Any ideas on whats wrong?

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Any ideas on whats wrong?

Postby mydogearl » Wed Feb 13, 2008 10:56 pm

01 Dodge Ram 1500 318 115K. Ran good for the first 45K miles that i owned and then last year, it started running rough. Missing, backfiring, "coughing," "spitting," if those help describe. The truck is also a 5 spd and has true dual exhaust with glass packs minus converters so it is pretty darn loud and the backfiring is very violent. Anyway, I changed the plugs and back to perfect. a couple months later, it starts the same ole crap. I havent checked to see what the plugs look like but i probably will tomorrow. What could be causing the plugs to go bad if in fact that is the problem. The new plugs dont even have 10K miles on them. Thanks in advance.
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Postby HotDog » Thu Feb 14, 2008 4:43 am

I'm no mechanic.
That said, if it isn't a factory exhaust, you may need to change a chip, or reprogram the computer, to compensate for the loss of back pressure.
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Postby Smackaduck » Thu Feb 14, 2008 7:03 am

True duels suck and suck gas as well.
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Postby ajmorell » Thu Feb 14, 2008 8:02 am

Your problem isn't the exhaust. Less backpressure is generally speaking a good thing...pretty common misconception actually. What size exhaust tubing are you running, that play a bigger factor than the type of exhaust you are running.

If your plugs are continually getting fouled obviously something isn't right. Pull a few and compare them to this:

http://www.gnttype.org/techarea/engine/plugs.html

That should give you a pretty good idea of what is going on. If you're not sure post a pic of the plug(s).
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Postby ajmorell » Thu Feb 14, 2008 8:03 am

smackaduck wrote:True duels suck and suck gas as well.


That's not true. Freer flowing exhaust increases engine efficiency so technically mileage should increase. The reason that it doesn't 99% of the time is because people can't keep their foot out of the gas with a loud exhaust.
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Postby mydogearl » Thu Feb 14, 2008 10:05 am

plugs are fine. exhaust tubing is approx 2 in, possibly 2 1/4"
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Postby ajmorell » Thu Feb 14, 2008 12:35 pm

That should be about the right size for that motor then. Ideal size for a single pipe on the 318 is 3" and 2 pipes at 2" diameter each only has slightly less volumetric flow.

When is the last time you had 02 sensors replaced?
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Postby KCDuckMaster » Thu Feb 14, 2008 1:38 pm

Im pretty sure your exhaust is not the problem. This sounds like spark timing. If you have a distributor with a solid state ignition then I would be checking to see if it has skipped a tooth on the gear. If you have DIS ignition then I would be checking the crank and cam positioning sensors. If you have access to a Fluke 98 or a Modis then I would use that to graph the signal from the sensors and you should see a digital signal(fully on or fully off nothing in between). If it looks a little funky then it may be the reluctor ring might have a gap plugged or it might be broken or the sensor could have some crap collecting on the end of it which will cause it to give an inaccurate reading. Since those sensors are magnetic, they can pick up alot of crap.

Thats my guess!
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Postby ajmorell » Thu Feb 14, 2008 2:18 pm

KCDuckMaster wrote:Im pretty sure your exhaust is not the problem. This sounds like spark timing. If you have a distributor with a solid state ignition then I would be checking to see if it has skipped a tooth on the gear. If you have DIS ignition then I would be checking the crank and cam positioning sensors. If you have access to a Fluke 98 or a Modis then I would use that to graph the signal from the sensors and you should see a digital signal(fully on or fully off nothing in between). If it looks a little funky then it may be the reluctor ring might have a gap plugged or it might be broken or the sensor could have some crap collecting on the end of it which will cause it to give an inaccurate reading. Since those sensors are magnetic, they can pick up alot of crap.

Thats my guess!


Those are 2 things I never thought of, but could very easily be the culprit. Don't most motors only have a crank or cam position sensor, but not both?
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Postby KCDuckMaster » Thu Feb 14, 2008 3:43 pm

Some do have both a Crank position sensor and a Camshaft position sensor, this is especially true on newer vehicles. However your also right because some have one or the other, it just depends.
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Postby mydogearl » Thu Feb 14, 2008 5:29 pm

ajmorell
I had forgot about the O2 sensors and that might be it also.

I also for got to mention that it isnt running like this all of the time. It might run great or run really bad or sometimes inbetween. Even so much that I might accelerate and it will run rough, come to a stop at light, accelerate and it run good.
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Postby greenster » Thu Feb 14, 2008 6:59 pm

I'm not much on dodges. but it could it possible be a vacuum line?
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Postby sea duck » Thu Feb 14, 2008 7:50 pm

This truck has both cam and crank sensors.You many whant to check the coil, if the fines are spliting apart and rusted the coil maybe bad and somtimes you can see small sparks between the fines. Also ck under the distributor cap and spark plug towers for corrosoin. If you have the cap off remove the rotor and the cam sensor to ck the metal piece they come loose sometimes. do you any way to ck fuel pressure? If you can the fuel spec 49.2 +/- 5 psi. Any more info you need on a dodge let me know I will try to help.
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Postby mydogearl » Thu Feb 14, 2008 7:51 pm

that brings up another problem, if it is the vacuum lines causing this problem (or maybe both). not knowing too awful much about vehicles i only figure this problem is the vacuum lines. back in the summer, i was movin my brother to cincy and was haulin a stock trailer full of furniture. we noticed the A/C was actin up and it has done this ever since then (even with the heat). the fan will be up and blowing but when i accelerate nothing comes out and when i decelerate or have the throttle at a constant position, it will blow out air. you still hear the fan blowing when accelerating but nothing comes out.
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Postby sea duck » Thu Feb 14, 2008 8:24 pm

I think you are talking about two problem. For the a/c problem there is a ck valve in line. Try to follow the line that come out of the fire wall where the a/c line go through and follow back to the engine there should by a round piece that the line plugs into, it may be on the right side of the engine on the intake. If you can blow through both way it bad replaced it . I do n ot thinks it a vac problem.
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Postby KCDuckMaster » Fri Feb 15, 2008 1:30 pm

A vacuum leak wouldn't cause a misfiring and back firing. It would only cause a high idle, poor fuel mileage, and your check engine light would come on for lean 02 sensors.

About your a/c there will never be a check valve in an A/C system because there is no need for one. Maybe sea duck is talking about the orifice tube or expansion valve (only one of the other, not both and most likely the orifice tube). When the problem occurs do you have it set to blow out the vents or the floor? Because the diverter door is probably operated off engine vacuum and the default position is to blow out the defrost so when vacuum is lost the door automatically closes and the air is blown out the defrost so maybe check your defrost vents the next time it happens.This happens when you get into the gas engine vacuum falls and when your cruising with the trailer your engine load is higher and when ever engine load increases manifold vacuum decreases. So my guess on that would be you have a diverter door vacuum solenoid that is leaking. If I were you and if that is the problem I would live with it because I can guarantee you that will not be fun, if you must have it fixed I would highly, highly recommend that you take it to a shop.
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Postby mydogearl » Fri Feb 15, 2008 1:36 pm

i have it set to blow out both but i havent realized if it is coming out the bottom or not. i just know it isnt coming out the top
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Postby ajmorell » Fri Feb 15, 2008 7:43 pm

KCDuckMaster wrote:A vacuum leak wouldn't cause a misfiring and back firing. It would only cause a high idle, poor fuel mileage, and your check engine light would come on for lean 02 sensors.

About your a/c there will never be a check valve in an A/C system because there is no need for one. Maybe sea duck is talking about the orifice tube or expansion valve (only one of the other, not both and most likely the orifice tube). When the problem occurs do you have it set to blow out the vents or the floor? Because the diverter door is probably operated off engine vacuum and the default position is to blow out the defrost so when vacuum is lost the door automatically closes and the air is blown out the defrost so maybe check your defrost vents the next time it happens.This happens when you get into the gas engine vacuum falls and when your cruising with the trailer your engine load is higher and when ever engine load increases manifold vacuum decreases. So my guess on that would be you have a diverter door vacuum solenoid that is leaking. If I were you and if that is the problem I would live with it because I can guarantee you that will not be fun, if you must have it fixed I would highly, highly recommend that you take it to a shop.



I'm not sure you're right on that check valve. I know for a fact that the defrost default due to vacuum pressure drop is common on Jeeps such as mine, and the fix to the problem is to install a check valve.....I read this straight from the TSB.
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Postby rmh » Fri Feb 15, 2008 7:58 pm

May be dumb but: my 03 F-150 was doing the same thing whenever it got damp/humid out. Starter coil was shorting out.
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Postby HotDog » Fri Feb 15, 2008 10:29 pm

WOW
I'm still no mechanic, but I'm now enlightened.
It's great that we have so many guys willing to help a fellow hunter out.
Bravo to you all.
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Postby sea duck » Sat Feb 16, 2008 12:12 am

When I go to work on monday I will get the part # for the check valve for the vac control that shoyld fix the a/c problem, or you can look for the vac line that come out of the fire wall where the a/c line come out it is a little black tube at the end should be the ck valve .It is appox 6-8 inch from the fire wall. I think the part number is on it, or go to the dealer and show them or give the # to me and I can ck dealerconnect that is the mopar fac site for all dealers, that will tell me how much it is. I think there under $20.
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Postby waterfowlhunter » Sat Feb 16, 2008 6:52 am

Have you had it scanned (most autoparts stores will check it free now)

Is the check engine light on now or has it ever came on? If it did come on did you have it reset properly or just clear the light be disconnecting the battery?

Have you replaced the fuel filter and checked the fuel rail pressure? common for what you are saying your is doing.

the exhaust is not an issue. True duals or with a equilizer pipe are fine but on a stock engine a bit of back pressure is necessary for the sensors to read CORRECTLY but in most casesyou will see a few hp and 1 or 2 MPG gain with duals if you can tolerate the noise.

fuel filters should be replaced every 25,000 miles from my experience due to some stations not filtering very good at the pump.
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Postby sea duck » Sat Feb 16, 2008 9:15 am

Sorry waterfowlhunter gas power dodge truck from 94 and up don't run a fuel filter out side the tank, it is a sock on the bottom of the fuel pump in the tank. I have omly seen very few with problems. I seen enough fuel with problems.
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Postby KCDuckMaster » Sat Feb 16, 2008 9:57 am

Sorry Sea Duck
I know what you mean now, i wasn't thinking about the vacuum lines when I made my comment,I was thinking you were talking about just the refrigerant system.
But ya now that you mention it it could be a defiant possibility if that thing is leaking.
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Postby mydogearl » Sat Feb 16, 2008 10:38 am

rmh, i havent noticed any correlation between dampness and it runnin rough, it just does it randomly.

waterfowlhunter, i have not had it scanned. what does this involve? also, the check engine light (along with the Brake and ABS light) have been on since i have owned the truck. i attributed this to the truck being a salvage vehicle.

what i still think is weird is that the plugs were bad, i changed them and it ran great again. then a few months later it runs rough again with the exact same symptons but the plugs are fine. but i'm obviously no mechanic.

thanks again everyone
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