I noticed in my shop manual, that the ECM just grounds the solenoid to open the purge valve. There are about 4 conditions that the ECM needs to energize this solenoid, but I haven't seen anything in TC's latest $6E tdf to modify the settings. Maybe it just isn't that important.

Anyways, I think I might have a badly burnt PROM, since I can hear the little purge gizmo, which is about 10" from the canister, buzzing along very fast, guessing several 100Hz. This is with the car warmed up at idle. If I just blip the throttle, it stops buzzing. It is quite loud actually. I need to put a good meter or scope on the line, to see what is going on. I was thinking the little gizmo was bad, but it is the ECM that is telling it to open/close so fast. When I pull the connector at idle, she quiets down. Is this normal operation? The solenoid is just controlling a vac valve, so it should be just open or closed.

TIA!!!

 

The CCC runs at a PWM, Pulse Width Modulation strategy.
Sounds like this might be what you're looking for.


;====================
; CCP
;====================
0276 FCB 140 ; 140 LV8, MAX FOR CCP CHANGE
0277 FCB 1 ; 100 Msec, DELAY BETWEEN CCP UPDATES
0278 FCB 110 ; INT, INCR CCP ID INT GT THRESH
0279 FCB 75 ; INT, DECR CCP ID INT GT THRESH
027A FCB 4 ; %DC, IF INT GT LC278 ADD TO CCP
027B FCB 3 ; %DC, IF INT LT LC279 SUB FM CCP
027C FCB 43 ; %DC, NO CCP IF LT THRESH % TPS LOW
027D FCB 38 ; MPH/16/5, SAVE CCP IF Vss GT THRESH
027E FCB 110 ; BLM, SAVE CCP IF GT THRESH
027F FCB 110 ; BLM, DISABLE CCP IF GT THRESH
0280 FCB 120 ; 50c, ENABLE CCP COOL THRESH
; CCP OFF to ON
0281 FCB 7 ; MPH/16/5, ENABLE CCP IF Vss GT THRESH
0282 FCB 10 ; %TPS, DISABLE CCP IF Vss GT THRESH
; CCP ON TO OFF
0283 FCB 4 ; MPH/16/5, ENABLE CCP IF Vss LT THRESH
0284 FCB 5 ; %TPS, DISABLE CCP IF Vss LT THRESH
;----------------------------------------------
; CCP DUTY CYCLE vs MAF
; ARG + DC% * 2.56
;----------------------------------------------
LC285: FCB 8 ; 9 LINE TABLE
; %DC AIR FLOW, Gms/Sec
;----------------------------------------------
0286 FCB 16 ; 6.3 0
0287 FCB 32 ; 12.5 4
0288 FCB 48 ; 18.8 8
0289 FCB 80 ; 31.4 12
028A FCB 160 ; 62.5 16
028B FCB 255 ; 99.6 20
028C FCB 255 ; 99.6 24
028D FCB 255 ; 99.6 28
028E FCB 255 ; 99.6 32

 

Hmm... I thought I added a number of "parameters" regarding CCP and told TunerCat about them?

I had to do those a while back for a buddy that removed his CCP on his MAF car and I needed to ensure the ECM didn't try to operate it.

The CCP, similar to the EGR needs to be "properly disabled" just like the EGR - and I prefer the "Temperature" (see address x'280) by setting it to a very high number.

It's funny how many of those "commercial custom eprom writers" never do this, and it affects the calibration.

 

Thanks for the info fellas. I guess I didn't realize that the ECM controlled the purge via a duty cycle. My shop manual doesn't mention that. Just gives 4 conditions that must be met for the ECM to energize the solenoid.

But what about when the conditions are NOT met? I had 2 conditions false, (0 vehicle speed and TPS at idle) and the little hockey puck valve was buzzing along quite nicely. When I pull the connector, it quiets down, so I know the ECM is the cause.

Looks like there is a table for "MAF vs CCP duty cycle". Possibly more stuff as well. I am using TC's latest ECM_6E ver W, and there is no CCP stuff. Maybe they just haven't release to the public.

Tonight I did some engine off tests to see if I could understand what is going on. The volts levels did not seem to relate to what my manual indicates. IE, ign on, pinA reads 12v, pinB reads about 0.3v.(Should be also 12v.) Then I ground the diagnostic terminal, and pinB goes to about 11.8. So I don't know what is going on. Yea, I know this is getting away from PROM burning, but I didn't have this condition last year. I have a recently burnt PROM, and wonder if got messed some how. Good stuff anyhow!

 

A weak driver in the ecm can do exactly what you discribe, as well as a leaking capacitor, and a host of electrical or mechanical ills. There also might be a gatcha written in the code some where. The actual code can vary some from the tables, again wny I mention developing source code.

 

Actually I think I answered my own question when I typed the above post. Seems as if the logic is backwards. With ign ON, the ECM grounds the purge, thus the measured 0.3v AT the connector of the sol, which is reasonable. When I hit the diag terminal with a jumper, the ECM opens the switch, so I measure bat volts on pinB, which was the same as pinA, indicating no current flow thru the solenoid. So maybe the PROM I got in there now has got some reverse logic stuck in there.

Got to get my scan tool hooked up now!