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

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

Reply to
Art McGinn

Check for vacuum hose tears / failures.

Clean throttle body.

Reply to
Mr. V

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.

Reply to
jonesg2

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

Reply to
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 .....,

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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.!

Reply to
jonesg2

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

Reply to
jimmy

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

Reply to
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.

Reply to
jonesg2

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

Reply to
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.

-- Tony

Reply to
Tony

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

Reply to
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.

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Reply to
jonesg2

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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

Reply to
Michael Pardee

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
Reply to
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 .

Reply to
jonesg2

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.

Reply to
zoltamatron

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.

Reply to
z

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

Reply to
jimmy

Is there a junkyard near you?

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

Reply to
James Sweet

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