88 Buick VIN 3 stalling, ECM?

[shannen]

I have always found that a component which you _know_ is bad, but which
exhibits no symptoms whatsoever, will always require replacement after two or
three good bashes.

Shannen

TBK wrote:

> Go in and tap the ECM. Not BASH, but tap.
>
> Tk
> -----Original Message-----
> From: Clare Snyder <snyder at huron.net>
> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
> Date: Friday, July 03, 1998 11:42 AM
> Subject: Re: 88 Buick VIN 3 stalling, ECM?
>
> >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!!!
> >