Bench Testing $8D ~ Error code 33 Map Voltage High

[dave w]

I have an $8D system on the test bench. When I run the system, I get an Error Code 33 Map Voltage High. I'm wondering if the ECM is smart enough to know when the RPM / KPA are out of range to trigger Error Code 33? I have a vacuum pump on the MAP sensor to vary the voltages seen by the ECM. I would think high RPM's at near 100 Kpa would be OK with the ECM. I would think low RPM's at 35 ~ 40 Kpa would be OK with the ECM.

Just wondering if anyone else who had an $8D system on a test bench had the same or similar Map Sensor related Error?

Thanks,
dave w

[Six_Shooter]

Use a 5K ohm potentiometer instead. Wiper as your signal, the outer pins to ground a VRef.

[dave w]

Use a 5K ohm potentiometer instead. Wiper as your signal, the outer pins to ground a VRef.

Thanks!

dave w

[EagleMark]

It's smart enough. I had added some of the MAP and EGR test values to $42 to avoid these issues. Her'es what I found real quick in a asm.

;-------------------------------------
; ERROR 33
;-------------------------------------
L8283: FCB 218 ; PK/NEUT HI MAP/BARO RATIO THRESH, 0.85
; ARG = RATIO * 256
;
L8284: FCB 218 ; DRIVE HI MAP/BARO RATIO THRESH, 0.85
; ARG = RATIO * 256
;
L8285: FCB 5 ; TPS > 1.9% FOR ERR 33 TO BE SET
L8386: FCB 40 ; THRESHOLD IS 500 RPM TI INCR CNT'R
L8287: FCB 80 ; 1 SEC ERR TIME THRESH
;
;-------------------------------------
; ERROR 34, MAF
;-------------------------------------
L8288: FCB 38 ; MAP HI/BARO LO RATIO THRESH
; ARG = RATIO * 256
L8289: FCB 96 ; 1200 RPM THRESHOLD
;
L828A: FCB 26 ; IF RPM >= 1200 & 10% TPS
; ERR 34 CAN BE SET
L828B: FCB 4 ; .05 SEC TIME REG FOR ERR
L828C: FCB 216 ; DEFAULT MAP IF ERR 34, 51.6 Kpa
; ARG = (Kpa * 2.71) - 28.06
;
;-------------------------------------
; ERROR 33/34 DEFAULT MAP CALC PARAM'S
;-------------------------------------
L828D: FCB 72 ; MAP DEFAULT COEF
;--------------------------------
; MAP DEFAULT BIAS vs RPM
;
; TBL = A/D BIN
;--------------------------------
L828E: FCB 160 ; 0 RPM
L828F: FCB 64 ; 800
L8290: FCB 40 ; 1600
L8291: FCB 24 ; 2400
L8292: FCB 0 ; 3200
;--------------------------------

[JeepsAndGuns]

I can test $8D on my test bench/harness I built. Never had a light for the map sensor. I have a vac pump hooked up to the map sensor to give it some vaccum when running the system. But even in the few times I ran the dist with a drill and never gave the map sensor any vac, I never got a map sensor error code.

[dave w]

I can test $8D on my test bench/harness I built. Never had a light for the map sensor. I have a vac pump hooked up to the map sensor to give it some vaccum when running the system. But even in the few times I ran the dist with a drill and never gave the map sensor any vac, I never got a map sensor error code.

That's what I was wondering. I seem to remember, the other $8D systems I bench tested did not have MAP error codes. Maybe I need to try a different MAP sensor? Thanks for the input JeepsAndGuns.

dave w

[dave w]

I tried a different MAP, same code 33.

dave w

[JeepsAndGuns]

I'm sure you already double checked all the wiring, all the pins and checked for proper 5v refrence to the map sensor?

[dave w]

I'm sure you already double checked all the wiring, all the pins and checked for proper 5v refrence to the map sensor?

The wiring should be OK.
Using TunerPro RT I get the following MAP Sensor Voltages:
100 Kpa = 4.75 Volts DC
60 Kap = 2.62 Volts DC
20 Kpa = 0.50 Volts DC

dave w

[dave w]

I went back to a previous (Feb 2012) $8D bench test I did. This $8D application was for an Edelbrock MPFI system. Same results then, error code 33. Maybe it's the way I bench test using a complete system, everything hooked up, then spin the distributor?

dave w

[EagleMark]

There are some RPM, time and TPS qualifiers in the Error 33 above...

[EagleMark]

The Error 33 was on first frame of log, before start so it was probably stored.

The way you started the bench engine it had 57.xx MAP when key on then RPM increased, does not look like it fell in line of passing test. Start with clear codes, no vacuum, start bench engine and apply vacuum.

Batt volts were also a little low in the 11.xx volt range which is sometimes an issue?

[JeepsAndGuns]

I have pretty much everything hooked up when I do mine. Well all the basic stuff. I have a TB with tps, iac, a map sensor, coil, ignition module, injectors, iat, cts. I do not have a knock sensor or a o2 sensor. I have a bin set up with egr turned off, and codes for knock sensor, egr, and o2 sensor turned off. I use it just for bench testing ecm's.

http://www.youtube.com/watch?v=2aj9OpJUi-A

[EagleMark]

Just watched your video and you start with no vacuum, MAP was 100. Dave W has 57.xx MAP when key on before RPM. So that may be it?

[JeepsAndGuns]

Yea I have taken a few times when I tested one and wanted to run it for a min or two and would apply some vac right after I started spinning the dist. Kinda simulating a running engine.