Spark Plugs lasts 3-5 months??

[rauljimenez]

Hello guys is me Again. I got a weird problem and I think you guys could help me solve it once and for all.

My spark plugs on my Isuzu Rodeo 3.2L 24 valves seem to last from 3 to 5 months after changing them with some new NGK. After that lapse of time the car suddenly starts shaking badly and the Tachometer (RPM) goes down and up down and up like a miss.
Also I checked my exhaust air to see how the car was behaving and it sounds like a MISS from the air coming out of my muffler. When things are perfectly , air flows freely in the muffler , now when the car shakes the air comes and then goes and comes ON and OFF.

The thing is , once I replace with 6 new plugs my car runs smoothly again for 3-5 months before it starts to happen again, is getting on my nerves guys. What could be the culprit for this problem that has been haunting me a long time.

 

[Jon]

Well, what plugs are spec'd, what plugs have you been using?

 

[rauljimenez]

Jon , engine calls looking at Haynes manual for Champion RC12YC or equivalent at 0.044 inch. Right now the plugs i've been using for the changes are NGK BKR6E 11.

 

[Drew99GT]

What do the 5 month plugs look like when you take em out?

 

[rauljimenez]

Also I checked the owner manual straight from Isuzu it says to use :

FR2LS/BKR6E-11/K20PR-U11 any of those.

Do you guys think I might need a hotter plug maybe??

 

[rauljimenez]

quote:

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Originally posted by Drew99GT:
What do the 5 month plugs look like when you take em out?

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Thats the weird thing, they look very normal to me not oil fouled , just normal grayish tan deposits , but as soon as I install 6 fresh new spark plugs everything is perfect again.

 

[y_p_w]

quote:

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Originally posted by rauljimenez:

quote:

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Originally posted by Drew99GT:
What do the 5 month plugs look like when you take em out?

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Thats the weird thing, they look very normal to me not oil fouled , just normal grayish tan deposits , but as soon as I install 6 fresh new spark plugs everything is perfect again.

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I'm a big ignition expert or anything, but sometimes new plugs can cover up for a weak/marginal ignition. The ignition might have a difficult time with even mildly worn plugs, but new ones are easy on the ignition. Could be as simple as a worn distributor or points or old plug wires. Worst case might be the ignition coil.

Some of the iridium plugs are supposed to reduce ignition voltage requirements with a smaller center electrode. Sounds similar to Champion's EZ Start lawnmower plugs, which reduce voltage requirements by using a tiny (standard) center electrode.

 

[punisher]

quote:

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Originally posted by y_p_w:
I'm a big ignition expert or anything, but sometimes new plugs can cover up for a weak/marginal ignition. The ignition might have a difficult time with even mildly worn plugs, but new ones are easy on the ignition. Could be as simple as a worn distributor or points or old plug wires. Worst case might be the ignition coil.

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That was the first thing that crossed my mind as well. As soon as plug resistance reaches a certain level the ignition lacks the voltage to jump the gap.

 

[rauljimenez]

The Isuzu Rodeo doesn't run on distributor but basically 3 COILS with each coil distributing spark to 2 plugs , i'll have to check that too. like 6-7 months ago I replaced a Coil because it was fried.

 

[jsharp]

Weak ignition is my theory too. Small engines and motorcycles used to have this problem constantly. Plugs that looked almost perfect just wouldn't fire. The ignition systems were just marginal. A GM mechanic said told me their early HE ignitions also had a similar problem. When you gapped the plugs to the recommended setting in a few months they had difficulty starting.

Their solution was to decrease the plug gap slightly. If the you're sure the rest of the ignition system is ok, you might try going to something like .040" from the recommending .044" and see if that helps.

 

[TheLoneRanger]

Raul, I'd check the plug wires, along with the terminals. Regarding the coil you recently replaced; there's probably a poor plug wire or connector that connects to that specific coil. That's possibly why the coil failed.

If you have an ohmmeter, the wires are easy to check by reading the resistance from end to end. Something in the range of 8K to 12K ohms per foot is normal.

 

[TxGreaseMonkey]

Cross-reference plugs frequently don't work well. I would find out what OEM plug came with that engine and use it. I have seen substituted plugs cause many problems on cars, motorcycles, mowers, and trimmers. Next, I would go over the complete electrical system, checking condition of coils, plug wires, battery, alternator, and ensure main ground and all electrical connnections are corrosion-free.

 

[y_p_w]

quote:

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Originally posted by TxGreaseMonkey:
Cross-reference plugs frequently don't work well. I would find out what OEM plug came with that engine and use it. I have seen substituted plugs cause many problems on cars, motorcycles, mowers, and trimmers. Next, I would go over the complete electrical system, checking condition of coils, plug wires, battery, alternator, and ensure main ground and all electrical connnections are corrosion-free.

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He said he was using the factory spec'ed NGK BKR6E-11, so that's probably not it.

 

[y_p_w]

What year Rodeo? NGK lists different plugs for the 3.2L (6VD1 engine) depending on year.

For 1997-2002, NGK lists BKR5EY-11; those were the DOHC years. For 1993-1996/2003, they list the BKR6E-11.

I was thinking maybe go with a V-Power plug, but the number you gave apparently is listed as V-Power.

 

[rauljimenez]

quote:

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Originally posted by jsharp:
Weak ignition is my theory too. Small engines and motorcycles used to have this problem constantly. Plugs that looked almost perfect just wouldn't fire. The ignition systems were just marginal. A GM mechanic said told me their early HE ignitions also had a similar problem. When you gapped the plugs to the recommended setting in a few months they had difficulty starting.

Their solution was to decrease the plug gap slightly. If the you're sure the rest of the ignition system is ok, you might try going to something like .040" from the recommending .044" and see if that helps.

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Sharp thanks, I will look into a possible weak ignition system since a lot of you guys are pinpointing it. I changed my plugs to a hotter one NGK and gapped them to .040" as said, lets see how it goes now.

 

[rauljimenez]

quote:

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Originally posted by TheLoneRanger:
Raul, I'd check the plug wires, along with the terminals. Regarding the coil you recently replaced; there's probably a poor plug wire or connector that connects to that specific coil. That's possibly why the coil failed.

If you have an ohmmeter, the wires are easy to check by reading the resistance from end to end. Something in the range of 8K to 12K ohms per foot is normal.

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Yep I changed the plugs to NGK wires thinking that was the problem like 9-10 months ago, checked resistance and everything looks ok.

Are some engines prone to using a lot of spark plugs?? Maybe is a flaw in the system but I doubt it.

 

[TxGreaseMonkey]

If he bought the car used, it's best to check the emissions plate/sticker under the hood. There are differences sometimes in manuals and emissions plate information. Emissions plate information is supposed to be the final word.

 

[rauljimenez]

Wanted to update, I used a hotter plug and so far everything is going smooth and no pre ignition either , thanks everyone