map and vss codes

[NAJ]

All of your readings are in range. The only thing that seems low is Baro Reading. It should be reading whatever Barometric Pressure is in your area.
With the Key On Engine Off and the Scanner Hooked up Wiggle and Tug on the Connectors and Wires at the Map and see if you get a change.

[NAJ]

I just realized you said Map Pressure is reading 11.31" HG and Vac going to Map is 18" HG, the Controller obviously is not getting correct Voltage or the Controller is Faulty. Backprobe the Signal Line and Sensor Ground at the Controller to see if you are reading the same as you were at the Map Sensor.

[rtcabal]

well, i started tracing wires and checking continuity yesterday. (i'm going to do this by memory): the 5v wire went straight to the smec, and it looked good and tested fine; the map signal wire goes to the throttle body sensor and the smec, both checked out; the ground goes to several other places, including the vss, for which i'm getting a code. unfortunately, we had an impressive storm blow through chicago yesterday and i didn't get to finish. hopefully i'll know more this weekend. going to try getting the vss real clean, too, as the harness had some moisture/gunk.

i'll also double check that 11.31'' reading.

anything else i should do? this is quite the conundrum.
thanks again for taking the time to help out.

[rtcabal]

here's an update, i hope it helps.

i traced the ground from the map, thus exhausting map wiring as a problem (right?). the ground is common to many sensors: vss, coolant temp, distributor, etc. i checked (with a diode tester) continuity and made sure that every wire was visually acceptable. is there more i should do in this department?

i hooked up the scantool and went through the 'sensor test mode' some more. here's the readings i got:

mode/ abbreviation/ description/ reading

04/ COOL/ coolant temp (volts)/ 3.8
04/ COOL/ coolant temp/ 145 (and climbing)
11/ MAP/ map pressure/ 10.8-11.3
11/ MAP/ map voltage/ .8-1.5 (idle-2k rpm)
11/ VAC/ vacuum pressure/ 17.411
12/ BARO/ barometric pressure/ 28.212
13 /BARR/ BARO read update/ ^same^

i included the coolant info because my gauge hasn't worked for a spell (prior to this problem), though i find the info the scantool reads to be logical.

any ideas where to go from here?
Edit/Delete Message

[NAJ]

Right now you have me scratching my head.
The only thing I am seeing is that your Barometric Pressure reading still looks low. You say the Controller is reading 28.21 and I just checked your local weather and Barometric Pressure is 29.95.Unless the scanner is reading in a different formula than conventional pressure readings this is not correct. I tried to Google for info on Barometric Pressure but you have to have a Masters Degree in Mathematics to figure it out.
The Controller gathers Baro readings with the Key On/Engine Off and then compares this reading to Manifold Vacuum to get a "Manifold Absolute Pressure". It upgrades Baro readings under "No Load" driving conditions.
If Baro is incorrect Fuel and Timing Control will be off thru the entire operating range.
Right now we need some more ELECTRICAL GURU'S to chime in and see what I am apparently missing.

[formulamd]

I had the same problems with my car having map problems. I traced my wires and had a solid 5 volt reference. Along with a new map sensor and still have the map sensor 13 code. Turned out that the smec was faulty. You may want to make sure you have all good grounds and trace every wire back the the smec before you do what i did and buy a smec.

[NAJ]

I agree that is a very good possibility.Flow Charts lead you through checking the System and when the Wiring and Sensor checks OK the Controller is at Fault.
Also check the Terminals at the Map and Controller for Damage,Corrosion and Push Out.
We had a TD Member with a Problem that turned out to be a Wire in the Controller Connector was not Locked In and when the Connector was Plugged in the Wire Pushed Out and when it was Unplugged the Wire pulled back in place.

[rtcabal]

i had thought about this as a possibility, too. i have another smec, but its from an '89. i know they have different map sensors, anything else?

is there a way to test the smec?

also, the way the problem came up--my first sustained boost session after a rebuild--makes me think that this is something different.

regardless, i want this f&%*er fixed...

[NAJ]

We are apparently missing something, Did the problem start after the 1st Road Test after Rebuild or 1st Boost Run after Rebuild? Is the Map Code the only Code that is continuely coming back or is the VSS Code there also? Did you notice if anything else happened before the Vehicle went into Failure the First Time?
Also are all External Grounds Hooked Up,Tight,Clean and Secure?
Has the Vehicle been Driven since this Problem Started?

[rtcabal]

it ran fine for a week or so, but this happened the first time it saw sustained boost, as in more than just a second, but several seconds.

its giving me vss after being driven (which it has been, but not much). it will not give me the vss code if i erase the codes and just let it idle.

nothing else weird happened, no.

i'm going to pour through the wiring some more, i guess...

[NAJ]

Here is the Official Chrysler Flow Charts. There are 2 different Code 13's
Repairing Fault "Map Pneumatic Signal"
1) Tee a vacuum gauge into the vacuum line at map sensor.
Did the gauge read zero at idle?
YES........
NO. (step 2)
2) Snap the throttle open and closed while observing gauge.
Did gauge instantly drop to zero and return?
NO, Repair restricted vacuum supply line to map sensor.
YES (step 3)
3) Key off, disconnect map sensor 3 way electrical connector.
Check connector for damage, push out or corroded terminals.
Any push out, corrision or damage?
YES, repair or replace as necassary
NO (step 4)
4) Key on, measure voltage at VT/WT wire of map sensor connector.
Is voltage below 1 volt?
Yes, repair the VT/WT wire for an open circuit in harness
NO, replace map sensor
Repairing Fault "Map Pneumatic Change"
1) Start engine and let idle,is idle smooth and steady?
NO, look for other problems creating misfire or surge,not map sensor.
If there are other faults follow path for the next fault.
YES,(step 2)
2) Turn engine off,tee vacuum gauge in line to baro solenoid.
Start engine and observe gauge with engine idling.
With DRB 2 (Chrysler Scanner) go to "engine parameters" and select
"map gauge reading".
Are vacuum readings within 1" of the same?
NO, (step 3)
YES,watch vacuum on DRB 2 and turn engine off, did vacuum quickly drop
to zero?
NO, repair vacuum line for restriction,also inspect baro solenoid.
YES, map sensor is not currently a problem
3) Key off, move vacuum gauge to other side of solenoid.
Start engine and watch gauge readings.
Are vacuum readings now within 1" of the same?
YES, replace baro solenoid
NO, replace map sensor

[rtcabal]

from above:
"4) Key on, measure voltage at VT/WT wire of map sensor connector.
Is voltage below 1 volt?
Yes, repair the VT/WT wire for an open circuit in harness"

ok. my voltage just now was .44-.5. i'm going to spend some time tracing wires...

let me know if you've got any other ideas; i'm stumped.

[rtcabal]

i switched the smec with one from an '89. gave me:

'map hi 14' and 'f/a L 51'.

i know that the computers use different map sensors. notice i'm not getting a 13 anymore. maybe if i use this computer and a map for an '89? does this at least tell me that my smec is indeed the problem?

i want this fixed!!! ahhhhhhhhhhhhhhhhhhhhhhhhh!!!

[NAJ]

The VT/WT wire is the controllers 5 volt output to the TPS and MAP. Disconnect the TPS connector and see if there is 5 volts there,that will narrow down your search. If there is not 5 volts at the TPS then backprobe the controller connector term #6 to see if there is 5 volts present.
You keep mentioning SMEC,1990 used a SBEC the difference will be 1 or 2 connectors.(SMEC uses 2) The 1990 model year 2.5L turbos used 3 diferent controllers. 1 for AA/AG/AJ bodies, 1 for AS body only and 1 for AP body only.
Your Mini-Van is an AS body.

[rtcabal]

right. i didn't realize that there was a difference between '89 and '90 computers. the motor is from an '89 dodge caravan, and the vehicle, computer and wiring harness is a '90 plymouth voyager. at least that's what its registered as...

i've traced the violet/white wire. and, yes, it is actually 5 volts, including at the TPS. i misspoke earlier when i said it was '.44-.5'. sorry.

in the end, i'm leaning towards a bad computer. is there something fishy going on?

thank you...