[owenski]

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