1994 Volvo 850 Turbo, 139k. Well, to make a long story short, drove the car to Maryland and back 3 straight weekends (6 hour drive each way) with no problems. The CE light came on a couple of weeks back, slow front o2 sensor. O2 sensor is rust welded to the downpipe, so I drove it as-is, still getting high 20's MPG on the highway. At home, let the car idle for @20 minutes, drove it out of the driveway to move another car, shut it off, went to re-start it and it just turns over. I push it into the garage, figured maybe somehow the connection to the rotor corroded or something. Replaced the cap and rotor, started right up. Went to start it again, wouldn't start. A couple of days later it started once and after a few seconds stalled out, and hasn't started since. I ran a compression check and have good compression (timing belt was done at 132k), I have fuel pressure, but no spark. Pulled the plugs, so spark when grounded. I replaced the coil, no luck, so I ordered a used ECU, still does not start. Is there anything else to try? I'm pretty stumped. I checked the Cam Sensor and it is dry, no oil blowby. If anyone has any idea, it would be greatly appreciated.

Have you tried pulling codes since it won't start?

:( Yep, only 435 the slow response from the front 02 sensor........

Have you tried unplugging the mass flowsensor and starting?If not try that it won't run very good over idle.
Could also possibly be the cam or crank speed sensor.

:( Yep tried unplugged MAF, didn't do anything. I'm just trying to figure out what else can cause the ECU not to send the signal to the coil ( I have 12v when ignition is on from the coil); Cam sensor, crank sensor, knock sensor, anything else you can think of? I've had Turbo DSM's all my life for my toys, and just switched over to the Volvo Turbo world, so I'm not real familiar with the engine yet. Thanks for the help.

I will keep racking my brain and see if I can come up with anything else.
One more thing there is a relay bye the cooling fan relay.It is about the fan and radiator.Try making sure the plug is connected to the relay good.I know it will stop the car from running.

Yes, yes.... That particular relay is really something! Check the connections, the contacts may be weary due to age.

:pokey:

Another thing to check is all the connections at the battery for corrosion.I just had another problem with corrosion on a car causing something similiar.

hello,i have a 1995 volvo 850 t5 2.0 l and i have the exact same problem,so spark at all ,changed the coil and the power stage,checked the rpm sendor,still nothing,i have 12+ on the coil but no pulse...any ideas what i should check after this?do i have 2 try change the cam sensor?

I would try a new cam sensor.

thanx a lot for the answer,
do u know if there is any way i could check the one i have on the car?does this tipe of sensor ussualy die instatly like this?
i try check it cose i want 2 avoid buying it if is not abbsolutly necesary,this tipe of car has extremely expensive parts in my country,this sensor is like 350-400$...and i just changed the cluch 1 and half mounth ago wich was a small fortune:))

I don't have the books to look up the way to test it.
You can look at it and make sure it is clean and not full of oil.
Sometimes the seal leaks and fills it with oil.

The thing with sensors is that they look perfectly well on the outside, but when made to work, are useless. <_<

I have the pleasure of seeing how my mechanic changed the Pickup/RPM/Crank Sensor once. Once the mechanic took it out, I quickly asked for it and to my surprise. "Eh, doesn't look like its bad..." :angry:

So, i figured that i would hold onto it, just to be sure, if the problem still occurs, I'll just ask him to refit the sensor. True enough, the problem did not recur... :grin:






I'll try to attach a photo of the sensor if I can find it.
:)

OK, found it!

:grin:

no,that is the RPM sensor (flywheel sensor) wich is ok,that one can be tested in 2 ways and i did and is working,i`ll atach a pic with the cam one...this is the one and this i do not know how 2 test:)

It still trying to find some info.Since I don't work at the dealer anymore I can't just look it up anymore.

Glaad,

Yes i know. Just sharing to you how a sensor (any for that matter, maybe) may look fine on the outside but is useless when run.

:)

Good that you've posted up the cam sensor - never had to change it yet, so, first time for me to see it.