97Q knock sensor

[CJQ45]

Is there a way to remove the knock sensors from a 97Q without taking the intake out?

If it has to be removed - what is the procedure? Any help would be much appreciated.

97Q 68k miles

CJ

[duck3986]

CJ,

I have a 98Q and just did this job recently. There is no way to get them out without removing the plenum.

If you decide to tackle the job let me know and I can help.

BTW, what are you experiencing that makes you feel they need replacing?

Don

[CJQ45]

Hey Don,

Thanks for the reply, I know my knock sensors are out. How did you remove the plenum? Did you have to cut hoses or were you able to reuse the same ones? Any pictures would be very helpful - or a highlight of the procedure you used and tools needed.

Thanks for your help

CJ

[elwesso]

Duck, wed appreciate doing a writeup here

[duck3986]

Unfortunately I didn't save the pictures, but to be honest, it was difficult to really get much perspective from the photos.

All in all, there were only a few tricky parts to the job.

First you get a few basics out of the way........

-pull the fuel pump fuse and crank the engine to alleviate fuel pressure-disconnect the battery-remove the airbox and ducting up to the throttle body-remove the plastic V8 cover-I removed the throttle cable assembly which attaches to the throttle body-remove throttle body

The key to this job is to document screws, bolts and hoses. I used masking tape and a sharpie to wrap around bolts or hoses. For vacuum hoses, I'd number the hose and the coresponding fitting so as to eliminate guesswork when putting stuff back together.

What I recall from here is that you need to remove all hoses, electrical connections, remove the hardline vacuum plate (???) to the left of the engine which has 3 or 4 vacuum lines attached to either side of it and remove the other throttle cable assemble to the left side of the engine and just move it asside (I didn't pull this from the car completely). I did not need to cut any of the hoses, some were tough but with a little effort they would come of without damage.

Then work on the EGR valve. You'll need a big box wrench for one of the bolts. Mine came off without too much effort.

Then you should be able to pull the plenum off pretty easily. Again, keep track of what bolts go where.

From here on it's just removing a lot of bolts for the runners and fuel injector rails.

There are some vacuum hoses that are attached to the underside of the runners that needs to be disconnected. Also there is a fuel line that runs under the runners. This was the tricky part.

I didn't complete remove the injector rails. I got them to disconnected enough to move them out of the way, but ended up breaking quite a few of the "fingers" that wrap around the tip of the injector. Fortunately in 5k miles I haven't had any issues, but those fingers are very brittle and will break off very easily.

If I were to do it again, I might try to completely remove the fuel rails.

I did cut the fuel line that runs behind the runners. I wished I hadn't because it was a bear to reconnect when reinstalling. Again I think that line could have been left in tact if I had removed other connections and then pulled the fuel rails with that line as the one connection between left and right side.

If you get the fuel rails out of the way and the connections under the runners, the runners will lift right out.

Take care with the rubber gaskets (size of a half dollar) that the heads of the fuel injectors sit in. They are loose. Some will come out when you pull the fuel rail. I had one pop out while I was pulling the runners and it fell into the intake valve port. No big deal because it's too big to get past the valve, but I didn't realize it was missing until I had already reinstalled the runners!

The knock sensors come out very easily. Make sure you do both, not just one. I also replaced the wire harness.

When reinstalling be sure to use an alternating pattern as you tighten the bolts on the plenum and runners and stagger the tightening as you go along.

If you've marked everything, it's suprising how easily stuff went back together.

I found a little can of 3in1 oil was very useful when attaching fuel lines and vacuum lines. Just a dab of the oil on a fitting would usually facilitate easy reconnection.

While you have the throttle body and plenum off, do some cleaning of the EGR, IAC, throttle body and runners. Use brake parts cleaner and a wire brush and/or a cloth.

If you run into a jam or have a specific question, you can email me a picture at [email protected] or call me at 603 759-7361 and I can go out, look at my car and try to recall what I did.

Don

[CJQ45]

Very impressive write up - I'm gonna try to do this over the weekend. I just hope I can put everything back together!

Do I need to change the harness as well as the knock sensor? Thanks again for the detailed write up.

CJ

[FarFetched]

First chek resistanced on Knock sensor 500-620 KOhms at 25F

[duck3986]

I can tell you that I didn't have a code and didn't check the resistance, but my car had a sluggish running condition, especially in hot/humid weather.

I had replaced plugs, fuel filter and MAF. I figured based on over 90k miles and all the heat under there, that it was a good bet to replace them anyway.

Once replaced my Q ran as good as new.