Hi Guys!

This is a great forum!!

Here's what I know about my 89 B280F:

1.) Temp-sensor for the gauge is in the back of the engine, driver's side. Two wire, gray connector.
2.) Temp sensor for the ECU and for the ignition computer is in the thermostat housing near the water pump in the front. (black connector, like the one used for injectors)
3.) Knock sensors are in the middle under the V-shaped water rail.
4.) Oil-temp sensor is the oil drain plug at the same time.
5.) Temp switch which turns on the AUX-fan if the readiator gets to hot.

I found a sensor or similar on the lower portion of the engine near the front on the passenger's side. It is a one wire sensor and has a black wire attached.

It measures almost 0 Ohm to ground and after starting the engine the voltage jumpes almost imediate to +Ub. Stopping the engine causes 0 Volts again. So it seems as the sensor is powered only while the engine is running which makes sense. What does not make sense to me is the fact, that the sensor measures almost 0 Ohms and still achieves Ub when the engine is running. Looks like an thermo time switch, doesn't it? But I am pretty sure it is not a time switch, since it has the LH 2.2 and not even a cold start injector. 0 Ohms are even while the engibe is hot (Florida, like 200 degrees regarding to the oil-temperature).

I am pretty sure it is not some kind of a over temperature cut off switch for the AC either (This switch would actually make sense, but then it should not jump to 12V when the engine is running). If I detach the cable and turn on the engine, the AC is still working.

So what it is for?

The reason why I am asking is I have a pretty high fuel consumption and I changed pretty much everything already including brand new injectors which did not make any difference, although I had a problem with the connections of the knock sensors.

I appreciate any input!!

Gerold

Things to consider with high fuel consumption...
The V-6s B280F require a valve lash adjust periodically.
Your AMM should be 0 280 220 008 not one with last three digits 007.
Your CO% should be 0.6 optimal, 0.2 to 1.0 acceptable.
Your oil should be 15W/40 for extreme driving.
The parking brake should be properly adjusted.
Otherwise, check your right foot flexation or the exhaust system for restrictions.
BTW, what do you consider high consumption?

My sources....


Volvo 780 V6 Air Mass Meter
0 280 213 006
Fits: 01/1987 - 12/1990 Volvo 780 V6


Volvo 780 Turbo Air Mass Meter
0 280 212 007
Fits: 01/1989 - 12/1989 Volvo 780 Turbo


Volvo 780 Turbo Air Mass Meter
0 280 212 016
Fits: 01/1990 - 12/1991 Volvo 780 Turbo

Thanks for the answer!

Please check my other posts regarding what I've done/not done so far. (valve adjustment included) It is getting confusing otherwise..

My AMM is a 0 280 213 006!! This could be it!! Would you please provide me with the source of your data?

No CO meter, sorry! They do not even have an inspection down here. I use the output of the ECU to monitor the mixture and can measure the pulse width, though.

I am using 10/30 during the winter and 15/45 in the summer.

Parking brake is adjusted, however the brakes are dragging slightly (please see other post)

My foot is quite unflexible as soon as it is on the accelerator pedal.

I am not able to get more than 20mpg (was down at 18, now not quite 20). The BMW 325is '90 gets 24, even with me behind the steering wheel ;-). This is quite a difference.

The mixture isn't right at slightly opened throttle (= most of the times) and is the reason for the poor gas mileage. There are only a few possible causes left over!

First I thought the point where the charcoal valve engages is off. Because:
Idle: mixture ok
light part throttle =steady speed: rich (If valve opens, additional air comes through charcoal canister, should be mapped in the ECU or cause leaning out, but I have a RICH! condition)
more part throttle (light acceleration+, mixture is fine)
full throttle or more than like 3500rpm -> rich =ok

My conclusion was, that the map in the ECU thinks, that at a given rpm the valve must be open and additional air comes unmeasured into the intake and therefore enriches quite a bit, but actually it isn't open yet. -> rich. The O2 correction is not capable to correct this to that point, that the mixture is right again.

All the other possible causes do not make sense to me like:

FPR: sees a steadily changing vacuum I believe, not a jump in the vacuum as you open the throttle slightly.
same with the crankcase ventilation. I do not know how this exactly works, though.

It could be a wrong vacuum routing, however. This car was a mess when i got it, it is almost perfect now!

Does anybody have a vacuum routing or can provide me with a picture of the engine compartment so I can double check?

Thanks

Gerold

Gerold
The AMM is to be an 006 not a 008, sorry I typoed. Supplemented my car with a set of green books for the 780 including the Specifications book TP 30518/10,
page 93 lists two AMM for a B280 engine I--0 280 213 006 or II--B 280 151 615 both listed with Volvo p/n 1 336 354-4. The coolant sensor is 0 280 130 032 Volvo p/n 1 346 030-8 and has a lower resistance as it gets warmer, line resistance or a bad ground could cause ECU to richen mixture. IAC motor 0 280 140 501 Volvo p/n 1 317 957-7 could be sticking or leaking, but your problem sounds more consistent indicating a sensor offset. Will try to get vacuum routing, have found cracks in hoses to throttle body on mine.

Brakes:
Brakes are still slightly dragging. I can spin the wheels and they won't turn more than one revolution. A BMW 325 E30 spins like 5 revs+, same with a Taurus 93. This could be an issue at higher speed as well as at lower speeds (higher losses in torque converter @low rpms). There must be some air in the system which prevents that the calipers retract. I bleeded the hell out of it but found the threat where the MC could be an issue (was dragging exactly the same way before I replaced the MC, but this could be b/c it was leaking internally)
Disks don't have the rusty ring on the outside btw. This prevents free spinning as well as I have discovered.

Catalytic converter:
I haven't pulled it. It could be partly clogged. However, I unscrewed the test-plug in front of the cat and the airflow/area was similar to the exhaust pipe.
Not like mentioned in an earlier threat, but I do not know for sure.

Thanks for the answer!

I did like 1000 things already, let's see if I can think of at least most of what I did:

Air:
airbox thermostat
airfilter
Airintake cleaned all the way through
amm replaced and adjusted (CO)
ICV cleaned, works perfectly
TB cleaned, all three gaskets new
TB switch refurbished and adjusted
TB closes fine

Fuel
new injectors, the updated ones
new injector o-rings
injector cleaner treatment performed.
Both fuel pumps new
new sock
new filter
Check valve checked
Partly new hoses (engine compartment)
Linkage adjusted


Connections:
parts of the harness replaced (all heat related break downs)for:
knock sensors
flywheel sensor
oil pressure switch cable
oil pressure gauge cable
Every single connection on the car serviced (de-oxidation spray, slightly bend contacts to asure connection and sealed).
Grounds certainly included.
Battery is fine and strong


new oxygen sensor (spliced version)
all sensors identified and tested.
all connections back to the ECU tested
new FPR
new FI relay


Cooling
new thermostat (low temperature)
new thermo switch in the radiator
new fan
new fan relay
fan clutch silicone treatment
radiator flushed
new radiator hoses all the way round
all new o-rings


Ignition:
all new bogi ignition cables
spark plugs (platinum nkg)
new rotor and cap


engine electrical:
new starter
alternater refurbished
knock sensor replaced (mechanically broken)
flywheel sensor works fine!! It is a Bosch model, has a by far higher output signal than the one for other engines (had both)



transmission:
transmission linkage adjusted
transmission power flushed, new filter, dextron III, shifts smooth, but not from p into d


engine mech.:
front engine seal replaced
valve adjustment performed twice already
intake manifold gaskets new (6 o-rings)
intake manifold cleaned
All the vacuum hoses replaced, tight connections, check valves replaced
charcoal canister valve is working fine.
new belts
oil and filter every 2500
compression 195 195 200 on one bank and 195 200 205 on the other bank


brakes:
new master cylinder
all four calipers rebuilt
4 new flex hoses
flushed
parking break linkage cleaned and adjusted


suspension and steering:
all new shocks (incl. nivomat)
new strut mounts
all new bushings in the front
new inner and outer tie-rods
new lower ball joint
power steering flushed
allignment done

Oil pressure sensor!

Bet you're worried that question went 15 hours without one attempt. Must be the V6 that scared us.

No one likes the frog motor :(...

Could you do me a favor?

Change your alias. It's juvenile and I think invites the conflict seen in this thread.

Thank you.

-JSBB
--
My signature.

Right. Anybody else wants to publish his comment?

I was in the impression that there are some more open minded and more intelligent people within the volvo enthusiasts. Well, life is a never ending learning process I had to discover!

You are encouraged to stay in your little "real" volvo world and I will be happy to move on.

Regards,

Gerold

Gerold:

By the words in your post I wonder if you took offense to mine? If so, none was meant - it was more an intelligent observation of human behavior - readers skipping the potentially unfamiliar and difficult questions without looking beneath the surface. It was a commiseration of sorts, to let you know we are reading you.

If it wasn't posted about a V6, I'd think your oil pressure sender question would have been answered within a few minutes on this board, as you provided every clue needed for the simplest diagnosis. A no brainer - so to speak - that usually attracts lots of well-intentioned helpful replies.

Don't be ashamed or sensitive about your V6 purchase, especially knowing the father of the Mustang selected its predecessor for his own life's work. Open mindedness includes having a skin thick enough to consider what fear of the unfamiliar inflicts on all of us, including you.

However, the use of pejorative terms for the French, could be avoided, as that appears to be intentionally closed minded.