Mrmerlin

FWIW I suggest to replace all of these parts if you remove the intake,

the flappy vacuum pot, TPS, ISV, both Knock sensors, CPS, hall sensor and either replace or verify that the oil fill spout is flat.

and use Hondabond to reseal this part also consider using the 928 INTL block off plate for the oil fill

James Bailey

Yes and some people enjoy building a ship in a bottle ..... " have gained access to the knock sensors without taking off the inlet manifold."

dr bob

I did the rear sensor with intake in place. The hose clamp for the boot was easily accessible with a nut driver through the legs of the intake manifold. Just needed to unseat the lower end enough to get the wrench on the bolt that holds the sensor to the block. Less than half an hour start to finish.

the flyin' scotsman

For the 'newbies' you analysed a diagnostic report to determine that only the rear knock sensor was bad?

I'm curious as I work with a new tool I'm working with

dr bob

I used a Spanner borrowed from Rob Edwards (thanks Rob!) to geta short list of failed/faulted sensors. Rear knock sensor and the Hall sensor showed on the diagnosis. Rear sensor is sensor 2 in the diagnosis. Rear sensor was in fact fragged at the cable connection to the sensor, but there's no way to tell that without the Spanner or after removal.. Hall sensor fault was cured by correctly routing the FOE harness where it passes the sensor at the right cam cover at the lift bracket.

----

There's a valid case for doing diagnostics like this on some regular basis. Our annual Sharktoberfest gathering almopst always includes access to the tool, for instance, and I'm pretty sure that SITM visitors have similar access. Rob makes his available in SoCal regularly at clinic days, and I'm sure they are scattered around the country with other owners. FWIW, the cost of the Spanner is easily recovered with the first couple sensors you don't mistakenly replace, so don't discount the value of purchasing the tool from John or one of his distributors.

mark kibort

can you elaborate on the routing of the front passenger side cam sensor? that is interesting. what is the ramifications of that not being routed properly on performance. (assuming the car is running).

im wondering if that could have been my issue for why I have increased power. (not dynoed yet). my rear knock sensor was pretty beat up cable wise. I could have been disturbed in the engine exchange to where it is working now, temporarily. I have a new one to install, but have not had the time to install it yet. (a little scared I might not be able to get it in there without removing the intake)
thanks,

mk

Bill Ball

The knock sensor bolt should be torqued to 15 ft lbs for the sensor to operate correctly. Not sure how easy it is to get a torque wrench on it with the manifold in-place.

Earl Gillstrom

One other comment on intake refrish.

If you powder coat or paint the water bridge, be sure that at least one of the bolt surfaces on the bridge are BARE metal.

The temp 2 sensor uses engine ground and the bridge MUST be grounded to the engine block.

It is grounded through the bolts.

dr bob

Sure. The Hall sensor output is a very low-voltage wave. I had routed the Front of Engine (FOE) harness over the lift loop hole rather than below it when I did the TB last, so the harness was passing over the Hall sensor wiring. That harness needs to go low on the outside lift loop, so the hold-down bolt for the clamp is above the cable itself, and the cable then loops back below the cam drive rather than above it. This was a poor housekeeping issue on my part during reassembly, doing it the easy way rather than the right way.

The FOE harness includes the primary power feed from the alternator and battery to the CE panel, so a lot of current passes through there when the engine is running. All but starter primary, fuel pump, injection and cooling fan power route through that one wire. So there's a decent magnetid field around that harness, enough to muddle the Hall signal and get the EZK to log it as a fault.

IIRC, your 'new' chassis from Mark A is an '89, so it should have the later diagnostic connector. You can get upgraded smarts for your controllers, enabling communications through the better connector to a Spanner or SharkTuner to hep diagnose this stuff intelligently rather than constantly trying to guess where those ponies got off to this time.

Tails

I fully support dr bob in his suggestion that a diagnostic examination of your shark is definately a cost saving device. I can save a lot of money in not renewing items when they are working correctly, by renewing items until the fault is removed.

The only down side is chasing faults to desire and urgency to get all working correctly, but it is worth it. My recent diagnostic check showed that no faults were detected, however, my previous check indicated that I had a Hall Sensor Fault and a HF sensor fault on the RR RDK unit.

Hall sensor removed, cleaned away the accumulated gunk and checked it out using a metal piece that I passed thought the sensor field and got an indication of voltage via an analog multimeter. I cleaned up all my RDK HF Sensors of a lot of gunk and the also cleaned the circular rings on the aft drive shafts and the ring on the front, checked the electrical connections and reassembled. Carried out another diagnostic check and all was well- no faults detected. Also checked the knock count and all was acceptable.

Tails 1990 928S4 Auto

mark kibort

Thanks! makes sense!

However as far as the 87 (not an 88 as we once thought, and I dont know where we got that from), I dont get much upgraded, besides two newer coils, with covers and some much cleaner fuse panel wiring, but the wiring harness is still the same old stuff where, for some reason, the entire diagnostic plug wires are stripped of its connector and tape up in a bundle. All I need to do is get a part of this harness from a bad harness that is getting tossed, so I can splice in the wires via the right colors, or put the old wires in a plug in the proper place. THEN, I might be able to use the shark tuner and see what is going on. bottomline, there is some new found power and I have no idea where it came from. I think a dyno run might be in order when I get the car back from getting caged this week. !

mk

the flyin' scotsman

Are the LH and EZK brains '87?

If so they have to be upgraded with '88 eproms to access the diagnosis capabilities.

rawky

Is an intake off/refurbish/replace job do-able in a day? Or would I have to consider the 928 out of action for a few days?

Rawky

John Speake

I would schedule 2 days work, about 4-5 hours each day. More if you find you need unexpected new parts

rawky

Ok, I had just wondered how long it would take...!

Rawky