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2.9 Issues


softshellcrab

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I placed a note on the forum before about my issues. First of all, the Ranger runs, and it responds, but it has very little pull up hills, rarely can go over 60, even down hill. I took it to a Ford independent mechanic and asked him to look at it. He did the electronic interrogation and found numerous codes. He said he wanted to do a exhaust back pressure, but was afraid to disconnect the O2 sensor because of the extensive corrosion. He basically said he didn't want to deal with it and told me to find someone else.

At this point, what should I do. The options for mechanics around here are pretty slim and I'm not going to do it myself by replacing all the sensors that "could" be bad. What is your suggestions? The truck is in great shape and is worthy to be salvaged. I'm thinking of dropping a 4.0 in it and calling it a day. If I do get a 4.0, will I be able to use my existing tranny?

Thanks for your help.
 


RonD

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Sensors rarely fail.

I would invest $25 in a Vacuum gauge.
And then read here: http://www.gregsengine.com/using-a-vacuum-gauge.html

You could have the start of a clogged exhaust system, which is what the mechanic wanted to check.
Or you could just have low compression, worn rings or valves
Does it use oil or do you see puffs of blueish smoke when taking off after idling?

I think '91 2.9l still used MAP sensor, it is on the Firewall passenger side toward the center, it has a vacuum line that runs to the upper intake, find it and check that vacuum line/hose carefully, remove it and make sure it can hold a vacuum.
MAP is manifold absolute pressure, this sensor's data tells computer how much fuel to add via the injectors, MAP sensors rarely fail but vacuum hoses do get old and crack.

Next would be to spend $10 on a new fuel filter, usually you would notice a feeling of running out of gas under load or at higher RPMs if filter is getting clogged up.
A new fuel filter is not "throwing money at a problem", it the same as a new oil filter or air filter, general maintenance.
And I would look at the air cleaner and its housing, restricted air flow will cause high rpm issues and lack of power.
 
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Die.Fledermaus

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... He basically said he didn't want to deal with it and told me to find someone else.

At this point, what should I do. The options for mechanics around here are pretty slim and I'm not going to do it myself by replacing all the sensors that "could" be bad. What is your suggestions? The truck is in great shape and is worthy to be salvaged. I'm thinking of dropping a 4.0 in it and calling it a day. If I do get a 4.0, will I be able to use my existing tranny?

Thanks for your help.
He is actually correct and looking out for your best interest, it is a time suck. It is very hard to charge a reasonable flat rate for “a labor of love” or “rust and corrosion” delays. But he is honest upfront, a lot to be said about that.

You will have to be the one to do a majority of the work no matter if it is stock or not. Assuming you like it. Don't use reason if you like having a hobby, never keep the receipts, evade, evade, evade when cornered about what you spend.

If you like, keep it stock. If you really like it hot rod it. If it is not the thing for you, buy a soulless appliance every 7 years.

Yes tranny will work, but better to source the later stronger trannys 4.0 had from the factory when you do the swap.
 

softshellcrab

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Sensors rarely fail.

I would invest $25 in a Vacuum gauge.
And then read here: http://www.gregsengine.com/using-a-vacuum-gauge.html

You could have the start of a clogged exhaust system, which is what the mechanic wanted to check.
Or you could just have low compression, worn rings or valves
Does it use oil or do you see puffs of blueish smoke when taking off after idling?

I think '91 2.9l still used MAP sensor, it is on the Firewall passenger side toward the center, it has a vacuum line that runs to the upper intake, find it and check that vacuum line/hose carefully, remove it and make sure it can hold a vacuum.
MAP is manifold absolute pressure, this sensor's data tells computer how much fuel to add via the injectors, MAP sensors rarely fail but vacuum hoses do get old and crack.

Next would be to spend $10 on a new fuel filter, usually you would notice a feeling of running out of gas under load or at higher RPMs if filter is getting clogged up.
A new fuel filter is not "throwing money at a problem", it the same as a new oil filter or air filter, general maintenance.
And I would look at the air cleaner and its housing, restricted air flow will cause high rpm issues and lack of power.
Thanks for your info. It for sure needs a new exhaust-Cat, O2 sensor, while I'm at it. It does not burn or leak oil. The engine responds, the RPM's increase accordingly to the throttle input. It sucks on hills. I don't think that my engine has any serious issues other than the numerous codes it sets off when hooked up to the computer. The guy told me today to get the exhaust fixed and he'll continue to track down the code issues. Even he said there is nothing wrong mechanically, but he told me to do the exhaust and then he'll reset the codes and go from there.

Since the Ranger has never been touched mechanically since 1990, could you list the different sensors that could cause loss of HP. It is really worth keeping, not to mention it is my wife's dead father's old truck, it has sentimental value to the family.

Thanks again.
 

RonD

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What you have described, low power on hills and limited RPMs, really doesn't read like a sensor issue.

About the only sensor that comes close is the MAP sensor as mentioned above.
This sensor is used by the computer to calculate air flow into the engine, so computer can open the injectors the correct amount of time to get the 14:1 air/fuel mix.
BUT...........there would be stumbling and bucking complaints as well as low power complaints, if MAP sensor was failing.
A vacuum leak in the MAP hose is a different matter, check it.

'91 2.9l will also have a TFI spark system, these have 100% failure rate at this age, 24 years old, so some parts have already been replaced or will need to be.
BUT..........there would be other symptoms if spark or spark timing was at fault.
Good read here on TFI system: http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

And just for a statistic, over 60% of DIY sensor replacement was unneeded, sensors were good.
25% of professional mechanic replaced sensors were still good.

Here is a list of engine sensors on a '91 2.9l
TPS(throttle position sensor), tells computer where throttle plate(gas pedal) is, this allows faster acceleration response because of the lag time between "foot on the gas" and MAP sensor showing vacuum drop.
It has 3 wires:
Power 5volts
Signal back to computer, .8volt closed--4.6volts wide open
Ground
Very easy to test this sensor with $15 volt meter.
If this sensor only goes to 4volts then you will never have full throttle so less power.
Common issue on the Ranger is for the throttle cable to stretch a bit, so you don't ever get full throttle, easy to fix this issue, read here: http://www.therangerstation.com/Magazine/Summer06/throttlecablemod.htm
Yes, that easy, put a zap strap on cable end

IAT(intake air temp) sensor, colder air is denser than warmer air, so colder air needs slightly more fuel to be added to get the 14:1 air/fuel ratio and full power.
These hardly ever fail and your complaint would be poor MPG more than performance issue.

ECT(engine coolant temp) sensor, this is a TWO WIRE sensor only used by the computer(there is a ONE WIRE sender used by the dash temp gauge).
ECT tells computer when engine is cold and warmed up, when engine is cold computer runs it richer with a higher idle, Choke Mode, as ECT warms up idle will starts going down and computer will lean out fuel mix.
Complaint if this sensor fails is that engine runs better cold than warm or better warm than cold, but ECT sensor rarely fails and isn't the only reason for engine to run better cold or warm.

O2 sensor, this reads the OXYGEN in the exhaust, not the fuel
O2 sensor lasts from 100-200,000 miles, as O2 sensor starts to fail you will get a CEL with a code about O2 sensor "switching slowly".
O2 sensor tells computer oxygen content in exhaust, too much oxygen means misfire or not enough fuel was added so most of the oxygen wasn't burned, Lean.
Not enough oxygen means too much fuel was added so no oxygen remained, Rich
Look at tail pipe and listen to the engine.
Black smoke at tail pipe mean too rich, and VERY hot Cat converter
Pinging/knocking in engine means too lean

If you have an EGR system you will also have an EGR sensor that tells computer if EGR valve is open and by how much.
Failing EGR system will cause rough idle and loss of power at all RPMs, also pinging if EGR is not working at all.

That is it for engine sensors, on the '91 as said above you do have the TFI spark system, it has a sensor/pickup that tells computer the RPM and when to open injectors.
On newer engines the TFI sensor was replaced with CPS(cam position sensor) and CKP(crank position) sensor.

You then have engine Controls
IAC(idle air control) Valve, this is a computer controlled valve used to set idle, it allows more air(higher idle) or less air(lower idle) to pass by the throttle plate.
This can get dirty inside, and can be cleaned by removing it from the upper intake.
Complaint would be unstable idle, stalling at idle, idle not changing when cold or warm.

EGR modulator/solenoid, computer opens and closes this valve to send vacuum to EGR Valve to open it or close it.
 
Last edited:

softshellcrab

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You are amazing. You need to write a book. Thank you very much.
 

softshellcrab

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I don't know if I have a EGR sensor. I see on some of the part sites that a EGR valve "may" be on the 2.9 then I read in the forums that some 2.9's didn't have one. Where would a EGR valve be located? I went to CarQuest to get a PCV valve and they did not have a EGR sensor, he said it wasn't listed for that engine. So who knows?

I"m still waiting for the cat to be shipped.
 

RonD

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Most states follow the Federal emissions requirements, Calif. often had stricter requirements for vehicle emissions

EGR system is added for emissions requirements.
This means not all engines will have them even in the same model year and engine type.
California having the strictest emissions requirements means any vehicle originally sold in calif. may have an EGR system and the same vehicle sold in, say, Ohio may not.

Manufacturers base the cost of adding the EGR system to all vehicles that year or just Calif. vehicles by that years emission requirements.
It is also based on performance; to meet emission requirements, the computer/ignition may have to retard the spark timing to lower NOx if an EGR system is not used, this is less expensive than adding an EGR system, but lowers performance.

Over the years emission requirements have gotten stricter so many vehicles now have EGR systems no matter what state they are sold in.

So your '91 may or may not have an EGR system, that is strictly based on where it was first sold and the emission requirements of that year in that State.
If you still have the Vacuum Diagram on the upper Rad support it will show you if there is an EGR system because it used the engines vacuum lines to operate.
I think the door tag may also have Federal or Calif. also, but can't remember.
 
Last edited:

Mike Tonon

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86 and 87 2.9l's had an egr valve and a larger throttle body, 88 and later had no egr valve and a smaller throttle body.
 

softshellcrab

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What you have described, low power on hills and limited RPMs, really doesn't read like a sensor issue.


I finally located a vacuum gauge and did the first test, and it failed. The idle was pretty much fluctuating around 15-17. The quick throttle test: 0-20. It looks as if I need some rings.

My question is: what should I do, buy a long block off of Ebay or rebuild this one? A long block is going to set me back $1700 plus I have to get the core back to them. I'm leaning to a rebuild of this unit, If I can find a reputable mechanic.

Also, will i need to bore out the cylinder walls? If so, what is the next size up will I need to get for pistons?
 

RonD

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Low and especially jumping vacuum gauge doesn't always mean bad rings.

I would do a compression test first.
All spark plugs removed
Throttle propped open, i.e. put something on the gas pedal
Test each cylinder with at least 4 "compression hits", you will know
Write down results as you go
That's a dry test

Then redo the test but add a teaspoon of oil to each cylinder before testing, this is a wet test.
Write down the results

Wet test results have no meaning with out dry test first.
2.9l engine has 9.0:1 compression ratio, so at sea level you would expect 160 psi on compression test, new engine.
But a Compression test is not about high numbers, too many variables in DIY testing.
It is about "averages"
Look at the dry test results see if there is a very low cylinder, i.e. most are showing 155 but one is 120.

Now look at the wet test results and compare average with dry test results, if you get 140 dry and then 160 wet then yes your rings are an issue, if you get 150 dry and 155 wet then they are not.
ALL rings leak air, metal on metal doesn't seal well, it isn't suppose to, but it seals well enough.
Adding the oil to a cylinder will always produce higher numbers, unless you started with 0, lol, i.e. burnt valve.
What you are looking for is how much did the dry number go up in each cylinder.
A marked improvement means rings are worn.

If there is no marked improvement from dry to wet then rings are fine, but if your average wet test is below, say 140, then you could have a valve issue.

As far as a rebuild:
If you can pull the engine then I would call some machine shops in your area to get quotes.
While the actual rebuilding does take some time the bulk of the labor is in removing and reinstalling the engine, and that is just basic wrench work that most DIYers can do.
You can rent a u-haul truck(if you don't have a friend with a truck), and rent an engine hoist for a day for under $50.
Take the engine to rebuilder then do the same rental when it is done to put motor back in, so $100 to do $700 to $1,000 of shop mechanics labor.
And most repair shops don't do the rebuild in house, they send engine to machine shop and then add a percent(mark up) to that charge on your bill.


And no, unless a cylinder is scarred they are just honed(smoothed) and new rings are installed on the original pistons if they are in good condition.
 
Last edited:

kimcrwbr1

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Put your hand behind the exhaust pipe and have someone give it gas. The pressure coming out should increase with engine RPMs. If not take it to a muffeler shop and they will be able to tell you if it is cat or muffler. With the palm of your hand slap the muffler if it is full of catalist it probably needs both.
 

softshellcrab

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Thanks, that helps. I found a engine re builder in the area who does it all in house. I might take it down there and have them do all the testing. I can barely see most of the spark plugs from the top of the engine, getting underneath the engine is not my idea of having fun. I"m not even a good shadetree mechanic!
 

kimcrwbr1

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I prefer the smaller ma&pa mulleler shops, They will normally only change what is necessary but you should replace the O-2 sensor/s as well if the exhaust was restricted.
 

bryanshayden0310988

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2.9 adjustments

I have a 1989 Ford Ranger XLT 4x4 with a 2.9 liter V6 that has 386k miles on it. I've owned it for 2 years now with no problems with the engine. I've had problems with the transmission but that's not my problem lol. I'm not familiar with the 2.9 at all. I've owned a 4 cyl diesel and a 4 cyl gasser. I have a loud ticking especially when it revs at higher rpms. I heard all kinds of responses which Idk if they are true or not. I do know they are my rockers that are ticking. The question is the valve train fully adjustable so I can minimize the ticking from little to no noise?
 

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