knock sensors

Post by **natsoundup** » Fri Dec 05, 2003 2:12 am

A couple of weeks ago I reporter in that my car was throwing two codes...one for the engine temperature sensor, the other knock sensors.

There were no symptoms at the time.

Last night, I began noticing the sluggishness and hesitation.

The question is can the plenum be removed to get to the knock sensors without damaging any hoses underneath?

I don't mind doing the knock sensors, but time and money would hurt to do all of the under plenum stuff right now.

Post by **Q45tech** » Fri Dec 05, 2003 2:12 am

You always change the 2 KS and its harness [since it also containd the wiring foe the ecu coolant temp sensor].You never know how many hoses you will break or need to break.

Not much difference in $900 or $1200..........you will kick yourself if you get a leak a year later.

Post by **natsoundup** » Fri Dec 05, 2003 2:12 am

Does the check engine light always come on when knock sensors are an issue?

Sorry to be a PITA, but the car also did a little bit of bucking this morning...more than just hesitation. Pulled an MAF connector symptom as well.... eratic idle.

I am going to pull it into the garage this weekend...and do some MAF wiggling as well.

Don't get me wrong...it still threw the 13 and 34 codes.

Post by **Aus94Q45** » Fri Dec 05, 2003 2:12 am

How old are the hoses? Back to your original question, I looked at the same issue. It looks like you could remove the plenum without disconnecting everything and possibly get to the KS's. Again, I have not tried it, but it looks like you could disconnect various upper hoses and move the plenum to the side to access the sensors. However, I will defer to those here who have performed the ultimate Q DIY job -- plenum removal!

Post by **natsoundup** » Fri Dec 05, 2003 2:12 am

Well my hoses are 10 years old, which should answer that question.

What I would like to do is take care of the knock sensors now, and do the hoses before the summer. Time and money issues now to a certain extent.

Post by **DAEDALUS** » Fri Dec 05, 2003 2:12 am

Most people would rather take out a 2nd mortgage than do this job more often than is necessary. You have to weigh the value of your time and the risks of not replacing the hoses against your budget. Hopefully Qdemption and Elwesso will be able to give some feedback before you begin--they will soon have the most recent plenum experiences. I am certain at least a few hoses will have to be cut off to get the plenum off. Truth be told, I have bad knock sensors on my Q, and I am simply dreading having to go back in there. Woulda shoulda coulda, I just didn't know any better when I pulled my plenum and covers a couple years ago. I've had the parts sitting around for perhaps a year now.

Post by **natsoundup** » Fri Dec 05, 2003 2:12 am

yes, I am trying to buy some time to see what issues the other guys come up with.....

In the interim I think I am going to pull my MAF connection and clean it up.. that would be too simple , though....

Post by **AZhitman** » Fri Dec 05, 2003 2:12 am

I watched the tech at the dealership pull and replace my plenum in 45 minutes yesterday. That guy's getting fast!

Third time the plenum's been off in 2 weeks.

Post by **fxjackso** » Fri Dec 05, 2003 2:12 am

I have had the plenums off of my two (sequential) Q's, and I can do it in a relatively short time, but I will say that the knock sensors are bolted on at the base of the "valley", and it is difficult to get there. I was replacing water hoses, so I had removed even the hose connections and regasketed them. That enabled me to do the KS easily. With the hoses in place-a different story.

With luck, a few extensions, a crows foot socket, and patience, you should be able to replace the KS without replacing more hoses than those that break when you remove the plenum, but I second the opinion that you should do more, not less, when you start the job.

Ohm the injectors, and consider a power balance test, in case you have one or more that could be replaced.

Post by **timatt** » Fri Dec 05, 2003 2:12 am

Could someone please elaborate as to why pulling the plenum is such a difficult job? I've never done it (yet) I'm not really doubting it, but after looking at mine I'm wondering what I don't know. what am I missing?

Timatt

Post by **Q45tech** » Fri Dec 05, 2003 2:12 am

This has been discussed a dozen times !

THE KNOCK SENSORS DON"T ILLUMINATE THE CEL as they are not life and death to the engine like MAF, CAS, Coolant temp, TPS, O2 total failure are.

DAEDALUS:As long as you have a minimum of one good one you might emulate the other. Dangerous unless your hearing is sensitive and your coolant temp is well controlled.

Post by **Q45tech** » Fri Dec 05, 2003 2:12 am

I have replace my hoses [many not all] twice, once at 6 years [early 1996] [70k] and again at 220k [summer 2001]............I just had to change another hose at 258k [maybe a defect or my workmanship].......I too am reluctant to go back in.............but I have 4 injectors and 2 KS and harness on standby.

Ripping and snorting the plenum off in 45 minutes is a sure way to reduce the hose life...........think 90 minutes is fast enough!

Post by **natsoundup** » Fri Dec 05, 2003 2:12 am

Thanks for chewing me out a bit Dennis. I just didn't remember seeing the CEL- Knock sensor thread.

When it comes down to it... I am going to do knock sensors, all the hoses, valve cover gaskets, and probably plugs.

First I will clean the MAF sensor. The way I see it, I couldn't get the parts in from Joe until midweek. So it could be a good weekend project next weekend.

Merry Christmas to me, I guess.

Post by **maxnix** » Fri Dec 05, 2003 2:12 am

natsoundup wrote:When it comes down to it... I am going to do knock sensors, all the hoses, valve cover gaskets, and probably plugs.

Merry Christmas to me, I guess.

Attaboy!

Think the early Q45 use silicon bead and not gaskets on the valve covers. But I guess you are referring to your 1994.

Mery Christmas to your new Q45!

Post by **liff** » Fri Dec 05, 2003 2:12 am

I am still looking for the person with the knock sensors for 94 Q-----------------------------------------------------------------------------------Are there any acceptable non factory injectors that work for the 94 Q .assuming I change all eight at once

[email protected]

Post by **natsoundup** » Fri Dec 05, 2003 2:12 am

there's a guy on ebay selling some . 90 bucks each....nissan parts

That's the best I have found...I will likely buy two. and get the rest of the parts from Joe

Post by **Q451990** » Fri Dec 05, 2003 2:12 am

Which Q are you talking about, the 90 or 94?

Heath

Post by **Q45Viper** » Fri Dec 05, 2003 2:12 am

Well, one more item to add to the list that I did not think of perhaps. I'm due for plugs, should THEY also be done when the plenum is off? Anyone contemplating this plenum/valve cover thing should really talk to Joe at Scottsdale. He really knows what needs to be done and can advise you what you HAVE to do and replace when you are under the thing or risk doing it twice. He did not mention plugs so I'm assuming they are not "plenum removal dependent?

Post by **liff** » Fri Dec 05, 2003 2:12 am

To: natsoundup and all --I checked on Ebay but found no knock sensors under Missan Parts or Infinity parts --maybe I erred in some way .???

Post by **DAEDALUS** » Fri Dec 05, 2003 2:12 am

If you're only doing the plenum and not the covers, then there's just a little labor overlap. Getting the harness out of the way is probably the biggest task between the 2 jobs. Worry about the plenum job at first. If you still have energy when it comes time to put the harness back, then go ahead and do the plugs then.

Post by **natsoundup** » Fri Dec 05, 2003 2:12 am

Heath-- I am talking about the 94.... the 90 has been an amazing vehicle except for the transmissions...so I guess everything equals out..

For liff.... I typed in Nissan Knock sensors or Nissan knock sensor...and came up with the listing.... elwesso nabbed some...

to daedalus-- first of all we should do a forum on explaining our handles.... I just figured while I had everthing apart, I would go all the way..... now that I have three cars in the driveway...I can afford to keep one in the garage for a couple of weeks....

Tomorrow, I am going to make the 16 year old get on his back and adjust a couple of belt pulleys on his 90.. my wife says I have to stop hoping he will do the work..and just make him do it.....for some reason the cold weather has made a belt or two squeal..that doesn't make sense

Post by **Q451990** » Fri Dec 05, 2003 2:12 am

The belts will tend to squeal more when it's cold. More at start-up before the idler pullies get warmed up - probably a combined cold harder belt and an idler pully bearing that's worn some.

Heath

Post by **natsoundup** » Fri Dec 05, 2003 2:12 am

Heath....I am going to tighten them up a notch today...and report back.

It seems a bit warmer this morning....we'll see.

Post by **greg_atlanta** » Fri Dec 05, 2003 2:12 am

I'm doing the same thing this week.... dropping car off at T-3 tomorrow. I think knock sensors are OK but want them to check while doing hoses, plugs, etc.

Need to get the car road-trip ready again, been afraid to go anywhere for a year with a coolant hose bulging and fuel hoses seeping in cold weather.

Post by **Q45tech** » Fri Dec 05, 2003 2:12 am

The problem with KS is that where they are mounted it is hard to contort your body and head to the point you can see all around their perimeter.....[tiny cracks]......without removing them, cleaning them, and closely examining them.

The number one disabler of techs is back pain from all the years of bending over!

Most rely upon measuring the resistance [if there are no KS codes] at the harness interface on the passenger side of engine.

This is an instant test, but means little in the long run, as they could fail the next day based on age.............then the consumer blames the tech for not forcing them to change the KS while they were in there.........techs are relucant to ask customers to spend an extra $500 on the unknown potential of a future problem that appear ok today!

The labor to get a good look at them is pretty much the labor to change them, once the plenum is off and fully exposed.

Once we start changing hoses, changing KS and harness only adds an hour [$70] plus parts profit.

Post by **greg_atlanta** » Fri Dec 05, 2003 2:12 am

Dennis: OK to replace my KS if there's a chance they'll fail in 2-3 years. Slight chance they may have been replaced when Troncalli rebuilt engine in fall 1999 at 130K miles.

(Actual mileage around 192K but odometer shows 149K).

Thanks!

Greg

Post by **greg_atlanta** » Fri Dec 05, 2003 2:12 am

Doug from T-3 called me this morning and KS need to be replaced..... I hope that plus new plugs gives me some extra oomph. I want to chew up my tires by next fall and buy some new ones.

Post by **Q451990** » Fri Dec 05, 2003 2:12 am

You will definately notice the difference! The word "effortless" always comes to my mind when thinking about acceleration after getting a knock sensor problem corrected.

Heath

Post by **liff** » Fri Dec 05, 2003 2:12 am

to moderator for my handle "Pop Charger " additional info under cars would be Two 1994 Q45s--one active and one standard. Active has 125,000and standard has 135,000 milestks liffloctation:dayton ohio

Post by **natsoundup** » Fri Dec 05, 2003 2:12 am

is T3 going to replace those knock sensors without doing an under plenum job? I just ordered two from the guy on ebay for 180 delivered. Seems like a good deal.

And if they do it without changing hoses, do they still have to replace all 8 plenum gaskets....that would seem like a necessity.

knock sensors

knock sensors

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