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Discussion Starter · #1 ·
:help: Hi all,
I'm experiencing problems with the ignition system on my truck. Please let me explain... Some weeks ago, while visiting a friend's workshop, I asked if the noisy and irritating valve on the passenger side exhaust manifold could be tack welded in the open position, to avoid the constant clatter of this metal valve flapping on idle. Suffice to say, that this valve was welded in the shut positon, rather than open. This resulted in the air-pump and associated plumbing being damaged by the force of the exhaust that had no where else to go, except up the stainless steel plumbing that normally blends fresh air into the exhaust, via the manifolds.
I have opened up the welded valve on the exhaust manifold, removed the fresh air pump, blocked-off the plumbing to the manifolds and was hoping that this would remedy my problems...apparently not. Since this whole saga took place, I have noticed that the truck is very difficult to start, runs very rough and seems like the timing is very badly out of sync or the vacuum is too high. I have a service manual and reading this, it seems that the symptoms would indicate that the "computer" that regulates the timing may be malfunctioning. This gizmo sets the timing in two modes - one for starting and the other for "running". If anyone has knowledge or experience in regard to my dilemma, I would appreciate some guidance, as I'm neither a mechanic or an electrician. Unfortunately, the workshop that caused the damage, is located 250 miles from me and there are no other mechanics in my immediate area that I would trust or believe have enough knowledge about this system (Dodge Rams are pretty rare here).
Look forward to any suggestions and advice that you can offer.
Thanks in advance.
 

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My first thought is that the timing chain/gears have slipped a tooth. The weld may have overstressed the chain? This will cause all the problems you mention and may cause a backfire through the carb or TBI.
 

· The Legendary Cross Ram
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Wow, big problems man!

What engine?
 

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Discussion Starter · #4 ·
Timing chain is fine. 318 2 barrel carb running through a 904 trans with lock-up converter. All factory standard equipment and untouched except for what I've had to remove (air pump, hoses, belt and plumbing blocked off).
To clarify - when I start the motor, she runs very rough, idles badly and the exhaust is fuel rich, like it's over-choked (which it's not). When finally warm, she runs better, although idles too high at about 1500 rpm. I've adjusted the timing back and forth, to see if this was the problem as well as carb settings - it's not. The motor was running like a clock prior to the exhaust manifold valve being welded in the closed position as opposed to open. Since then, she runs like a pig and won't re-start if shut down when warm. The service manual does describe this symptom as a possible failure of the "computer" that adjusts the timing, because if the computer is not working properly it can go into "limp mode" which is only to get you out of trouble and sets the timing on the start position (0 degrees I believe). There's no vacuum advance can on the side of the distributor - this is done by the computer, so I believe. Anyone out there with a similar set up to this, who's had problems with their computer?
While I'm not a mechanic, I can do most jobs myself, however when it comes to factory or dealer diagnostic tools and instruments - I have no resources. I'm thinking about changing over the distributor from another 318 I have that's a twin point Mallory, to see if this makes any changes. Without knowing what else this computer does though, I'm very much in the dark. Any electronics geniuses on this forum who can help?
Thanks again guys.
 

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I run the same year and engine as you, Aussieboy. I removed my fresh air pump after it siezed, but I've had no problems associated with that (removal of the valve you mentioned, the piping, and the pump, followed by an upgrade to headers).

A few years ago, I noticed that my truck was idling very high. I thought it was an advance problem, but everything checked out OK. Turns out, it was where I lived that caused the problem. Dust had worked into the throttle cable, and stuck it so it wouldn't open all the way. The result was a real rough idle and trouble starting because of flooding.

Another thing you might check is the electric choke. The choke on mine doesn't work very well at all, and sometimes will stick closed in colder weather. I don't know if it was a faulty rebuild or if it's just a bad carb.

Also, is your carb emission controlled? I don't know if it's the same for your carb, but I'm told that my 2bbl has plastic metering screws that were factory installed at a certain setting, and have probably just worn down over the years. The remedy? Drill and tap the old screws out and install new ones. That's what a Holley rep. told me.

Good luck in any case. Hope this helped.
 

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Discussion Starter · #6 ·
Thanks for all the advice Vegvisir. I have looked into my problems and think that it's a combination of several things - the computer which adjusts the timing and possibly a faulty EGR valve too. My service manual indicates the symptoms as being caused by a faulty "spark control computer", however without the diagnostic equipment like a dealer has, it's going to be pretty hard to determine if this is stuffed or not. I have a couple of other people looking into all options and with their help I hope to figure it out.
Ideally I wanted to get rid of all this anti-pollution crap anyway, and do what you have done and install a set of headers and twin system, to allow the motor to breathe more freely and increase power a little too. Catalytic converter would go too in this process, as the vehicle is old enough to get away with this here, without anyone questioning the system.
I've checked the carb and throttle cables and all seem to be fine. The truck was running like a swiss clock prior to all this, so I can only assume that the problem somehow relates to what was done by this ignorant mechanic's apprentice (welding shut the pre-heat valve on the exhaust manifold, rather than welding it open).
I'll keep you posted as to what I find out and how this problem is resolved.
Again - many thanks for your advice and input.
 

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Re-read your original post and found I misunderstood it. Are the spark plugs ok? You might do a compression test on all cylinders. You may have blown an intake manifold gasket from the excessive exhaust heat and backpressure. EGR valve may now be held in the open position from the exhaust back pressure. Could have a vacuum leak?
 

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Always glad to help out, Aussieboy.

Hope it works out as painlessly as possible!
 

· Aka Force Fed Mopar
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Worse case scenario, you could have warped the valves on that side, in which case you would either need another head or have that one redone. I would check the EGR valve 1st though, it would make sense that the increased heat and back pressure could have blown it out. And a bad EGR will make it run like that. You should be able to just unplug the vacuum line going to and see if it makes a difference. If that is the problem it should clear right up when you unplug it. I don't even run run on any of my trucks, I just bolck it off with a plate.
 

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Discussion Starter · #10 ·
Thanks again for all the suggestions and advice.
I've checked the EGR valve and it is working properly. I also re-checked the timing and it too is fine. I played a little with the carb adjustments and removed the needle and seat to check for dirt or blockage. Once I had done all this, I attempted to start the truck and it was a little easier but still not as it should be. I've spoken to a fellow Mopar enthusiast here and he seems to reckon that I could have somehow caused some damage to the carb when it was struggling to draw air in, as a result of the exhaust valve being blocked? Who knows??? In any case, I've decided to change over to a 4 barrel intake and 600 cfm carb, as the factory 2 barrel carb is not really the best item in the world. I had the same carb fitted to my 318 powered 71 Challenger and since upgrading to a 4 barrel and 600 holley, I've never had anymore problems with the ignition system, starting the car etc and now get better fuel consumption too.
I will be making the improvements next week, including removal of the anti-pollution crap, catalytic converter etc and also plan to upgrade the exhaust system to a freer flowing one. I will post back here once this has happened with a report.
Once again - thanks to all of you who took the time to offer advice and suggestions. ;)
 

· Aka Force Fed Mopar
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Sounds like a good idea. What city do you live in? I have an uncle that live down there, I think over by Melbourne.
 

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Discussion Starter · #12 ·
I don't live in the city (couldn't stand that). I live about 350 Kilometres south of Perth in Western Australia, which is the most isolated city in the world and about 2600 kms away from Melbourne. My nearest neighbour is 8 kms away and my local town is 20 minutes drive away has one pub (bar), one gas station a post office, small supermarket and a population of only 500. I think I know most of them too.
Not too many Mopar fans here and getting work done on anything mechanical other than farm machinery is a bit hard. Still it's far better than city life, as I can talk to most people here on a first name basis, I don't have to lock my car or look over my shoulder, people are friendly and genuinely mean what they say, when they ask you how you are. City life is okay I suppose, but not for me. I think you might call me an Aussie version of a "red-neck" which I would take as a compliment. Australia is the most urbanised country in the world, with more people living in cities than any other place. Our state, which covers 1/3 of the continent has a population of 1.9 million people, of whom 1.6 million live in the capital and only 300,000 people who occupy an area the size of all the land east of the Mississippi river, to use USA as an example.
 

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Discussion Starter · #14 ·
okay - problems sorted out finally...replaced the intake manifold with a four barrel, new Holley 750, found the distributor to be faulty too, so it was also replaced, as was the fuel pump. Man that was an expensive exercise, but finally she's running as good as, if not better than before. I also took the opportunity to ditch the catalytic converter and have the radiator core replaced.
Starts first time every time now. Uses a little more fuel, but that's okay by me. The 318 is a little tired, but should last me for another few years anyway.
Thanks for all the suggestions and advice.
Cheers from down-under!
 

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congrats! Glad it all worked out.

If your truck is anything like mine, it'll last for years and years...
 
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