Running Rich / Bad Cat?
 

Hi guys,

A couple of months ago I deleted a few things including the double throttle with the butterfly valves and ACV with air pump etc. It is also a JDM model so there is no EGR or AWS to begin with. I decided to leave the idle speed control installed.

When putting it back together I accidently got a couple of vacuum lines mixed up including the one that goes into the MAF. Long story short I drove the car about half a mile down the road before there was a huge bang and a large bloom of black smoke coming out the exhaust. Thankfully, the engine seems fine, and I think it was old build up in the original cat getting released. I quickly fixed the issue, and the car drives fine again.

However, it is now drinking fuel at a much higher rate, and it stinks of fuel coming from the exhaust. I was originally getting around 18mpg which has since dropped to around 12mpg. I also have an idle issue after the engine gets up to temp. I think it might be back pressure in the exhaust throwing off the 02 sensor but when I have inspected the Cat it seems fine with no damage from what I can see. Before I go ahead and get a high flow cat I am wondering if anybody else has experienced this? I have the PFC which I have reset several times hoping to solve the fuelling issue but no luck. I also have deleted the OMP and I now premix which I did at the same time as the delete. I also replaced the 02 sensor and checked the injectors and fuel lines for leaks, and all seemed fine. It also has a fresh set of new plugs and a tonne of major boost leaks fixed at the same time hence why I am struggling to identify the change that has caused the issue.

Any insight would be appreciated.

Cheers.

Doesn't sound related to the cat.
I'd check your fuel injectors. Almost sounds like one of them is leaking during combustion. Maybe try a fuel pressure test to engage the fuel pump and look / listen for leaks.

Thanks gracer. I'll have an investigate and post an update. 👍

On the money. One of the secondary injectors is sticking open. I could hear a small hiss noise when presing my ear to the manifold with the ignition on. I gave it a small crank without starting it and one of the injectors continued to dump fuel for a good 15 seconds before returning to the hiss sound. Probably explains why it started first crank when I put new plugs in then went back to needing 4 or 5 after. Probably soaked with fuel.

Thanks again.