Hi there,

A while ago I bought my 1991 volvo 940 16V.
It had no power when I bought it. (and still doesn't)

It had a leaking head gasket, but no coolant in the cylinders/oil.
I redid the head, valves and seals.
New timing belt, water pump etc.
New spark plugs, wiring.
New injectors (rebuild/conditioned)
New O2 sensor

Still no power and uses a lot of gas.
Renewed the coolant temp sensor & MAF (AMM)sensor.
Nothing changed.
No vacuum leaks, however I measure only 16 on the intake.

The timing is set by the computer, but there must be an initial setting, right? Why else would the distributor be movable/adjustable.

Whatever I do the timing stays at 30 degrees ATC! so it's way advanced, as following the book it should be 15 degrees BTC.
Checked with the timing light.

So I pulled the cover of the timing belt housing and checked the camshaft lineup which was ok. Even with several connectors unplugged the timing stayed at 30 ATC...... No fault codes either.

Now I am at the point that I don't know what to do.

I don't think the cat is plugged.

I read all the forums and spend Hours to figure out what it can be.

Can it be the idle control valve leaking? But on the other hand I think this valve doesn't do anything when taking off.

The 1991 B234F does not have an EGR valve.

One thing I have to mention is a connector which goes nowhere under the intake manifold. The other 3 are connected to the coolant temp sensor, the next, and the knock sensor. I swapped the one from the knock sensor and coolant temp sensor. No difference, except an error code knock sensor. I connected everything the way it was, did reset the error codes and it's fine, that means no error codes.

Could it be the crank positioning sensor? It works, otherwise it wouldn't run?

**** I wish I still had my 1989 8V 740, which I gave away at 590.000 KM and still going strong!

Somehow I think it's the ignition timing or so.

Please let me know what you think as I ran out of options.

Thanks,

Richard

 

indeed, the ignition timing comes from the crank position sensor.

are you SURE all the timing belt notches are lined up correctly?

I've heard of the harmonic balancer (rubber block under the crankshaft pulley) allowing the pulley to get out of whack relative to the crank. this would cause all kinds of strange in the timing and running.

 

I changed this belt as well.

The timing stays at 30 atc with no changes....


Thanks for your reply.

Richard

 

Yes the timing marks are bang on..

 

the harmonic balancer isn't a belt, its a rubber block behind/inside thene fanbelt pulley on the crankshaft.

you might verify the engine is at TDC when you think it is via pulling the spark plugs and turning the crank by hand until the #1 piston is at the top of its stroke, then check the mark on the crank pulley.

 

I took the stuff off to check the timing belt and balance belt.

Balance belt was out, wonder why, but probably my mistake.
So pulled the timing belt and balance belt off and reinstalled.
Great.

Now when I put the bottom cover on with the timing marks on there it showed it was sitting on 20 degrees after tdc, while the crank pulley was still on the tdc mark. Soooooo, I think you're right the pully/harmonic balancer did shift. However when everything put back together I timed the timing using a timing light. Still at 30 degrees BUT that makes sense as the ignition needs 10 be 10-15 degrees. (20 to start with - 30 degrees read)

The balance thing belt out of wack does not have anything to do with the ignition. The pulley is however (for the reading) only for now it works. Going to change the pulley as soon as I find the main reason in fuel consumption.

I checked the MAF sensor following the Volvo manual, 2.5 - 4 Ohm between sensor pins 2 and 4. Crap it was 6 K Ohms !

So the new MAF is bad.... Going to try a new one as soon as I find one to try out.

So if the resistance of the MAF is super high, does that mean it tells the computer the engine is starving for fuel?

One other question left is the intake vacuum. It's on 14 on the gauge.
Can somebody measure the vacuum on their vehicle? I can find anything on the internet.


Thanks for your comments!

Richard

 

a 91 16V should have OBD. have you read the codes to see if there are any faults?

see Engine and OBD Diagnostic Codes

 

The old maf gave an code 1.2.1 as I remember correctly.

Now there are no codes. just 1.1.1 on pin #2 and #6

Grr. computers......

Thanks,

Richard

 

Check the rubber insert on the harmonic ballance pully. replace it as a whole; there is no other way. It deteriates and the outer and inner parts move and slip around.

 

Thanks for the replies!

I decided to build a "race" engine, instead of putting more time and money in this one.

Not sure yet what engine I am going to use. Looking also at a 850 T5 engine.
On the other hand I have the 16 valve head and the B234 block.

What I can't find is what engine control module I have to buy in order to hook up a computer to it. Would be nice if I could find a how to build a race engine including parts needed, step by step. Any ideas.

Looked around on lots of pages and found only global info.

Any ideas are much appreciated.

Thanks,

Richard