

Your turn. Any ideas? Any way to check the TP sensor or test the idle bypass valve?

Thanks in advance, guys. Lifesavers! :clap:

posted by  digital_shad0w

A bad TPS can cause a car to die.

One thing has me very curious.


posted by  DodgeRida67

The TPS provides feed back to the ECM concerning how much the throttle is open and how fast are you opening it. This is done by varying the voltage back to the ECM. The ECM uses it as an input for fuel/air mixture control as well as ignition system spark advance control

The ECM sends the TPS a reference voltage of 5 volts. If the car is @ idle, another wire will return a voltage signal 0f between 0.5 volts and 1.0 volts. Wide open throttle should provide a signal back to the ECM of between 4.0 and 5 Volts. These voltages can be checked by finding the reference wire, the signal wire and ground wire and backprobing. This link has a picture of the connector (signal return is also called ground) The sensor resistance between ground and TP can be checked with the connector disconnected. fully closed, the sensor will have a resistance of somewhere around 1 ohm. wide open throttle the resistance will be somewhere between 3 and 4 ohms. The resistance will vary smoothly from closed to open as the the throttle is slowly opened (you are looking for a worn or dead spot in the sensor's potentiometer. This link to Autozone has a good picture of the connector and which leads to backprobe and check

Your car probably has an EEC-IV Engine Management System and TFI distributor, I doubt you will be able to verify if timing is advancing exactly 20 deg. since you probably don't have easily accesable timing marks for a timing light. You can paint a mark on the crankshaft pulley and another stationary and see if the timing moves during the timing test

If you end up replacing the TPS, Ford used Loctite rather liberally on the screw threads and the small phillips screws may be a pain in the butt to get out.

Take the old part with you when buying a new one - there are three different ones listed in the various parts catalogs for this car and engine

This code, ran KOEO must be cleared up before running KOER

This is fun but we are still hunting for a problem. The only way to find it is through the process of elimination, one step at a time

posted by  tbaxleyjr

another minor comment - the 1989 Ford 2.3 L engine probably does not have a mechanical choke per say - it is a sequential fuel injected engine. The car also has an idle air control valve which regulates the idle speed based on input to the ECM

posted by  tbaxleyjr

Thanks a lot. I did a KOER test as well and an extra code was let out. I edited my previous post to reflect the results.

posted by  digital_shad0w

Hehe, i figured someone would question that. I had a friend who's intimately familiar with timing adjust my timing and replace the belt. He had his own timing light, which was used at that time. This is the next day, and I don't have a timing light myself to play with.

Sorry for the confusion.

posted by  digital_shad0w

I am glad yours still had timing marks. My 94 Areostar with a 3.0L had a port to pickup a magnetic pulse from crankshaft position sensor and could not use an inductive or anyother light.

To test, backprobe TPS electrical connection and verify voltages. Disconnect sensor and check its resistance (previousm post) use a digital meter to avoid frying computer parts or the ECM

The only tests you can do to the Idle air valve is to backprobe the connector and make sure the ECM is sending about 10.5 volts Key on, Engine OFF. Otherwise, pull the valve from the car and make sure the thing is not full of carbon. It is sometimes possible to adjust the curb idle speed on some of these IAC valves (your haynes book Chapter 4 will tell you how to adjust using a feeler gage if possible), others such the one on my Crown Victoria are not adjustable. A clogged idle air valve is a common problem

Based on the age of the car, and if you have the money, you would probably be better off replacing both the Throttle Position Sensor (about $40) and the IAC or idle air valve (about $60)

The Idle air valve will not cause the car to die but it will make it a pain in the butt to restart and cause idleing problems since @ idle the throttle plate is closed and this valve is the only way the engine gets air.

posted by  tbaxleyjr

I know first-hand what he's talking about. My car has needed a bunch of sensors in the past month. Each one has caused what I thought could have been big trouble. :banghead:
For instance, the Oxygen sensor made my car shoot black smoke and the engine would rattle and shake when I hit the gas. :evil:
Also, the Coolant temp sensor is also going bad. It causes the car to stall after idling cold for less than 5 mins. :banghead:

posted by  93GrandAm

As far as the IAC goes, you can also, with it disconnected, measure between both pins of the IAC with VOM for a resistance of 6 to 13 ohms= good. Check from each pin to the metal housing for a reading of more than 10k ohms= good. If these aren't within rang it's bad

posted by  lectroid

I finally took it to a dealership to get it checked out. It turns out the cylinders that were running lean were getting about 30 or so psi (compression). That seems to be the problem, but it could be almost anything. Any ideas what would normally cause this?

posted by  digital_shad0w

30PSI compression............ :doh: :doh: :doh: :doh:

posted by  DodgeRida67

Yeah, I mean what's most likely to cause this? Keep in mind that it's cylinders 1 and 4. Head gasket? Valves? Demons posessing the block?
[EDIT: This is bad information. Keep reading for correction.]

posted by  digital_shad0w

What's the compression in cylinders 2 & 3?

posted by  DodgeRida67

something sounds a little goofy here since this car probably would not run at all with 50% of the cylinders running that low (of course the first post says it doesn't)

are you sure 1 and 4 read 30 psig compression? Was this a compression test done with all plugs removed and the throttle body blocked open using a pressure gage one at a time in the spark plug hole? If so, were looking @ possible serious stuff here such as head gasket or something like that.

If this was a true compression test, was a leak down test performed too?

A lean running engine @ cylinders 1 and 4 usually indicates serious vacume leaks @ the intake, throttle body, or fuel injector o-rings although other problems may be there.

Im with DodgeRida67 on this one. Lets see the figures for each cylinder.

posted by  tbaxleyjr

Hey guys,

Sorry for the brief hiatus. Cylinder compression is as follows:
1 : 160#
2: 35#
3: 30#
4: 155#

"Head gasket blown between cylinders" says the dealer's report.

On a related note, What parts need to be replaced when replacing a head gasket? I see things like shims, head bolt sets, etc. Is there anything else that would be a good idea to check out or change when the gasket's getting replaced?

Parts from Advance/Discount Auto Parts are as follows:

Head Gasket ( ESULTS&MfrCode=FHP&MfrPartNumber=1035&PartType=100&PTSet=A)
Head Set (?) ( ESULTS&MfrCode=FEL&MfrPartNumber=HS8993PT5&PartType=101&PTSet=A)
Head Bolt Sets ( =Head%20Bolt%20Set)
HeadSaver Head Gasket Spacer Shim (?) ( ESULTS&MfrCode=FEL&MfrPartNumber=8471SP&PartType=100&PTSet=A)

They do have another head gasket that's 13 dollars, but I'd rather drop the extra 40 and not have to do this again. Check out the links above, and if you can offer any information, please do. I won't be doing this myself (obviously, I'd rather have someone a bit more familiar with engines crack mine open ;)) but i'll be watching it, hopefully learn a few things.

Thanks for all your help once again!

posted by  digital_shad0w

I'll buy in now on a blown head gasket between 2 and 3 cylinders.

Don't know specifics about a ford 2.3L but know the valve cover and intake manifold will have to be removed. The timing cover will need to be removed as well. Gaskets will be required for covers which were removed. Head bolts on most cars are used once and thrown away if loosened or removed since some of the torque specifications elongate the bolt so close to the yeild point is is not wise to re-tighten them

Since the timing cover will be off of the car, you may want to consider a timing belt and water pump while the engine is torn apart anyway

posted by  tbaxleyjr

Dont forget exhaust manifolds. :smoke:

posted by  DodgeRida67

I am glad you remembered - I forgot

posted by  tbaxleyjr

did u check the cam to see if the lobes were wore down?

posted by  farmeracing2005

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