car: 850. 2.0l 20v. 1993.

ok, been working on this volvo, had clocked up crankshaft breathing like they all do at some point.

after fixing that, i ran the car and it acted rather strange.
idle is around 8-900rpm for first minute or two... then it revs by it self up to 3000 rpm, and back down again, sometimes it does that several times, than in a spilt second it dies.... i start it again, and it fires up like before.

WHAT IS WRONG????

i have already changed air flow sensor, idle control unit, cleaned the throttlebody, checked (i think) all pipes and hoses, vacum, gas and air...... .now i am out of ideas.

regards.
Karl.

 

Check to make sure the you connected the hose that goes from the brake booster to the idle control valve, also check to make sure all hoses at the vacuum tree are connected. I'm betting it is a loose vacuum hose Do you have a check engine light?

 

check engine light is on... i am also sure it´s vacuum problem, but i´ve been looking for something that causes this, but without luck.
i will keep on looking, and all advice are appreciated.

 

Hi Karl, welcome to the site.

My guess would be that you have a bad ECU. Check other things first but that's just my guess.

 

Thanks rspi, glad to be here..

but about ECU, yes, that would make sense... what i have done so far..

- cleaned and overhauled crankcase breathing. (Pvc)
- replaced air flow sensor.
- replaced many hoses and connection.
- replaced idle control unit.
- replaced V-vis solenoid valve
- re-route vacuum hoses. ( just to try something.)

None of above had any effect on my problem.

maybe i´ll borrow ECU and try that tomorrow..

thanks for breaking up this boring pattern i was getting stuck in..

 

its weird because it sounds vacume related.

check the vacume line that runs into the left side of the manifold, is that one connected?

 

Since the check engine light is on, do you happen to know the code that caused the check engine light? That would help point in the right direction. Could be an ECU, but if it was running fine before you took it apart, I'm a bit skeptical that it suddenly crapped out at the same time you did work on it. Don't get me wrong, it could happen........

 

Dear Karl, take a breath, don't take this the wrong way but these parts you replaced, did you replace with new or used?

Did you replace them because they tested bad or just as a "shotgun" approach to try and cure the problem??

Did or do you have codes?? This is major as it can point you in the right direction or make guessing for "us" easier. Do you know how to pull the codes from your under hood diagnostic panel ?? You can also check to see if you have an OBDII port near your shifter. It's really rare in 93's but you might be lucky. OBD1 under the hood you have to do yourself or with a friends help, OBDII you can take in to a parts store and they can pull them for you.

Second picture is where you'd see the OBDII port. It's covered by a rubber coin holder, upper left in the picture, corner of the coin holder visible. Very few 93's have it but it's worth a look just in case.

 

Will it run with the MAF unplugged?

 

Sounds like a bad maf and vaccum leaks don't have much expierence in the 10 valve but 20 v will do that with a bad maf.

 

ok, before i started working on this car, it had been running bad, it started up fine, but had little power, or more like it was struggling to accelirate.
just to much pressiure building up in crankcase area.
after pcv cleaning, it got better, but previous owner was trying to fix this problem, and placed hoses on both crank breathing and oil drain where oil trap is suppose to be.. both of these hoses he connected to air intake by drilling holes in to it.. (real genious!) and air filter box full of oil.

after i connected this correctly, it ran alot easier, but like i mentioned before, with some defects.

the parts i´ve tried, are borrowed from friend of mine who has same model, that ran fine, but has no tags, so he ain´t using it.

now i noticed, that pressiure is building up inside the engine, even though hoses from oil trap are "blowing steam", when i remove oil cap, it sounds like i am opening a coke bottle.. "whizz"... back to square one.

 

There just shouldn't be that much pressure in the crankcase, if the PCV system is functioning and not blocked. You should check compression.

 

compression reading is 145 psi. all very even.

i am going to take the manifold off again, and start all over.
there must be some thing that i am missing.

will keep you informed soon as i spot something.