RKAT values

My fuel trims at idle are: Bank one. -0.14 Bank two -0.19 The MAF at idle is 18.50 kg/h give or take a tenth or two. Not sure if I should be concerned with these numbers. Also my crankcase oil smells a little gaseous. FRA values at idle are: Bank one 0.99 Bank two 1.00 Any replies appreciated..

Have this img stored to my pc. It's been loooong time when last played with these. But it seems that you values are not far from good? Maf should be 17kg/h +- 2,5kg/h

Quotes source post: 15990437

Rkat/Tra are the addition or subtraction of Ti (injection time) near idle. Fra is the multiplication of Ti in the load ranges. example of changes in Rkat/Tra due to removing the oil cap... set point for CEL code is +- 0.36 Your Rkat/Tra values (-0.14 -0.19) indicate the DME is reducing injection time by 0.14ms and 0.19ms to correct for a rich mixture. How old is your oil? If you are smelling a fuel smell from the oil, this can indicate that an injector is leaking fuel into the engine when not running, and the gas fumes can be causing a rich mixture at idle and the reason for the DME reducing injection time at idle. If the oil is not new, I would change the oil then see if the Rkat/Tra values go back closer to 0.00. The set point for a code is 0.36 +-... Your Fra fuel trim for load values looks very good.. perfect is 1.00

Thanks for getting back to me. Appreciate the write ups you guys posted. I will change the oil and filter and take another look at fuel trims. My engine oil is around 1000 miles or a little more old. I will let you know how things end up.

Well not much has changed concerning fuel trims after changing oil. My numbers remain at -0.16 & -0.19 TRA after about 40 miles. O2 readings before cats fluctuate between 0.08 and 0.84 volts. Pretty consistently. After converters readings stay around .98 to 1.02 volts, if I'mn not mistaken. Hope for some additional input as to what should be done to alleviate the cause of negative fuel trims. TIA. One more thing is I get P1602 fault " open circuit supply voltage". Couldn't find that in the Bentley manual.

Quotes source post: 15990437

Is yours a 3.4 or 3.6? What was the idle speed and was a/c ON when you took the measurements above? Stock airbox? 18.5kg/hr at hot idle seems a bit high especially for a 3.4 (if it's a 3.4) Is your reading TRA or RKAT? Their units are different. TRA is in decimal and RKAT is in %.

Quotes source post: 16010890

Your Tra fuel trims are about half way to setting a code/CEL. Although not ideal, is still in the ok range, and should not be a big cause of alarm, I'm guessing you no longer smell the fuel smell from the oil? One thing it points out is that there are no vacuum leaks which is the most common cause of out-of-spec fuel trims, but in the opposite direction. The 996.1 fuel system has a fuel pressure regulator with a vacuum line attached which lowers fuel pressure under high vacuum/idle, if this isn't working, fuel pressure will be too high at idle and cause it too run a little rich. This should be checked. If all this checks out, I would just consider it a normal condition for the mileage/age of the engine. As the engine ages there is less vacuum, therefore the fuel pressure at idle will be higher than a lower mileage engine with higher vacuum. This is why the adaption is created in the first place, and you are still within specs...

Quotes source post: 16010960

Ahsia is right, 18.5kg/hr does seem a bit high at hot idle, have you cleaned the MAF lately?

Thanks PT3 and Ahsai for your input with all this. While I was changing the oil I removed the filter housing. I needed to check continuity from X59/1 to change over valve. There wasn't any. Regardless I disconnected the MAF then reconnected. My Value for kg/hour is now at 15.5 . My car has the 3.4 litre engine. Connector might have been making poor contact? Do you guys recommend using Deoxit on any of these connections? Back to fuel trims. At idle with all accessories turned off is how I took readings. I don't own a fuel pressure gauge. I may pick one up or just order a regulator. I will check to see if the regulator vacuum line has fuel in it as well. I will post my findings after checking these old parts. Appreciate the input.

I posted I would get back to the forum with my findings. I picked up a fuel pressure gauge and noted the following: 1. Static pressure is 55# 2. Idle pressure is 47# 3.removing vacuum line from regulator showed a spike of 7# to 54# at idle. 4. Leak down after engine shut off showed up as a reduced pressure after 30 minutes of 3#. My reason for all this investigation is because my exhaust is sooty out of left bank, plus the gas smell of the oil. Will most likely invest in new injectors in the near future.

Quotes source post: 16069939

Left bank (right tailpipe Bank #1) or left tailpipe (bank #2)?

Quotes source post: 16072356

great question. Tis the first option.

Running rich enough to foul the pipes is a pretty good recipe to stick a piston in any motor,, especially one with AL bores.. You can send the injectors out for cleaning/rebuild testing relatively cheap.....

Thanks for the input. I think piston replacement might be a little too drastic a solution at this point in time. Possibly not down the road though. Don't think these injectors are rebuildable. I like the thought of relatively cheap, but I don't think just cleaning will do the trick. Best option would be to replace these injectors, but expensive. Hoping for longveity and this seems like the best solution. I'm open to all suggestions though. Appreciate response.