J Sweet: where is B230F eng speed sensor?

(Or anyone else)

Re: 1992 Volvo 740 turbo 4-cyl in line....
I know you are familiar with these 740 cars. I rechecked the codes
being set, and the code for a bad speed sensor is being set. I found
bad wiring at a speed sensor on an '89 740 sedan a few years ago, and
this fixed something like the current problem...won't idle at all. But
I can't remember where the speed sensor was mounted now. I am thinking
it was an inductive type pickup, probably sensing the flywheel
rotation?

Do you access this sensor possibly by removing the center console?

thanks, geronimo

 

Engine speed is picked off the ignition system. Older cars use a hall
sensor in the distributor, newer ones use a flywheel sensor. What do you
mean by it won't idle at all? Does it die if you let off the gas? Does
this have the LH-Jettronic fuel system with an air mass meter? If so try
unplugging that and see if it runs better, if so that's your problem.

 

The crankshaft position sensor (if your car is so equipped) can be
found near where the transmission and engine meet, on the top, below
the head.

 

Could the code mean vehicle speed instead of engine speed? I wouldn't expect
the engine to run if the engine speed were unknown.

Mike

 

The engine speed sensor is found @ the rear of the engine just in front
of the transmission that being said the engine speed sensor is just used
for starting only nothing to do with the engine running. it sounds like
you have another problem the Volvo code is 214 for the speed sensor if
you could post back with all the codes then we can see if we can resolve
your problem
Glenn

--
"*-344-*Never Forgotten"
Is for the New York City Firemen who lost their lives on September 11,2001.
The official count is 343, but there was also a volunteer who lost his life
aiding in the initial rescue efforts. And I will never forget them as
long as I live,
nor should any American.

 

Yea it is the LH Jettronic system. Yea, it dies as soon as you let
off the gas. You have to really punch it hard, and then it is revving
up to 3000+ to keep it from dying. All this trouble started after
fixing a leak in the turbo...three bolts were left out. But the car
was driven around town for a while after the repair, running better
than ever with the exhaust leak gone...before it overheated and
developed to idle problem. The fuel system code being set is 3-1-1,
which is "speed sensor", not crankshaft sensor. Come to think of it I
do think the sensor that I found with shorted out wiring on the sedan
740 I use to have was on the top of the bell housing. Perhaps once
the distributor is removed at rear of valve cover, then it can be
accessed?
When I unplugged the AMM on the 740 sedan which had same control
system, the engine could be started but wouldn't run, it would stall.
And it is not setting a code for a bad air mass meter....but we saved
the one from the defunct sedan, still have it, so we could try tht
also.

 

The only code being set now is 311. This is when jumpered for fuel
system. Shows only 111/no problem under ignition. Well, I have a print
out from an article off the internet showing all the codes for 92 740,
and it listed 311 as speed sensor.

Yea, now I remember... I got to the speed sensor by removing the
distributor at the rear of the valve cover, and it was then accessible
at top rear of engine. It was not the sensor itself that had gone
bad, but the two wires right at the connector that were shorted
together. Combination of a lot of heat and something acting as a
solvent over many years had turned the plastic wire insulation into
goo, allowing the conductors to come together. So it was a fix that
cost nothing. The sedan could be started, but would not keep
running....until I fixed the wiring to the sensor. So I am hoping
that the same thing happened with the sensor on this 92 turbo wagon.
This no-idle symptom occurred at the same time as the engine
overheated. And the overheat has been something of a periodic ongoing
problem, but an internittent one. It had been running fine without
any overheating for quite a few days, with perfect idle, then the
brother fixed the exhaust leak on the turbo...and then after driving
around town a little right after the turbo fix, it overheated.
I asked him if he could have disconnected a sensor perhaps while
working on turbo, he said no. Now I find it setting this 311 code,
when it was not setting it before the turbo fix/overheat incident.
Thought at first the timing had jumped, but I have the timing at least
close...and varying the cam sprocket just slightly either way is not
fixing the no-idle problem at all.
Am I on the right track possibly, or no?
Are you sure it is 214 for the speed sensor? I wish I had the
factory manual, but all I have is this info from a Volvo site on the
internet.

thanks all, Geronimo

 

The AMM changed from time to time, make sure the number matches before
you try swapping them or you can burn out a good AMM and damage the ECU
in the process.

How badly was it overheated? You might want to do a compression check,
the cylinder head may have warped. Normally if the flywheel pickup
sensor fails, the engine won't start at all.

 

James......We don't have a compression tester, but I can tell from
turning the crank pulley (you almost can't by hand when it is
certain points!) that the compression is abt the same as before this
breakdown occurred. There isn't water being lost anywhere it seems but
out the reservoir cap pressure relief. I removed the crank
position/speed sensor. It's three-wire. ( Yea, you're right it is
sensing position as well as speed...as my code printout actually calls
it a "crankshaft position/speed sensor". ) The two signal wires were
OK, but when I tugged on the bare ground wire, it came out.... there
probably was no connection there even before I yanked (gently) on it.
Problem is the foil outer shield, which no doubt is also a ground, is
still intact. So I am not sure if the sensor was really inop. Any idea
if the sensor can work if the third wire, the bare ground, is broken?
If I try a new one, and it doesn't fix the complete loss of idle, what
should I check next?
No doubt we don't really have the timing exactly right, as for some
strange reason, when you line up the crankshaft marks and line up the
cam pulley marks per the haynes manual, it is so far out of time that
there is no compression. The mechanics (we bought the car from) who
put the engine in this car did something to change the timing marks.
We made a new mark for the crankshaft pos. after verifying #1
at TDC. And then we found a position for the cam sprocket by
experiment where the car starts easily. But no adjustment--- like
changing the cam sprocket one or two teeth either way--- fixes the
problem, complete loss of idle. You have to punch the gas really
hard immediately when it starts, and then it will rev up really high;
it will then start to die, and you have to relaese the gas pedal, and
punch it hard again. Even if you floor it and hold it, I don't think
it will run constantly.
Should we check the vacuum? Can't check it at idle, but what
should it read when it revs up to 3000 or so?
I have a timing light, so if we can just get it to where it idles
again we can see if the ECC module is setting it correctly....because
I know if the timing is too far off it could cause it to overheat.

 

Figure out why the timing marks are wrong before you proceed any
further. It's amazing how critical that is, off by a single tooth is
enough to make the engine run horrible and a few teeth will keep it from
starting at all. You'll never figure out the other problems you have
until that one is nailed down, wouldn't surprise me if that's your whole
problem.