This post is for a friend of mine. He is an older gentleman (81) and not much of a computer/internet person, so I stepped in.

He has a 2006 S-type v6 with approx 62,000 miles on it. He bought it used back in July/August and is the third owner.

His car's check engine light came on, so I went with him to a local auto store and they pulled the following codes:

P0171 and P0174; Bank 1 and 2 system too lean.

He said he uses only Premium gas and that slightly before the light came on, he occasionally heard what he claims to be knocking. Maybe the knocking was a precursor to the Check Engine Light.

The car drives fine. Although, he claimed the car shivers sometimes when he is on idle or stopped at a stop light.

Anyway, I looked at the past forum posts on this site, and saw someone said he had the same check engine issue and it was caused by a vacuum leak...a broken/cracked air tube. I'm going to look into that later today.

Just wondering if anyone has any other suggestions.

Thanks in advance

-Sal

 

With both sides lean and no misfire codes, you're probably looking for a common cause earlier in the air flow than the engine banks. Probably not the fuel.

So, an air leak, yes quite possibly. Or a misreading MAF.

In case you can borrow (or buy) an OBD tool with "live data" (meaning it can read sensor and other values on demand rather than only codes), have the engine warmed up and then at idle look at the fuel trims and again when you rev it to about 2500rpm. An air leak will tend to be noticeable at idle (so will show in the trims) but will be relatively unnoticed at higher revs - so if it's an air leak the trims will reflect it.

Check the air filter fits and isn't blocked and the trunking between the filter box and the engine.

Oh - and see what other 3.0 owners say.

Hey, and well done for lending a hand!!

 

WTG Sal for helping out!!!

I agree with Jagv8 above. The following thread will help you out considerably. The MY 2003 through 2008 3.0, V6s are identical. Make sure the MAF is checked.

Also did anyone fit a new air filter recently?

https://www.jaguarforums.com/forum/s...ics-faq-52720/

 

I forgot to say - some threads talk about a PCV hose elbow but that is for the earlier version of the engine (before 2003), I believe.

 

Thanks for the replies.

By the time I got to his place after work, it got a bit dark so I didn't get a good look. I'll go back there tomorrow (Saturday) around noon to see it better.

I will note that there is a knocking noise coming from the engine. It must be because of improper combustion as noted in the codes. (Please correct me if my statement seems illogical.)

I asked him about the air filter, and he said the dealer changed it about 2k miles ago when he went in for an oil change.

And thanks for your comment JagV8: I was actually looking for that PCV elbow hose...haha.

I'll be using Rick's faq when I take a better look at the car tomorrow. I'm also going to the auto store to see if I can use their OBD scanner again.

Thanks again

 

Sal as stated earlier start at the air box making sure the lid is properly fitted, these lids are really tricky. If a Jaguar dealer replaced the filter then it should be ok, if a non-Jaguar dealer did the job, I would double check it. It is advisable to remove the intake tube and remove the 10mm bolt airbox hold down out to check the lid.

As I was typing the above, if the owner also lives in the Miami area (duh) START at the MAF sensor, remove the 2- T20 screws and clean it really good with a MAF Sensor cleaner, not carb or brake cleaner. The sandy enviroment in Miami would wreak havoc on that sensor. Beware that a aftermarket sensor runs about $125.00 (AutoZone and the like). I am going to place my money on the sensor.

Let us know tomorrow I will be checking in frequently.

edit: I just noticed that you have an '05 V6, pull your MAF Sensor out and switch it with your friends and see what happens. Take it to the auto parts store and have the codes cleared. Thats what I would do first off!!

 

Swap the sensor? Yes!

The car may take a while to relearn its fuelling. Either be patient (a couple of drives from cold) or disconnect the battery for 5 mins.

 

Okay, so I swapped the MAF's.

Patience is unfortunately a virtue I never had...so I took the unplugging the battery route.

I was always told to unplug the negative terminal first, then the positive one when taking out a battery. Apparently whoever put this battery in, didn't really make the negative terminal bolt easily accessible with my ratchet or wrench; not enough space. Maybe he didn't think of me when he put it in...haha.

I noticed the negative terminal is the ground; is it okay to just remove the positive terminal only for our purpose and then reconnect it?

If not, then I'll just go with the other route. Maybe I'll borrow his car and take it for a few drives.

 

By the way, the air filter, box, lid, and all the tubing look alright to me. I made sure it was all tight and correctly fitting. Everything seemed okay.

 

I am confused, did you disconnect the battery to switch MAFs? You don't have too. Just unplug the MAFS and plug back in.


Or did you switch MAFs and then try to clear the codes by undoing the battery terminals

 

Sorry for the confusion.

I swapped the MAF sensors from my car to his.

JagV8 mentioned in regards to your recommendation to swap the sensors:

"Swap the sensor? Yes!

The car may take a while to relearn its fuelling. Either be patient (a couple of drives from cold) or disconnect the battery for 5 mins."

So, to speed up the process, I wanted to disconnect the battery like he recommended.

Anyway, please forget about the battery issue for now.

I just took the car for a few drives around the neighborhood and I can't hear the knocking noise anymore. I didn't get the codes cleared yet though. Still need to go to the auto store to do that (I think I will purchase one of those tools from ebay).

 

Okay, so I was going to go to the auto store right now and when I turned on the car I noticed that the check engine light was gone.

I always thought you had to manually clear that light. Does it automatically go off when the car detects the problem is gone? Sorry if it may sound stupid, but I am not much of a mechanical person per say...

 

I believe you have nailed it Sal. When I replaced a defective MAF in a fellow members 3.0, it took all of about 5 seconds for the ECM to correct the vehicle.

I hope your friend appreciates your effort. Replace the MAF.

Sal do NOT purchase a code reader from anywhere but the internet, Amazon has some great deals.

 

Awesome. Special thanks to the both of you for your help. Really appreciated.

I saw the MAF for sale at a local auto store for $79. Its made by Cardone and to my knowledge is a re manufactured part.

I saw a few code readers on Ebay. I'll check Amazon like you mentioned as well.

By the way, when I was looking for any air leaks I found a coolant leak. So that's my next project for him...haha...seems pretty simple though.

Thanks again and my friend also sends his best regards.

 

Glad to help Sal and friend!

If interested in a cheap scan/reader, this is what I and fellow members use: Amazon.com: ElmScan 5 Compact USB OBD-II Scan Tool & OBDWiz Engine Diagnostic Software (423001): Automotive

 

Hey, going well so far! Good to hear.