Hello all.
I'm new here.
I have a 2002 Dodge Dakota SXT 4x4 Automatic. V6.

Can anyone tell me if its easy to change the spark plugs and wires and cap and rotor?
Someone told me that 2 of the spark plugs are really hard to get too. Is this true?
I have the check engine light on and had someone run a scan on it and the codes were, missfire, cat problems, and the o2 sensor after the cat.
So I think the last two problems are because of the missfireing.

I'm getting quotes for around $180 - $280 to have the plugs, wires, cap & rotor changed out. but I priced out the parts for around $90.
Should I do it myself or have a mechanic do it?
I have worked on cars before, and I'm sure I could do it, but I'm worried about the 2 spark plugs that are hard to get at. Do I need a special tool to get to them? Would it need to be put on a lift to get to them?
Any input would be great.

 

It's easy to change plugs on a 3.9. $180.00 for plugs, wires, cap and rotor is way too much money for the job. You can get the plugs, wires, cap and rotor all at Napa. Get Autolite 3923 plain copper core plugs. You need to ask for 3923 specifically, because their books won't list it for a 3.9. They cost about $2.00 each. Get the Napa cap and rotor with brass contacts, part numbers MO 26 and MO 28, should be about $24.00 for both. Get a set of Napa Belden premium plug wires for it. Here the set costs about $36.00 but according to Napa's web site the Belden wires are on sale this month. The also have a free Napa hat with any purchase this month too. The brass cap and rotor and premium wire set will get a better spark and higher voltage to the plugs plus they won't corrode up as easily.

The two plugs that are hard to reach really aren't so hard if you have patience and the right tools. The one closest to the firewall on the driver's side is the worst one. What I do is use a regular 5/8" spark plug socket and a 6" extension on my 3/8" ratchet. Pull the boot off the old plug, put the socket on the extension and insert it into the heat shield on the plug till it seats on the nut. Then reach in with the ratchet and angle the handle back towards the firewall and snap it in place on the extension. Then operate the ratchet and loosen the plug, and you can just turn the extension and socket to get the plug out. I wrap the extension and socket where they join together with electrical tape so the socket won't pull off and get stuck in the heat shield.

Same procedure on the passenger side rear plug too, it's not hard at all. Remove the air intake box, tube and the air hat on top of the throttle body for better access. In the FAQ here there is a diagram for the firing order and spark plug wires to the cap if you need it.

The bad O2 after the cat doesn't make sense to me. I have never heard of anyone having to replace the downstream O2. I guess if the cat is bad then it could affect the O2, but I never heard of it. Hit the cat with a rubber hammer or your fist-if it rattles it is bad and needs to be replaced. I never replaced a cat before so I don't know how much they cost. I think I have read on here that it wasn't too bad. If I were you I would replace the plugs, wires, cap and rotor t reset the PCM by disconnecting the negative battery cable and hold the ignition key in run for half a minute. Connect the battery and see howthe truck runs then. You can also turn the ignition on and off 3 times and leave it on on the 3rd time and any trouble codes will show in the odometer. There's a list of codes in the FAQ too.

Let us know how it goes. And welcome to the forum.

Jimmy

 

It's a pretty simple job. Anyone that can turn a wrench ought to be able to do it. I don't remember two of the plugs being hard to get to... if they were too hard I would have remembered.

Just keep track of what wires went where on the cap. Swap them one at a time and its easy. You will know right away if your firing order is off.

EDIT: silvercc just totally made my post look retarded. I posted right after him. So just read what he wrote.

 

thank you so much guys.
I will check it out tonight and let you know how it goes.


Is there anything else I should know?

I changed the air filter the other day and it seems to backfire more often now.
Is it cause i didnt reset the computer? (disconnect the battery)
or does that have nothing to do with it?
Is the backfireing just cause the plugs are getting worse and worse?


Do you think the o2 sensor will be fine once the new plugs are in?

I'll check the cat tonight. Thanks for the tip.

 

silvercc - "In the FAQ here there is a diagram for the firing order and spark plug wires to the cap if you need it."

can you help me find the diagrams please? I cant seem to find them in the FAQ....

 

Does anyone know what the spark plug gap should be?
Will I need to gap the new plugs or do they come pre-gapped?


These are the codes I'm getting....Does anyone know what they mean?

P0152
P0442
P0432

 

The new air filter is allowing more air into the engine now, which is probably adding to the backfiring problem. It should not have anything to do with not resetting the PCM.

Gap on a stock ignition should be .040. Check the emissions sticker on the bottom side of the hood to be sure. Yes, you should always check the gap on the new plugs before you install them and use a little anti-sieze on the new plugs. If the ones you have now are the originals, they may be in pretty tight. Make sure to get the ratchet and socket on the old plugs straight and get a good grip on the old ones when removing them. Use a bit of dialectric boot grease on both ends of your new plug wires. I replace my own cap, rotor, plugs and wires every 20,000 miles. I buy all my parts the day before and do the job the next morning with the engine stone cold. It's easier that way plus I don't burn myself on hot engine parts in the process. That's also a good time to remove the throttle body and clean it and the IAC valve. And I lube all the throttle position lever and the pivot points on the TB and reinstall it with a new gasket.

P0442 is the code for the evaporative system leak. Meduim leak detected. The first place to look is under the driver's side of the truck there is a black metal canister with some rubber emission hoses on it. Check all the hoses for breaks and cracks, if nothing found there check the emission hoses under the hood on the driver's side. There's a bunch of hoses there and you have to trace them back and find the one that is bad. The Dodge dealer uses a smoke machine that injects smoke into the evap system to find leaks, kind of like putting a flat tire in water so the bubbles tell you where the hole is.

P0432 is the code for the cat being at half efficiency.
P0152 is the code for bank 2 oxygen sensor 1 being shorted to ground. I *think* bank 2 is the passenger side and I am pretty sure sensor 1 is the O2 before the cat. I can check my Dakota Service Manual when I get home and get back to you with the right info. I bet if you replace the bad O2 sensor the cat will work right again and the code will clear when you reset the PCM. The bad cat and bad O2 can definitely be the cause of your backfiring problem. You can also get places like Advance or Autozone to just use their code scanner to reset the PCM too. Or you can buy a decent scanner pretty cheap at Harbor Freight.

How many miles on your truck? I replaced both of my own upstream O2's at 95,000 miles as a maintenance item. I ordered mine from NTK.com and they cost about $32.00 each, a lot less than the dealer, and NTK is the supplier for the factory sensors anyway. Whatever you do, do not use a Bosch O2 on your 3.9. They do not work well at all on 3.9's. Depending on the miles on your truck it might be best to go ahead on and do both upstream sensors. You can get the socket for them cheap at Harbor Freight tools, or they cost about $15.00 at Advance or Autozone.

Here is the link for the PCM trouble codes:

https://dodgeforum.com/forum/1st-gen...ine-light.html

When you click on the 2nd Gen FAQ link here, scroll all the way to the bottom of the page, there are some diagrams there. The one on the upper left is the firing order for your 3.9. I have the Dodge Factory Service manual for the 3.9 at home. If you want a copy, PM me your name and address and I will mail you a copy on CD. It's a 77.8 MB pdf file and is too big to email.

Jimmy

 

since I didnt get the code for "missfire" this time. (the guys at auto zone tested it and said I had that code but when I did the test by turning the key 3 times and I didnt see that code) Do you think I dont need to change the spark plugs?
DO you think it could be JUST the O2 sensor? Or a vacuum leak?


heres some other thigs it does...
The truck bucks sometimes and backfires. When I push on the gas it seems like it slows down or dosent go any faster, but if I floor it it will go up to about 5000rpm then finally shift and then it backfires and sometimes it dosent backfire, it just works normally but shifts at high rpms.....also, when I floor it, theres barely any power. Its loud but no more power then it had while driveing normally.
I noticed if I'm very gentle with the gas peddle it dosent do it as bad or as often... and it also seems like it has more power and seems to shift more like normal if I'm gently on the gas peddle.

Any thoughts?

 

That sounds like the Throttle Position Sensor is bad. You need a digital volt meter to check it, which you can also get a decent one cheap at Harbor Freight. Check the center wire on the TPS for voltage with the key in the run position but with the engine not running. You should have about half a volt with the throttle closed, at rest. Then as you slowly open the throttle by hand the voltage should slowly increase and be about 4.8 to 5 volts with the throttle wide open. If the increase in voltage is not smooth or you have any different voltage amounts, the TPS is bad. Another sign the TPS is bad is if it wont start unless you floor the throttle. TPS is on the driver's side of the Throttle Body.

The bucking problem is probably more due to the O2 than anything else. But when the O2 is bad it will cause lack of power and it will whack out the signals to the Idle Air Control valve on the back of the Throttle Body and cause bucking, stumbling and a bad rough idle. It can cut off the engine when you are at a stop light. Remove the TB and the IAC is on the back side of it, remove the 2 torx screws holding it in and clean the pintle end gently with a shop rag soaked in carb cleaner. Don't drop the IAC or handle it roughly or you will be buying a new one. You just want to clean the balck crusty crud off the pintle end. Check the O-ring in the orifice when you reinstall the IAC. Be sure it's not broken or cracked.

It sounds like your truck needs a good tune up. Depending on the miles on it yes I would say for sure change the plugs, cap, rotor and wires. Clean the TB and don't forget a new gasket for the TB, $1.50 at Autozone.

Jimmy

 

Thanks Jimmy

I think I might have to take it to a mechanic to find the exact problem.
I dont want to dump a bunch of money into it and find out its was something else.

What do you suggest I do?