I have had this car for 10 years and I seem to have a new issue each year. This time, the engine is very hard to start in cold weather. It turns over quickly and will eventually start in about 30 seconds or a little more. I also get a warning on the DSC system but I assume its just because it did not start. Once it starts its fine driving but it sputters a bit when it first kicks. It has 81,000 miles. No problems at all once it is running so if I take it to a mechanic its running fine and does not show any warning lights.

 

Test the fuel pressure to see if the pump is beginning to fail.

Are there any DTCs stored in the system?

 

No stored codes

 

The DSC warning points to a weak battery. A weak battery may spin the starter, but the high current makes the voltage drop and the electronics (computers, really) struggle with that. If possible, have the battery load tested, or measure the static voltage at the terminals (you should have well over 12V).

Best of luck, keep us posted.

 

That makes sense as it has happened in very cold weather which is tough in batteries. The battery is probably 5 years old. Easy enough to test, thanks.

 

The battery should have a minimum of 12.6 volts when checked with a voltmeter across the terminals. If the voltage is less than 12.6 volts, you can charge it at 2 to 5 amps for 8 hours and retest.

At five years, it's probably best to replace the battery. Make sure it's fully charged since many batteries in parts houses are on the shelf for several months prior to being sold.

 

Some of us have found the Bosch AGM to be quite nice for this car. No maintenance. Don't forget the tubing for the H2...

 

I checked the battery this morning, it read 11.93v. I think we are on the right track. I have put a charger on the battery and checked the water levels which were ok. I should probably have guessed this was the issue as I had been away for a month and only used the car for some short trips after returning then the much colder weather came in and I had the problem. I will see if the battery holds the charge and then if the problem goes away. Thanks for the input, judging from the size of this battery these cars must be very sensitive to the voltage. I have only seen batteries this big with diesels.

 

The other issue with this car is the ability to hold fuel pressure after shut off. If the hard start continues after checking this battery, see if "priming" the fuel rail helps (turn the key until you hear the fuel pump run and stop, then turn the key off, then on again to start). This return-less fuel system has a pop valve that sometimes fails and lets all the fuel pressure leak out back into the tank. Fortunately with this design, there is a fuel pressure sensor that happens to be readable with a standard OBDII code reader. It should read around 55 psi at all times. Of course, fuel system maintenance can only help. Start with a new fuel filter (driver side rear wheel well), and then a good quality injector cleaner (like Techron). Also, would not hurt to get some good reading of the fuel trims to check for air leaks.

Best of luck, keep us posted.

 

At 11.9 volts, the battery may drop below 10 volts when the starter is engaged. If the voltage drops significantly, the fuel pump may not run.

 

As this only happens in COLD weather and the engine runs normally when up to temperature, a faulty temperature sensor is also a possibility.





Of the four temperature monitors, the ECT is the one with a flakey reputation.

Graham

 

Would that be recorded on the scan?

 

I have had the charger on it all day using the slow charge setting. Voltage came up to 12.5 and it started right up without any hesitation however the voltage during startup dropped to 11.07v. It looks like this battery has about had it.

 

Don't jump to conclusions on your battery. With the large transient current drain cranking, 11V doesn't sound bad. A free test at the local parts store will give you a much better idea on thumbs up or thumbs down. If it holds 12+V for days, then it may be good enough "for all practical purposes." Even a new battery sitting dormant over the winter months will exhibit lower voltage in the cold, especially if setting connected with a bit of a parasitic drain.

Where I'm going with this is, assuming it's parked in a garage, you might sink a little money in for a battery tender to keep voltage up and avoid the risk of a dead battery freezing over the winter.

For extended parking in Michigan winters here, I pull the ground to avoid parasitic drain and periodically hit them with the battery charger or start them up. Whenever practical, the batteries come in out of the cold.

 

I had this problem once... It forced me to go ahead and clean up as many of the major sensor wires I could. Especially MAF sensor. Then, the two (on my 2002) cam position sensor connectors (I don't think it was that), knock sensor connectors, and a few around the throttle body... Removed the breather to get to things and the engine covers. And the sensor at the the underside of the bell housing. Flywheel position sensor,,, or something like that. Problem went away. I think it was the MAF myself - but couldn't be 100%.

This might prove how little know, but it will be good to know... Is there a temp sensor that talks to the ECU? On my XJS and 928, the temp sensor can play a big part in causing misery... XJS will not start unless a proper (resistance?) signal isn't being sent...
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