alloro

10.5 VDC at coil -- Notice it will even fire and run for 1-2 seconds. I replaced the coil just a shot in the dark. I did not believe it was bad but they were on a close out special of $20 versus the normal $50-60 and I figured, well, take a shot.

TDC -- Yes, I did have my finger in the spark plug hole so I knew it was the compression stroke .... then turned the crank by hand to get the piston at max height. It is almost impossible to get the piston to stop excatly at the top by using the starter. There are no timing marks on the crank pulley.

Starting fluid -- Yes, it has been sprayed with starting fluid before cranking, during cranking, and even as it fired for the 1-2 seconds. I also tried pouring gas into the intake before pullling the injectors.

PCM -- Yes, I agree about the PCM. I don't know 100% for sure the usedPCM is ok. It does not behave any differently than the original and that would seem to be unlikely if it was bad as it would have to be bad in exactly the same way.The seller told me it was working when removed from the auto. I don't believe I can get some one to let me try it on their vehicle but that would be a way to test both PCM's I have.

I have been reading some articles on the internet about the Dodge/Chrysler ignition system and how it works. These articles keep talking about the sync between cam positon sensor and crank position sensor. Of course you need the DRB tool to check and adjustthat. I do know there is an exact wave form required to get the engine to run. You would have to have a scope to check the waveform.

Let's just admit it --- THIS IS THE HELL VAN !!! LOL

Thanks again for the thoughts. It does make me think about any mistake I may have made in testing. I will keep looking.

There must be something I am overlooking or don't know about. Have to remember -- it is just a machine.

DB

 

Did doing this change the 'no start' behavior in any way? I mean even a few pops, backfires, few extra seconds of run time, anything?

 

alloro

Starting fluid - Anything I did with starting fluid or gas had no effect.No backfire, no pops, or anything I could point to. If I stretched, I would say it acted as if it were flooded.I can tell you this ---- when I cleaned the center distributor cap terminal and installed a new coil wire, the engine did run a little longer one time--- maybe 4-5 seconds and very rough but it did not backfire.Then it reverted right back to start and run for 1-2 seconds. No improvement with new rotor and distributor cap.

I am convinced it is getting gas and spark. I am also convinced it is at least roughly timed after comparing rotor position with the piston position.

I am just trying to think of what might be wrong at this point. I've run out of things to retest and recheck. LOL

Thanks,
DB [sm=dontgetit.gif]

 

Try sticking a penny between the throttle arm and the idle set screw to open the butterflies a little bit on the TB. Or something that is the thickness of a penny that will not fall off. Next, try starting the van. If the van runs or stumble starts, then the IAC is messed up. The penny trick repostions the TPS on the end of the butterfly valves in the TB and fools the PCM. [8D] You can test again with the IAC connector off and the penny trick to evaluate the engine running. If the penny thickness is gone, the van will not start as the IAC connector is off. However, don't drive around town with no IAC since it works with the PCM and the PCM to the O2 sensors. This is only a test.

If the IAC is the problem, then replace it and CLEAN the IAC ports and the IAC slot under that port in the TB.
https://dodgeforum.com/m_525409/tm.htm

The TPS is basically a potentiometer in general terms. I've had one stick inside once. Taking it off of the TB and easily rotating the tang from start to full travel loosened the grim inside of it. It then worked again without an issue.

You can connect the TPS to an analog ohm meter (which is much more sensitive than what is needed), then rotate the tang on the sensor and watched for resistance to increase with increasing rotation. It's really interesting to see if there are any sudden drop-offs or spikes, which would tell what part of the TPS potentiometer was bad.

Remember, the TPS, MAP, and IAC all work together so it's a pain to mess with them. [&:]

When my vehicle's IAC was acting up, the vehicle threw no codes. It drove me nuts hunting the problem down. That's why I wrote up the "How to Clean the IAC" thread.

 

stev

Thanks for the comment and suggestion.

IAC ----Even though I have had no problem with uneven idling,I took your advice andused a penny to hold the butterfly open slightly. I then tried to start the engine. The engine fired and ran for about 3-4 seconds and died. 5 or 6 additional attempts to start the engine the same way,it fired and ran about 1-2 seconds and died - same as before. I checked each of the two resisters/coils in the IAC. One had about 51 ohms and the other about 54 ohms. I removed the IAC and cleaned the pintle and the opening then reinstalled. Tried to start the engine. Engine fires and runs for about 1-2 seconds and dies.

I assume one of the coils is to move the pintle and the other is to sense the pintle position. I do not know for sure. I may need to go back and check and see if the resistance changes as the pintle is moved to be sure a varying signal is going to the computer. I would think that ifthe computerneeds a signal and is not getting one, -----> CODE.

I don't see how this could keep the engine from running unless the computer just needs to see an input from the IAC. As far as I know it only comes into play at or near the idle speed. Of course, I am so baffled I am not sure I am thinking straight.

Got any other thoughts ??? [sm=thanx.gif]

Thanks,
DB

 

This is a long shot and I don't know if it applies to these Dodges or not. Other vehicles that I've worked on that fired and died had a bad oil sending unit. The reason being, that once the engine fires the PCM looks for oil pressure. If it doesn't see any it shuts the engine down to protect it. This safety is bypassed during startup for the obvious reason of there not being oil pressure at that time. If your oil sending unit is bad and if this safety is built into these PCMs, then it would explain why your engine will fire for a few seconds then quit. Most vehicles that have this protection use either a 2 or 3 wire sending unit. Single wire sending units definitely do not have the safety feature.

 

DB,

It seems that you're on the right path. Something that's not being sensed right with the IAC, TPS, MAP and O2 sensors.

Did you try getting readings from the TPS as mentioned above by turning the tang and checking for a skipped reading?

As for the IAC, did you clean the slotted port under the IAC port hole inside the TB? It's not that easy to locate, but it's there. That little slot makes or breaks an engine from starting and keeping an idle. If by chance it's really gunked up, then you have a no-start without codes. I've been there and done that already.

Since the penny trick allowed the engine to sputter run for a few seconds, you understand that the spark is there and the fuel. Some how the air mixture is being blocked for a steady running engine.

Just out of thinking out loud, there is a vacuum hose that connects to the TB right betwix the MAP sensor and the TPS. Is that hose intack with no leaks? Of course in time, the emission OBD-II would pick this up as a small leak.

Another no code start ...
http://wwww.dodgeram.org/tsb/1997/08-21-97.htm

Does this van have an OEM Theft/Security VTSS system?
http://wwww.dodgeram.org/tsb/2000/08-24-00.htm

Was the battery cable pulled off while the engine was running prior to this no start condition?

How are the wire connections to the PCM? Any twisted or broken wires?

What about the ASD relay?
Solving the mysteries of Chrysler ignitions: (read every page of this article!)
http://findarticles.com/p/articles/m...05/ai_n8942314
Here's one snipet from it ...
"...ASD Relay. When you perform a diagnosis for a no-start condition on a Chrysler vehicle, remember that the ASD Relay will not activate without a crank signal. Many techs waste time trying to figure out why there's no power at the injectors, coils and other components without manually activating the relay. The relay can be activated using a scan tool and Chrysler's Actuator Test Mode (ATM). In fact, a scan tool also can be used to verify the system's ability to produce spark. Since the ASD Relay powers up numerous circuits, components that don't seem to be related to the ignition system can cause a no-start condition. On some systems, for example, the oxygen sensor heater elements are switched by the ASD Relay. So a shorted 02 sensor can lower the voltage available to the ignition system to the point where the engine won't start. Remember to check the available voltage at the coils) while the ASD Relay is activated and compare it to source voltage. By the way, Chrysler checks the 02 heater circuits by activating the ASD Relay after the engine is shut down. Note that this relay also supplies power to the fuel pump. It stands to reason, then, that if you're working on the fuel system, you'll want to disconnect the battery before cracking open any lines! ..."
Hope something here helps DB! [&:]
Peace!
Stev

 

Stev, you just knocked loose a memory.
Once when I was in Baja an aquaitance with a 97jeep cherokee ran his battery down completly.
He had a jumper pack, and each time he would start it, it would run for 2 seconds and die.

Long story short, when a good mechanic got to the vehicle, after tinkering for a few minutes,he asked if there was an alarm system.
"yeah, but I never use it"
The mechanic asked for the key, and closed all the doors. Locked them with the key, unlocked them all with the key, the vehicle started and ran fine.

Running the battery all the way down just reset the alarm/ engine kill.

I witnesses this one other time with a chrylser in Baja when the owner ran down the battery, and then his buddies battery. They asked me for a jump. I brought my battery jumperpack and did the key trick. They were so happy I got all their leftover beer, liquor and food.

 

alloro ---- Oil Sending Unit

A pretty smart idea if you ask me!!! I think this has a good chance of being the problem because it fits the pattern of what I consistently see. I located andstarted checkingthe oil sender unit tonight. Pulled the connector off and checked for continuity per my Chilton manual. Per the manual:

A ---> Continuity (no resistance)at 0 oil pressure ------ and
B ---> open (max resistance) at about 10 psigand above

I found an open circuit at 0 oil pressure ---- Therefore, bad sender unit per above right? Well maybe -- I pulled the the sender unit out and hooked up to my air compressor. Pumped up to about 60 psi and bled off the pressure slowly. Here's what I got --

60 - ~10 psig ----> open = max rsisitance- agrees with manual
~10 -~ 2 psig ----> closed = no resistance- agrees with manual
~2 - 0 psig -------> open = max resistance -disagrees with manual

I am not exactly sure how this sender and gauge work. I have a combo oil pressure gauge and idiot light for oil pressure. I am concerned that the open circuit from about 2 to 0 psig may be just for the idiot light. I have to dig into this some more. May have 2 sender units -- 1 for light and 1 for gauge.

Ok, time to try to trick the computer by simulating a good oil sender unit. I used a wire to close the circuit on the oil sender leads ( A above) then fired the engine and pulled the wire out (B above) to see if the engine would run. Tried this several times but no luck.

So maybe this oil sender unit is not bad. I'll have to check again.

Thanks for a good idea alloro!!


stev I am out of time for testing tonight. I will reply ASAP.

landyacht318 ---- I wish it were that simple but I do not have an alarm system. But you have rasied the question --- Can it be that I just need to reset the computer ???I thought that just disconnecting power from the computer was all that was needed to reset it. Maybe alloro can answer this.

Nite folks and thanks for the input.
DB

 

What the heck is going on with this site lately. I post replies and they show up in the list, only to be gone the next time I enterthe thread?

Well here goes nothing, again...

At zero oil pressure you should have continuity to be able to turn on the idiot light, not an open. Also, I'm having difficulty in following the results you posted because you don't mention how your meter leads are hooked up.