Boy, do I feel like a total IDIOT on this one.

Just over a year ago I bought my '06 XJR. About 3 weeks after I got it plated and on the road, the check engine light came on. I pulled the codes....P0171 and P0174.....the IMFAMOUS trouble codes. Quick check of all my vacumn lines, found the one on the backside of the intake/supercharger was off. I plugged it back in, cleared the codes, thinking that was it.

Next morning on the way to work the check engine light came back on. Pulled the codes again....same codes. I checked everthing again, all good. (or so I thought.....I'll get to that in a minute)

Over the last 8 months between being deployed short-time (US Navy), and other things.....I pulled and cleaned and tested all of the sensors, O2, MAF, etc. I've researched for months how to troubleshoot my car to fix this problem . The same codes always came back.

My R never went into restricted mode or anything like that. I would try a few things, clear the codes, and the check light would still come back on withen about 50 miles.

Last week, doing the oil change and cleaning up the engine bay, I pulled off the black plastic shroud that "horse-shoes" the supercharger/intake, and while cleaning looked at the vacumn line I reconnected 8 months ago. It LOOKED connected. In fact it was off again, but the fitting end of the line was sitting on TOP of the vacumn port. At a glance it looked connected. .

I refitted the line, this time grabbed a zip-line and zip-tyed it on. Cleared the codes again, and saying to myself if this doesn't do it, then its finally off to the dealer and let them figure it out.

One week, 2 tanks of gas under all different driving conditions.....and NO CHECK ENGINE LIGHT. 8 months of banging my head against the wall over this problem, and a 5-cent zip-tye fixed the whole thing.

Anyone have an aspirin?

 

well i had a similar problem with my jag, but mine was even funnier , including the dealer nobody could able to find out why my jag was miss shifting and stuff, like they kept telling me tranny was effed up gotta replace it, so i drove the car like that for 5 months and one day i remembered that once upon a time i had a 97 E500 when i was living in europe and it had the same problem but i fixed it by replacing the mass air flow sensor. So i took my car to dealer and told em to check the maf and bam that was the problem! they were gonna charge me 8 grand for the tranny i ended up paying 150 for the sensor. and i ll get u an aspirin =D

 

JagMaster,

Can you describe "miss shifting" in more details?

 

Sure thing mate, it's like the car wants to shift but it just can't find the correct time to do it and when it tries to shift it takes about a second or two to place the gear of course in the mean time the clutch is open so what happens is the car becomes unstable for a second until the gearbox shifts. But shifting is not smooth at all, you deflly feel like transmission is messed up. Also when you floor it, it takes 8 seconds to get 60, usually u must be getting 60 in 6 seconds. Also when you kick down it never downshifts. I just can't believe a stupid sensor would cause all of these. And by miss shifting i meant like while shifting the rev goes up because the clutch remains open for two seconds.