440 idle problem
 

Hi

I have a 1995 440 1.8 SI (B18U) which has an idle speed problem and was hoping someone might be able to help. Bought the car two years ago and its been reliable with only an occasional problem with the idle that would rise to 1500 rpm but would then settle down after a while. Searched online and hearing of other owners having this problem changed the idle motor soon after having had the car. This did not cure the problem and it did not bother me much so did not take this any further.

Recently on starting the engine would idle at just over 2000rpm and would rise to 3000rpm when it warmed up. To be able to drive the car I disconnected the four pin plug to the idle control motor and the revs went no further than 2000rpm. After doing some research I found it is possible to control the motor manually by applying 12 volts across the top two pins of the motor and set rpm at 1200 when warm, which is ok in this weather but is going to be a problem when the weather starts getting colder.

To try to repair this problem I have to date tried:

• Changing plugs and air filter as part of service
• Changing idle motor back to original
• Looked for vacuum leeks and changed one rubber pipe which was starting to break up
• Renewed coolant temperature sensor (was noticing an unusually low reading on the gauge)
• Cleaned flywheel sensor
• Managed to get cheap spare ECU on ebay to try
• Renewed exhaust\inlet manifold gasket while on holiday recently (engine runs better, but did cure idle problem)

Might be time to get rid of it now perhaps as the water pump is starting to make some noise and the rear end is getting creaky.

I know this thread is 5 years old but I would like to resurrect for my problem. I also have a 1996 1.8 volvo 440 with a B18U engine and it has the exact same problems as the first posters did.

Like him when you start the car in the morning it would idle ok but after about 10 minutes of driving the idle would jump to 2000 and then on to 3000 and stick.

Like him I have also done the following to try and cure the problem.

Changed plugs and air filter
Changed oil filter and new oil
Renewed front engine temperature sensor
Changed idle stepper motor the new Bosch one I got from local Bosch dealer.
Changed some rubber ends on the vacuum pipes and on the charcoal filter, which where starting to break up.
Managed to get a cheap ECU unit from Breakeryard website as the back of my original one had some corrosion on the circuit board.

Also took it up to my local Smw Volvo dealership for a £75 diagnostic test

Their diagnostic test showed up these three faults below

Number 1 vacuum air pipe split
Number 1 vacuum air pipe valve missing
Manifold gasket needs replaced

I got Volvo to replace the number 1 vacuum air pipe and put in a new vacuum air pipe valve, as it was only an extra £35 to do this on top of the diagnostic price.

I got the manifold inlet gasket from Volvo parts when I was there that day and I am going to get my own local garage mechanic to fit it, as he is a lot cheaper than Smw Volvo.

Now my question to other members is should I also get my own mechanic to replace the exhaust manifold gasket when he is doing the inlet manifold gasket and does anyone know if this is likely to cure my idle problem?

Also I have noticed if I disconnect the air vacuum rubber hose from the bottom of the MAP sensor when the high idle problem happens it lowers the idle to normal but does make the engine run rough and smell bad.

Any help on this problem would be greatly appreciated as its been driving me nuts

Exhaust manifold gasket failure doesn't effect the idle (haven't experienced it ever), it just makes the car noisy and the engine bay gets filled with smoke (if it's really bad then some may get into the cabin) but since it's directly under the inlet manifold you can have it replaced as there's more room there if the inlet manifold is removed (the exhaust manifold can be examined as well for cracks etc. in the process). After the repairs check for fault codes again... but when the idle stepper motor was changed was the throttle cable adjusted?

Also found this for the B18U engine (don't have this in mine so it was new to me :) ), might be worth having a look at:
You mentioned that it's alright when cold but as it warms up the revs rise. Could be that the flap is always closed and is sucking in cold air for a longer amount of time (would also mean that the engine might not warm up fast enough). Just a thought...

Attachment 30194

Throttle cable adjustment... (fault code above picture is for auto gearbox and crank position sensor...).

Attachment 30207

Thanks for the quick replys guys.Yes when I put the new bosch stepper motor in I did adjust the throttle cable to take the slack out of it.

Yes the idle fault only happens after about 10 -15 minutes of driving and I think I know that air flap valve with the two rubber pipes running into the bottom of that big pastic air pipe from air filter to injector head.

for a matter of interest do you know which way the 2 rubber hoses go in that air hose hot cold flap valve??

I have it booked in next week to the local garage for them to change to inlet manifold gasket I bought from volvo so if the faults still there after that I will be stuck as I am running out of ideas on this problem

If the idle rises after warming up it makes me think of a leaking intakemanifold gasket. If cold the leak is thight but after warming up the intakemanifold expands and the leak opens. Try spraying some WD40 around the gasket with a warm engine. If the idle rises while spraying you know the cause.

(Here is a update)

I have been driving around with the new stepper motor disconnected for the last few days to see what happens.

I have now noticed with the new idle stepper motor disconnected the fault still happens so its not a electronic stepper motor fault or a fault from the new second hand ECU

I have also found when the high idle fault happens If I stop and open the bonnet to unplug the rubber manifold vacuum pipe from the bottom of the GM MAP sensor(located just under the right drivers side wiper arm) it seems to lower the idle back to 1000.

Doing this makes the engine sputter alot when I accelerate but at least you can drive home safe with a low idle.

Thanks alot for this information as I have some spare time today and have a can of wd40

Will report back with my results tonight

If you have a multi meter you can check the resistance from the MAP sensor.
1.3kohm measured between the connectors on the map.
Voltage should fluctuate between 1.6v-5v depending on vacuum in the intakemanifold (throttle open=less vacuum or closed=high vacuum)
Also check the hose which connects to the manifold for leaks or blokkage.