Guys, I could really use some help here, 2012 5.0 XKR Denso - to cut a long story short - Last year towards Christmas I fitted the Powerhouse upper Pulley and had a Powergate 3 Remap done to suit, The mapper is reputable with vast Jag experience - with terrible weather (N.Ireland) it was months until I was able to get it out for a good hard blast,

Car felt great and pulled strong right up the rev range then at 4500Rpm in 3rd it would bog down, cut back, and then pick back up, I told the tuner this and he sent another file though, again... it felt great but again would bog, I Flashed back the ORIGINAL file to the car and ran in 3rd - AGAIN it would bog, the odd time it would pull a p0087 low fuel rail pressure code, -

I have checked the fuel rail pressure on my icarsoft
Engine off LPFP 460kpa (66 PSI)
Idle pressure is 6340Kpa (932 PSI)
Maxes out at 15000Kpa (2175 PSI)
Voltage for the sensors looks good.

This leads me to think there's something else going on... I'm getting no misfire codes, changed all the plugs still ran the same, I Have SDD so reflashed modules as there were some outstanding updates - this seemed to clear it up, however, it seems the issue has come back.

Dyno today to show what's happening 4th gear pull - with the stock tune but with the upper pulley, I hope someone can give me some insight to smooth things out.

Thanks guys! Realizing I didn't cut a long story short at all...

 

Changing the pulley probably impacted the maximum boost you are running, right? If you are running more boost, then you need more fuel.

Q1. Are you getting proper fuel pressure across the range? You shared only few data points
Q2. Any way you install wideband O2 gauge and monitor A/F? That would tell you if you are running lean.

Sounds like you are running lean and computer pulls back timing. Since you installed the pulley, old A/F mapping is probably not good.

 

Thanks for the input -

- Yes if I do a live log with my icarsoft it shows the fuel pressure is nice and high right the way throughout and only drops once it pulls back at 4500 under WOT
- What parameters should I be seeing VS not be seeing on the wideband AF Data? I can easily check this if i know what I'm looking for as "Normal under which circumstances"

It certainly feels like it's pulling back, the problem is even with two different tuned modfiles for the pulley it was still pulling back.

 

I can only speak based on my experience with tuning boosted (turbo) engine but the logic is probably the same for superchargers.

The ideal A/F mix ( for emissions, power, and such) is around 14.7 for NA engine. However, running the same on a boosted engine will cause knock and engine damage. This was a problem with older boosted engines where you could not detect knock. If your mixture was tool lean you would blow up an engine eventually. To compensate for increased boost at WOT, you need to inject more fuel and this would lead to lower A/F ratios. Many old timers used to tune their ECU to produce ~10 A/F at WOT to be safe. 11 A/F might be fine as well, it really depends on the engine and operating conditions (like fuel used).

I seem to remember reading on this forum that stock tune produces 9-10 A/F at WOT which is very safe under all operating conditions. You can buy a tune that bumps that up a bit to increase power. It's safe if you live for example outside of California and have access to 93 fuel (stock system is tuned for 91). Higher octane fuel allows you to run higher boost.

So, if you have access to wideband A/F data (sometimes called wideband O2 sensor or lambda sensor), you should be able to tell if your system runs lean. I would be cautious of anything higher than 11. You can also try to fill your car up with high octane fuel (94 or higher) if you have access to it to see if that makes a difference. You still might experience knock but it might be higher in PRM range.

To me it should like a tune issue and switching back to stock tune does not help because you increased boost by upgrading the pulley. But it could also be one of your injectors/plugs not working properly. Not sure how you can check for that. If plugs are old, they tend to "open up" and not ignite properly (due to higher boost).

 

Okay great help thank you - I took the car for a run there and checked what I could find related to Lambada and A/F ratio - both were very similar figures throughout the run but nowhere near what you're saying.
attached is one of the 100 data points from idle to third gear WOT - with as much rpm as I could get for the road. when I slacked off the throttle the lambada number increased slightly to 1.3 or so.

New plugs in it and I'm running 95 super unleaded.

 

Do you mean 95 RON? That would be 91 octane.

 

Good catch. Try higher octane gas.

Looks like Jag calibrates output sensor data. Typical O2 sensor produces voltages between 0.1V (very lean) and 0.9V (very rich). The fact that you are getting 1.3 under some conditions suggests some kind of calibration. Sorry, I do not know how to interpret your data. At least it looks like recorded value is pretty close to Commanded value.

BTW, how does ignition timing advance compare between different cylinders at the same RPM? I would expect it to be pretty close between cylinders.

 

Also, is there data in ECU from a knock sensor? Perhaps you can see what the count is. If it's non-zero then you do have knock and ECU responds. Can you also monitor boost? Is there a boost sensor?

 

Interesting part of the story is related to poor performance on OEM soft (as my 1st hypothesis was related to poor tune). I had upper pulley without a tune on my car. First run on a dyno (before remap) was very good - normal, steeping curve.
BTW changes in boost on upper pulley only is actually small.

So my bet would be that you have a problem with "hardware" (powertrain).

Not sure about fuel (but the code...). Actually OEM fuel supply is good enough for 600+ setups. I'm wondering if supercharger is working well (what boost it generates) and if the wastegate is holding the pressure.

 

Apologies, I'm in N.Ireland here the minimum we have is e10 which is a 95 octane rating - just checked my receipt, Super Unleaded E5 which is 97 octane

 

I had a look into this last night as it didn't make much sense, comparing it to your figures. (I'll try and get better data today)

As far as I can see the AF commanded equivalence ratio relates to Stoich measurement being balanced at - 1 - where 0.850<1 = Slightly rich under load and 1.3>1 = slightly lean under deceleration

I've 3 different OBD readers here so I'll check if i can see the timing on each individual cylinder today.

Cheers chum

 

I'll check this out this morning and report back asap. Thanks

 

It is interesting, I did originally think it was the fuel pumps until i checked the pressures as it would throw the p0087 but it only did this when it pulled back. - Do you know what I should be seeing on the wastegate actuator data at idle and under load?

 

Unfortunately no.

 

Probably a stupid question, as I have no knowledge in this area, but what ‘mode’ are you running in (normal, sport, dynamic, manual)?
I’m asking, as the active exhaust is closed in the normal & sport modes until you get over 4k rpm, and maybe the change in back pressure has an effect. If you’re in dynamic or manual, it’s supposed to be always open. Just a thought.

 

I'm running in sport with the flappy paddles - Exhaust with de-cats, xpipe and a larini rear box so no exhaust actuators... unless there is still a fuse 19 in place that's causing some tomfoolery.

 

RESOLVED -

Chased this up all weekend, Faulty High Pressure Fuel Pump was the culprit -

Went on a rampage this week, put my Link LX obd reader on and got some new info - at WOT my boost was there, BUT Fuel pressure was dropping from 2100 right down to 430 Psi - this was causing the mess on the graph -

Quick test - there are x2 High Pressure Pumps on the lower left side of the engine (viewed from the front) above the rear undertray.
they are covered in two sponge noise absorbers.

pull the electrical connector off the front pump and start engine - check pressure
(should idle around 650psi when warm)

replace electrical connector and remove the rear one. start and check pressures again,

Mine revealed the front pump was good, the rear one was sitting at 45psi and spluttering - You can actually feel the front one ticking hard and the rear one didn't even feel a tick off it.

x2 new pumps on the way and an oil change for good measure.

Then........ hopefully I can get another dyno and then get this lower pulley and tune on.