It seems that every time I disconnect a sensor this SOB runs fine for a day/few hours and then goes back to the original no-run-no-idle state. I don't dare drive it any length of distance least I want to walk home.

Weird thing, if I manually skip the 3000 to 1100 ohm range it seems to run without a problem. But I never went any distance and disconnect the potentiometer to set ohms....which prob put the computer back in learn mode?

I've replaced, O2 sensor (2nd one in the mail), cts (3 times), iac and tps.

The only thing I haven't done is use it for target practice on a mortar range, but I'm real close.

Once the engine temp is closing in on fully warmed up (190) it runs just fine.

 

Do you have a way to do some data logging?

 

no. I'm 1/2 tempted to get a BT obd2 reader and install the Torque app. but not sure about dropping the money if it doesn't work on 98 rams.

I'm also curious about the crank p sensor, but I would think if it were going, I'd have the same issues even after a sensor was disconnected or battery disconnected.

Disconnected O2 sunday afternoon, started and ran great around town for 30 min and then idled for 20 min later that night. Yesterday was -13 and started on the 2nd cranking, tried to on the 1st. So I thought all was related to after market o2.

was 15 this morning, wouldn't start until the 7th or 10th cycling of the key. Idled 5 min and then reved twice and died.

So frustrating!

 

I wouldn't condemn the computer just yet. PCM failures are more rare then people believe. There are some tests you can do to check the PCM but I don't think you're there yet.

 

Torque is awesome. Works amazingly. Use it all the time.

 

I guessing the only thing I HAVEN't swapped in this pile of rust is the crank shaft position sensor...but I really hate throwing 80$ in the fire if doesn't do anything.

Will Torque give me any information on the CKPS?

 

You may start by explaining what exactly is the issue/problem. What you have replaced so far and when was the last tune up? Any codes? If you dont have a scanner take it to one of auto part stores that will read it for you. Need to know what codes you are getting! From what i understand it's not starting-running when cold. ???
Do you hear the fuel pump priming the system? How many miles on it?

 

I don't drive this thing often, so the mileage is still pretty accurate in my sig. 176K

In the winter months, when temps start dropping below freezing it does not run worth snot when cold. Most days if it's below 15f it will not start before the battery is drained. Will not idle from cold start longer than 5-7 minutes. Will not stay running when driving unless I keep feathering the gas during a stop, at cruising speeds of 50+ it will buck and shutter. Until full operating temps have been reached. Once the thing is fully warmed up, runs just fine. Same for spring/summer and fall months.

I have NOT done the plenum yet, don't know if I'll keep this truck long enough to justify the work/expense. Fuel pump is very noticeable when you turn the key on. Every time. Can still hear it when the truck is running.

Last month I replaced Cap and rotor, wires, plugs (champions) and coil. Have replaced (in the last 12-18 months) EGR valve, throttle position, Idle Air control, Upstream O2, Coolant Temp sensor and battery. Thermostat was replace 2 years ago trying to get heat in the cab.

I'll have to run down and have code read...after I plug the O2 back and clear the codes.

When it dies it will diesel and struggle. Sometimes longer than others, if I add just the smallest amount of throttle it will stay running.

When I muffed up the plug the other week for the Coolant temp sensor wouldn't even run when fully warmed up...have fixed that.

Prob would have been best to continue with the last post....cold blooded SOB.

I thought i was onto something with O2 sensor and then the coolant sensor, but it seems the computer goes into limp mode for a short period until the poo hits the fan again.

 

That's either poor mixture, or symptoms of a failing crank sensor......

Have you pulled the plug off the PCM, and made sure all the connections are clean?

Yours is a 98? Erm, you shouldn't even HAVE an EGR valve....... that went away in 96. Where is the EGR valve that you replaced?? This needs to be figgered out before anything else happens.

 

Yeah, after thinking on that for the afternoon, decided it's not the EGR valve...wrong vehicle. Did massive tune ups on 3 diff cars in the last 5 months...they all tend to look the same after a while. Grease and bloody knuckles, fingers, forearms...

I'm starting to think crank shaft sensor as well. what ever the issue is with the stupid thing only appears when things are cold and contracted. Might explain why there are issues from frozen to being thawed out, but not during any other time? Those straws are getting awfully short.