Replaced PCV car still hard/does not start in cold

[Fetch]

25 deg F outside, car will crank and crank and crank, after jumping and cranking even MORE it slowly starts to catch, and will eventually run, once running it is ok!
Hot start of engine instant/perfect everytime!

Disconnecting MAF and/or ICV did _not_ help this at all, I was under the impression a disconnected MAF should put it into limp home mode, and be able to start even with intake leaks.

I replaced the PCV plate and gasket, decent amount of oil pooled in the intake manifold, cleaned out what I could.


No CEL lights after PCV plate replaced.........WAS getting O2 sensor codes.......


Bottom of old PCV gasket and plate was oily, may have leaked?
Car seems to drive better, but STILL random loss of power, random lugging at times, sometimes runs perfectly.

Sometimes WOT switch reduces engine power, other times WOT works as expected.

Temps have not dropped below 30 yet after PCV replace, but at 30 deg car takes 5-10 seconds of cranking to start, usually dies after first start, needs to be cranked more.


Really intake gaskets!?!?!?! Some temp sensor??? Is it possible DME is damaged in a very slight and random way from when a coil was shorting out????
I'm about to leave it idling 24/7 since that would fix this cold starting problem. ha.

[Tiger]

Clean ICV also...

Two other possibilities... bad CPS and fuel pump.

[632 Regal]

clean the ICV, mine was sticky helped the idle situation. Did you reboot the computer after the PCV job? If not then reboot start and let idle till it resets things. If it cant find an idle and stalls or throws a code than you intake gaskets are probably leaking... dont forget the front plate gasket.

[Fetch]

I cleaned the ICV about 400 miles ago, was filthy, greatly improved things.

I rebooted the computer after the PCV job, and have put about 200 miles on the new PCV and PCV plate gasket.

The car idles perfectly throughout the whole temperature range once the car is actually running, solid 600rpm or so warm, 900 or so cold.

It's just the random loss of power (which happens seemingly less with new PCV & gasket) and hard starting that is driving me crazy!

I know I still need to test the fuel pump (I even have a spare one too), but I need to get a proper pressure gauge for that first.

[632 Regal]

im still betting on intake gaskets and front plate gasket

[Tiger]

If you got the spare pump, just switch it out. I don't think it is the fuel pump. Now, my choices are... fuel injection tempeature sensor and CPS.

[Fetch]

I think I'm on to something with the coolant temperature sensors!!

Bentley ranges for IAT & ECT Temp Sensors:
14 deg F: 7-11.6 K Ohms
My outside temp guestimate 38 deg F: Should be around 5 K Ohms
68 deg F: 2.1-2.9 K Ohms
176 deg F: 0.27-0.40 K Ohms

38 deg F outside, car sat overnight:
IAT: Intake Air Temp Sensor: 4.75 K Ohms (Good according to Bentley)
ECT: Engine Coolant Temp Sensor (white plug): 4.94 K Ohms (Close to IAT & good according to Bentley)
Other ECT: Other Engine Coolant Temp Sensor (black plug): 14.67 K Ohms (Bentley doesn't list values for this one, but if it's the same sensor as the white plug sensor it's WAY OFF)

Took car for a 30 min drive:
IAT: Did not re-test
ECT: Engine Coolant Temp Sensor (white plug): 0.27 K Ohms (Good assuming 176 deg F coolant temp)
Other ECT (black plug): 0.57 K Ohms (Little outside of good range assuming 176 deg F coolant temp)

I thought one of these was supposed to drive the cluster coolant temp guage, but here's my idea:

Car runs decently when it's warmed up because the other ECT black plug sensor is pretty close in the correct range, car loses some power when it's not in the correct range

Car doesn't start in the cold because the cold reading on this other ECT black plug sensor is SO far off in reading (~14 K Ohms when it should be ~5 K Ohms)

Pleaseeee tell me I'm on to something here! :) Shouldn't both coolant sensors right next to each other read very similar Ohms?

[Tiger]

When the car is hot... shut engine off and pull one plug out and turn ignition to on to see if that is the one that sends signal to instrument cluster temp gauge. If not, turn ignition off and unplug the other.

Engine needs to know how cold it is so it can do enriched fuel to start up the car.

[Fetch]

Sigh, well, I tried that, the sensor that had the whacked out cold reading is the sensor for the gauge cluster, which works correctly. So it seems the computer's ECT sensor is working correctly/within specs according to my tests. So scratch off problems with the coolant temp sensors.

I also tested the CPS while I was at it: Reads 580 Ohms, the spec for M60s is 540 Ohms with +/- 54 Ohms, so it looks to be fine...I did not inspect the air gap.

Hmmmm what's next, fuel pressure test...