So after "upgrading" to a k&n filter and oiling it, I've been having issues with my XJR.
My intake temperature readings have been reading at about 200+ degrees Fahrenheit, I thought it was my MAF acting up so I got a replacement but I'm still getting the same readings...
This morning I decided to leave the MAF unplugged and try to start the car and for some reason it did and it ran fine like it has been lately.

Now I'm totally lost as to why it's starting up... as for as I know the compute checks the air flow reading from the MAF to keep the car running.

I've also noticed that I have lost power throughout the rev range...

Any ideas of what could be wrong... maybe a faulty ECU?

 

As to why it runs without the MAF, that is just a backup strategy designed into the system. The lost power is due to the default fuel mapping strategy wanting to always assure no lean burn, and I bet it also sets the timing back.

As to the inlet temperature reading 200, I would say you have a wiring issue- check the circuit from the MAF to the ECU. Look carefully at the connector pins.

 

Thanks for the reply. Is there a way to "fix" the mapping and timing?

I'll check the wiring tomorrow for any issues.
I noticed there are a few ground connections bolted into the frame under the air filter box assembly. If those aren't grounded correctly would it cause these types of issues?

 

Not sure if it is relevant here, esp since you have unplugged the MAF, but I have read reports in this forum of suspected MAF problems from oiled filters where some believe the oil coats the "hot wire" of the MAF and causes issues.

It's been mentioned in other forums for various makes/models too.

K&N disputes this BTW as FUD.

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That's what I thought was going on since I think it started happening after I oiled my k&n filter.
After I bought the k&n filter I ran it without oil for about a month and I didn't have any issues. But I have gotten a replacement MAF sensor and I'm still having the same exact issues

 

There's many schools of thought on this one, but personally I happen to agree and for those reasons wouldn't use a K&N filter ( just my 2c worth )


Hope to hear

 

Get some MAF spray cleaner and go from there. Those oils can cause problems for sure.

 

An interesting article speaking to K&N versus normal filters, linked through JagRepair.com:

K&N Air Filter Review - Debunking the Myths (and why OEM is better)

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I also forgot to mention... with my MAF sensor unplugged.. I'm still getting an air intake temp reading.
Is there another temp sensor for the intake that isn't in the MAF?

Also to point out...
With my XJ6 I've generally had good luck with everything. I replaced the oem paper filter with a drop in k&n and have been running it for the past 70k miles and I've never had any issues. With oil and everything.

 

Isn't there an air temp sensor of some kind in the front brake cooling duct?

If so, I'm not sure what systems it sends data to though, ECU versus A/C for example?

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If I remember correctly, the drivers side sensor in the air duct to cool the brakes is the outdoor temperature sensor.

There is however another "sensor" type thing that plugs into a harness on the passenger side but doesn't protude out into the duct like the drivers side. I'm not sure what it does exactly.