BA XR6T RUNNING RICH

[stancez]

Hi all, I've had an issue with my car running rich now for month's, I've replaced alot of parts trying to figure out what the cause is with no success.

 

A while back my car started to run super rough and rich, figured it was a vacuum leak somewhere or coils. Turned out it was the lower plenum gasket, replaced and it fixed the idle issue but not the over rich condition.

 

Since I've done the following trying to figure out what the cause is:

 

Purchased new oem coils/plugs

Replaced TB gasket,

PCV valve,

Plenum gasket,

New battery,

Venum high flow cat/Y piece,

New fuel filter,

New O2 sensor,

New Bosche Map sensor.

New O-rings/micron filter on injectors.

 

Just picked up the FORscan tool and the O2 shows as 0.9v on idle, when I rev the car to redline in park it'll head back to a more Stoich reading and idle more smooth for about 5secs before going back to 0.85-.90v

 

I've ordered another VOD 02 sensor in the hopes the previous bosche one was d.o.a but I'm at a loss as to what the issue is?. Thermo?

CHT sensor?. There's a other guy on here who had the exact same issue but it seems there's was no conclusion, any help would be greatly appreciated t.I.a.

[k31th]

is the car tuned? it might be a previously tuned car with a plenum gasket leak and now that you've fixed it it's running rich...

[stancez]

Yeah I got it tuned I have 3 different settings but since the issue, reverted it back to stock map.

[k31th]

what other mods do you have that it needed a tune for? or is it just stock with a tune? also, what sort of tune is it; custom dyno or generic?

[El Andrew]

What exactly do you mean by running rich? As your long term fuel trims are pulling fuel out? Or measuring on a wideband?

[stancez]

Custom dyno tune. Intercooler and injectors. No wideband installed, rich as in using not pulling fuel out. Just went for a drive and monitored the 02v and it's stays at .90v and only when blipping the throttle it'll dip down and then return back to .88-90v should be around .45v stoich correct?

Edited 26/08/21 01:28 AM by stancez

[El Andrew]

I'd try logging your long term fuel trim and see what it is saying too

[stancez]

From my understanding long-term is what the car has learnt over time?. Can you explain why and also what value I should be looking for on a stock tune?. Put it this way the cars fuel trip on the dash over time has gone from about 13.1 to as high as 25L per 100. managed to get it down to 19 by driving it like a nanna.

Edited 26/08/21 07:26 AM by stancez

[stancez]

Update installed the new o2 sensor. Now it seems to be running better around town went for a drive and got the fuel trip down from 19 to 16. Where it still seems to run rich and cause issue, is idling.

Edited 30/08/21 08:46 AM by stancez

[El Andrew]

Sorry - missed your reply above. Basically a short term fuel trim is an instant adjustment for current conditions (based on the lean/stoic/rich signal it's getting from the oxygen sensor). If the PCM finds it is continually adding or subtracting fuel from the base, then it adjusts long term trims. They adjust quite quickly though. Long term fuel trims should be within +/- 5 percent or so.

When you say you have loaded in the stock file, do you mean the actual stock file? If so, that will run rich if it isn't know you have bigger injectors (or they deliver more fuel for a given opening time)

Could be that the oxygen sensor was part of your problem but not all of it. I had a minor boost leak and a failed actuator a little while ago - made troubleshooting very difficult.

Check the fuel trims and see what they say. If you had it tuned, I'd give your tuner a call too and see what they say. Or if you want a second opinion, most places will do a few dyno pull for Les than $200 and would hook up a wideband. A reputable place should be able to tell you if the tune is ok or not.

Could still be mechanical too, like a failed fuel pressure reg or blocked fuel return line.