98 S70, N/A Long crank... engine Temperature Switch related?

Post by **theWIFES_S70** » 10 May 2016, 11:52

Hey everyone,
Just wanted to get some feedback. I installed an FAE Coolant Fan Temperature Switch (https://www.fcpeuro.com/products/volvo- ... -9186486-1). Earlier in the Spring when I got the P0116 and P0117s and the car wouldn't start... I know, I know, always go OEM... Well, at the time, I was having a crisis of faith and was hoping I could get some goodness out of the FAE one...

Today, I noticed a really long crank to start the car. Could this be related to this sensor? Even on a cold car? I read the post on here a week ago about a warm engine start problem. (In which case, the non-OEM ECT would make sense...) Before the Fuel Pump and relay both went out, the car used to crank on immediately. (I really miss that feeling...) Ever since the Hella pump rebuild it's taken a little longer, but today, wow...

What are the common causes of a long crank? Thanks again for your input everyone!

Post by **sleddriver** » 10 May 2016, 17:41

What's the definition of a cold start in Queens this time of year?

Disconnect the ECT cable and see if it'll start. If so then it's Tango Uniform. If the sensor resistance is too low when cold, the ECU will think the engine is warm/hot and not dump in extra fuel (by increasing the duty cycle to the injectors). Pulling the harness, causes the resistance to go to infinity, telling the ECU the engine is VERY cold and to "pour-on-the-gas".

To my knowledge, the 98's only have one engine temp sensor and EVERYTHING engine/coolant/cold/hot is based on it.

Post by **theWIFES_S70** » 11 May 2016, 08:19

sleddriver wrote:What's the definition of a cold start in Queens this time of year?

Disconnect the ECT cable and see if it'll start. If so then it's Tango Uniform. If the sensor resistance is too low when cold, the ECU will think the engine is warm/hot and not dump in extra fuel (by increasing the duty cycle to the injectors). Pulling the harness, causes the resistance to go to infinity, telling the ECU the engine is VERY cold and to "pour-on-the-gas".

To my knowledge, the 98's only have one engine temp sensor and EVERYTHING engine/coolant/cold/hot is based on it.

Well, a cold start as in, starting the car for the first time in two days!

OK, will try that. Thanks for the advice.

Post by **jblackburn** » 11 May 2016, 09:30

For sure - a bad ECT left me with all kinds of starting issues.

Post by **sleddriver** » 11 May 2016, 12:18

I meant how cold is it in the mornings in Queens?

Post by **theWIFES_S70** » 11 May 2016, 20:52

I filmed a video of the crank... (This morning it was 55 degrees.) What do you guys think? I feel like it's fuel related (the engine, once at operating temperature, purrs like a kitten and starts like, well, like the groaning buffalo that our cars like to mimic)... I should just pony up the money for an OEM sensor, huh?

Post by **jblackburn** » 12 May 2016, 10:27

Flip the key on (to II) and make sure you have fuel pressure at the end of the fuel rail before replacing the temp sensor. A bad fuel pump check valve can do things like that as well.

That start doesn't seem too bad - mine took 45 seconds to a minute to get going when the sensor went bad - on a 70* day!

Post by **theWIFES_S70** » 12 May 2016, 10:34

jblackburn wrote:Flip the key on (to II) and make sure you have fuel pressure at the end of the fuel rail before replacing the temp sensor. A bad check valve can do things like that as well.

That start doesn't seem too bad - mine took 45 seconds to a minute to get going when the sensor went bad - on a 70* day!

Hey jblackburn, this thing?

We only need this if we have taken the air pump out, right? I miss the instantaneous start we used to have before the fuel pump/relay hiccup. Maybe we should be putting the fuel pump in the "always use OEM" section, too, huh? I will keep an eye on it but won't worry about it too much. I really appreciate your feedback!

Post by **jblackburn** » 12 May 2016, 10:45

Yes, splicing a check valve into a fuel line could work.

But in the meantime, just flip the key to II, don't crank, and look near the throttle body end of the fuel rail - there's a little blue cap and a port you can depress with a rag in hand to see if there is strong fuel pressure there or just a dribble.