I upgraded the upper pulley on my xjr, and went for a test drive and it does pull a lot stronger, but a check engine light came on. Using my OBD2 scan tool it gave me a P0171 code. Why is only bank 1 running too lean? Also, the engine stalled but it turned out my rubber gasket got sucked into the throttle.

I do have a 3.5 inch intake, and I also modified the snorkel on the air box. I have put the end of the stock snorkel back so it's just the end that sort of "trumpets" out and the rest of the snorkel is a 4 inch tube.

I thought this upgrade would not trigger codes.

I will try and remove my 3.5 inch intake and put the original one back on and see if I have any luck.

Has anyone else done the 10% upper pulley with an intake and had any problems?

Also, I live in phoenix so its in the 90 degrees here.

 

Well I would guess you found the intake leak!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

bob

 

Doesn't lean mean that there is too much air?

Also, I did replace it with the factory tube and drove around a little bit. My scanner has logged and pending fault codes, and this time, it showed lean codes as pending, meaning it is an intermittent thing. I cleared them, and drove casually, not stepping on the gas, and no codes showed up as pending or logged (I'll easy off the gas from now, on).

All of this represents under 30 miles, so it may need to relearn the extra air?

 

 

Yes, lean means too much air but too much air in relation to the injected fuel. If there is air leak somewhere between the MAF sensor and the cylinder head intake ports, this will cause more air coming in than what the MAF registers. Another cause of incorrect reading by the MAF could be the condition of the air flow coming into the MAF. If this air is too turbulent, it can cause "under-reading" by the MAF causing lean mixture. Are the air filter box and the filter element standard?

The smaller pulley on the supercharger should not cause lean mixture since, whatever air the supercharger is pulling (and pumping into the engine), is measured by the MAF and the ECU should inject correct amount of fuel for that air (mass of air). If you have no air leaks and if you are using the standard air box and filter, the problem could be the new relationship between the engine rpm and the amount of mixture (which should not be lean) being forced into the cylinders by faster spinning supercharger. As I understand, with a 10% upper pulley, a reprogramming of the ECU is required.

I just installed a 6% upper pulley (for which no reprogramming is required) and have no issues at all.

 

Addicted to boost,
Not sure what a hard reset is but the car sat with the negative terminal on the battery disconnected for about 5 days. Would this count as a reset?

M.Stojanovic,
That makes sense. Thanks for the explanation. And I had a 3.5inch-diameter intake tube but have replaced it with the stock one. The air box snorkel however, is slightly different than stock. I put the end of the stock snorkel, the part that looks like the bell on a trumpet that is located in the fender well, on a 4inch tube into the air box before the airfilter.
I thought the 10% didn't require tuning? Eurotoys mentions that the ecu would benefit from the tune with the pulley but that it is not required. I got the pulley from a member, who, I believe got it from eBay. The listing said tuning is not required either.

With the stock air tube on, I went for a 70-mile drive, in the city and the interstate. In the city, the codes for running lean on both banks would intermittently show as pending, but more so in the city. It would show on the pending log, not the actual logged codes so at no point, during the 70-mile drive, did a check engine light come on (good news?). I also stepped on the gas a few times and proceeded to check for any pending codes and would NOT see any lean codes. I do hear a louder whine, and can feel it pull stronger. I'm guessing that the ecu is adjusting properly?

Further, there was a pending code (P1111) for intake air temp, and would consistently show in the pending log. Pending logs don't usually trigger a check engine light until it consistently triggers. Would this affect anything?

Shall I try driving with my 3.5 inch intake tube now? When I first tried it with the 3.5in intake, it pulled like a train, but I had to take it off due to the check engine light.

 

You disconnect the negative cable from the battery and touch the positive terminal (cable connected) with the negative cable and hold it there for minute or so.

On harder acceleration, it will not run lean as the mixture will be somewhat richer. The situation when the lean condition may occur is when cruising with a light throttle.

The intake air temp will be higher with the smaller pulley and this could also be a contributing factor for your lean running - the hotter the intake air, the leaner the mixture will be. It will be trimmed down by the ECU but not to a great extent; anyhow, a contributing factor. With my 6% upper pulley, I also upgraded the charge cooler pump and the radiator. I think, with the 10% pulley, you should definitely do the mentioned upgrades, otherwise your additional boost will be short lived as the ECU will start reducing it (and/or do other things to reduce the engine power) when the intake air heat goes up.

Probably because the intake air was overheating.

 

M.Stojanovic,

If I do a hard reset now, will the ecu have adjust again, even after the 70-mile drive? When exactly does an ecu reset? Only when you do the negative to positive? I don't want my ecu to reset and readapt every time I disconnected the negative terminal.

And yes, I did notice the lean codes were pending in cases where I wasn't on full throttle. Why would it run a little leaner under light throttle though? If it runs a little richer under full throttle, and given that the codes didn't show up in the cases where I did go full throttle, then I'm not really reaching my fuel delivery limitations, am I?

As for the IAT, I upgraded to the bosch pump. On my drive last night, while on the interstate, the IAT was within 4-6 degrees hotter than the ambient air (good?). In the city though, it ran 10-15 degrees hotter, I believe (I may have to verify this).

Do you think I can change to the 3.5 inch intake now?

Thanks for the input.

 

A hard reset clears all the (PCM's) learned values and also the OBD monitors (used e.g. for smog checks).

Generally there is no need to do any hard resets.

Do a proper look up on what P1111 means. Always always always use Jaguar's code meanings unless you want to give yourself a hard time.

The entire intake system MUST be 100% vacuum tight. (You're going to need things like new cats if you have leaks.)

 

JagV8,

Okay, I'll leave the car as is without resetting it.

And my OBD scanner gave the wrong meaning I guess. Others on the forum claim that the p1000 and p1111 are system checks, so I won't be concerned anymore if I see them.

As for leaks, I did notice I forgot to clamp the two by-pass hoses on the manifold on the top part, but they are sitting in their position without any appearance of being loose. I will clamp these back, and try to switch back to my 3.5 inch intake tube and ensure my intake duct sits securely on my throttle body.

What's interesting is that, I would think running lean is noticeable in driving. First few starts had a little bit of a rough idle, but that's it. It feels like it's running better. I read on another forum that the fuel delivery would starve once you go above an additional 70 horsepower. I wouldn't think I'm starving of fuel with just an intake and pulley, or no?

 

Code p1000 means "the on-board diagnostic tests have not been completed", Code p1111 "all on-board diagnostic tests have been completed" so you can ignore these (see page 1 of the attached document which also contains all "p" codes for AJ26 SC engines).

With regard to lean mixture, if you have no intake leaks then perhaps you should check and clean the MAF and also make sure that there are no leaks in the vacuum/pressure hose going from the right charge cooler to the fuel pressure regulator. If you have not already done, check the fuel pressure as well.

 

Sorry, here's the "attached document"

 

I clamped the two by-pass Valley hoses up top (I had forgot to do this when assembling everything back). I also pinned the rubber gasket to the intake tube and clamped the 3.5 inch intake tube to the throttle body, so I'm sure the gasket won't be sucked in this time. And I will try to clean up the MAF and check for fuel pressure if/when I can.

I drove it some more and the check engine light has not come on, and the lean codes seldomly come on as pending (intermittent). I think it is still adjusting. Also, not sure if it's worth mentioning, but my EGR valve was pretty clogged up with some black stuff (carbon build-up?), so I cleaned it as much as I could when assembling it back.

 

Next check fuel trims: STFTs to make sure it's relearned, then LTFTs to see if less than about 5. See the huge number of threads about this.

 

On my scanner, I can't seem to find a way to view long term FT's, but in short term FT's, I see a range from +20% to -15%. I drove around 60 miles yesterday with the 3.5 inch intake again and the codes showed up maybe 2 times, while driving in the city. No check engine light either. It's definitely tolerating the additional air supply compared to a few days ago.

 

You should not even be near flagging codes so something is very wrong.

Studying fuel trim data may be your salvation.

 

I am interested to do the same modification using a 90mm intake pipe adapted to the original air filter box.

AZjag1999 are you using the original MAF sensor?

I have seen there are some 3.5 inch MAF units for sale, I wonder if anyone has sucesssfully installed one of these....?

 

I 100% agree. I know there is a lot of room for adjustment in these models from what I have heard from other threads and this doesn't occur with these modifications.

I do belive that it will take time to adjust, as I have lately seen it more tolerable on the added air and the cleaned egr valve. No check engine light, just the codes that intermittently show as pending on my scanner.

Another thing I'd like to add is that I replaced both fuel pumps several months ago, but they were non-oem ones I got for a very low price. They aren't from a well-known manufacturer but it was my only real option at the time. I think they are able to keep up with the fuel pressure since when I changed them, I did an initial fuel pressure check and came up with 39 psi at idle. I will do another check if I keep seeing leans codes as intermittent.


just_byron,

Yes, I am using the original MAF sensor. There are aftermarket MAFS and there are some threads on that topic. Just be aware of the potential of problems that may occur if you go with the pulley--though rare, like in my case.

 

So I've been driving the Jag a little more. I haven't seen it flag any codes anymore, so I decided to take off the snorkel end that I had put on my air box mod and have a 4inch diameter tube feed air into the air box from inside the fender, so it's just like stock but with a bigger tube that goes into the airbox.

On gradual acceleration (I'd say 70% throttle), the car pulls just fine and strong. But if I am going around 35mph, and step on it, the rpm's don't seem to pass anywhere from 3500 to 4500 rpm and so there is also no acceleration in speed either.

Could this be my transmission slipping? Pinging/engine knock/pre-detonation? Or could it be the secondary fuel pump not kicking in?

I picked up a fuel pressure test, and will test it tomorrow. I am not sure if I'll be able to get much from the test though since the Rev limiter hits only 3000 rpm. I will see if there's anything if'y about the pressure though.

Any ideas?

So many problems that have come up after the work I've done to it...

 

The problem was that the snorkel was concaving and was starving the engine of air. I've put the snorkel back so it is more reinforced and have not had the same issues.

Also, I've not gotten any more lean codes, so I think I'm good there.