Hey guys so recently my 98 xjr has been having an issue when starting cold and even if i started after its been sitting for a short period of time and is still warm. It shakes and rumbles for a about 20 seconds or so and then it goes away and drives just fine. Sometimes its pretty bad and im not sure what it could be. A couple of weeks ago i put in a K&N air-filter drop in and shortly after the rough idle began. Could that be the case? Thnx for any advice.

 

Could be or by fluke , I am not an expert but is your throttle body clean ?

 

Does the filter use a oil wet media -- if it does I would not use it as the oil can effect the "MAF". I would also check to make sure nothing is now loose or cracked -- a small leak can be a problem when cold.

 

i think the filter came pre-lubed. I will check to see if the Maf is clean and if anything is loose. Thnx for the replies fellas.

 

Just to add - Some people have had the flexible ribbed tube from the filter to the TB crack - and they say it is hard to see - I'm not sure what you moved around to put the filter on.

The oiled filters can be an issue - A lot of the Porsche guys use them with no problems others can directly trace MAF problems to them.

I know a lot of people end up removing them -- Can not say this is your problem -- just information

 

i inspected the maf and it seemed ok..although i did find some oil in the the intake tube..is that normal? Ill make sure to check for cracks, i remember when i changed the filter the oil was there. it seemed a little much. also could this be a simptom due to the nikosil issue? thanks again for the responses i really do appreciate it. lmk what u guys think. thnx

 

Very good chance the oiled filter has contaminated the MAFS element. A few shots of sensor cleaner, not carburetor or brake cleaner will probably clear it. The same stuff can be used to clean the throttle body. Gunk around the valve can cause the ECM to search for the correct fuel mixture for a minute. Here is a link to the MAFS/TB cleaning procedure: http://www.mediafire.com/?43rs029k5l7uici

The oil in the duct is, indeed, a sign of engine wear, Nikasil or not. Unless there is a lot of it I wouldn't worry about it. A compression check is the ultimate test of wear.

You should also clean the part load breather tube on the other side. It can cause stumbling problems. Careful, the old plastic can be brittle. I broke mine the first time and had to JB Weld it back together.

 

thanks for the advice and the link testpoint. i will check back with the results after. i love this forum.