Mechanics

3800 ENGINE RUNS ROUGH AT COLD START UP

1996 Buick Regal • 175,600 miles

15 Miles on rebuilt engine New Temp sensor replaced twice new MAP sensor new TPS New upstream O2S New Thermostat
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Firemnted
May 5, 2012.



Lets get back to basics. How are the plugs and wires?

Did you use the old injectors and have they been cleaned with direct injection?

I would not go to any sensors till you cover all your basics first.

Roy

Used injectors but cleaned. Plugs and wires are new and rechecked. The car did sit for 11 months with a full tank of fuel treated with sea foam. I have a scan tool and had no output from the sensors I replaced. The car starts and runs perfectly every time when it gets to 150 deg. F vida the scan tool!

Tiny
Firemnted
May 5, 2012.
Monitor the coolant sensor when cold

Roy

70 Deg. This morning and out side temp. Was 57.2 so I replaced it today with no change

Tiny
Firemnted
May 5, 2012.
Air intake temp. Was 47 Deg.

Tiny
Firemnted
May 5, 2012.
Air intake will not effect it. It is the coolant sensor, the temp of the coolant. It gives a richer mixture when cold. It may be running lean

Roy

That was what I thought and why I replaced it a second time day the first was when I rebuilt the engine! I still have the original should I try that?

Tiny
Firemnted
May 5, 2012.
The temp sensor you said, was that the sensor by the thermostat housing or on the back of the head

Roy

Thermostat Housing

Tiny
Firemnted
May 5, 2012.
What was the reading on the scan tool when cold?

Roy

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