Something very wrong! (pre cat) (UPDATED)

Andy_Coupe

Right ive done the pre cat mod today, which basicly took all day :lol: Just got back from a test drive, first of it felt miles better and on the motor way it was great, pulled a lot better. There was a 40mph restriction and at the end of it i shifted in to 3rd and put my foot down it picked up then felt like it was misfireing then picked up again and it was fine. Stoped at the lights and it was ticking over rough with a strange nose coming from the exhaust! Whats gone wrong?

Mark_Dj

You may have damaged one of the oxygen sensors while doing this mod. It may not even be in tight enough? Give the area another look over and check everything is in place and tight enough. You should not have any trouble from this mod. Good luck.

Andy_Coupe

Only removed the sencor on the rear of the cat the other i unpluged from the engine bay!

Mark_Dj

So you did this mod with one sensor still on the exhaust? If so you may have damaged that one as I would think the exhaust would have took a battering removing the pre cat. Or it may have been covered in crap from the pre cat as it gives of lots of dusty stuff.

Andy_Coupe

Mark_Dj said:
So you did this mod with one sensor still on the exhaust? If so you may have damaged that one as I would think the exhaust would have took a battering removing the pre cat. Or it may have been covered in crap from the pre cat as it gives of lots of dusty stuff.

Good thinking Mark, will remove the sensor clean it up and see how it goes from there! May even fit a new gasket on the manifold to down pipe.

Mark_Dj

It's probably just manky, full of dirt from the Pre Cat mod. Hope it goes well for you 🙂

Andy_Coupe

Mark_Dj said:
It's probably just manky, full of dirt from the Pre Cat mod. Hope it goes well for you 🙂

Hope so mate! It seemed to get worst the hotter the engine got, it even struggled to start after the run i give it! Had to give it some trottle to start it up.

Baz

hope you get it sorted ok m8 😃

vocky

you should let the ecu settle for 30 miles or so after removing the precat

you might be better disconnecting the battery for 30 minutes and then drive smoothly for 100 miles to reset the parameters

Andy_Coupe

Well i had some advise from AS too, i changed the gasket on the manifold to down pipe, this has made a lot of difference, its now 90% better than it was yesterday and drives better too! Checked the sensors too to make sure they wrer tight... they were fine. Just got back from a 30 mile drive and it only played up 4/5 times, first was at a set of lights where the revs dropped below 500 and the car was shuddering. The other times were in the low revs accelerating where it hesitated with a sound i can only describe as though it was fireing on 3 cylinders but alot faster, the longer i drove the btter it got so im hoping its the ecu catching up..... fingers crossed!!!!!!!!

Mark_Dj

I hope it gets better soon. It will just need to get settled I think 🙂

Baz

did you also check the manifold m8 maybe come lose whilst you were working on it just thought id say cos mines had a few bolts lose and was causing like you say a misfiring sound luckily i tightend mine and that sorted the problem 😃

Andy_Coupe

bazastra22sri said:
did you also check the manifold m8 maybe come lose whilst you were working on it just thought id say cos mines had a few bolts lose and was causing like you say a misfiring sound luckily i tightend mine and that sorted the problem 😃

I while ago there was a spiting noise coming from the manifold and that was down to a lose bolt, all are now tight up!

Andy_Coupe

UPDATE

Still having slight problems notsure.gif Its only happening while idling or as i set off with a warm engine, as i said above it sounds similar to a car running on 3 cylinders but a lot faster, or a demented subaru if you get what i mean :lol: . I did notice while parking up that there may be a leak on the cat to centre pipe join, could this be causing any props? Need to get this sorted before my re map is done.

Mark_Dj

Any luck yet Andy, how is the car running? I have just read your post on AS and was not happy about a few comments from people. I have done this mod myself and know what to look out for. They are saying you can't have any dust. I had grey like dust after drilling and hammering away for ages. I should know as my girlfriend was doing her nut for making a mess in the spare room at home. Hope you get it sorted mate. You are the only person I know who has had any trouble from this mod. Good luck 🙂

Did you also know the links in your signature have been changed on AS, they point back to AS. I ain't bothered what links you lot have in your sigs on here :roll:

Mark_Dj

car.crash said:
:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: . well lets see you fix it. over to mark dj now astra coupe

Not sure what you mean by Astra Coupe notsure.gif

car_crash

no names or site names were mentioned so calm down. anyway its all your now mark dj. i will stay out of that thread you can do it

Andy_Coupe

Mark_Dj said:
Any luck yet Andy, how is the car running? I have just read your post on AS and was not happy about a few comments from people. I have done this mod myself and know what to look out for. They are saying you can't have any dust. I had grey like dust after drilling and hammering away for ages. I should know as my girlfriend was doing her nut for making a mess in the spare room at home. Hope you get it sorted mate. You are the only person I know who has had any trouble from this mod. Good luck 🙂

Did you also know the links in your signature have been changed on AS, they point back to AS. I ain't bothered what links you lot have in your sigs on here :roll:

Hi mate

The trip to work yesterday still had a little problem which was when i was stopped at the lights, im convinced it was only running on 3 cylinders then when i drove it was fine. On the way home it was fine and trouble free :shock: Will be checking the plugs today before i go to work just to see how they are. I know what you mean about the dust as i had a load come out when empting the the bits of pre cat out and i even shoved the hoover down to get out what i could! Since the new gasket was fitted it has been a hell of a lot better but not perfect, which still might indicate a leak somewhere, but both sensors are so tight i cant undo them and it has a new gasket and the bolts are also tight. Im working today so ill let you know how the drive goes!

Oh and as for sig links notsure.gif

Andy_Coupe

Went to the vxl stealers today with a tub af vasiline..... well its a good job cos they bent me right over! Their tech2 bought up fault codes with the EGR valve but they said there is also a possability the ECU is screwed! Well its in on friday for the EGR valve. The guy said its £900 for a new ECU if needed, but he said it can be fixed else where with a wink of the eye. Cars ARRRRRRGGGGGGG

Mark_Dj

Strange. When I first bought my last 2.2 it was running crap, so I booked it into Vauxhall and they fitted a new EGR. They also said my Ecu may be broke. They fitted the new EGR and all was good for about 2 weeks, then I got the same running problems again. I took it back to then and they said my Ecu was broke, I had to pay £610 for a new one fitted by them. My old Ecu had been re mapped so I think I may have had problems from that when it was done, not sure how long the last owner had it mapped before it started to play up. I just hope it's not your Ecu as it's alot of cash..