mechanics advice required car running rich and misfires

[clarky5178]

As said my car is running mega rich and I cant find the problem, it misfires when you try boot it up and pops and bangs and only builds about 2psi of boost its the 1.8T auq engine I've changed spark plugs, tried a new maf sensor changed map sensor and n75 valve also changed coils around and checked for boost leaks. Can anyone tell me if they have had this before or know the fault. It through up a code saying system running rich bank 1. But all cylinders are the same plugs are black as hell already.

 

[clarky5178]

Can no body help me on this? Does it sound like coilpacks going or what? It's getting the recall done tomorrow. And then trying to mot it.

 

[aaron-gardner]

Lamda sensor it sounds like.

 

[clarky5178]

Lambda is reading high but still working though. Normally if they fail they don't get a reading.

 

[jake-1991]

+1 on the lambda sensor

 

[clarky5178]

I didn't think they made that much of a difference to fueling.

 

[aaron-gardner]

Failing completely I's one thong but on it's way out will explain high readings. Have you done any modifications to the car? Downpipe or de-cat/ sport cat? But basically you get 2 Lamda sensors pre cat and post cat. Pre cat I's the main one for controlling oxygen to keep it running correct but post cat I's for emissions so a high emission reading on post cat may indicate pre cat has failed. But either way it definitely sounds like the lambda.

 

[clarky5178]

The car has the following mods done to it,

Forge front mount
Induction
Oil breather
Heatsheild
3" turbo back miltek
Decatted
Remap.

One doesn't take a reading it just sits at 1.275 constant the precat sits about .999 but fluctuates as I rev the car. I don't want to replace both if there good though that's almost 200quid.

 

[aaron-gardner]

Well if you have had it mapped properly since the Decat then the post cat I's rendered obsolete so you would only need to replace the pre cat.

 

[clarky5178]

I'll get the garage to replace it if it's still rich after the coil pack recall.

 

[Dan1720v]

That's running lean if it's 1.275... Which could be an air leak...

What's the lambda values at full throttle?

 

[clarky5178]

That's the post cat one it's not working now as there's no cat and it's been mapped. It's the first one that might be the faulty one. It reads 0.999 at idol and raises then drops when you rev the car.

 

[clarky5178]

I know it's running rich as you can smell it and see the black smoke plus my spark plugs are black from running rich too. So I know it's not lean

 

[Dan1720v]

Can I ask who mapped it?

 

[clarky5178]

The car was ment to have been mapped by jabba sport. I've fitted a cat and new lambda and still splutters under load. Don't think it's as bad though.

 

[leoncupra2012]

If its been mapped before it was de catted it will run rich as my cupra did , but I've pmd u clarky check your inbox

 

[Mr OCD]

They do run rich on a stage 1 map with a decat ... my own car is atm but that is not your problem. If the lambda is fine then you either have an air / boost leak... but like others I suspect the pre-cat lambda.

 

[LEE69]

I didn't think they made that much of a difference to fueling.

The first lambda is all about the right fuelling

 

[clarky5178]

i have changed the lamba and now fitted a cat on the car but it still missfires under load. im really stuck with this cant seem to find the issue.

 

[Banzaiii]

I am having a very similar issue on my 2001 Leon 1,8T.
Sparks look like they've been hanging over a bon-fire, missfiring and hesitating under load, rough idle and loads of black smoke.
I've tried a new air mass sensor with no luck, so went back to the original one. Replaced the throttle body twice. Both came from the scrap yard - the first one didn't seem to be alive at all, the second one seemed to work - the car ran great after the swap, but a day later it started acting up on me again. Might be the lambda in my case then... Which are the wires to check the signal?