Hi Guys,

I had a bad year with the car last year. Cut a long story short, the gearbox failed and I had to have that rebuilt...ouch!

Since I got the car back, it seems to be running very rich - not sure that there is a connection, it might have been doing this before the gearbox rebuild...

I can't seem to find any info on why the car would do this, plenty on lean running, but nothing on rich running.

Why I think it's running rich? Smells very rich when standing behind the car. The fuel consumption is ridiculous, driving with an egg under my foot seems to return about 13mpg, I used to get nearly 30mpg when driving like this. Steady motorway driving returns less that 20mpg, before would be nearly 30mpg.

Any thoughts on what to check and where to look?

many thanks,

Matt.

 

Get an OBD device capable of reading the fuel trims, like a cheap ELM327. Do you have the CEL/MIL on?

 

I got a cheap bluetooth ECU reader, but it doesn't seem to be working, which is annoying. I have no warnings on the dash. All I am going on is the smell and the fuel consumption...
Can you recommend a reader that works with the car???

 

Is is supposed to be used with a mobile app? I use TorquePRO on an Android device, but there are other combinations.

For this car, make sure the protocol is ISO-9141 as ODBII diagnostic is only available there, not on CAN or SCP.

 

yes, it is supposed to be used with a mobile app. I couldn't seem to get it connected. I will try again with the info that you posted. Many thanks,

 

Ok. So I got connected to the ecu and read the fuel trims. Both banks running at 19.5% short term (engine warmed up) long term 14.5%. Not sure what any of that means

no fault codes - surprised me!

any ideas guys why it’s running so Rich?

 

Trims are a matrix of numbers indexed by Load and rpm. I assume these numbers are at idle. You can instruct TorquePro to record the values and drive around, varying the Load and rpm. Then check the numbers when not driving. These long term trims should ideally be near 0, but really less than 5%. These can go negative, too, when running rich.

I would say start by doing a good cleaning of the air flow meter. Use a dedicated spray and make sure to clean the little tunnel. Leave the sensor upside down for a bit so the cleaner soaks everything. The little pill on the side is the air temp sensor, not the air flow meter itself. Be sure to check the o-ring at the base for good sealing. These XK8 air flow meter are pretty generic and not terribly pricey, so maybe you can just change it.

Next, do a smoke test to find all the air leaks, there are are just too many opportunities to list out.

Best of luck, keep us posted.

 

A substantial air leak would cause pretty rough running and also trip the CEL due to the uptik in fuel to correct for it . It seems odd that it hasn't thrown any codes.

Tossing stuff out here, but it's it possible for the trans shop to have misconnected the upstream!/ downstream O2 sensors at the junction block during the reinstall?

 

how would I Check that?

 

I shall get on to cleaning the MAF or at least looking at it tomorrow - might just replace it anyway. Not sure when or if it's ever been cleaned or replaced.

I shall start investigating the vacuum leaks to see if there are any, or any that I can find....

I've done some reading up about these values, and am surprised at my readings, but maybe I need to run it or record it for longer. Just it smells of fuel standing behind it when idling, and the consumption is shocking now.

The other thing I noticed today, was every so often there was something like a loud click, like a relay, followed by an obvious demand on the engine, since the MAF reading increased - jumped in fact and the revs upped slightly before settling back. I am guessing this is the AC compressor kicking in periodically?

Thanks and I will post back how I get on.

 

Another thing to keep in mind is that you have oxygen sensors, so if somehow the mixture does not burn (say, way too rich with an injector stuck open), it would technically read lean as there is plenty of excess oxygen. So, no codes at all? You should at least have P1111.

 

no no codes when I checked.

 

To my knowledge, you should at least have P1000 or P1111. You may have to poke the app a bit more to get these.

 

+1

there's always one of P1000 or P1111, but they are pending codes so may not show in some tools or you have to look in a different part of the tool.

If those trims were +ve (i.e. not -ve) then it's NOT running rich. It would be lean and you should follow the many posts about that and air leaks.

However, as posted already, lean can mean bad combustion which leaves O2 (air) and fuel so can smell rich. In that case it's likely doing catalyst damage bit by bit.