Hi I have searched but didnt find a problem like mine.
I have a 96 Caravan with 75k miles 3.8 eng.
I am using a Innova CanOBD2 reader.
I have been having a problem with the engine stalling… maybe when I pull up to a light… go to give it gas and notice its died… restarts no problem … or driving down the road it just dies and as long as it is above 30mph it will restart itself or I put it in nuetral and restart.
I had an error of PO106 Map sensor and replaced that and that took care of that code.
But now I am trying to get it emission tested and before I can complete a drive cycle with only the EVAP monitor to complete it will stall and all the rest of the emission readiness EVAP, Catalyst, EGR, and Oxygen heater monitors go back to the not complete state. So of course with all the info gone … No DTC’s I am at a loss.
Anybody hear of a problem like that ???
I sure could use some help !!!
Bob
You MAY have an IAC (Idle Air Control) fault. Perhaps the control motor is acting up (Dirty) or the throttle body needs cleaning (Use a throttle body spray cleaner).
It seems to me that in order for the monitors to reset the ECM must be losing power. ven a momentary loss of power will reset all monitors and adaptives and the car will die.
~Michael
Use the Chlton’s, or Haynes, repair manual to check the sensors. Use a multimeter to check the resistance, or voltage, of the throttle position sensor (tps). Connect the multimeter to the terminal of the tps, start at IDLE, and slowly depress the gas pedal. The voltage should vary smoothly as the pedal is depressed. If there are voltage spikes, flat spots, or drops, that could be a faulty tps. Check the idle air control (iac) valve, also. Use a MAF spray cleaner. It could help. Also, use a throttle body cleaner.
I like that. I think you either have a short or a break in ECM main and/or memory power. Not having the wiring diagrams or ECM pinout, it’s hard to direct you any better than that, but I think Michael nailed it with his suggestion.
I’d agree with Dartman about the ECM, either power to it may be getting interrupted or the ECM itself may be failing, but I’d like a clarification of
“… or driving down the road it just dies and as long as it is above 30mph it will restart itself …”.
How does it restart itelf? What exactly do you mean by this?
Jay what I mean to say is…
Just driving down the road or freeway and it will just die and since it is an automatic transmission if it is above about 30 mph if you just wait a couple seconds leaving it in gear it will restart itself but if it gets below 30 then the auto tranny will disengage and you have to put it in neutral and use the starter.
Oh and when the engine dies all other accessories like the speedometer they all work ! ?
I havent found the location of the ECM in my Haynes manual yet… but I would guess in behind the fuse block… I read somewhere that there is a module of some sorts in the passenger side kick panel.
Now the MAP sensor code is coming on again… guess either the new one is bad or I didnt need a new one… better check volatges.
Yes Michael that does make sense.
Today I will use my Haynes manual and check all resistances and voltages I can find and check all the connectors again and spray the IAC and throttle body and check all electrical connections …although when the engine does die the speedometer and all other accessories still seem to function and since it is an automatic transmission if I let it coast while it is above 30 mph it will resatart itself…just so intermitent !!
and the bad part is now I am trying to get it to pass emissions but I have had it there 4 times and it says not ready so that is when I bought a reader so I would know it was ready… which hasnt happened yet !!!
Now the MAP sensor code is coming on again… guess either the new one is bad or I didnt need a new one… better check voltages.
http://www.autozone.com/az/cds/en_us/0900823d/80/1a/46/ba/0900823d801a46ba/repairInfoPages.htm This is a page from Auto Zone showing the engine wiring diagram. Click on Fig.6. As you can see, the ASD relay (Automatic Shut Down) controls power to the ECM, fuel injectors, and ignition coil pack. The ASD relay could be the cause of power loss. The horn relay (in the relay box, under the hood) is the same type as the ASD relay. Swap’em.
With the engine idling, use a stick to move the wiring about, under the hood. If the engine falters, one of those wires has a poor connection.
The ECM is “under the hood, driver’s side, front side of tower, mounted on the fenderwall”, says Auto Zone’s parts locator.
hellokit…
Thanks a heap…
I hadnt been to the Autozone site … what a site !!!
those diagrams beat the Haynes manual all to hell !!!
Thanks a heap !!!
Yes, the Auto Zone site is good for engine management wiring diagrams; but, the Haynes, or Chilton’s have wiring diagrams, of other areas of the car, which one may not find anywhere else (with the exception of the factory service manual wiring diagrams)!
I have an idea for an indicator light to check for power when one is driving: Get some 12 volt L.E.D.s from Radio Shack. Check for 12 volts at #16 terminal of the electrical connector plug for the OBD II scanner, on the bottom edge of the dash. Put one lead of the L.E.D to the #16 terminal, and the other lead to a ground (metal of dash panel). The L.E.D. should light with the ignition key ON. When you are driving, and the engine misfires, or stalls, watch the L.E.D. If it flashes, or goes out, the ECM may have lost power.
You could, also, tap into the dark green/orange wire coming off the ASD relay, and add an L.E.D., and place it where you can see it as you drive. If it flickers, or goes dead, that circuit has lost power (12volts).
Thanks hellokit …good ideas because the problem doesnt even get in the freeze frame data because it has been flushed so it dont show on the reader and the reader reads every 30 sec or minute… not sure of the timing.
Yes the Haynes has good trouble shooting… voltage & resistance readings but the diagrams are a little lame.
I am off to do the deed !!
Bob
In addition to looking at the main power to the computer, look for the keep alive voltage. There is a small fuse that supplies battery voltage at all times to the computer memory and accessories that require full time power for memory retention. If the keep alive voltage is absent, the computer will go through its self tests and store the information but lose it when the ignition key is turned off.
Researcher…
I saw that fuse and wondered if that was what that was for… like the memory battery in my computer !
Thanks
Bob
Unfortunately, the '96 models were plagued by more than their fair share of electrical gremlins.
Pull the IOD fuse in the power distribution center (PDC)under the hood and check for corrosion and tightness of the connection. Also check the two power leads into the PDC for corrosion and tightness.
Maybe a breakthrough…
I took the vehicle out this afternoon and it did fine then I took it out tonight to see if I could get the drive cycle to complete so I could get the caravan emission tested but within five minutes the engine shut off… I was doing a little over 30 mph so I shifted to neutral and restarted it and it came up with PO340 camshaft sensor so thats a new one !!! so tommorrow I will cleanup the connections.
Just dont know why that would cause it to drop the drive cycle info or maybe any code will cause it to want a new drive cycle … now that could be !!!
I notice that the camshaft sensor uses the same 8volt supply from the PCM as the crankshaft and speed sensor but my speedometer still works when that happens although it may happen for just a moment and maybe I wouldnt notice the speedometer wasnt working at that moment…Hmmmm