wcahill

I recently purchased a 1998 Infiniti I30 Automatic and have had several problems which I am uncertain how to solve. The vehicle has 68,000 miles and is generally in great shape. It has consistently gotten over 20 mpg in a combination of city and highway.

Shortly after getting the car, the Service Engine Soon light came on solid yellow. I did some research and pulled the codes. The flashing readout was 0304 0309 and 0705 (not necessarily in that order since they keep repeating). I understand that 0304 is the knock sensor and that it generally doesn't turn on the light. The 0309 doesn't seem to appear in any of the listings that I have found for this car. The 0705 is a leak in the evap control system. I reset the system and after about 850 miles the light came on again with the same codes. Further I took it to Auto Zone who used a OBD II code reader and pulled the following codes:

0325 Knock Sensor
0440 Evap Control System
0325 Knock Sensor
1448 Aux Emissions

Looks like a different numbering system but essentially the same issues. I again reset the system and last evening after driving another 250 miles the light again came on and I pulled the same codes as before. Since my gas milage is OK, the Knock Sensor doesn't seem to be having a detrimental effect on the car (most of what I have read indicates that this code does not turn on the light). It seems that the main problem that is likely turning on the light is the emission system.

I hesitate to take this to an Infiniti dealer because I am suspect they will just start changing parts. Also it will be hard to determine if they fixed the problem since the light seems to stay off for substantial periods of time. If the light were not coming on I would have just assumed that all was fine as the car runs extremely well.

I did replace the gas cap the last time the light came on figuring that would be a cheap fix if it were bad but to no avail.

I have a second concern. After driving around 70 mph for a period of time I sometimes hear an intermitant knocking coming from the engine area when the car comes to a stop. This can only be heard when the car is stopped and in drive and even then fades in and out. (The oil is recently changed and all fluids are at their top marks.) This noise does not happen all of the time. Reading some posts on the forums the sound seems similar to those in discussions that I have read related to a timing chain tensioner guide. However, since the noise is so intermittant I am not quite sure if it is a current problem, a future problem, or possibly just how this car sounds from time to time and not a problem at all.

If anyone with experience in any of these areas can shed some light on these issues I would be very grateful. If all else fails I will probably just take it to an independant mechanic and have them scope out these issues. Would an independant be recommmended over a dealer to work on these types of things? Whom ever I go to, I would like to narrow down what I ask them to do to save money and if these things are easy to diagnose would even attempt to fix myself if it can be done without a lot of expertise or equipment.

These seem to be nice cars and hopefully these issues are easily and cheaply resolved. Thanks for any advice that you can provide.

I30tMikeD

iTrader: (8)

I would change the knock sensor. It can be picked up for about $100 (I have a used one in working condition for $50). You can change it yourself. It's kinda hard to get to without removing the intake manifold, but if you can get to it then it's a simple procedure.

Those codes are probably always there, they just don't always trip a CEL. The knock sensor code can be a ghost code that only appears when another code is present. Just because the CEL is not on does not mean there are not trouble codes.

I also believe that the EVAP system can be taken apart and cleaned. I would change the knock sensor and clean the EVAP system and that would most likely take car of the problems.

Either way, the codes your getting are not something to be really worried about as far as causing any long term problems with the car. You will just see better power and gas mileage with a new knock sensor.

wcahill

Do you know where I might find detailed information on how to find the various evap system parts on the vehicle and the cleaning procedures. I have located the section on replacing the knock sensor.

Thanks for the input...