mike77

Good news. I've found something else to fix. While I was putting my coolant bridge back I noticed this.




it is located just under the fuel damper just beside the fuel rail attached to a holder on one of the coolant bridge bolts.

What is it? Will it involve disassembling my car to replace?

It's a 1990 S4 btw


Many Thanks
Mike

Rob Edwards

That's the front knock sensor. R&R will involve removing the intake manifold so that you can properly torque its mounting bolt, which is important so it works as intended.

davek9

I see an intake refresh in your near future.
Your car will run w/o knock sensors, however, will be down on power.

mike77

Thanks Rob. This is just the news I was hoping for

Yup it looks like intake is on the cards. I've been doing everything I can to avoid it right now as I don't have the time.

I need to use the car in a few weeks I'm thinking of a temporary bodge which involves insulating tape and perhaps a glue gun. I think the sensor may actually be working as it didn't come up on the scan.

Rob Edwards

I'd started to craft a response that there is roughly 1.5" between the bottom of the lower plenum and the valley floor of the engine, and if you have talented child labor (or really small hands) and the right tools you might be able to get to the mounting bolt- would require an extralong 13mm gearwrench, the MAF and MAF elbow would have to come off- would be almost as big a PITA as just doing the intake entirely. Not sure how one would get the sensor mounting bolt re-started, and would be no way to tighten properly.

Would just wrap it with self-vulcanizing tape and leave it till you can do the proper R&R.

mike77

I've just had the coolant bridge and the oil filler off and am wondering if it would be possible to put a hand in through the front. They are back on now so don't think I will try.

I like the sound of self vulcanising tape. Sounds easy I'll go with that. It's not clear from the picture but the bottom of the plug is damaged and the base of the spades are exposed. Was thinking a blob of glue from the glue gun may hold it together and keep the spades insulated

Chalkboss

This is what I did before a full intake refresh. My knock sensors looked like yours... that said, expect to find lots of crispies when you dive into the intake. Like others, I opted to change out everything cause I didn't want to be pulling it apart fixing things and troubleshooting as the situation arises. It's really not a bad job at all, I think I was just intimidated by the sheer size of Dwayne's write up. This is a great resource to use, especially if you have the tools and motivation.

soontobered84

You could, as a temporary measure, slit a piece of hose and slide onto the offending wire to insulate it.

davek9

mike77, if it didn't show up bad on a Scan, then I would just fix the connector problem with self-sealing tape and then do it correctly when a complete job can be scheduled.

DaveK9

FredR

Mike,

Just had to get my socks back on again after they fell off from laughing [cruel]! Sooner or later the bugger will get you to do the manifold even if we fail to do so.

If your diagnostic tool says it is still working OK then do what I did when my knock sensor connectors fell apart- I simply filled the void with a black silicon RTV and as it was going off shaped it to the profile of the piece and then when set wrapped it with self vulcanising tape. ST2 told me the sensors are working correctly. You can also refurb the connectors but frankly just replace the knock sensors and the CPS when you [eventually?] get round to the inlet manifold. Also wrap some of the tape along the cable to the extent you can- it is a bodge but it has been working for me for a while. I planned to remove my manifold next winter but had to remove it to do my breather mods a few weeks ago- was not planning for this and so had no new sensors to put back in [would you believe]!

This approach will buy you a bit more time but no guarantees as to how much before one or both pack up altogether.

Welcome to 928 ownership sport! Just remember 928 ownership is like that job painting the Forth Rail bridge- by the time they get to the end of it, it is time to start painting it again!

Rgds

Fred

mike77

Yes I laughed too and I just knew replacement would involve the intake.

Pretty much every connector I've looked at is suspect. Makes me wonder what the condition of the engine harness and the fuel injection harness is like. I know the one plug I pulled on the fuel rail was brittle and a chunk snapped off. Not cheap to replace if it falls apart.

FredR

Half of my engine wiring harness had gone completely so I recently did a partial rewire of that through to the oil pressure sender, oil level switch, alternator voltage line and a/c trigger using some locally available wires but not correct colour code- hope to deal with that later. I ran those cables in a flexible conduit along my [non stock] lower engine brace and then up the inner fender wall to the 14 pin connector where they joined the rest of the cables.Hopefully this will get me through to winter time or when I move to my new home next March [garage with a/c].

The stock heat shrink wrap just goes rock solid and presents a problem in itself. I cut that back and ran some of the cables in a new conduit & wrapped the 16mm power supply cable in the self vulcanising tape. I had to do some r/r on the MAF connector and similar on the injection part of the harness- again most of that probably could do with replacement.

A not so obvious advantage of the sharktuner system is that if some of the MAF signal is attenuated due to resistance losses it can be compensated for but obviously it is not a wonderful solution. In our heat I reckon that the decay process in the engine bay happens that bit quicker. Initially I thought it was a problem due solely to our extreme heat but then Louie Ott told me many years ago that the same decay happened in his neck of the woods in Oregon. I dare say better heat resistant insulation materials are available these days but whether such is available in the factory colour specs I do not know. My friend Mr Dictys did a replacement harness using a UK supplier [i have the details somewhere] when he was still in Dubai. I understand the three pin connector for the oil pressure sender is just not available- perhaps an alternative has been found?

Rgds

Fred