Knock Sensors

[pirenuri2]

I own a 98 Q45 with 143k. According to infiniti customer service sparkplugs and alternator were replaced at 130K. Around the same time, infiniti techncians suggested replacing knock sensors, but previous owner declined it

About a month ago, "check engine" light came up. Computer showed bad MAF and knock sensors. My mechanic said if MAF is bad, knock sensor failure is normal.After replacing the MAF twice (first one was defective) the car only runs fine until it warms up. Then it starts having acceleration problems. More importantly it starts smelling like rotten egg.

Although computer no longer shows KS errors (after Maf replacement)

1- should I replace knock sensors?2- should I replace both? Or is there any way for an ordinary mechanic to inspect them?3- some users mentioned buying them from ebay for around $50. Is that a good idea? If so, what is the part number?4-is there writeup available describing how to replace them.

Thank you very much.

[qship96]

Knock sensors and MAF are not inter-related at all. Search "knock sensors" here, there is a ton of information on price, diagnosis, how to replace,etc....one of the most talked about items around here- brew some coffee,search and learn more than you ever thought possible!!!!!

[Jim1999Q45]

I posted re the KS on eBay. Part of that explained why engines with all the sensors might run better cold:

" Couldn't understand why my 99 Q ran well until the engine warmed up. One post pointed out that, when cold, the engine runs off preset inputs from the ECU. When the engine warms up, it switches to receiving sensor input and runs the engine accordingly (so the bad KS is probably retarding the ignition on acceleration). Another post said that cheap KSs were available on eBay sometimes."

I don't know why your KS code went away-- maybe it's still bad, anyway. I have a similar issue after the engine warms up, and expect a new KS to solve the problem. It should be delivered by the weekend (I hope). I'll post here and on my thread to let you know how it turned out.

Re installation-- A search, here should turn up one re installing KSs on a Maxima-- in 20 minutes. The parts I remember are about testing the KS before installation and connecting the harness before installation. There's not much room to work around an installed KS.

Just looked at the service manual (p. EC-257)-- it says that the MIL will not light for a KS malfunction, and freeze frame data will not be stored. Maybe the code only shows up if there is another issue.

Good luck! Jim

[maxnix]

Buying KS off eBay for $50 almost assures you factory rejects, at best.