Need H_elp with an 89 MPFI 2.8 V6 (Need MAF...)

[thergen at svn.net]

I had a 2.8 with a bad MAF.  Rapping on the MAF with a screw driver (don't
smash it) would cause the car to stumble at idle.  I think the car had
about 20k miles on it at the time.

With a bad MAF, I found drivability was acceptable (not great) if I simply
disconnected the MAF.  There was a MAP only prom available (search the
TSBs) for my application that could be used instead of replacing a bad
MAF. 

At 115k miles, the alternator went bad (I think the six year old battery
contributed to its death).  It was the 100 amp model.  The diode bridge
was partially visible (remove plastic cover off back of alternator case)
and the diode's package looked blistered from heat.  It ran very hot
compared to the replacement unit.

Silicone may not have been the best choice for sealing the [air] temp
sensor.  The O2 sensor may be affected.  Anyone have comments on this?

The same vehicle could also develope an unstable idle after highway
driving while sitting at a stop light for an extended period.  It turns
out the O2 sensor was lazy, but no trouble codes were set.  Replacing the
O2 sensor fixed the problem.

Chicago huh?  Is your S10 4wd? I felt fortunate to get a plane out of
there after the holidays before the snow hit.

hth,
Tom


On Mon, 4 Jan 1999, Kurek, Larry wrote:

> Guys:
> 
> I am having a slight problem with the 2.8 MPFI motor I put in my S10 in
> place of the old carb motor with the hole in the side of the block :)
> 
> I was driving home last night and it started cuting out at anything between
> off idle to about half throttle...kind of like it was running out of gas,
> but it wasn't since I JUST filled up the tank. The fuel pump is new, and is
> getting great pressure, so I don't think it is a fuel problem. However...the
> motor seemed to fix itself and run great again. No SES light either. Once I
> got home, I decided to check the obvious....coil connectors, wires, etc
> etc...all seemed fine. However, after a quick test drive, I popped the hood
> and it almost died out on me.. came back, and set an SES light...code 34,
> low MAF reading. So, I backprobed the MAF connector and all was OK, I
> checked for any loose connections and didn't see any either, so i reset the
> ECM and it seemed OK. Well, on the drive to work this morning, same damn
> thing. Again, a code 34. One of the causes for this code is a leak between
> the MAF and the throttle body. I checked this as well, and the only thing
> that MAY be a problem, is the temperature sensor bung I siliconed into the
> elbow. The silicone looks to have pulled back just a bit and there may be a
> SLIGHT opening into the elbow. Could this be enough to cause a problem? I
> can't emphasize enough how small of a leak this may be. Are these MAF
> sensors that sensitive? FWIW, I am also running an open element K&N filter,
> and it has recently gotten quite cold here (Chicago area). 
> 
> Sooo....any ideas?  How do I go about testing the MAF itself? Like I
> mentioned above...the connector checks out fine with +B, ground, and +5v. 
> 
> Does anyone have a spare MAF that they would be willing to part with? This
> is a three wire MAF out of an 89 Camaro 2.8 V6. It isn't the hot wire
> variety, but seems to use a thermistor instead?
> 
> Finally, I did note that the lights on the car dim on occasion for a few
> seconds at a time. Could this be a bad alternator? Could this cause the
> problems with the MAF? I'm stretching here guys...I don't want to get
> stranded in sub-zero temperatures in the middle of nowhere...
> 
> Thanks!
> 
> 
> Larry
>