Dakota Forumz banner

1 - 12 of 12 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1
96 w/ 3.9L 4x4 auto club cab..


Bought about 3 years ago and I did a complete upper engine gasket replacement per mechanic suggestion. Also did tune up with new plugs, wires, cap, and rotor. New vac tubing, belts, hoses, grommets everything rubber. new pcv, breather.



All was running well but would get random misfire codes thrown even when I didn't fill the misfires. 301, 303, 305 so continued exchanging some more parts, coil, tps, cps, iac. Each time seemed to run awhile and sooner or later throw the misfire code again, finally about 5 months ago replaced all 6 fuel injector.



Finally seemed to be running more than a month infact about 5 months without a misfire code then while scouting for my hunts driving around at 10-15mph it stalled started back up and stall 2 mins later started back up and drove home fine.


That was the start of my down fall about 3 weeks ago. it progressed to randomly stalling coming to a stop and randomly starting right back up or taking 2 mins to start back up with smell of gas in the air.



Tested fuel pressure and that was correct and would maintain pressure when stalled. Replaced the IAC 4 days ago (I believe again because but couldn't find where I bought the last 2 years ago if I did) drove fine for 2 short 15 min trips and then yesterday didn't start at all and unfortunately I didn't have time to see why.



So went today to check and started right back up so I went for a drive and it stalled doing 50mph first time its stalled at more then an crawl or idle. It did seem to try to fight itself from dying and sounded like a couple pops as I floored the gas pedal. This happened 3 times each time I pulled off the road and it started right back up so turned to head home. It chugged once like about to drive and since it seems slightly better at higher RPM I went from Drive to 2 and about quarter mile or so went back to drive and made it home without dying.



I haven't replaced the MAP or PCM but figure everything else is roughly no more than 3 years old and less than 20k miles I don't have to drive far or much. Only codes it has thrown so far was the misfire ones and even with the stalling today it didn't throw a code at all.


So what do you all think?
Appreciate any help.
 

·
Registered
Joined
·
1,073 Posts
Step 0 - grab a copy of the factory service manual. (Hint: It's not a Chilton Dakota or a Haynes Dakota, but a Chrysler Corp. Dodge Division Dakota ... Bishko is the current publisher of the official books, but you can also find them used on Ebay, plus there's a few web sites with links to download.)

Step 1 - Get a competent OBDII reader than can handle the live data stream.

Step 2 - Ask the ECU what it thinks is going on.

Work from there.

RwP
 

·
Registered
Joined
·
7 Posts
Discussion Starter #3
I have the huge purple dealership repair manual...

My OBD II reader can do logs(haven't looked into how that works though) and I'm not buying a $500-1000+ drb tool to talk to the ecm

So something more helpful would be appreciated
 

·
Registered
Joined
·
7 Posts
Discussion Starter #4
Update:

So I thought I'd put a few of the sensors to the test with my multimeter.. I disconnected the connectors on the map,iac,tps turned on the truck and went to test wires for voltage and ground continuity first.

On each of the 3 wires sensors I got two wires with 5v and one with a fraction of a volt. On continuity I got no continuity to ground but 1 wire came up with 125-150 ohms to ground. Truck key in off I got ground continuity back and no voltage on anything like it should be...

Am I right to think the ECM is bad?
 

·
Registered
Joined
·
1,073 Posts
I have the huge purple dealership repair manual...

My OBD II reader can do logs(haven't looked into how that works though) and I'm not buying a $500-1000+ drb tool to talk to the ecm

So something more helpful would be appreciated
Don't need the DRB to read the live data if you can do logs; dig into that and do it.

Nobody mentioned the DRB; I said a competent OBD2 reader and read live data.

(That can be a $20 ELM327 adapter and Torque Free for that matter!)

As to your readings - you can't really read resistance across a live circuit, it causes the readings to go bonkers (which you noted!)

The ones that you can manipulate (the TPS, the MAP if you have a vacuum pump and can suck vacuum on it, etc.) should vary.

What you're seeing is perfectly natural with the sensor disconnected. You see the 5V supply, and you see about 0 (it's not actually 0 due to normal leakage on the input, plus a pull up resistor to condition it for open circuit usage).

Try measuring the input line with the sensor connected.

RwP
 

·
Registered
Joined
·
7 Posts
Discussion Starter #6
I'll test again in the morning with the wire connected but I wasn't seeing a little voltage on the input I saw 5v on the hot 5v on the input (without looking lookingat a schematic I couldn't tell you which was hot and which was input because the voltage was the same) and no continuity to ground on the ground.
 

·
Registered
Joined
·
1,073 Posts
Turn the power off, THEN check continuity to ground. And you could easily see 5V on the input; consider. It may have a 10K resistor from 5V to the input as a pull up, and your multimeter may have 10Meg input. It'll be so close to 5V it's not worth considering.

That's why you check it with the sensor connected.

Also, check ground continuity with the power OFF. Only.

Plus, where were you checking resistance to? Consider that at TTL current levels, 125-150 ohms is effectively nothing. See note about the resistance of the pull up.

RwP
 

·
Registered
Joined
·
7 Posts
Discussion Starter #8
Continuity was there with power off and the low omhs with power on so from what your saying that's good..

I guess I heard wrong I thought there would be no voltage on the signal wire when disconnected but did just see a YouTube video that showed the 5v only when disconnected as a good way of making sure the signal wire wasn't grounded.

So I'll start my sensor testing over again now that my information had been corrected. My ECM not being bad will be good news but not having a solution to my stalling issue will suck. Hopefully I find something in the sensors.

Thank you
 

·
Registered
Joined
·
1,073 Posts
Once again, grab a competent OBDII reader (and once again, a ELM327 Bluetooth/OBDII adapter and a copy of Torque Free on an Android device with Bluetooth counts!) and monitor the data stream; see what the ECU thinks is going on.

Or, you know, start firing the parts cannon at it. Kind of your choice.

RwP
 

·
Registered
Joined
·
1 Posts
I had this same problem. I found that the wires at my coil were not connected properly. I had replaced the engine and didn't realise that the connector at the coil was bad. fought that for about 3 months.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #11
Retested, map,tps,crank shaft, cam, iac, and I see were I went wrong with them being hooked up vs not hooked. Everything tested ok. Started the truck up went to wiggle and jiggle connectors and grounds plug wires and even changed the cap/rotor. It died once and only once wiggling the wires to the black connector going to the computer. Could not get it to do it again.

Drove fine for about 3 days and tonight died shortly after starting it before I got it into drive. Started right back up got to the end of the Street about 200 yards and died took some cranking to start it then would just die and start and die got it started for a 3rd time kept it reving about 2000-2500 dropped it into great done fine until the next slow down to pull into a parking lot and dried......

I had torque lite guess I didn't understand the log feature and learned something about PIDs but can't see where to get any or Dodge didn't share it's secrets I guess. But up graded to the torque pro version. Anyone have a bit of knowledge in what to select, PIDs, or anything of the sort to help me use Torque Pro to narrow my issue I'd appreciate it.

Ready to take it to a nice mechanic that's worked on my wife's car in the past but with it being random I rather not wait a week to heard he didn't find anything in the hour or so he takes to look at it.


I'll double check that connector on the coil it could be oxidizing or something I guess
 
1 - 12 of 12 Posts
Top