My Felicia 1998 1.3MPi is experiencing power loss when the engine has load which is accompanied by a hissing sound. This cannot be reproduced when the car is in neutral.

I am assuming that it is a problem with the air intake system, but so far have not found anything to blame it on.

Any ideas?

Try the inlet manifold gasket, had this on my felicia a few years ago, quick and easy to fix if that's the problem...

also have a quick look at the brake servo check valve to make sure it's not leaking

Will try those things tomorrow, thanks.

Is thre a chance that the exhaust is partially blocked?

95% sure it'll be your inlet manifold gasket due to you saying it only hissing under load, ie when sucking in more air

It might also be the oil return breather pipes, the small pipe that runs from the engine top cover to the throttle body or the fuel pressure regulator vacuum hose. If any of these are loose or split, it will have the same effect as the other two suggestions.

It might also be the oil return breather pipes, the small pipe that runs from the engine top cover to the throttle body or the fuel pressure regulator vacuum hose. If any of these are loose or split, it will have the same effect as the other two suggestions.

you got the haynes manual then;)

hehehe Yep!

Have replaced oil return breather pipe with genuine Skoda part (£1.35), after waiting 10 days for it. Not entirely confident that the jubilee clips holding it in are sufficiently tight as it is difficult to find small clips.

The old one was very stiff and missing its jubilee clip on the throttle side. When I extracted it there appeared to be a hole underneith where the clip would have been.

In the interim I used a bit of fuel hose, which was damp/oily on the engine end when I took it off today. FYI

However, I don't think that was the problem.

If the brake servo check valve were the issue, would not the brakes be stiff?

not necessarily no, it depends just how bad it is leaking

Not sure if this helps

http://www.autoshop101.com/forms/brake05.pdf

There's a whole load more articles here.

AUTOMOTIVE TECHNICAL ARTICLES

I know the answer ... EXACTLY the same happened to me .... HISSING UNDER LOAD ... and NO POWER.

Its the lining of your back box that has collapsed. The back box has a fiberglass lining (wear gloves it hurts you).

Mine collapased and blocked the exhaust (managed to fish it out with bent out coat hanger (helps if someone reves the engine at the same time) lol good times

anyway if you menage to get it all out then a new back box is not necessary (and its sounds nicer too ) or just be a little girl and give up and get a new back box (£30 off fleabay)

hope this helps ... im 99% sure this is your problem.

my back box collapsed about 6 month ago, and yer, it realy did cut the power right back.

Hey pink skud did you manage to pull the fiberglass out or did you replace it?

I pulled mine out but my hands were FULL of Fiberglass ... OWWWW

I like to think that either exhaust sound or flow are now improved due to my bodge

got a full custom stainless system made instead.

got a full custom stainless system made instead.

Catalytic converter back only? One Silencer? How much? So many questions, sorry

£280, cat back, full sport, one box.

but i do have a custom de-cat to

£280, cat back, full sport, one box.

but i do have a custom de-cat to

How does the de-cat work?

well. on the 1.6, the cat is part of the lower manifold.

the manofold goes 4 into 2, then 2 into 1 into cat.

so i got a second hand/scrap lower manifold an cat. i cut the section with the cat out, and welded in a peace of tube to replace it. easy if you have the kit.

Do you have to get the ECU re-mapped to account for the lack of cat or will it self-adjust? I ask because there'll be less back-pressure in the exhaust system, won't there?

Woooooo!!! I've cracked the ton :P

I see, the cat isn't like the 1.3 then, less easy to steal too on the 1.6 then, which is good as apparently people are stealing cats to sell for scrap.

Ohhhh I thought you said they were stealing CARS to sell for scrap...

Apparently trucks have been stolen for scrap value Trucks being stolen for scrap value - 29/10/2007 - RoadTransport.com

Thats bonkers - I m glad I own a 1.6!

omg i had the exact thing on my car. i had ery loud hissing as i was acclerating.one day i was puttin my foot down cause i got really annoyed an blew the welding seem on my back box clean open an did tht beast roar then lol got my speed back thn an needed to replace the back box.so mite be time to replace the exuast or at least the back box :D:D