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Discussion Starter · #1 · (Edited)
Hey guys, my '97 Buick PAU started stalling on cold start after cleaning and re-oiling my K&N filter and I've been chasing the problem ever since. The engine starts up great and quick as always but after about 20 seconds starts spitting and sputtering--sometimes stalling. A restart is sometimes hard, but once running, everything is gravy and she purrs like a kitten for the full drive cycle.

Thinking I over-oiled the filter and got oil on the MAF, I've cleaned the MAF 3-4 times with MAF cleaner, cleaned up the IAC valve, replaced spark plugs, put the stock airbox back on, changed fuel filter, ran a few fresh tanks of known-good fuel, and thoroughly checked for vaccum leaks. I'm throwing no codes and kind of running out of ideas.

I data-logged a cold start and stall, wondering if my coolant temp sensor was giving crazy readings, my MAF, or MAP, but nothing seems off the charts. In the attached picture (I can't seem to attach an excel file), I find it a little strange that MAP and MAF readings continue to climb into the stall condition while short term fuel trims are cut as RPM starts to dive, but I'm not sure it's enough to drop a few hundred bucks on a new MAF/MAP. What do you guys think?

Both graphs are of the same data, but with MAF/MAP readings on different axes as it's a little difficult to see the trends mapped on the same axis.
 

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I'd monitor fuel pressure. You can get a free rental gauge from the parts store and hook it to the rail port. If it's consistent, then drops out, you may have a pump, relay, or speed control issue (easy work-around). Not sure if the H-body electonics were similar to the ones in W's, especially 97's, but there were a few quirks/ticking time bombs built into these systems that can be addressed.
 

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Discussion Starter · #3 ·
I monitored fuel pressure through another cold start stall today. Fuel pressure was about 50-52 psi at key on, and stayed steady at 44psi at idle until it started sputtering and missing, at which point pressure started to slowly rise until it stalled, at which point it was back at 50 psi.
 
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