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Doc Hoy

Engine runs rough at idle, idles too low

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Two posts in one day after about a four month absence?! I need to get back to work. :o(

My 2012 TC idles a little rough and idle appears (to me) to be too low (Looks like about 700 rpm.)

I am thinking that a coil pack may have failed or may be failing. Not familiar enough with these to know if a sick coil pack will cause these symptoms. Truck has been running this way for about a month and has not gotten any worse.

Some questions:

1. Is there a simple adjustment on idle? If so can you describe the process?

2. Are there any coil modules on the market which should be avoided for reasons of quality, compatibility, performance or such?

3. Am I barking up the wrong tree as regards coils and idle problems? (I do understand that there are probably a hundred things that could cause a rough, low idle.)

 

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Do you have access to a scanner? The idle is set by the PCM.

Edited by G B L

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If you do not have access to a scanner, you might be able to get some data and codes through the hidden menu on the dashboard. I found out about this trick when I owned a Focus mk1, and since a gen 1 TC is based on a Focus, I guess it should work. I have not tried it yet on my gen 2 TC, as I only just now found the procedure. Visit http://mr-fix.info/ for starters. There are probably other places on the internet that could be useful with regards to the procedure , including Focus forums. You may also have to look for a full list of DTC codes.

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I would change spark plugs first. It may just be one missing cylinder causing all this. My bike got new plugs last autumn and in spring one (V2) cylinder failed to fire at all, sounded like a bag of rocks in a bucket.

These things break prematurely and luckily cost next to nothing. The only tricky part is getting the new one in without screwing up the thread.

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I'm no mechanic so take this with a grain of salt.  Check the cheapest things first like the air filter and fuel filter then move up to more expensive fixes.  Spark plugs are a common fix and depending upon how old and how many miles are on the vehicle, spark plug wires too should be considered.  If your battery was low and you jump started the engine, sometimes rough idling and sometimes rough driving will occur.  It is supposed to self correct over time.  If it does not then look to other solutions.  Some of the people here are born with a nose for this stuff and as they continue to contribute a most likely solution will resonate.  I have grown to respect and trust many contributors here.  :worship:

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Is it only the idle? Do you notice the issue at other times?  Is the AC on?

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Wow.....This generated a  lot of response. Thanks y'all.

From the top

To GBL: Don't have access to a scanner but I think it is about time I buy one and get used to reading it. Any recommendation on the right unit to get would be welcomed. Additionally, if the PCM is supposed to be controlling the idle and the truck is idling at 600 to 700 RPMs, I am thinking about a whole set of new possibilities (Which I anticipated when I first noticed and tried to think through the problem.)

To Dandy: Went to the website and it looks very interesting. Was a little concerned by the "Warning". When I have more time, Ill read more about it.

To MRTN: Thanks for the push. I was thinking about getting a coil set that includes the plugs. I am a tightwad so I would likely go for the cheapest ones I could find (About 45.00), unless I get some warning from y'all about ones to avoid.

To Loafer: I was thinking to look at other general maintenance types of things when I swapped out the coils and plugs. The truck has just over 200,000 miles on it. I bought it last year for 4200.00 and have been driving it trouble free (including driving by my employees) so this truck owes me nothing. Can't recall jumping this truck. I own two of these things and I had to swap out the battery in one of them but I am pretty sure it was the other truck. It runs smooth. I agree with your assessment of the caliber of the people who post here. Impressive.

To GBL: The problem is not obvious at anything above and idle and does not seem to be peculiar to AC on or off status. I will pay closer attention tomorrow when I drive it. (If I can get the darned thing to myself.)

 

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Keep us posted if it is only the idle and nothing else ,it shouldn't be much

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13 hours ago, Doc Hoy said:

To Dandy: Went to the website and it looks very interesting. Was a little concerned by the "Warning". When I have more time, Ill read more about it.

I originally found out about this hack from other sources that did not include any warnings. I tried it on my 02 focus several times, because I thought I was a cool trick, but I also used it to see if there was any DTC codes (I don't remember what the reason was), and I used it while driving to keep an eye on the engine temperature when I had overheating issues due to malfunctioning fans once, and a defective thermostat another time. As far as I know, this hack only allows you to read data, not to modify it.

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23 hours ago, Doc Hoy said:

 I was thinking about getting a coil set that includes the plugs. I am a tightwad so I would likely go for the cheapest ones I could find (About 45.00), unless I get some warning from y'all about ones to avoid.

 

 

 

Some cars and engines are funny about spark plugs.  Weird, I know.  But guys into Honda swear that NGK is the way to go. Whereas with the F-Series trucks and Econoline vans, no aftermarket spark plugs will work as well as Ford Motorcraft.......or so the enthusiast claim.  On my F-150, I defied the conventional wisdom of following fan-boys on an internet forum.  Amazon.com had a ridiculous price on E3 plugs ($0.88), and to me, they work.  I start the truck, and it runs.  But you hear horror stories all the time about how someone installed "Car & Driver" brand, or something else just as inexpensive that they found at a dollar store, and their car having nothing but misfires.

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I completely agree. I have been working on cars all my life and found the same applies - use the factory spark plugs. So - Motorcraft in Fords, AC in GM products, NGK or NipponDenso in Japanese brands, Bosch in german makes, and so on. They are relatively cheap and will always work right. I'll never put another set of Champion spark plugs in any vehicle I own.

Edited by zalienz

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It makes you wonder.  When you go to an auto parts store, you see on every wall, tons of product that is sold at a lower price when compared to OEM.  Why would anyone want less than OEM quality parts?  I can't imagine downgrading my brakes.......let me save $4, and installed brakes that don't stop as well.  My dad always taught me to upgrade, and never downgrade.  If you can get something that worked better, you do it.  It's worth every extra penny to have better brakes.  

 

Do you save a few dollars on dating, and have the ugly girlfriend?

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24 minutes ago, Fifty150 said:

Do you save a few dollars on dating, and have the ugly girlfriend?

But she's got a kind heart!

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Back to this issue.

 

I have been driving this TC with the minor miss in the engine. It is now getting worse.

 

Took it to a mechanic who read codes implying misfire of cylinders two and three. Compression is even in all cylinders. I had already swapped out plugs and coils to no avail but he tried coils again. No help. He pulled the connectors to the injectors one at a time and found that disabling each injector creates a noticeable change in engine performance.

 

Injectors are not expensive. I am thinking I might get a set and replace them.

 

Have anyone done this and if so, how bad is the job.

 

I also need O2 sensors which I would do myself if the project is not too intense.

 

Anyone done this? If so, any tips?

 

Also....Is there an ignition module and if so, where in the heck is it?

Edited by Doc Hoy

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I have replaced O2 sensors on other vehicles and they can be tough to get out.  Probably from all the heat cycles.  However, once the old one is out, its fairly easy.

 

If EACH injector caused the idle to drop, thats probably not the cause.  If ONE of them made no difference then that would probably be the culprit.  Same with plugs.  Coil packs, however, can exhibit intermittent failure, so the rule-of-thumb may not apply unless it is totally dead.

 

Sorry I was not much help.  Let us know what you find. ☺️

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How does the tc run off idle when driving or excelleraing?

How do you know the o2 sensors are bad?

When you swapped the plugs were they replaced?

When the coils and plugs were changed was the tc scanned again?

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GBL,

 

"How does the tc run off idle when driving or accelerating?"

 

1. Engine smooths out but slightly lacking in power. It is driveable and most would not notice the diminished power but I do since I have another TC to compare it to.

2. When attempting to accelerate from stopped there is no response from the engine whatsoever until the accelerator peddle is nearly to the floor. (It is as though I am not even pressing the peddle.) Then the TC takes off with nearly proper acceleration. (Throttle position sensor? Ignition module? Vacuum?)

 

"How do you know the o2 sensors are bad?"

 

They are original in an engine with 220k miles and the code for O2 sensors comes up.

 

"When you swapped the plugs were they replaced?"

 

Yes. Replaced four plugs and four coils. Plugs were a little fouled but no improvement in performance at all.

 

"When the coils and plugs were changed was the tc scanned again?"

 

Yes. Misfire on two and three came up. It was not scanned before the plugs and coils had been replaced.

 

I need a manual that shows me where the O2 Sensors and ignition module are.

I am thinking about changing the Throttle position sensor unless someone tells me the symptoms are a long way from TPS.

I am thinking about a set of injectors. (I know that the indication I described implies injectors are okay, but I am wondering of two injectors could be partially fouled.) Injectors are not expensive and if they are easy to change, what the heck.

 

As advised by a previous responder, I am thinking of the cheap and easy things. The reason for that is that I am convinced this thing will wind up at the Ford dealership and I don't trust them. They will pester me about every little thing that a truck with 220k on it should have replaced without regard to whether or not it needs it. Then they will "Easter egg" the problem changing everything they can think of until they find the actual problem. They will charge me for the entire project including the things that had nothing  to do with the symptoms. Are you getting an impression that I have a low opinion of Dealerships? Hope no one is offended.

 

If I have to resort to a dealership I will prolly pay them to diagnose the problem and then either fix it myself or let someone I trust fix it.

 

 

 

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You need to find a tec with a good scanner  .  You can

Check the tps sensor by taking the boot off the throttle housing and have some one step on the gas key on engine off if the tps is working.  the throttle plate will move.  the o2 sensors are on the head pipe on either side of the converter. If you have an injector Issue swaping  the 2-3 injectors for the 1-4 injectors will move the missfire. 

A good scanner will give you a lot of running info. it will also allow you to drop cyl's 1 at a time to check the rpm drop. 

One more thing to consider is the converter could be papartially blocked with 220000 on the clock.

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GBL,

 

I am thinking about getting a scanner and getting good at using it myself. However in this case my mechanic, who has been in business successfully for at least 30 years used his scanner (Don't know which scanner it is but I now he doesn't buy junk and he paid a lot of money for it.) and it returned codes consistently that the engine was misfiring on cylinders 2 and 3.

 

1. Would a clogged converter impact the performance of only two cylinders?

2. Is there a gas additive which can be used to gradually clear out the converter?

3. Do you have a recommendation as to which scanner provide accurate and comprehensive error data?

 

It appears that swapping out the injectors is easy to do. I can get a set of injectors for about 50 bucks. I am thinking that with the miles on the truck a new set of injectors is not such a bad idea anyway.

 

I have two of these trucks. The other one is a 2011 with 190k. It runs fine. I wonder if I should start planning on having the same issue with that one when the mileage reaches 205k. (That was a joke but I am actually half serious about it.)

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The  scanner selection is very large , If your tech has the right one there are lots of test they can do.  I have not had the opportunity to scan a Gen 1 TC so I do not know what you can interact with.  You should be able to see the cyl  Misfire info for all the cylinders. I am pretty sure that the injector pulse information should be available also . 

I am currently using A Launch scan tool It has good coverage.  The Chinese documentation is, how do you say "Greek to Me"

Did you say you pulled the coil power one at a time?  If so what was the RPM Drop for the Cylinders? Do you remember the Compression readings?

Comparing the two TCs how much less power does the 2012 have would you guess ?

 If the Compression is the same for all the Cylinders,  The Injector swap for fifty bucks would make the Tune up complete .  If there is no difference then when you change the O2 sensors it will be easy to put a pressure gauge into the pre cat hole and see how much back pressure the converter is causing.

I have had several converters that are not bad, but are plugged up with carbon and dirt , They Rob power and fuel economy, and restrict the full load performance.

Keep the up dates coming.

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I pulled the pulse to the coils one at a time. Each one affects the engine about the same.

He pulled the pulse to the injectors one at a time. Each one affects the engine about the same.

Neither of us watched exactly how much the RPMs dropped but I would same something like 200. Keep in mind it is already idling at about 700 RPM. 

He measured compression and said it was "good". Didn't say exactly what. But reported that there is no problem with compression.

Comparing of one truck to the other I'd say that power from one is about 20% off on the problem truck.

Question: As regards the back pressure on the converter, what should it be? (What is normal?)

Question: Have you ever tried additives like "Cataclean"? Do they work? How long does it take? Can I do more harm than good?

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Bought an Ancel 410 code reader. Seems to compare well with competition. I am sure there are better ones out there. I'll let you know how I likes it.

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 This is a good section of an online source  AA1 Car

How Much Exhaust Backpressure is Too Much?

Backpressure readings at idle on most engines should generally be less than 1.5 psi (10 kPa). This will vary somewhat from one vehicle to another depending on the design of the exhaust system, the size of the pipes, how restrictive the converter, muffler and/or resonator is, and whether it is single or dual exhausts. We've seen some idle readings as high as 2.75 psi on a few vehicles, but for most 1.5 psi or less at idle is normal.

A partially restricted converter, muffler or pipe may flow enough exhaust at idle not to cause a problem, but chokes breathing at higher engine speeds. So to test this possibility, you need to rev and hold the engine at 2000 rpm. A "good" reading on most engines at 2000 rpm should be 3 psi (20 to 21 kPa) or less. Again, there may be some vehicles that will read a little higher that don't have a problem, but the reading should not be significantly higher.

Pay close attention to what the backpressure reading does while you are holding it at 2000 rpm. If it remains steady, chances are there is no restriction. But if the reading gradually increases, it means backpressure is building up and there may be a blockage.

If you want to rev the engine higher, say to 4000 rpm and hold it, the backpressure numbers will shoot up. Most stock exhaust systems will show backpressure readings from 4 to 8 psi (27 to 55 kPa), or even higher. As before, if the backpressure reading is unusually high or it continues to climb at a steady rpm, it usually means there is an abnormal restriction causing an unhealthy increase in backpressure.

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Got it.

 

What about Cataclean?

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