88 Buick VIN 3 stalling, ECM?

[Clare Snyder]

Lynn R. Erickson wrote:
> 
> Some background:
> 
> 88 Buick Century wagon with 3.8 SFI(hah) V6, approx. 97k miles
> 
> My parents bought it new in 88. They decided to get rid of it about 5
> years ago because it had always idled rough, left them stranded once
> (crank sensor), and was intermittently prone to stalling when you let
> off the throttle at low speed around town. Figuring that an intermittent
> will eventually get bad enough to be continuous so that it could be
> diagnosed, I bought the car from them for my wife. My wife likes the
> car, and the rough idle and infrequent stall didn't bother me. _I_
> wasn't driving it.
> 
> However -- last week I drove it to Los Angeles and back(800+ miles each
> way). You haven't lived until you've had a car stall in the middle lane
> of Century Blvd. at LAX. I decided to fix the damn thing.
> 
> Some symptoms:
> 
> _seems_ to be heat related
> No problems at freeway speeds
> No ECM trouble codes
> During the sensitive time in LA, parking lot speed bumps would cause
> static on the AM radio and make the CE light flicker on.
> Still idles like sh*t -- never hasn't. Not just 90 degree V6 rough,it
> also misses.
> 
> Diagnostics:
> 
> All cylinders 140-150 psi compression cold. Hot? You jest! Not on my
> skin!
> New plugs and wires. Needed anyway. No change.
> New PCV. Needed anyway. No Change.
> 10" hg manifold pressure at idle. Is this normal? Reading taken from
> transmission vacuum line.
> 
> Got a scanner hooked up today. Following readings are at idle.
> 
> ECM PROM ID 1254 -- The ALLDATA CD shows a stall related TSB on this,
> but it isn't included in their (extra cost) TSB's. Sigh. ALLDATA is
> better than Chilton's, but watch out, some of their information is
> missing or flat out wrong (I got bit on a wiring diagram).
> 
> Some readings:
>                   ALDL Mode     Diag. Mode    Backup Mode*
> RPM               1000-1100        650          675
> Coolant Temp.     196 F            206 F        217 F
> Intake Air Temp.  156 F (why?)     86 F         84 F
> TPS                0.4 V           0.4 V        0.4 V
> O2 sensor         400-600 Mv       473-549 Mv   920 Mv*
> Spark Advance      28.6 deg        0 Deg        0 Deg
> IAC Position       51              38           49
> Integrator         132             129          128
> Block Mult.        133             133          113
> EGR Duty Cycle     0 %             89%          79%
> EGR Switch         Off             Off          Off
> Closed Loop        On              On           Off
> Fuel Mix           Lean/Rich       Lean/Rich    Rich*
> Learn              On              On           Off
> 
> *Sets O2 sensor rich error code.
> 
> About all I can figure out right now is to try a new ECM and get the
> latest service release on the PROM.
> 
> Anybody got any other ideas?
> 
> TIA,
> 
> Lynn
> 
> /*********************************************************/
> I may be stupid, but I ain't _that_ dumb.
> lre at xmission.com   www.xmission.com/~lre
> /*********************************************************/
The ECU/Prom would be my first step - they have been problems. The ecu
can not check itself, so if no codes and intermittent problems it points
there. Likely a bad solder joint or cracked trace on a PCB.
-- 
                               _/\_
                       --|-----([])-----|--
                         S    0/  \0    B
         Alls well that ends well!! www.snyder.on.ca is back
                  E-Mail service is back to normal
                  To avoid bouncing E-Mail messages
                    Reply to Clare at snyder.on.ca
                                OR
Remove the R from clsnyder in my E-Mail Address to reply. Stop the
spammers!!!
It's hard to soar like an eagle when your stuck with a bunch of
Turkeys!!!