: '95 Concours hard starting when it's cold outside



ED's85GT
10-22-07, 07:17 PM
1995 Concours 82,400 miles
When the temperature drops below 50F or so outside it's hard to start, the colder it gets, the longer I have to crank it, once started it runs like a new Cadillac .
I almost forgot to mention, this problem started last winter, when summer
arrived I kind of forgot about this issue (no problems when it's warm/hot outside) but now it's getting colder outside again.

Thanks.

Ed

PS No codes, no check engine lights.

misfit6794
10-22-07, 07:46 PM
Could be a couple things, all pretty easy to check. I would start with your fuel pressure regulator. There's a write up with pictures in the tech tips section, its very easy to check and very easy to replace, usually its the culprit with hard starting on a northstat. If that checks out, have your battery load tested (mechanics usually charge nothing to check it), it could be time to replace it, cold whether usually has a big affect on batteries that are almost dead. Your starter may also be on its way out, its under the intake manifold so you can't really check it, but if the fpr and battery are good it would be my next stop.

ED's85GT
10-22-07, 08:03 PM
Battery/starter have no problems cranking this motor over weather it's hot or cold outside, When ambient temperature drops it feels as if there isn't any spark or fuel.

Thanks.
Ed

Ranger
10-22-07, 10:58 PM
A leaky FPR usually aids in cold starts and causes hard hot starts. That said, check it anyway as it is very easy. Then put a fuel pressure gauge on it and see what kind of fuel pressure you have when it acts up. Maybe a sticky relay. If you have someone turn the key on (no crank) while you have your ear to the open fuel filler pipe, you should hear the pump run for 2-3 seconds.

Submariner409
10-23-07, 12:38 PM
A hard cold start might be the fault of an engine coolant temperature sensor. Below some preset value the sensor will call for fuel enrichment ("choke") for a brief period.

As ranger indicates, the fuel pump short cycles to pressurize the system, then goes to continuous run at engine start. Try this: Turn the key ON, wait 4 seconds, then START.

dkozloski
10-23-07, 05:03 PM
50F is not cold. -50F is cold. The engine was designed to start with no trouble at -26F.

ED's85GT
10-23-07, 07:16 PM
50F is not cold. -50F is cold. The engine was designed to start with no trouble at -26F.

I agree with you but my Caddy says it's cold, LOL

Ranger
10-23-07, 10:54 PM
Perhaps the OAT (Outside Air Temperature) sensor is bad and the car thinks it is -20. Is your OAT readout normal? Have you pulled the DTC's

ED's85GT
10-24-07, 12:23 PM
Perhaps the OAT (Outside Air Temperature) sensor is bad and the car thinks it is -20. Is your OAT readout normal? Have you pulled the DTC's
I have noticed my OAT giving some questionable values lately, Is this temp reading tied into what the pcm looks at? I tought that it was just for driver's info purposes.

Pulled DTC's

No PCM codes
No ACP codes
No SIR codes

Codes in history:

I027= PRND321 switch failure (I must carefully put it in drive to avoid this
from showing up)
I034= Loss of Powertrain control module data (I haven't got a clue)

T047= I haven't been able to find a definition for this one

S044= Lift or dive signal fault (did a brake job a couple of weeks ago and
I think I got carried away with the Jack/jack stands. I hope that's
what that is)

Thanks.

Ed

Ranger
10-24-07, 01:04 PM
I have noticed my OAT giving some questionable values lately, Is this temp reading tied into what the pcm looks at? I tought that it was just for driver's info purposes.

No, it is not just for driver info. The PCM uses it to determine air/fuel ratio. -20 is going to require a richer mixture than +50. HVAC uses it to determine whether a 70 requested cabin temp requires heat or cooling.