Firstly hi all

Now onto the issue:

I have a Volvo S40 1.8 2006. The car feels sluggish accelerating until the revs hit 4600 RPM then the car takes off.

So bellow 4600, normal acceleration then as soon as the rev counter hits 4600 I'm put back in my seat by the change in acceleration.

Is this normal for Volvo S40s? or do I have a MAF issue or a fuel issue?

 

Is this a turbo car? Sounds like severe turbo lag. You have a check engine light?

 

First off Dan, welcome to the forum.

There are several things that can cause these issues.

When was the last time you replaced spark plugs? Air filter? Fuel filter? PCV system? Is the issue at WOT or all the time?

 

It doesn't have a turbo. I've seen on here a few posts on rev sweet spot. Is it a possibility that its just designed that low revs its not as responsive, and then the power kicks in at higher revs?

I did have really bad oil consumption, but after months of research I asked the garage to replace the PCV valve, they didn't know what it was but they found it and replaced it after I told them where it was and what it did.

So no more oil burning, just the problem of the acceleration kicking in at 4600 rpm.

It happens in every gear at the same revs so surely its not fuel block, injector block or lack of air. if the issue was a blockage of some sort would it occur sporadically?

What happens if the CAT is blocked from the oil burn?

 

The one time I had a blocked cat the car would start and idle fine but had no power at all.

Ok, from your first post I guessed this was a recent issue. Is this sudden acceleration a new problem? Or has the car always acted this way?

 

First off, a Volvo with a bad cat will toss a code. Also a bad cat will usually cause the car to be limited at certain rev's and not get above a certain speed. Here is a way to clean the cat without doing much work.

I would never suggest a snake oil fix unless I did it myself. I did this on my way out of town for a road trip. LOL

 

Ok so I can rule out Cat pheewww! £260 saved lol. I had the rev issue pointed out to me, some one drove it and said it picks up at 4600 RPM that's when I noticed it.

With the PCV replaced it hasn't used any oil in 200 miles, usually it was doing 1/2 litre in that time. So I think issue solved.

Just this mysterious 4600 RPM issue? hmm scratches head...

Might just ignore it, the car went through an MOT with no advisories, I have run it with a computer on it and no codes or faults.

I will stick in a pippercross panel filter, some iridium sparks and see what happens.

A strange thing though cant find the fuel filter, is it built in to the tank? or the fuel pump? or am I blind lol.

And I cant see a Mass Air Flow sensor on the throttle body, does it not have that either?

 

The MAF is up by the air filter housing on my 1.9L engine.

The fuel filter is located next to the fuel tank underneath the car.

If you do not have any trouble codes it may be the car is designed to act just the way it acts now. I know other small 4 cylinder engines act similar. Low torque engines to provide good fuel economy in the lower rpm range. If you need more power you have to rev them much higher.