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When to change ignition coils?

sidneyhop

Well-Known Member
Joined
January 21, 2008
Messages
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City, State
Orlando, Fl
Year, Model & Trim Level
2000 AWD Limited
Im getting lousy city gas mileage lately and considering doing some maintenance to get it back to normal. I used to avg around 17-18 and now its getting 12.5 mpg in the city. Hwy mileage is still the same around 20 ish.
Are changing the coil packs as a preventative maintenance necessary or do you just wait until they fail?
Im also encountering a hard start issue where Ill have to turn it over a lot more than normal before it starts. It runs ok once its started though.
Ive read the 02 sensors going bad are another cause of poor gas mileage.
The only code is a med fuel vapor leak.
Thanks!
 



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I've got 265,000+ miles on our '00 Mountaineer 5.0L on the original OE coil packs. It still gets the same fuel economy that it got when it only had 179,000 miles on it. 15-16 around town 21-22 hwy. My '01 Explorer 5.0L has 195,000 on it's original coil packs and gets the same MPG as the Mountaineer.

Some may argue, but I see no point in changing coil packs unless they're causing misfires. O2 sensors are a different matter. They're only supposed to last 120,000 miles and can have a big effect on fuel economy w/out ever setting the CEL. My test is to stick a finger in my tail pipe. If it comes out black and sooty (same for spark plugs) it's probably time to think about changing at least the upstream O2 sensors. The downstream O2 sensors have no effect on fuel economy. I haven't had a reason to replace the O2 sensors in any of my Explorers or Mountaineers to-date.

Some other things that can tank your fuel economy is a t-stat that's stuck open or a bad ECT sensor.
 






Some other things that can tank your fuel economy is a t-stat that's stuck open or a bad ECT sensor.

Ive never heard of the ECT causing poor fuel economy. Thanks for the tip. Ill look into that, hope its easier to change than the 02 sensors.
 






Sure enough, no sooty tailpipe so temporarily ruling out 02 sensor. Ill switch out the thermostat and sensor to see if that does the trick.
 






Inkeds-l1600_LI.jpg


Is location 1 where the ECT sensor lives or is it 2?
Thanks
 






I believe on the 5.0L V8's the ECT sensor is the one with 2 wires. The other one is the sender for the temp gauge, which should only have 1 wire on the 5.0L.
 






I'd check the fuel pressure also given the hard starting. Yours should be a good 60-65psi at all times.

Clean the IAC solenoid too, that affects idling the most but it sounds like a few things might do with some extra care. The O2's are good to change as maintenance, 125k would be a good point, so would be 100k, or 150k depending on how the fuel mileage is etc. How old are the plugs and plug wires?

I did those things with my 98 after I had it for six months, usually I do that kind of thing earlier on. The PCV valve is the only thing I haven't gotten to yet, that monster is hell to just touch, let alone R&R. I bought my truck with 158k, I'm approaching 219K three years later.
 






I'd check the fuel pressure also given the hard starting. Yours should be a good 60-65psi at all times.

Clean the IAC solenoid too, that affects idling the most but it sounds like a few things might do with some extra care. The O2's are good to change as maintenance, 125k would be a good point, so would be 100k, or 150k depending on how the fuel mileage is etc. How old are the plugs and plug wires?

I did those things with my 98 after I had it for six months, usually I do that kind of thing earlier on. The PCV valve is the only thing I haven't gotten to yet, that monster is hell to just touch, let alone R&R. I bought my truck with 158k, I'm approaching 219K three years later.
Wheres a good place to check the fuel PSI? I changed the pump about 8 years ago.
Its got 175k ish miles currently and never changed the 02 sensors. Plugs and wires around 3 years ago.
The idle is fine, no problems there. It just takes an extra couple beats to start about half the time. Other times it starts fine.
 






View attachment 168399

Is location 1 where the ECT sensor lives or is it 2?
Thanks
This is for future reference in case anybody is looking for the ECT location. 5.0 v8 location (1) has the 2 wires and is where its at on my vehicle. Its closest to the thermostat.
 






Im getting lousy city gas mileage lately, I'm also encountering a hard start issue where Ill have to turn it over a lot more than normal before it starts. It runs ok once its started though. Thanks!

@sidneyhop,

Just saying - ever replace the Crankshaft Position Sensor?

It's extremely easy to get to and replace; (2) bolts and It's located in a high heat, water, road grime, high vibration area (next to your crank pulley)...

With the overall mileage you have on your Ex - it wouldn't hurt to replace it - some of your symptoms sound like it could be either the problem or part of the problem.

200,000 Miles is about all you can expect to get out of them before they start showing their age.

Standard Motor Products makes a great aftermarket one that has a super magnet on it, compared to the costly OEM Ford one.

$18.30 at Rock Auto - PC325 = Pretty reasonably priced for all it does in the hierarchy of ignition parts you might be throwing at your Ex...

LINK: https://www.rockauto.com/en/catalog...2462,ignition,crankshaft+position+sensor,7196

PC325photo%20primary__ra_p.jpg



Good luck and as always, Your Mileage May Vary...

P.S. How's that gas filter doin'???
 






P.S. How's that gas filter doin'???
Thanks for the tip on the cps.
Gas filter changed about 4 months ago trying to troubleshoot this problem. Didnt seem to have an effect.
 






To check fuel pressure, there is a port on the passenger side fuel rail. It looks like a tire valve and should have a tire valve-style plastic cap on it. You can use a fuel pressure tester or even a tire gauge (the round style gauge work best).

As far as your crank position sensor - never hurts to clean crud off of stuff, but it the CPS isn't working the engine will not run. Period. It's a Hall-effect style sensor with no moving parts. It has a weather-tight electrical connector so there shouldn't be any water getting in there.
 






Thanks for the tip on the cps.
Gas filter changed about 4 months ago trying to troubleshoot this problem. Didnt seem to have an effect.

@sidneyhop -

No problem - just asking the obvious since I saw no mention of the gas filter. Quite often the $15 Gas Filter is left out of the process, more than likely due to it's beer can size that gives the impression "how can that be clogged"?

So - back in December, out of the blue, my Ex started experiencing some lousy city gas mileage issues - and I take the same route every day. Additionally, just as you are experiencing, my Ex wasn't starting instantly when I cranked the key. Both problems occurred at the same time so I knew something was up.

Looked at the basics; My situation at the time was that the Ex had a Replacement Motorcraft Coil, Motorcraft Wires, and Double Platinum Champion Plugs and all parts had less than 10,000 miles on them. Also - no issues with the Camshaft Position Sensor making "squeaking" noise (Distributor Type Part located at the back of the engine on the 4.0 OHV). Less than year old brand new TYC fuel pump from Rock Auto and Motorcraft Fuel Filter - both replaced at the same time. Fuel Injectors are cleaned every 6,000 Miles with my pressurized fuel injector cleaner that hooks up to my Ex's fuel rail. IAC Valve & MAF Sensor are cleaned at every 3,000 Mile Full Synthetic Oil Change. That ruled out all of those parts and subsystems. So I was left with the factory original Crankshaft Position Sensor...

So, I cleaned & inspected the factory original Crankshaft Position Sensor that had over 205,000 miles on it, drove it for two weeks, the two problems that I was experiencing remained the same. Then a third problem cropped up. On two separate days, on the same route I drive everyday to work every day, on a steep grade I take in 3rd gear, my Ex coughed out a single slight misfire (with no check engine light afterwards). That sealed the deal for me...

Bit the bullet (lol), and handed over $20 to Rock Auto, to replace my factory Crankshaft Position Sensor with the Standard Motor Products offering. First thing I noticed when swapping out the factory original was that the new replacement's magnet was like a "super magnet" compared to the factory original.

After replacement - and all 3 problems cleared up instantly. Ex is back to starting on 1/2 to 1 revolution, City gas mileage back to normal (16 mpg on winter blend), and no more slight misfire on my daily driven steep grade. Additionally, the engine is slightly smoother at idle...

Here's a 5% off discount code for Rock Auto if you decide to pull the trigger ;-)

5% Discount Code: 1191391E850C2F
Expires: April 23, 2019

Please enter this code in the ‘How Did You Hear about Us’ box to receive the discount. Please enter ONLY the discount code



Hope that helps and as always, Your Mileage May Vary! ;-)
 






To check fuel pressure, there is a port on the passenger side fuel rail. It looks like a tire valve and should have a tire valve-style plastic cap on it. You can use a fuel pressure tester or even a tire gauge (the round style gauge work best).
I cant seem to locate the valve. Anyone have a pic they can post of where its at?
Thanks!
BTW it was not the CPS. Waiting on the ECT sensor to be delivered to try that.
 






The only code is a med fuel vapor leak.
Thanks!
I don't understand chasing other things until what you already know is an issue is fixed?

If this code is keeping the ECM in open loop mode, that might explain your low fuel economy. It's probably a vac leak, making it lean, then ECM tries to compensate. Hook up a scan tool capable of live data and (engine on) look at the long term fuel trims.

Hunting down a leak can be less than fun, but you might start with very simple things like making sure the gas cap is on tight and sealing good.
 






I don't understand chasing other things until what you already know is an issue is fixed?

If this code is keeping the ECM in open loop mode, that might explain your low fuel economy. It's probably a vac leak, making it lean, then ECM tries to compensate. Hook up a scan tool capable of live data and (engine on) look at the long term fuel trims.

Hunting down a leak can be less than fun, but you might start with very simple things like making sure the gas cap is on tight and sealing good.
Yes, I agree. I did try and track it down for a while but didnt have any luck, although I didnt have access to a live data scan tool.
-changed gas cap and hose going to the gas tank from the cap.
-changed fuel filter
-cleaned carbon filter under the spare tire.
-changed the other vapor thing under the battery.
-just changed the CPS and ECT
 






I didn't want to start another thread but can't find the same symptoms I'm experiencing.

Engine starts quickly, runs fine until shifting into OD at 40mph and then the engine stumbles. If I let off of the throttle it stops stumbling. If I give it more throttle or keep it in 3rd gear it is less likely to stumble. Idles fine. No CEL.
 






I didn't want to start another thread but can't find the same symptoms I'm experiencing.

Engine starts quickly, runs fine until shifting into OD at 40mph and then the engine stumbles. If I let off of the throttle it stops stumbling. If I give it more throttle or keep it in 3rd gear it is less likely to stumble. Idles fine. No CEL.

When's the last time spark plugs and wires were changed?
 






When's the last time spark plugs and wires were changed?

Unsure, I haven't since I bought it 2 years ago.

I have a new set of Motorcraft SP-432 plugs. Are the Motorcraft wires still the ones to go with? WR-6034?
 



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Can't go wrong with Motorcarft plugs and wires, but they're expensive. I used Autolite double platinum plugs and Denso wires on my last two 5.0L tune ups (from RockAuto). Autolite is offering a $2 rebate per spark plug through the end of 2019. You can also get an additional 5% off from RA by entering a coupon code in the "where did you hear about us" box at checkout. I believe this RA discount code is currently valid 12232161793979041
 






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