1998 S70 T5 - hard cold start

shegarty · Post by **shegarty** » 20 Feb 2015, 07:01

Hi all - way up here in the great white north winter is hitting us hard. It also appears to be hitting my S70 hard as well. She does not appear to like starting when the temp is below about -15ºC. I started using the (OE?) block heater which makes a big difference but this morning (-25ºC) she turned over, fired right away and then promptly shut down. After this despite numerous crank attempts she would not start again. When this has happened in the past waiting for the temp to warm up a bit always seems to fix it ... any thoughts? BTW, I do all my own maintenance and just replaced the cam seal at the distributor back in the fall that was giving a no start due to bad spark. Battery is good and still provides lot of power to crank. Fuel shouldn't be a problem as she will start and run fine when it warms up a bit.

Post by **Ozark Lee** » 20 Feb 2015, 08:10

There are a couple of "usual suspects" for hard starting. The most common is a bad ECT sensor. A non OEM sensor that is otherwise good can have similar problems. Beyond that a bad check valve in the fuel pump can cause starting trouble but that typically isn't ambient temperature related.

...Lee

shegarty · Post by **shegarty** » 20 Feb 2015, 09:33

Thanks Lee -

Ozark Lee wrote:The most common is a bad ECT sensor

- from what I understand this would usually throw a code and light up the lamba light would it not? I have had some problems with the EVAP that I am planning on tracking down in the spring but I have never had a code for the ECT. Is it possible that a bad or faulty ECT could account for the ambient temperature condition that I am getting now?

draser · Post by **draser** » 21 Feb 2015, 07:48

It may be possible that your ect is marginal and does not trigger code. Ect reads a high resistance when cold, in the range of 1600 ohms. Say yours only reads 1000 ohms, then ecu thinks engine is part warm and supplies less fuel. Easy enough to check by removing a plug, if soaked in fuel chances are ect works. In this cold though, gut feeling goes more towards electrics. So if you pull that plug check for spark as well.

shegarty · Post by **shegarty** » 23 Feb 2015, 12:30

Ok, so a small update looking for some ideas ... this morning in about -22ºC with the (OEM?) block heater plugged in for about 3hrs she turned over, fired immediately and ran for about 3 secs before promptly cutting out as if fuel was cut off. Further attempts resulted in the car turning over (starter engaging, engine cranking) but no ignition. As I was on my way out to work I didn't have any time to diagnose or troubleshoot. I am going to try when I get home but most likely it will be warm enough again for it to start without a problem. My thoughts are now leaning towards something electrical

draser wrote: In this cold though, gut feeling goes more towards electrics

and will maybe start with the fuel pump relay as I can easily jumper it or replace it with a spare unit. Any other thoughts???

Post by **Ozark Lee** » 23 Feb 2015, 16:32

As fuel pump relays die they tend to get temperature dependent and it can work both ways - hot to cold and cold to hot but usually the latter. It is easy enough to bypass it and see.

...Lee

shegarty · Post by **shegarty** » 25 Feb 2015, 06:52

Ozark Lee wrote:It is easy enough to bypass it and see.

of course that would depend on the weather cooperating

. It has been too warm (relative) to test the relay circuit but I have swapped it out for a known good relay. Not sure if it will be cold enough to test it in the next few days but will report back if it is. Thanks for the suggestions in the meantime.

Post by **northernlights** » 27 Feb 2015, 18:31

The rpm/crank sensor will shut the engine off if it stops sending a signal. It could be a marginal connection that gets jostled a little after startup when things are vibrating. Things expand when they warm up!

JeffHicks · Post by **JeffHicks** » 01 Mar 2015, 02:42

shegarty wrote:Hi all - way up here in the great white north winter is hitting us hard. It also appears to be hitting my S70 hard as well. She does not appear to like starting when the temp is below about -15ºC. I started using the (OE?) block heater which makes a big difference but this morning (-25ºC) she turned over, fired right away and then promptly shut down. After this despite numerous crank attempts she would not start again. When this has happened in the past waiting for the temp to warm up a bit always seems to fix it ... any thoughts? BTW, I do all my own maintenance and just replaced the cam seal at the distributor back in the fall that was giving a no start due to bad spark. Battery is good and still provides lot of power to crank. Fuel shouldn't be a problem as she will start and run fine when it warms up a bit.

I had this exact same problem with my 99 V70. Any time it was below Zero (F) the thing would do exactly as you described - kinda fire, then immediately die and refuse to start again.

My problem ended up being a fuel pump relay that was worn to the point where (apparently) it really hated the cold. I replaced the relay, and no more problems.

shegarty · Post by **shegarty** » 01 Mar 2015, 20:15

Just when I thought Mother Nature was going to give me a short reprieve with some warmer weather ... now she was refusing to start today in only -2ºC

So here's the latest:
***Pretty sure its not the fuel pump relay as I switched it out and no change - I can also hear the pump priming
***Checked for spark - decent from the coil (even tried different known good coil) - pulled cap to check cam seal as this was done not too long ago - all checks out good - haven't checked an individual plug yet as unlikely to be bad and its cold and dark here now

***After I finally got it started today (repeated turning over) tried unplugging the MAF (when engine cold) and she cleared up a bit. Upon plugging the MAF back in again she promptly stalled and when I checked she had thrown a P0102 code (not sure if that happened before or after plugging it back in)
***If you read further up this condition happened before when it was much colder without touching the MAF - she would turn over, fire and run for about 2-3 secs and then promptly stall out and then refuse to restart
***Replaced the MAF with known good one - no change, following the same procedure with replacement causes the same code - Before messing with all of this the MAF that she started the day with was BOSCH OEM and replaced by PO just over a year ago
***Once warm she will start up again no problem

I'm pulling my hair out on this one. To me it feels like some sort of metering problem. The previous mention of the ECT is I suppose my last resort but I am reluctant to replace it now that the source of the problem seems to have changed (previously only a no start in colder temps, less than -17ºC). Any thoughts ...