Tune up and Idle still Sucks

Hi all,
I bought a 1990 740 GL wagon for my wife, then she dumped me and took
the Toyota
(not as dumb as I thought ;-) Seems like ever since she left it has
gone downhill. The
clutch is making a horrible "beehive" sound when I depress it, the
waterpump is leaking
(I should be able to replace that without many problems), and now the
idle continues to
be erratic even after a homegrown tune-up.
It started wanting to stall at redlights, especially when I started off
in first (5 sp manual).
Once underway though there was no problem. Well I put in a new
distributor, rotor, plug
wires and plugs, and now its running worse! Now, the idle is very
erratic and it even misses
as I'm driving down the road (never did before). I was thinking it
might be the air mass meter
but it seems like maybe its not getting enough contact somewhere.
Maybe I didn't tighten
the plugs enough (barely did since I didn't have a torque wrench) or
the wires aren't making
good contact (I have them all the way on, but they are the cheap Bosch
wires)? I just got
the coil wire from the dealership so that isn't the problem. Could I
have somehow not put
the rotor on good? I put it back just the way it was. Anyway, any
advice would be appreciated. jimmy

 

i had a sudden rough idle on our '97 960 and it turned out to be a
defective coil. art

 

Check for vacuum hose tears / failures.

Clean throttle body.

 

I have a 1990 740 also , I tuned it up with no improvement.
First thing I did after a tuneup was pull the computer codes,
have you done that already?

What codes do you get?

The codes will help you zero in , its better than throwing expensive
parts at an engine.

Heres what I did to mine,
replaced the timing belt, the previous belt had 165K miles on it, hard
to believe but.
New crank pulley, old one had cracks throughout the rubber section.
New injector relay.

Starts and runs like a watch now.

 

Would a parts store have a gizmo to read the codes or do I have to take
it
to a repair shop? So far it is still the same. If anything, it is
getting worse!
I will probably have to take it in for repair...I will check the coil
as well.
Thanks to all for the help.
jimmy

 

Just read your codes for free. Its a volvo.!

Your 740 has its own onboard diagnostics code reader, its right there
under your hood.
Look on the driver side, right next to the hood hinge.
You'll find a small black plastic box.

Just pull the lid off, theres a probe which you pull out and insert
into the various holes, on mine its #2 and #6, they are numbered.
#2 is for ignition, #6 for fuel injection (I think).

Get some paper and pen and be ready to write the codes down as they
flash.
Press the button for a second, release, and count the flashing LED,
it flashes in series of 3's, for example ;
three flashes -pause- two flashes -pause- one flash,
written 3-2-1 is the code for a cold start injector (or its associated
wiring.)

Do it again and write down the next series of codes, one more time for
the 3 stored codes in its memory.
Now look the codes up .....,
http://brickboard.com/FAQ/700-900/EngineOBDCodes.htm#LH24FuelInjectionFault

make sure you know which ignition system you have, if its got the
regular cylinder shaped ignition coil you have the bosch system, mine
is rex regina with a strange looking square coil.
They have different codes, but its all there for you to look up, then
you have a good idea where the fault is coming from.

Just read and follow the directions,...... ignition ON, engine NOT
running. Simple.!

 

Cool. If it ever stops raining I'll get out and check it. Thanks!
james

 

Well I tried it and could not get any codes. Maybe it isn't working
but I pressed
the button after putting the probe in, pushed it and released it, held
it down, everything
and no blinks at all. The only time the LED light brightened was when
I was holding
down the button. Oh well, thanks for the info though.
jimmy

 

Clean the probe, clean the holes out, peer inside and make sure you're
in a hole which has a connection. The box is getting power, the LED
will light up whether the probe makescontact or not, so its probably
just not contacting properly.
Stick with it.

 

Thanks Jones for keeping me going! I cleaned the contact probe with
electrical parts cleaner and made sure I had the holes blown out and
low and behold I got a code! ;-) Says my idle air control valve is
faulty.
Now I just need to locate one of these (and hope its not too spendy)
and
replace it. YOU THE MAN!!!!
Jimmy

 

Ok you've made good progess, don't just to conclusions too quickly.

I'm not sure what the code you got was, but they don't usually mean the
xxx is faulty, it means 'there is a fault with the signal its not whats
expected'.

Check all the pipes around the idle air valve, take it off give it a
clean with fuel injector intake/carb cleaner, check/clean electrical
contacts, test on bench if possible (should change between fully open
and closed). Then if that fails start thinking about a replacement.

Also the throttle closed switch on the throttle body could have a
bearing on the operation of the idle valve.

 

Ok you've made good progess, don't just to conclusions too quickly.

Thanks Tony. I'll check all that tomorrow (looks like I'm off again
due to
an ice storm ;-)
jimmy

 

Tony is right, I've had codes which "point" to the trouble area but
throwing a new part at it isn't the best way, sometimes its just the
plug or a connecting hose...or the wiring.

Read up on the IAC valve first, theres some cleanup you can do and that
might very well get you going.

http://www.brickboard.com/FAQ/700-900/EnginePerformanceSymptoms.htm#Cold_Start_Dies_Dirty_IAC

 

In addition, a leak on the manifold side will cause the ECU to think the IAC
valve is bad because the ECU can't control the idle by using the valve.

Mike

 

Thanks for the advice guys! My main obstacle now is extreme cold temps
and
an ice storm that has enveloped Austin, Tx. Soon as the weather
clears, which
another round is supposed to come through this weekend as well, I will
get out
and clean the IACV. Plus I'll be putting on a new waterpump since the
current one
is leaking...
Reminds me of the Car Talk guys this last Sat. Fellow called up w/ a
740GL wagon
as well (1990 too, I believe) having some problems and they told him
after owning
that car a few years he will be able to go to a Volvo Dealership and
get a job as a
mechanic ;-)
jimmy

 

Same here in Boston, waiting for a waterpump gasket and the temps
plunged.

The volvo is simple to work on , its the diagnosis which takes my time.

Theres a couple used IAC valves on ebay, they are expensive new.

With a bit of work you'll be glad you ended up with the volvo.
The more I work on and drive mine,
the more I appreciate the design and engineering .

 

I'm glad you figured out your idle problems.....

Not to put a damper on things but the screeching "beehive" noise when
you press the clutch in is your release bearing going bad which = new
clutch in your future. Mine is the same story....it's only a matter of
time before it goes out. Mine has made noise for a long time and I've
just accepted the fact that when it goes out I'll be without a car
until I get it fixed (I don't depend on it for work). My short term
solution is to spend a little time as possible with the clutch
depressed.

 

That's always a good first guess, not just in volvos. i don't care
whether it's an idle air control valve or an idle speed adjust bypass
or an idle speed adjust motor or a choke in a carburetor, it'll get
gummy/sticky. Last time I suspected the idle speed adjust bypass was
making my Honda gallop at idle but decided to let the professionals
diagnose it, I ended up buying a rebuilt distributor before they
figured out it was the idle speed adjust bypass.

 

Thanks...yea I have figured that out. Very frustrating to see the
whole
car fall apart all at once! Seemed like a good deal when I bought
it...
Anyway, I will try and clean Idle Air Control valve this weekend, and
was
wondering if you guys had any tips? I have some Electrical Parts
cleaner,
do you think that would work as good as the Carb Cleaner? Is there
anything
I could really screw up by doing this? (I have already lost the clip
that keeps
it on and will have to get a new one at the dealership!). Thanks for
any
and all advice.
jimmy

 

Is there a junkyard near you?

Don't use expensive contact cleaner when cheap carb cleaner will work
better.