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For a while now it has a no load skip in the engine, and i just replaced the cap rotor, wires and plugs and still does it.
It idles fine, steady as a rock and accelerate hard well to, but in a 45 mph cruise, just maintaining speed there is a very mild skip. Sometimes I think it's just the NH roads surfaces.
In 06 when I bought it, it needed a new primitive ECU, which would run for long enou7gh to get 8 miles. Then it would heat up and quite dead. After waiting for a ECU cool down it would run an other 8 miles.
The replacement was grim and would only run a few seconds time. The replacement for that was good. These were rebuilt ECU units.
At that time I replaced the distributor complete as it has a worn shaft and the rotor was floppy. I just lubbed that too.
So all I have is another apx 15,000 on that tune up and have just done another less the fuel filter this time so far. It got a new air filter too.
What on Dodge 318's causes a No Load skip?
I am thinking a float bowel problem at this point.
I think there is nothing wrong with the ignition, and the carb is either leaking after accelerating the engine and going to a no load cruise mode, or a similar like leak is causing a overly rich condition as a bead of fuel not 'Atomized' falling into the intake manifold.
There could be a stuck float, a fuel logged (Like water logged) float, a bit of crud at the needle and seat inlet, and or too high of a float level for some other reason.
I just don't know the 318 real well, but I know it well enough, to hunt down this issue and nail it.
There is the possibility that there is a Dodge quirk I don't know though. Or the possiblilty that the coil is going bad, but it doesn't seem so.
I might have to vom the wires yet....... Be easier than tearing into that carb.
I removed the Champion plugs I had in there for 15,000 miles and they all have a near perfect burn. I replaced them with AC. I saw no tracking on the cap and or the rotor either.
In your opinion what brands of parts does 318's like best?
The wires are yellow Accel in 10mm diameter. The cap is Accel too. Once that brand was top notch, but it might not be as I hear it anymore.
There's such a wide range of possible failures here ...
I'd be starting out the diagnostics with my 'scope (currently a Snap-On Counselor 2) in the shop along with a vacuum gauge on the intake manifold, just to see if there's anything obvious that shows up.
Absent a failure showing there, then it's off to the dyno ... I mean the streets, where you can replicate the problem with the 'scope in it's 12v powered portable mode. I'd mostly be looking for an intermittent ignition problem, although I'd still be watching that vacuum gauge during the skip mode at 45 mph.
While the 318 is a very sound engine ... I'm wondering if this motor has been overheated or had some other mechanical issues in it's service life? Possible intake manifold leaks at the manifold or at some of the vacuum hoses, or the carb base gasket area?
If it's a carburetion issue, I'd associate this type of soft miss with a too-lean condition from the carb. Which wouldn't be a heavy float, causing a high fuel level in the float bowl and too-rich condition. Perhaps the carb has some passages slightly plugged up with stuff through the years, and simply needs to be kit'ed after a thorough soak and blow-out?
The ECU's you've been buying were not "overhauled", but only "repaired" for the specific fault that was found. Discrete components and circuit board repairs would have been done, but only to the extent that obvious problems were found. That's a far cry from an "overhaul", where all likely failure components are replaced, even ones not found to be a problem at the time of inspection, and the circuit board is completely re-soldered to eliminate any cold solder or failed solder joints. Part of that process would be to either test run the ECU in a vehicle or to use a computerized test process to "burn in" the ECU and verify it's correct functioning. No way an "overhauled" ECU would be released for sale with a 7 second service life out of the box before failure ... take it from somebody who was involved in rebuilding Bosch and VDO electronics for many years. Which leads me to wonder if there still isn't a problem in the exchange ECU that you've got installed now; the "dyno" test might reveal this as the problem area.
Absent having a 'scope that will let you duplicate the failure mode, you're pretty much stuck in guesswork ... Outside of VOM'ing the ignition wires, you might want to reinspect the rotor and cap, and take a real careful look at the distributor. If possible, I'd get that distributor into a test stand and be sure that it's performing within specs; the advance curve may be dancing around at the RPM at 45 mph and causing the surge/miss, too. You'd also want to go through the carb for a fishing expedition there, too. I've no experience with Accel wires or ignition components, but I've seen them used at the "tuning shops" in my area, and I don't believe those guys would use stuff that wasn't up to snuff.
Your spark plugs are pretty comparable for a carb'ed engine use ... I don't believe that a stock street 318 would be that sensitive; it's only when you get into really high performance applications or in FI systems that can deliver a consistent lean mixture that one 'plug might show significant differences in a given engine. "clean" 'plugs without a lot of build-up and a clean tailpipe suggest a lean mixture misfire and not a "too rich" condition ... where the excess fuel would carbon up the tailpipe.
One other possible tactic for proving an ignition cap/wire failure ... use a spray bottle of water at the ignition wires and boots. A trace failure there will yield arcing and an enhanced miss when a mist hits the wires .... it's an old Lucas trick from before 'scope days, but it was an effective diagnostic tool. A "weak" insulation will show up pretty quickly. A lean condition in cruise mode at 45 mph is a tougher load on the ignition than the rich mixture when the accelerator pump is adding fuel or when the engine is at an idle load. While the ignition coil for this vehicle shouldn't be a failure point, it wouldn't hurt to spray it too, just to see if it's arcing under the higher load.
Thanks Sun..... makes sence. No access to a scope anymore, I can wish.
Lariat In cruise, just staying at say 45 mph, in a 3/4 ton van on the level is the only time I sence a mild skip. There is no load on the engine to speak of, just keeping that 45 mph. I can detect no skip getting moving, or passing, or going up hill on NH mountain roads a bit, and it idles fine.
That's a no load skip. This is so mild it might be the road surfaces around here. There is no place not cracked and patched from frost heaves.
Sun, the ECU came in 06 when I first bought the van in Ar. I needed a rolling bed room. That 3rd ECU came in about the first 2 weeks of owning the van. The ECU orginal in it to me went 8 miles, many times trying to get the van to the camp ground and then back to the dealer. It took aout 30 minutes to cool and then run another 8 miles.
The dealer had a farm kid install the 2nd ECU, and i watched. That ECU would just start the vehical and then quit all spark. They left me like that.
At that point i removed the entire engine harness, all of it, and test that wire for wire. It proved sound. Next I tested ever component and they all proved sound too. I don't recall any skip back at that time, and drove to New England a rather round about way taking another apx 120 days or so.
I was pulling a 12x6x6 enclosed trailer with camping gear, my 01 Nomad, and the Nomads little trailer, and all over Ga, Tn, and Ky where it is as hilly as here in NH.
The plugs i took out were champs I put in back in 06. They all had a nice light tan burn, didn't look to need replacing, but the vintage of 86 to me means 15,000 is about it.
This other set of plugs is less than 1 week old, and I figured the skip was from a tired plug.
It may be a bit too lean, and the pilot mix screw might set that up better if I am too lean a smidgen since this condition should be with in idle low RPM cross over.
The plug color picture is at dead idle too.
The ECU has a sticker calling it rebuilt. This is one funky ECU too, as it has a vac retard unit mounted to it. Dodge does some weird stuff if you ask me. Also this is a fire wall mounted ECU. I don't know if this came before or after the air filter housing mounted ECU.
No where can I get any diagram of what's inside the unit, so my comment on a bi-metalic switch is a wild guess. But it acts just like that.
I don't think the engine was overheated, but I have never had it opened up. I am certain the milage was 15,500 when i bought it, but at first thought it was 155,500, which would be more typical of a 86 van by 2006. I am not real familar with rust free vehicals, but the proof came to me when I was doing rear brake shoes and it looked almost new still, and so did the rubber pedal cover. I know these can be changed, but even the backing plates looked factory new, as well as the return springs still in paint.
Converstion vans don't see any hard work so far as I can tell.
I like the term soft miss too, and it could be just that. I will go over all the vac lines and look harder at the carb base gasket(s) That is the kind of info I was looking for.
I can do the misting test and just yesterday mentioned that to another poster on CD.
I find the best way to get the engine cover off is to remove the passanger seat completely. More so now that the interior is all brand spankin' new.
In a moment I am going to start the new cloth on the door skins. This is all home made, no pre-fit parts. Pretty conservitive too.
So you have a 25 year old 318 with an original 31,000 miles on it. Obviously, it sits a lot. I'd suggest putting a vacuum gauge on it and take a look. If the gauge is bouncing, you probably have a stuck valve or a valve that's not completely sealing and it shows up as a miss or slight miss under load. If that's the problem, and there can be an endless number of issues that mirror this situation, I would suggest changing the oil and using the new G Oil in 5w-30. It's the only real polyol ester based oil on the market. It has incredible solvency and would clean up the accumulated sludge from all of the sitting. Contrary to popular belief, oil itself does not sludge. In previous years the sludging was caused by VI polymers condensing out of formulation. With todays oils that no longer an issue. Water, or condensate is the major issue today. FWIW, this G Oil is not good at handling condensate. You'll need to use the vehicle at least 30 minutes every time you start it to relieve the moisture/condensate. Normally if the ignition is the issue, it happens at high RPMs where the ignition system is stressed, not at low RPMs. You might also check all of the vacuum lines and make sure there are none leaking. You can check these lines with an unlit propane torch. When running the torch around the lines, if the idle jumps up, you just found a leak. I'd also suggest changing the PCV and use only a Mopar part. Fram parts, if that's what's on it, may be the issue. They're about as scientific with their parts as rocks, crud at best and cheap.
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