Help Please Experienced Mechanics

[cmh shek]

Hi guys, recently had a new header and catback fitted. But after a week the car's starting to make some worrying noises.

There's this ticking noise whenever I press on the accelerator at low revs, between 3-4k revs there's a buzzing noise, and then between 4-5k there's this loud rattling noise what seems to be coming from the engine or maybe header? Can't really pin point it but it's definitely in the front.

At first when it was all fitted, I could honestly feel lift pull a lot harder, but now it doesn't, not sure if it's just me getting used to it, but personally I think it's lost power.

I'm booked in to go back to the exhaust place on Monday, but just wanted to get your opionions first. The buzzing could well be a heatshield, I'm just worried about the ticking and rattling. Leak at the header perhaps? If so will it have caused engine damage?

What else can cause these noises? I know it's hard to diagnose these types of problems on the internet, but any ideas would be appreciated.

Oh and these noises only occur when under load, no noises at all when stationary, which is why I'm worried.

Cheers,

Chris

[farhanali89]

what manifold did you go for that may explain it?

im guessing you put the heat shields back on so its a manifold near stock design. Are you certain there is no noise when idling?

what about when you stand still rev, pop the bonnet and push the throttle rotor, hold the rev up and you will be able to hear it better. If its only when moving and in gear then i would take it back to the garage that fitted it.

[cmh shek]

It's a custom 4-1 manifold, so the shields were taken off but some on the exhaust system remain.

And when I opened the bonnet and pushed the throttle there were no noises, only under load at certain rpm's. Although when I pulled up on the drive last night, I did hear a distinct ticking noise when idling, could it be the timing chain tensioner? I checked the previous history and noticed it's had 2 replaced under warranty.

Gonna go check for the noise again in a bit and see what the local garage thinks. But if it's only under load, would you say it's definitely to do with the manifold?

[Corrolla18]

I would say that it is to much of a coincidence that this has started since the new system was fitted and so for that reason I would suggest that something is loose. If there are any leeks from the manifold then this would account for strange sounds however this would not cause any damage to the engine. It could cause a loss in power(as a certain amount of back pressure is required in an n/a car to maintain an effective combustion cycle. I have had rattles from an exhaust on previous cars - this was only while under load and again at certain revs, turned out to be a knackered cat.

Hope this helps

[cmh shek]

Hmmm...I was thinking it could be the cat too. It still has the standard cat on atm, could this be the problem? The system is 2.5" I believe, which is different to the standard 2.25.

I'm going back on Monday anyway to get a high flow cat installed so we'll see if this helps at all.

[Corrolla18]

Hmmm...I was thinking it could be the cat too. It still has the standard cat on atm, could this be the problem? The system is 2.5" I believe, which is different to the standard 2.25.

I'm going back on Monday anyway to get a high flow cat installed so we'll see if this helps at all.

Could be the cat but seems unlikely if there were no problems before, unless of course got damaged during install of the new system. If your having a new cat installed this might stop the problem then at least you know it's defo the cat. I've encountered a heavy load rattle before and this was down to the exhaust gases being to hot(should have had ecu tweeked) - this melted down some of the core and caused the noise.