1999 Lesabre another stumper


EMBY
10-02-2011, 10:56 AM
Hello all!

I've been working on this problem child for over a month and have run out of ideas.
Subject vehicle has 190K+ miles on it and has been maintained very well, and has run very good until about a month ago. Stopped at the local Home Depot on Hot August day and when I returned the car started and immediately died; repeated process multiple times, no change. There were no check engine light or codes triggered. Left car and returned about 6 hours later with van and tools. Started car, continued to run so I drove it home and it died in driveway.
I checked fuel pressure, marginally low @ 42 PSI, replaced fuel pump assy and in line filter. Checked spark plugs, all were blackened (rich) so I replaced plugs and old wires.
Car will start and run , poorly, for 5 to 15 minutes depending on outside temp. Once engine is warm it will start but will not continue to run. Still no codes. Unplugged sensors one at a time while running,; no obvious change. Has been a good running, reliable car until now. Any Ideas???

Mike B.

Tech II
10-02-2011, 11:45 AM
Are you losing coolant? Try running vehicle with MAF disconnected, when it won't start.....

Also check the vac line to the fuel pressure regulator for the presense of fuel...

big white bufflo
10-02-2011, 01:26 PM
this trouble sounds like a eletronic problem with heat soak it gets hot a shuts down one possible trouble is cam sensor very easy to replace and not costly it located to the left of water pump the cam sensor sensese number one and tells it to fire but is only needed on start up the other one is the crank sensor not a costly part but labor is around 300$ its location i behind the harmonic balancer .these will throw codes

Jrs3800
10-05-2011, 10:41 AM
The cam sensor is a #1 TDC reference, this is used for True Sequential Fuel Injection...

If the cam sensor did not have a pulse the PCM will throw a code for this, but the engine will continue to start and run, with lower performance as well as lower MPG's..

Being that the car seems to start and die.... I am wondering if the ICM is not giving controls to the PCM once it surpasses 400 Rpm's( Possible the handshake isn't happening )

Has the PCM stored any fault codes at all?


as for fuel pressure, Key on should be 48-55 Psi, dead idle should be about 45 Psi give or take a few, this would fall into an acceptable range...


so just to get it straight, when you pull the MAF connector there is no change correct?

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