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Old 06-14-2010, 09:47 AM   #1
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Check Engine Light Problem!

My Check Engine Light has come on again and the Hex Code is 43 (Multiple Cylinder or Single Cylinder Misfire). This has happened a few times before and once I found my Ignition Wires were breaking down and arcing to the block. Fixed that up and nothing happened again until yesterday...Any suggestions for a fix? The plugs, cap and rotor are less than a year or so old and I put new wires on in October or November. If anything, I'm going to replace the plugs, cap and rotor along with the pick-up under the cap on the distributor and the ignition coil when I change the oil next week.

Appreciate any kind of help! Thanks

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Old 06-14-2010, 09:50 AM   #2
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take visual inspection of plugs...are they fouled up?

What yr jeep? 4.0L?

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Old 06-14-2010, 10:13 AM   #3
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did it get wet in there???

x2 on new plugs to be sure they're not fouling.
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Old 06-14-2010, 10:23 AM   #4
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1997 Jeep Wrangler Sahara 4.0L....Plugs might be fouled, but I figured it would do it more often. A detail I forgot is that it only does this when I'm on a highway trip, when I'm driving for awhile at speed (70mph for 30+ minutes)
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Old 06-14-2010, 10:43 AM   #5
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"""""it only does this when I'm on a highway trip, when I'm driving for awhile at speed (70mph for 30+ minutes) """""

Sounds more like they are overheating and breaking down, rather than fouling.

Are they the correct plugs that the designers intend for it to use - called out on the underhood label - or are they aftermarket trash?

Just because a plug works in a Yugo doesn't mean it's good in a Jeep.
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Old 06-14-2010, 10:48 AM   #6
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They're double platinum Champion plugs...98% about their correctness becasue I went round and round with a guy about it and we're pretty sure they are the right ones because they were a replacement/upgrade for the plugs the book called for
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Old 06-14-2010, 10:58 AM   #7
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I wonder if you had gotten' some bum gas somewhere... How long has it been doing it? More than a whole tank of gas?
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Old 06-14-2010, 11:07 AM   #8
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Much longer than a tank of gas....it been on and off for about a year now. I've just been avoiding the highway trips and it's perfectly fine. It's just the little things it's been doing to me that makes me want to sell her for a newer Jeep...
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Old 06-14-2010, 11:09 AM   #9
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So you tried to find an aftermarket substitute, but they didn't have it, so you got a substitute for the substitute?

"The book" - Jeeps factory service manual? Or a parts house computer? Parts house computers combine part numbers because they are similar and fit the hole. They do that trying to cut down on inventory - at your expense.

The only thing you can believe is the underhood label - and it doesn't say plat anythings. Plats don't work well unless the head was designed for them.

But then, maybe the ex onion slicer at Autochina does know more than the designing engineers do.
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Old 06-14-2010, 11:09 AM   #10
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Can you feel it stumble/miss when @ highway speeds?

if its heat related, it may be the coil. (its been a long time since I've worked on a car w/ a distributor....) but I do remember that coil/ coilpacks will start causing issues with heat.

IIRC, dbl plat plugs are for the distributor-less system. I used to always run Copper for distributor systems...Always had hell w/ Plat plugs fouling...IMO its the ignition system that must be designed for platinum plugs vs the head being designed for them.
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Old 06-14-2010, 11:19 AM   #11
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-No stumble/miss or anything, light just comes on....Jeeps got 132k miles on it with original coil so I'm gonna replace that just because.
-The parts book along with our cross-reference book say the plugs I have are ones for my engine.
-This is news on plug type...I work in an auto shop and we've just always done life expectancy for plats and dbl. pats and so on..never knew it mattered on the ignition system type...I'll probably pick up some good Copper plugs along with the other parts to put on and get her running right again
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Old 06-14-2010, 11:30 AM   #12
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Quote:
Originally Posted by Brad[LK1] View Post
-No stumble/miss or anything, light just comes on....Jeeps got 132k miles on it with original coil so I'm gonna replace that just because.
-The parts book along with our cross-reference book say the plugs I have are ones for my engine.
-This is news on plug type...I work in an auto shop and we've just always done life expectancy for plats and dbl. pats and so on..never knew it mattered on the ignition system type...I'll probably pick up some good Copper plugs along with the other parts to put on and get her running right again
I'd try the plugs first, and then the coil if you can get one cheap and the plugs doesn't fix the issue. I'm not a fan of throwing parts at a problem...but the plugs are a definite cause of many issues on Jeeps in particular...
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Old 06-14-2010, 01:11 PM   #13
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Plats or other stuff does not depend on the ignition type! It depends on the placement and the turbulence in the head! The thin little center electrode isn't carrying heat away fast enough. Overheat the cylinders long enough it'll burn nice holes in your pistons. Then a CEL won't be a problem.

The ignition only provides the spark to get the fire started.

The computer is detecting a misfire and is telling you, whether you feel it or not.

Look at it with a scope - you can spot a plat - it looks like a real plug that's fouled.

I guess it's too much trouble to look at the underhood label? The standard plugs are cheap.

Does the underhood label say copper? If you want no more trouble, use the exact numbers on the decal! Clear the codes and enjoy.
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Old 06-14-2010, 02:30 PM   #14
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Under hood label it is! thanks
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Old 06-14-2010, 02:47 PM   #15
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The platinum tipped plugs have no thinner electrodes than any other plug does, I don't know where you come up with that kind of stuff rrich. The platinum is merely an ultra-thin coating over the top of the the underlying electrode. The platinum coating's purpose is simply to reduce wear of the underlying electrode, the platinum does not replace the electrode itself... it is just a coating. Go use a micrometer on the outside contact and you will find it is no thinner at all. None whatsoever.

For the early distributor equipped 4.0L engine, two single-tipped platinum plugs are very well known to work well... the Champion 7034 and Autolite AP985. I ran the AP985 for over 90K miles in my '97 TJ and it was a superb plug that showed no wear whatsoever when I checked it when it had somewhere around 65K miles on it.

Brad, I'm familiar with your 43 code DTC which is somewhat common on early '97 and '98 4.0L engines. You can even see multiple 43 codes, like 12 43 43 43 55. Most often than not, it is the result of a bad (weak) batch of valve springs that were installed in the TJ's early 4.0L engines. The problem is resolved by replacing the valve springs but if the problem has gone on long enough, it's likely the valves and/or valve seats might have burned a little so you may also need a valve job to completely cure it.

Replacing all the usual items like plugs, distributor cap, rotor, ignition wires, fuel injectors, fuel injector wiring harness, etc. won't help with this particular problem. Jeep finally came out with a TSB (tech service bulletin) to address this problem after spending several years figuring out what was causing it. Their TSB is simply to replace the springs & clean the combustion chambers with Mopar CCC (Combustion Chamber Cleaner) but, again, a valve job is often ultimately needed to completely cure/stop the 43 codes.
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Old 06-14-2010, 03:06 PM   #16
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Thanks Jerry..I had heard about that problem too in dealing with the weak springs....Guess I'll have to save up some money here to get her fixed up.
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Old 06-14-2010, 03:37 PM   #17
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Now my question is...What's the cost of valve springs and a valve job? Any estimates?
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Old 06-14-2010, 03:44 PM   #18
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Quote:
Originally Posted by Jerry Bransford View Post
The platinum tipped plugs have no thinner electrodes than any other plug does, I don't know where you come up with that kind of stuff rrich. The platinum is merely an ultra-thin coating over the top of the the underlying electrode. The platinum coating's purpose is simply to reduce wear of the underlying electrode, the platinum does not replace the electrode itself... it is just a coating. Go use a micrometer on the outside contact and you will find it is no thinner at all. None whatsoever.

For the early distributor equipped 4.0L engine, two single-tipped platinum plugs are very well known to work well... the Champion 7034 and Autolite AP985. I ran the AP985 for over 90K miles in my '97 TJ and it was a superb plug that showed no wear whatsoever when I checked it when it had somewhere around 65K miles on it.

Brad, I'm familiar with your 43 code DTC which is somewhat common on early '97 and '98 4.0L engines. You can even see multiple 43 codes, like 12 43 43 43 55. Most often than not, it is the result of a bad (weak) batch of valve springs that were installed in the TJ's early 4.0L engines. The problem is resolved by replacing the valve springs but if the problem has gone on long enough, it's likely the valves and/or valve seats might have burned a little so you may also need a valve job to completely cure it.

Replacing all the usual items like plugs, distributor cap, rotor, ignition wires, fuel injectors, fuel injector wiring harness, etc. won't help with this particular problem. Jeep finally came out with a TSB (tech service bulletin) to address this problem after spending several years figuring out what was causing it. Their TSB is simply to replace the springs & clean the combustion chambers with Mopar CCC (Combustion Chamber Cleaner) but, again, a valve job is often ultimately needed to completely cure/stop the 43 codes.


Good post. Good info.
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Old 06-14-2010, 03:44 PM   #19
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I forget what I paid for my valve springs Brad but it wasn't very much at all. $70 or under seems to ring a bell, I did mine probably 6-7 years ago so it's a bit fuzzy. I think I paid a guy $100 to install them as I don't really enjoy working on engines any more. Valve job costs are all over the place from when I priced one, $500-800 or so. But heck, I see ready-to-install remanufactured complete ready-to-run heads that are ready to bolt onto the engine for $500 or so in Quadratec's catalog. If I needed to do a valve job, I'd seriously consider just replacing the head which has already had a valve job performed on it itself for that price. Knowing Quadratec's usual high prices, you might even find one for less $$$.
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Old 06-14-2010, 03:50 PM   #20
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ok. so springs should be my first option to look into and if that doesnt seem to solve the problem a valve job would be next. I was thinking that this all had to be done at the same time. That'll be easier and hopefully it doesnt come to vlave work. Thanks for all the help Jerry. It's much appreciated!
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Old 06-14-2010, 08:30 PM   #21
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Jerry I guess you've never looked at the center electrodes.

Here's a Bosch's site that shows the Bosch plat electrodes look at the picture in the center - tell them they are wrong. They say it's a solid platinum wire - but what do they know?
http://www.bosch.com.au/content/lang..._Spark_WEB.pdf


And another site that talks about Champion plats.
“””””Champion Double-Platinum Power spark plugs have platinum on both the center and ground electrodes. The center electrode is platinum fine wire that is riveted onto the nickel alloy center electrode. The ground electrode has a platinum pad welded to its surface. ”””””

This is from CHAMPION Double-Platinum Power Racing spark plugs

Sorry I don't have one laying round to snap a picture of. When I come across them they go in the trash can. But next trip into town I'll get one for a photo.

They may work OK in some rice burners that were designed to use them, but too many people have tried them in Chevys, Fords and Jeeps etc and tossed them.

Look on the internet search platinum plug problems - lots of examples.

"""""The platinum tipped plugs have no thinner electrodes than any other plug does, I don't know where you come up with that kind of stuff rrich. The platinum is merely an ultra-thin coating over the top of the the underlying electrode.""""""
---- eyeballs! -----
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Old 06-14-2010, 08:49 PM   #22
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For what it's worth my '99 runs great with the Champion 4412 truck plugs. A simple copper plug. Much like the plain 985 autolite.

Harder to find but I was told by a VERY knowledgable ex onion slicer at Autochina that they're a heavy duty plug, hence the "truck" part.
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Old 06-14-2010, 08:57 PM   #23
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Jerry I guess you've never looked at the center electrodes.

Here's a Bosch's site that shows the Bosch plat electrodes look at the picture in the center - tell them they are wrong. They say it's a solid platinum wire - but what do they know?
http://www.bosch.com.au/content/lang..._Spark_WEB.pdf


And another site that talks about Champion plats.
“””””Champion Double-Platinum Power spark plugs have platinum on both the center and ground electrodes. The center electrode is platinum fine wire that is riveted onto the nickel alloy center electrode. The ground electrode has a platinum pad welded to its surface. ”””””

This is from CHAMPION Double-Platinum Power Racing spark plugs

Sorry I don't have one laying round to snap a picture of. When I come across them they go in the trash can. But next trip into town I'll get one for a photo.

They may work OK in some rice burners that were designed to use them, but too many people have tried them in Chevys, Fords and Jeeps etc and tossed them.

Look on the internet search platinum plug problems - lots of examples.

"""""The platinum tipped plugs have no thinner electrodes than any other plug does, I don't know where you come up with that kind of stuff rrich. The platinum is merely an ultra-thin coating over the top of the the underlying electrode.""""""
---- eyeballs! -----
You're of course entitled to your opinions but there are sure a whole lot of us happily running platinum plugs in our Jeeps. Sorry you have such an irrational hard-in for platinum plugs which is only your loss and no skin off my nose.
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Old 06-15-2010, 12:26 AM   #24
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And you yours.
But remember, this thread is supposed to HELP a guy with a problem. Putting in the correct plugs eliminates the problem with using the wrong plugs. And it's a cheap and easy experiment.

Jerry did you even look at those sites that show the center electrode is thinner? How 'bout looking at one of your spare plugs and comparing it with a standard plug? You flamed me for saying they are thinner, but aren't those pictures proof?

Side note - use a reverse application guide on the double plats you use. You'll find they are for a 4 cyl PT Cruiser and an older Chrysler 300.
I wonder how anyone ever discovered to put them in a Jeep? (Maybe the Yugo plugs didn't fit?)

The weak valve springs - maybe - high speed misfire is a symptom of weak springs. To prove that's what it is, run it at the 70 MPH or so for awhile, then when the CEL comes on, indicating it's seeing a misfire, accelerate to 80 or increase engine RPM 300-500. If it is weak springs, the valves aren't closing fast enough, the pushrods will start going slack - extra clearance - you'll hear it rattling like crazy. Don't go faster, and don't do it for a long time. It's an easy test.

The plats -
Notice the porcelain around the center electrode protrudes more, nearly covering the tip. Since the thin wire does not dissipate heat - carry it away - like a regular steel wire or copper wire, the tip stays hotter. Too hot it can cause pre-ignition misfire - audible or inaudible (probably what the ECM is seeing.) At the higher speeds the tip does not have quite enough time to cool before that flash point.

I'd be worried that the plats on his - maybe not on yours - could be causing that pre-ignition - dangerous. That's the reason that SplitFires cause so much grief - too much dangling out there and overheating.

Funny how the simple brainless task of looking at the underhood label is so difficult.
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Old 06-15-2010, 08:12 AM   #25
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Never thought a quick question would lead to such an argument on the size and performance of a $5 or less part......I'm gonna start by tracking down the "right" plugs for the Jeep since my Yugo Fire Sticks aren't the right ones and go from there looking at springs after that just to elimate the possibilty of the cheaper wear out parts going bad first and working my way up to the other things. I like Autolites so I'm probably gonna try their copper ones or the AP985's...wires are less than 7 months old so they're staying and i'll put in a new cap, rotor and maybe some other small parts.

Thanks for all the help guys!
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Old 06-24-2010, 02:42 PM   #26
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check engine problem

well i have been in a similar problem...
i get overheated teh last week...
because the water pump break the seals
and the engine do the same... so i open the head of the engine chance the seals and brushing the head....
well everything was normal until yesterday....
the F$%& lights "check engine" goes on...
i dont know if its for the water... maybe the sparks... maybe one of the cylinders wents sick.... or the gas cap... lol

im working on it... i found that my sparks are not so good (maybe for the overheat) it was platinium IIII Bosch, changed in October 2009... or the hose to alternator....
well see if something here helps...

my jeep is a YJ 1992... Greetings...

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