1998 S70 T5 Low Compression after stall, will not retart

Post by **pfeener** » 13 Jan 2007, 19:15

The air pump is strictly for emissions. You could remove it entirly and the car would still run fine....wouldn't pass inspection..but it would run fine. The IAC is only for idle control. Even if it's broken, the car will still start...might not idle...but it'll start.

Does it sputter at all when you turn it over or does it just crank. As far as the spark interval; for every 2 revolutions of the crank you should see the plug fire once. Are the plugs wet and can you smell gas after you've turned it over a few times? If so I assume you're getting enough fuel. If the fuel is there and so is the spark this baby should at least sputter a little. I would check the distributor cap and rotor for cracks or breaks and the only other thing I can think of is the crank or cam sensor. It's these sensors that tell the ECU the timing of when to fire each plug.

Post by **MadeInJapan** » 13 Jan 2007, 20:01

Flooding.

Trilarry · Post by **Trilarry** » 13 Jan 2007, 20:51

I have an extra camshaft sensor I will swap out. The crankshaft sensor showed the required 250 ohms but I will check it for debri.

Are you saying that if one of these things are the problem my symptom of low compression would dissapear or the gas wash would go away?

I have flooded the engine by the smell of fuel after cranking as Made in Japan mentioned and by the dripping plugs.

I believe you are onto something about the timing. I have fuel, I have spark but somehow maybe not at the right time. I will visually inspect the crankshaft sensor even though I did not get a code for it.

I'm starting to get on the same page you're on! Thanks for hanging in there with me. I now believe that the compression is a symptom like you said. So now I will look in the direction of items that affect timing and spark.

Besides I'm getting plenty of oil on the cam as I veiw it thru the fill cap. So lifter are an after thought.
I'm rejuvenated! All I need is some daylight.

Thanks PFEENER
TRI

Post by **pfeener** » 14 Jan 2007, 08:56

Yes the low compression symptoms should go away after you get it running again.

Does it sputter at all when you turn it over? or just crank away?

Post by **rmmagow** » 14 Jan 2007, 09:40

Careful here, I had exactly the same symptoms in my old Mazda 929. The timing belt had skipped a couple of teeth due to tensioner failure. The belt itself looked ok but it was way off leading to low compression reading on all cylinders. Please check the alignment of your belt before it breaks.

Trilarry · Post by **Trilarry** » 14 Jan 2007, 12:46

It does not sputter, it just cranks away. I eliminated the belt and tension. The timing marks or dead on. I'm getting ready to check my crankshaft sensor and swap out the camshaft sensor, I will let you all know how it went.

One question I have, anyone ever heard of the O2 sensor causing a no start condition?
Thanks
Tri

Post by **pfeener** » 14 Jan 2007, 14:37

No, I've never heard of that. Like I said, it's very basic...compression, fuel and spark...that's it.

Post by **MadeInJapan** » 14 Jan 2007, 16:35

Trilarry wrote:One question I have, anyone ever heard of the O2 sensor causing a no start condition?
Thanks
Tri

Yes, and when a MAF sensor goes out too.

Trilarry · Post by **Trilarry** » 14 Jan 2007, 18:32

changed out camshaft sensor and cleaned crankshaft sensor, still no start, Somehow I believe I'm getting too much fuel in the cylinders. I will check out O2 sensor in the AM
Tri

Post by **pfeener** » 14 Jan 2007, 18:59

The thing that keeps bothering me is the car doesn't even sputter. I would think if your getting spark at the correct time and compression that it would sputter, pop, backfire whatever, but something. If you think you're getting too much fuel you could always disconnect the individual fuel injector connectors, hold the throttle wide open and crank it over. After a minute or two it should at least start to sputter. Pull the MAF sensor connector and see if there's any change. You can always unplug the O2 sensor as well and I believe it will try to start using a default value supplied by the ECU.

Read this thread as well.

https://www.matthewsvolvosite.com/chat/p ... hp?p=19039