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Discussion Starter · #1 ·
I do not know what the "Art of Diagnosing Engine Problems" is. Maybe some of the great people here know or have a theory. For myself, I feel fortunate to have found this forum (one of many forums on the web concerning Dodge vehicles) and after lurking around reading post after post after post, feel like this is a place to find solutions. However...

...What is the proper way to diagnose an engine problem here? Search and read all the posts that come close to the problem or problems? Whoo-boy, is that a bunch of work and during the search-and-reading, one can get side-tracked far away from the direct path. I'm not complaining. Just trying to learn how to diagnose problems on this or any forum.

My problem: stumbling engine (intermittent struggling for fuel)
Suspect: fuel pump, fuel filter, injector or injectors.
What we've done so far: replaced fuel filter, cleaned throttle body, verified a healthy fuel pump and fuel regulator. New plugs-wires-cap-rotor, EGR-PCV. Also, we are running fuel injector cleaner in with the gas (will run a can through 3 tanks).

This is a 318 Van (1993 Elk Conversion) with 163k miles. Will be flushing out the cooling system today...block, heater, etc. Will replace the thermostat too (195 degree).

Starts great each and every time. Runs smooth at idle and highway speeds. Seems to go into stumble mode around 35 mph (going to flush and replace transmission fluid too).

Gentlemen, I'm one to take a logical and systematic approach to diagnosing and fixing this or any engine problems. Me and my mechanic have a bunch of common sense to throw at this issue. Thanks to everyone here who knows how to diagnose engine problems.
 

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The stumbling around 35 mph would be more like that the Torque Converter Clutch Lockup is not engaging properly. Or if you are just at 35 mph when the stumbling occurs without trying to go faster you may just be feeling it lock up as it should do.

When the TCC Lockup happens the Engine RPM will drop a little, is that what you are experiencing? Also if you mph speed goes up and down between maybe 31 to 37 mph you may experience the TCC Lockup engaging and disengaging.

Changing the tranny fluid may or may not help, but would not hurt to try it.

The art of engine diagnosing is not easily explained, but the basic understanding of how the engine, transmission, drive lines, axle, brake system plus the electronic engine management and the newer transmission management systems work with each other must be taken into account. Also to take into account is the older (pre 1982) non computer vehicles verses the 82 and newer computer controlled vehicles. As the years progress from 1982 the Engine Management Systems have gotten better but with more electronic sensors that can play havoc in fixing them. Having the best discription of what ALL is going on when there is a problem helps alot also.

In my case I have a 77 Impala, no computer, simple system-it needs fuel, spark, compression-have all of these and it will run. Very easy engine to fix. My 97 van has the OBD-II computer management system with emission monitoring to help keep the air we breath cleaner. When it has a problem one thing to check first is the PCM for any codes, then look up what causes the symptoms that are happening and test all components until the right one that needs replaced is found. Sometimes that can be a headache of its own.
 

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Discussion Starter · #3 · (Edited)
Thanks.

The stumbling can occur around 35 and 65-68 mph. It is an intermittent problem.

Yes, we have our eye on both the injectors and the TCC as to the cause.

I'm not much into the codes at this point. I've disconnected my battery too many times and fear that all codes have been cleared. Plus, it seems that after reading through many, many posts here on this forum, chasing down codes is not an easy path to the solution. But, what do I know? I am a pre 1982 amateur mechanic.
 

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Does the transmission have lockup? ... not all did.
A transmission with a 3 terminal electrical connector above the shift and throttle linkage is an OD type with lockup. 2 terminals has OD only without lockup.
 

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Discussion Starter · #5 · (Edited)
Yes, it has the lockup.

Just completed a cooling system overhaul. Flush, flush and more flush. Replaced all the hoses and the thermostat. Pulled temperature sensors and cleaned them before reinstalling. Flushed heater core.

We will be flushing the transmission tomorrow.
 

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Discussion Starter · #6 ·
We may have this problem diagnosed. TORQUE CONVERTER SHUTTER may be it.

Found this web site: Allpar.com . Boy is this the site for diagnosing problems.
 

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I once suffered from TC clutch chatter but the vibrations/ shudderings happened only from 48 to 58 under light acceleration. A500 tranny. Overdrive and lockup.
Under Harder acceleration the lock up would not try to engage until after 60 and there never was a shudder.

A flush with ATF +3(at that time) cured it.

There is a bunch of very knowledgeable people at allpar, but you can't beat this forum for b van specific issues and experience.

After flushing your tranny, I'd recommend going a little further and drop the pan to replace the filter. The flush might plug it up and cause failure. Install a drain plug.
 

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Discussion Starter · #8 ·
Thanks. Good advice.

Went to get a flush of the tranny. All the local shops around here hook up a machine to the return transmission line coming from the radiator. This machine flushes and fills.

We asked each shop if the machine will fill with the proper fluid. All said yes. We further asked about ATF+4. None of the shops could confirm the type of fluid. So...we did not do a tranny flush today.
 

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Can you confirm your problem by unplugging the connector thus disabling the TCC and seeing wether the problem remains.
Although you just replaced it, EGR would then be my next suspect. I just got off a long merry go round thanks in part to a so called "new part".
 

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ATF+4 can be used... It's a compatible replacement and is a synthetic rather than a synthentic blend that ATF+3 is... It will withstand higher temperatures which is added insurance. It does cost more though.
 

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Thanks. Good advice.

Went to get a flush of the tranny. All the local shops around here hook up a machine to the return transmission line coming from the radiator. This machine flushes and fills.

We asked each shop if the machine will fill with the proper fluid. All said yes. We further asked about ATF+4. None of the shops could confirm the type of fluid. So...we did not do a tranny flush today.
Wise Idea. I paid the extra to have mine done at the Dodge dealer so I was sure they would use the correct fluid.

There's Something to be said for dropping the pan changing the filter, and adding a drain plug. Then easily replacing 4 quarts at a time. I like to let it drain overnight, and undo one of the lines at the radiator so that more fluid drains out.
 

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ATF+4 can be used... It's a compatible replacement and is a synthetic rather than a synthentic blend that ATF+3 is... It will withstand higher temperatures which is added insurance. It does cost more though.
I think he was saying that the local shops that do fluid flushing could not confirm that they would use ATF+4; that's why he didn't get the flush done.

In general, they do not use ATF+3 or ATF+4. They use an universal fluid and put in an additive that's supposed to 'make it the same', but it isn't even close.


That's what we did after we had to rebuild ours (thanks at least in part to the PO getting a flush done and the shop putting in the wrong fluid - and not changing the filter). A drain plug is a wonderful thing and is the first thing I do on every vehicle I buy.
 

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Discussion Starter · #13 ·
Went to the local Jiffy Lube to inquire about the tranny flush/fill they do. They use a universal fluid with an additive to make it ATF+4. Also, I suggested to them that it was NOT a flush. Rather, it was a suck all the old fluid out and replace with new fluid.

The owner did not like my reference to his tranny flush (calling it a suck-out and refill).

I left.
 

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Interesting that they take the Dexron/Mercon and add the "additive" that magically make the fluid ATF-4. I do not know how they can take a standard petroleum fluid and make it full synthetic by just using an "additive".

Sounds like the Dodge dealer and/or just doing it yourself and adding the drain plug for future fluid changes is the best way to go.

And you are right they do not even try to clean the system, just change the fluid.
 

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Let it drain overnight wth the valvebody lossened a few turns and most of the fluid will drain.
If you think an additive could make a dinasoar oil synthetic, you would be fulling yourself.
 

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Discussion Starter · #16 ·
Problem Solved!

We ran a can of Injector Cleaner through the throttle body (drip system) for approximately 30 minutes. Also did a transmission flush/fill. This B250 Van runs real smooth now.

We've tested this van for at least 50 miles. No stumble at any speed. No shudder. Smooth acceleration. Transmission seems to shift properly.

My opinion at this juncture is as follows: This van with 163k miles just needed everything cleaned, flushed and freshened up. We bought this van from an old retired couple who claimed that it had been maintained. He even had records. However, all that he did to maintain the van was change oil every 3k or so. The tranny and cooling system were never touched (could not find records in his pile of records to prove maintenance was done).

It's a good thing that we paid very little for this van. We've spent approximately $500 so far going through the motor and suspension, upgrading and cleaning up things.

Final note: We will be running a can of Sea Foam Injector cleaner in with the gas on a regular basis. And only premium gasoline for this van.
 

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Final note: We will be running a can of Sea Foam Injector cleaner in with the gas on a regular basis. And only premium gasoline for this van.
Good thoughts here.

Use a can of SeaFoam every other oil change or every other third oil change. That would be the best method for keeping things clean and keeping the cost down per can.

Also, forget running with premium fuel. Most of the fuel stations have additives in the higher octane fuels. Mobil and Shell mix these in to drive your engine clean, per their slogans. Overall, you get less real fuel content paying at the pump for premium VS using mid-grade 89 octane. So, thinking about the value, cost and saving while still having a good share of octane, mid-grade is the winner.
 

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This ties in with the topic of differently branded stations getting there gas from the same local fuel distributor. I believe the Car Talk guys said that each brand added good stuff AFTER getting it from the distributor. If that were true, it would mean each tanker load needed to be treated by the driver. That would open up a wide door for sloppy quality control and/or cheating by a particular company....
 

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Interesting that they take the Dexron/Mercon and add the "additive" that magically make the fluid ATF-4. I do not know how they can take a standard petroleum fluid and make it full synthetic by just using an "additive".

Sounds like the Dodge dealer and/or just doing it yourself and adding the drain plug for future fluid changes is the best way to go.

And you are right they do not even try to clean the system, just change the fluid.
Magic snake oil. My opinion. :gr_patrio
 

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Discussion Starter · #20 ·
Not to start a "forum brawl," but I retired from a Chevron refinery. Made diesel, gasoline and jet fuel from sweet crude oil for many years. As a result of what I experienced during all that, I would not run anything but premium gasoline. Cleaner, more MPG and better specs than the other grades.

Many times our lower grades were mistakes that had to be blended with premium just to bring them up to spec.
 
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