Intermittent High Idle, Dies on cold starts, bad mileage

I don't think you really understand what this fault code means, it means that likely all the engine cylinders are misfiring at random no set pattern, not any particular cylinder. I would start with checking for engine vacuum leaks like the intake manifold gasket. that is all I can say since you provided no make, model or year and engine type and size information.

Cadillac Deville 2001 won't start, engine won't ... - CarGurus

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CarGurusJan 21, 2014 - Cadillac Deville 2001 won't start, engine won't turn over - My cadillac won't start. ... Crank not starting - service theft system in dash: There are 2 starter ....I have a 2002 Cadillac ... that all of a sudden stopped turning over ...

2001 cadillac northstar cranks but wont start. - YouTube

? 3:50
https://www.youtube.com/watch?v=t5SBKPut7G8
Mar 30, 2014 - Uploaded by eastcoasthoopty
2001 Cadillac wont start thought it was the chip in the key but it was ... I have a 2002 Seville In the morning I start my car noproblem, once its ...

Cadillac Deville 2001 won't Start - YouTube

? 0:43
https://www.youtube.com/watch?v=aUdX_Vnt1qI
May 10, 2013 - Uploaded by Shane Moore
Cadillac Deville 2001 won't Start .... i have a 2002 cadillac DTS. My issue is it will not idle, it will not start unless you have your foot to the gas all ...

2001 cadillac deville starting problem - YouTube

The over heating start with flush radeator

Could be a bad water pump,clogged radiator.

check for inlet manifold for leaks, also check cold start injection ( may be leaking)

Try checking the ac relay.Thank you for asking and I hope this helps you.Please leave me a 4 thumbs up.

1 st drain the oil if excessive for it will just aggitate in the oil pan and it will not pump through the oil pump resulting in internal engine damage. The belt should be replaced every two years on any Northstar motor. A tune up is also recomended as well with high milage

replace fuel filter first. cheapest and easiest.

Hi I own a cadillac with the same motor. Never smoked but had all the same issues, ran fine cold but after a little driving (less than 2 miles) it shook like nothing else. The cause was the motor self destructed had to replace valves all 8 bosh injectors 2000 dollars later she is like new. Sorry about the bad news goodluck.

I am not sure if this will help you but PO27 is listed as "Open Throttle Signal Switch" which could mean that your throttle position sensor needs replacing. Although with Cadillacs, it could mean anything. I hope this helps...