RUNNING RICH

[srdtvr]

My Pre serp Chimaera runs a bit rich and struggled on the emissions last MOT is there an obvious solution or could it be any number of things ?
What do I check first
Cheers

[blitzracing]

The ECU should keep it emission complient, and if it cant there is a fault. There are no adjustments you can make. A faulty AFM (or AFM connections) can cause it to run rich and is quite a common fault, but proper diagnostics are better than guesswork.

[srdtvr]

OK Thanks
maybe the AFM connections are the first and easiests thing to check then its over to someone with diagnostics I suppose.

cheers

[QBee]

Blitz knows what he is talking about, as does Chimpongas, who happens to live close to you.....

[EGB]

srdtvr said:

OK Thanks
maybe the AFM connections are the first and easiests thing to check then its over to someone with diagnostics I suppose.

cheers

Clean the electric connections on AFM and ECU with electrical contact cleaner from Halfords or Servisol. May Help.

[Mr Supercharged]

You could try borrowing an ECU mate to interrogate the ECU and see what readings you are getting. I have quite a lot of parts which I have removed from my car which could be used to swap components to see if that helps, if you are local to Gloucester you are welcome to come over and I will try and help you out but I am unsure how we could test your emissions. I am on the look out for a gas analyser currently.

[T1pper]

Hi,
Is it getting up to temp, it will run rich if too cold iirc the temp should be above 70.
Just a thought??

[blitzracing]

A wrong temp reading will make the ECU put in to much fuel- but it then picks this up and backs the fuel off again, to try and keep the emmisions correct and it can make the car snatch as the ECU now has to make bigger fueling corrections than it should. An ECUmate or RoverGauge will tell you the temperature the ECU thinks the engine is running at, and both will show you the amount of fuel correction the ECU is applying. You can get a simple reading from the lambda probes with just a test meter to show if the mixture is being cycled as it should, but you need the diagnostic tools to show how what the ECU is trying to do to get the Lambdas to cycle- ie the readings from the back of the probes may be fine, but the ECU might be adding or removing 20% fuel to get the mixture correct (the two fuel trim values).The ECU can also get in a twist if you have a misfire as well as it thinks unburnt mixture is the same as a lean mixture, so it adds more fuel, which does not really help and makes the engine run rich. You can tell a lot from the plug colours- if they are black on one side of the V8 only, then you have a misfire on that side (the ECU corrects each side on its own). Problem is a lot of TVR plugs run pretty black anyway, so you might not see the difference. I personally would not recommend the "swap parts" type of diagnosis, as you can add new faults as you go and simply end up going in circles.

[QBee]

blitzracing said:

........... You can tell a lot from the plug colours- if they are black on one side of the V8 only, then you have a misfire on that side (the ECU corrects each side on its own). Problem is a lot of TVR plugs run pretty black anyway, so you might not see the difference. I personally would not recommend the "swap parts" type of diagnosis, as you can add new faults as you go and simply end up going in circles.

I changed my standard NGK "7" plugs for iridium "6" plugs a while back, and took them out for a test a few weeks back after about 2000 miles to find that they were nice and clean. The car runs better too, though to be fair I was comparing new "6"s with used "7"s. However, the "7"s weren't exactly black either