98 S70 won't start

a799608 · Post by **a799608** » 16 Apr 2006, 18:56

car was sitting in my driveway idoling and it shut off. it would then start for about 5 seconds run extremely rough and then stall again. eventially car wouldn't start at all. i replaced the plugs, plug wires, distributor cap, router, nothing improved. i tested the primary and secondary winding on the coil, all okay. checked the voltage on the camshaft position censor and i think i found the issue. wire 3 has voltage the same as the battery, wire 1 has 0 resistance. wire 2 is supposed to have voltage of around 5 volts, the voltage is the same as the battery. i traced the wire back to the ECM, and am getting battery voltage directly out of the ECM post. Does this sound like a bad ECM, or am i not testing correctly? is there a way to test the ECM before having it rebuilt? also, i checked the fuel, and i have pressure at the injectors. the plugs have spark, but i'm thinking that if the cam position sensor is not functioning, then the timing would be off, which could explain things etc. any help would be greatly appreciated.

Post by **MadeInJapan** » 16 Apr 2006, 19:31

What model and year car?

ahmedshaheen · Post by **ahmedshaheen** » 17 Apr 2006, 01:23

did you look into the fuel line????? mine had the same thing , and it turned out to be the fuel pump, replaced it and everything was working fine.put the key into the position 3 and see if there is any fuel coming to the front, if not , then u know its the pump. You also need to test the fuel pump outline pressure it should be between 370-390 kpa or 235 LPH, if it is a turbo powered.

good luck!

a799608 · Post by **a799608** » 17 Apr 2006, 07:50

it's a 1998 S70 2.4L GT Automatic.

i've checked the fuel at the injectors, and i have pressure. i haven't tested the amount, but it appears to be pretty strong.

Post by **MadeInJapan** » 17 Apr 2006, 18:43

Unplug the MAF sensor and see if it will start and idle.

Hope you have a way to reset codes, because this will set some codes when you do this. It'll set a MAF no-signal code, an 02 code (most likely) and a code related to the turbo not getting enough air.

At least you'll be able to take the MAF out of the equation if you have the same symptoms with the MAF unplugged. If the car starts and idles with it unplugged but won't with it connected, you will then know it's the MAF.

a799608 · Post by **a799608** » 18 Apr 2006, 17:31

don't think it's the MAF. tried the suggestion and i had the same symptoms. if i unplug the cam position sensor, it sounds much different when attempting to start. i ran the voltage test on the throttle position sensor and i'm not sure if that's the problem or not. i'm getting some weird negative voltage when the sensor is pulled in. when it's unplugged i get the correct .76 V. i'm also getting 5.02 V on the hot wire, and .03V on the ground. when i plug the sensor in, things go to like negative 4.06 V with the throttle in idol. at full throttle, i'm still negative at around -.34 V

VolvoS70Driver · Post by **VolvoS70Driver** » 18 Apr 2006, 17:34

I just started having the same issue. Filled it w/ gas, drove 40 miles, parked at the airport for a week. Got back in, started and idled perfect. Actually let it idle for a few minutes while I check my voicemail.

Started driving home, no problems. As soon as I got off the interstate, the idle was very rough. Kept going and at the first stoplight it stalled. re-started and stopping at the next turn it stalled. as long as I was moving and around 2k rpm's or above, it ran fine, only at low rpm's or idle. by the time I got home a few minutes later, I had to keep my foot on the gas and brake at the same time to keep it reved up.

It will start for just a moment but as soon as the initial high speed boost is gone, it stalls. I changed fuel filter (looked original w/ 120k miles on it) but no luck. I will try the MAV thing if you could tell me what that is. Without a repair manual, acronyms on newer autos go right past me.

I did read a note in the owners manual that overfilling with gas could cause an emission problem and I do tend to get the most out of my fillups before gas jumps another $.20 each week. Could this be something ??

Thanks

a799608 · Post by **a799608** » 18 Apr 2006, 17:46

doug,

the MAF (MAV) is the mass airflow meter. chilton's book states that if this sensor is dirty, it could result in incorrect air/fuel mixture. it's located on the air filter box, on the intake hose. the air filter box is directly behind the battery. the sensor is on the right side of the box (side facing the windshield).

hope this helps. if i ever figure out what's wrong with mine, i'll pass the info on. i'm starting to think it's the trottle position sensor. this sends different voltages to the engine control module depending on the throttle position. sounds like this could be your problem too if the car would run while on the throttle, but not at idol.

mike

VolvoS70Driver · Post by **VolvoS70Driver** » 19 Apr 2006, 16:34

Mike,

Sure enough, disconnected the plug and she started right up. Pluged it back in and it stalled right away. Great News (relatively speaking)

So can this thing be cleaned or is it replacement time ? I am fixing to take out a crappy Fram air filter and put in a K&N but not sure what diiference that may make.

Many Thanks

Post by **MadeInJapan** » 19 Apr 2006, 17:04

Try plugging and unplugging the MAF about 20 times and see if it works then...could be the connections are just dirty. If not then you really ought to buy a new one, and unfortunately these are not very cheap. www.fcpgroton.com has them and you can trust you'll get a good one from them... and I've seen them on eBay, but not sure if I trust buying a used one or even one claimed to be new from there.

Also, you can try to clean it but the outcome is not always pleasing to the owner. Here's a thread about cleaning it:
http://volvospeed.com/vs_forum/index.ph ... =46629&hl=