map and vss codes

[NAJ]

What do you mean by "Fishy"? I assume that the vehicle was running fine before the rebuild? Did you purchase the vehicle with the 89 engine? What exactly was changed with the engine? Are all of the original 90 electronics on the vehicle? Which controller is in your vehicle a SMEC or SBEC.
I can run a VIN inquiry thru Dealer Connect to see the OE equipment but it may be too old and the info may no longer be in Chryslers System. If you would like me to check I just need the VIN.

[rtcabal]

ok. i'm a bozo. i dug up the title and it is an '89; i think i the guy i bought it from called it a '90 and it just stuck in my head. that being said...

the van was running without a check engine light before and after the rebuild. once again, the first time it saw sustained boost was when the CE light came on.

bozo move #2: i had the map unplugged when i got the 14 and 51. sorry to make this more difficult.

but, as for a breakthrough, with both smecs it gives me 'map 13', so the computer is not at fault.

keep looking for bad wires? i found one yesterday, not too bad, but could have been shorting, and fixing it didn't do doodle...

[NAJ]

The only thing that is different is the 5volt supply is from term #13 and the wire is still VT/WT. Follow the 2 flow charts I posted and see where they lead.Check terminal integrity thoroughly as this is often overlooked and assumed to be ok.
Don't be too concerned about the misinformation,we have all been there,you get so frustrated you lose focus,it is nice to have another set of eyes that are not involved,they will see things more clearly.
We could start a new thread on "stupid " things people have done.
When my head gasket went I had the vehicle towed to the dealership my Son worked at because they were open late.He finished the job the next night but he could not get boost,he could hear the turbo but no boost,I told him it was probably a vacuum issue and I would take care of it as I went thru this when I did the valve cover and the lines broke and I was hours trying to get the VNT solenoids correct.Stayed after work to correct it and 2 hours later after still playing with vacuum lines one of our techs said"Get out of the way". 5 minutes later it was fixed,when the induction hose from the turbo to the intercooler was installed it curled under at the bottom on the turbo end and was clamped that way, I had blinders on and only saw vacuum issues.
The best lessons are learned from making mistakes,this problem will get corrected and when it is done you will know your scanner and the MAP circuit inside out.
Hang In There

[rtcabal]

thanks for the motivational speech! i am a veteran at learning the hard way...

i went through the flow charts. check this out:

"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"

if i understand this correctly, then the vacuum reading between the baro and the intake should be different from the reading between the baro and the map. as i said before, they're both 18" exactly. bad baro, then??

[NAJ]

The vacuum/boost should be the same on both sides of the baro solenoid.
If you had say 18" vacuum going in to the baro and only 14" coming out that would tell you there was a restriction in the baro.
Your original baro reading of 28" is still a concern to me.That indicates high altitude not sea level.
Try something,hook up your scanner and record data with the key on/engine off and then with the engine running,then swap out the controller and see if any sensor readings are different.
Also with the scanner hooked up and the key on/engine off wiggle and tug on the connectors/wiring at the map and controller and the harness in between to see if any readings change.
If you do not find anything with that we will check map response,you will need a hand held vacuum pump and your scanner.

[rtcabal]

i just went and used the ATM mode to toggle the baro, then went to the solenoid test and it showed it toggling on and off. so i assume its not the problem.

one thing i did notice is that the map sensor reading coming from the scanner is around 12'', while the vacuum gauge reads 18''.

i will go now and switch around smecs like you said.

[rtcabal]

ok. i ran the sensor test mode with both smecs. they were consistent. here's what i got:

key on, engine off
map voltge: 2.4v, map pressure: 27.1, vacuum pressure: 1.3, baro pressure: 28.4, baro read update: 28.4

engine running
map voltage: .8-.9v, map press: 12.4, vacuum pressure: 16.0, baro pressure: 28.4, baro read update: 28.4

the map pressure and vacuum pressure did vary with the engine on between the two controllers. map was 11.3, but 12.4 with the other smec, vac was 16.0 but 17.6 with the other. but that seems close enough, right? those were the only variations.

also, i treid switching map sensors and got the same readings.

is it possible that something else is failing, like an o2 sensor, and the computer is misinterpretting it? i have yet to trace every single wire coming from the smec, but i'm about ready to. i wanted to get under the dash anyhow, as i have a short somewhere (radio and dome lights are out, as is my coolant guage--but these were happening before any check engine). so, no better time than the present.

thanks for all the insight. i couldn't have tackled this without you.
-t

[NAJ]

Your baro reading is still bothering me,your local weather says your atmospheric pressure is 30.20 and falling. .50 volts is a diffence of 3" vacuum/pressure.
Did you perform the wiggle test and watch the sensor readings?
Backprobe the controller with your voltmeter and see if the actual redings are what the controller are saying what they are.
Are we positive that the MAP sensors are for a turbo?
Your key on/engine off map voltage reading of 2.4 volts = .39 volts which is still showing altitude which would corrospond with your baro reading.
Your engine running voltage of .8 -.9 = 18-21" of vacuum.
You said you had 18" vacuum which would be .9 volts if you are reading .8 with.18" of vacuum then the controller is not recieving or processing the right info.

[rtcabal]

so the map voltage (which with a multimeter is .85, i guess that's why the computer jumps between .8 and .9) corresponds to what pressure its reading, and the scan tool tells me that its reading 11.3-12.4.

does that mean that the controller is not processing this information correctly? remember, i got these readings with 2 controllers AND 2 map sensors.

as far as the barometric pressure goes, a 2'' error margin between what the solenoid reads compared to the national weather association seems within reason to me.

the MAPs are identical. i witnessed the new one being looked up at the parts store; its for a turbo.

how do i backprobe the controller? with the harness disconnected the map won't get any voltage at all, thus can't send any. should i send a current through the harness with it disconnected and check that its consistent? or do i cut into the wire? i'm a neophyte with electronics...

at this point, i am still leaning towards a wiring issue.

[NAJ]

To backprobe, the connector stays plugged in and you use a backprobe pin or paper clip will do and slide it in thru the rear of the connector where the wire enters being sure that it makes contact with the terminal then you hook up your voltmeter and you can read live voltage without disconnecting the circuit.
If your live voltage readings are the same as what the controller is seeing the controller is not at fault but it is recieving wrong info.
Map voltage should not fluctuate unless vacuum is, is the vacuum to the map fluctuating by 3-5"? If not we have another symptom.
The controller uses the baro info combined with map info for fuel and timing control,if it thinks that you are at a higher altidude than you are fuel correction goes to the lean side do to lack of oxygen at higher altitude.
28" baro pressure is way up in the mountains,2" is a lot,my feeling is that this reason you have this fault, we just have to find the cause.
Did you perform the "Wiggle" test?

[NAJ]

Some more info,did some weather research,chicago is 528' above sea level,I am somewhere around 200'(Cannot find exact info) so we are fairly close.
I contacted my son and he is going to try to get here tomorrow or saturday with his scanner to get some readings from my car so we have a good baseline to judge your #'s by.
Also found a chart to convert PSI to "HG. PSI x 2.04 = "HG
Atmospheric Pressure at sea level is 14.7 PSI which = 29.98"HG
Naturally that changes with weather patterns but not that much, maybe
.5" HG. These are the readings your controller looks at for fuel and timing control.
Keep digging and as soon as I get more info I will post,If you find something let me know.

[rtcabal]

i fixed it. i can't believe it, but it was a vacuum issue. i hooked up the map directly to the manifold and no ce light. what a dufus; why didn't i try this before?!

well, all's well that ends well. i sure learned a lot.

i can't thank you enough, naj, for spending so much time and brain power on my dilema. if i can ever return the favor...

[NAJ]

Not a problem.glad to hear it is fixed.You sent this post just as my Son was hooking up his scanner to my car.
How was the Map hooked up before?
It should be Manifold Vacuum Source to Baro to MAP.

[rtcabal]

you know, i've got a vacuum block. it was sharing a line, but it was not that complex. also, i was using the vacuum gauge and it passed the test detailed on the flow charts that directs you to snap the throttle and watch the gauge. whatever. results are results and that's what i have. i'm pretty amazed, though...