merchauser

a friend has kindly lent me the use of a bosch hammer, and while a great number of functions are easy to understand,
there are others that I am having trouble with: specifically knock registration

searched but cannot find a user manual online

does anyone have a pdf of the manual?

John Speake

There is a very basic manual of how to navigate the screens, but for each car the WS manual covers the specific fault codes and their meaning.

What specifically is your problem with knock registration ?

merchauser

hi john, regarding knock registration,
not sure how to set up properly? is this at idle? what am I looking for?
I did an initial set up at idle and it read 0 knocks? not sure how I was suppose
to move forward with the test

also, would like to know more about what the hammer can tell me...

FYI the LH and EZK side showed no fault codes present

ammonman

Get the engine fully warmed up, then connect the tester. Select the EZK menu and go to knock registration test. Start the test on the Bosch tester, then take the car for a normal drive. As you are driving the tester will count the number of cylinder ignitions and count the number of knock signals detected by the knock sensors. The test will automatically terminate after 10,000 individual cylinder ignitions have been triggered and the number of knocks detected will be displayed. Per the WSM more than 50 knocks detected during the test is cause for investigation (faulty lifters, bad con rod, damaged crank/rod bearings, etc.)

Mike

worf928

This -^

To that, I add: you should, during the test, attempt to produce conditions where knocking might occur (i.e. high-load.) On a ‘round town test loop, low rpm high-load is easiest to test. High-load high-rpm needs a highway.

Just tooling around like Gradma with The Hammer in knock count mode probably won’t tell you anything useful unless your 928 is seriously ailing.

I always do at least two knock count tests: first is the low-rpm high load while navigating to the highway, then the high-rpm high-load when on the highway.

merchauser

[QUOTE][To that, I add: you should, during the test, attempt to produce conditions where knocking might occur (i.e. high-load.) On a ‘round town test loop, low rpm high-load is easiest to test. High-load high-rpm needs a highway./QUOTE]

ok, so I warm up the car, and then go for a drive. I understand I should not take a leisure trip, but how aggressive should I be?
running thru the gears, or get on the highway and maintain a constant speed of 60, 70 , 80?

how many knocks is normal?

and what does that tell me or reveal?

still would love to have a manual to look at.....anyone????

Dave928S

Detonation (knocking) is more likely to occur with wide open throttle under load (accelerating hard), and so you need to create those conditions for your test. As Dave noted, do a test under those conditions at lower rpm as you're getting up to speed, and when at higher rpm. How aggressive? ... very ... floor it.

See post #4 for knock count.

Too many knocks generally indicates timing and/or fueling issues ... or carbon build up ... or bad fuel ... or oil ingestion .....

Prolonged detonation = explosive pounding on engine components = engine destruction

merchauser

[QUOTEToo many knocks generally indicates timing and/or fueling issues ...][/QUOTE]

I wish I could grasp what I should be looking for. first off, the car seems to be running just fine and I have no complaints.

is it possible for the hammer to read an abundance of knocks, yet the car runs fine?? would that mean something to preempt?

worf928

The user manual is in the 928 WSM.

If on a test loop which does not include provoking knock via high-load conditions, ANY knock, whatsoever, means there’s something seriously wrong.

Even if the car ‘feels’ ok, knocking under non-high-load conditions is very bad.

A well-running stock S4 or GT should register NO knocks even when attempting to provoke knock with high-load tests.

A *bit* of knocking in high-load conditions may be within Porsche spec, but it still means your stock 928 isn’t in as well-running condition as it could be.

Last, by the time you *hear* knocking it’s too late. Most knock is effectively inaudible when you are in the driver’s seat.

Rob Edwards

PDF pages of KTM 301 operating guide from WSM:

https://webfiles.uci.edu/redwards/pu...2012-17-17.pdf

merchauser

thank you rob, the manual pdf helps a lot!

FWIW:

worf928

Typical for a 928 with some issues.

For the third time: if your ‘90 GT is stock, it should have 0 knocks.

merchauser

[QUOTE][For the third time: if your ‘90 GT is stock, it should have 0 knocks. /QUOTE]

Dave: sometimes I need to hear things over and over until it sinks in. lol. just finding it hard to understand
that my stock GT should register 0 knocks under all load conditions. I would assume that when being aggressive,
even a brand new car would register some knocks?? is there no wiggle room here??


can you elaborate on those issues? hoping there may be some smaller things I can do to preempt a bigger
issue like an intake refresh?

worf928

Why do you find it hard to understand? Knocking is destructive to bearings, wrist pins, pistons, etc. Warranty considerations are such that under all normal conditions a factory-stock running-as-designed engine is not going to knock.

Knocking is abnormal. It's destructive and if your knock sensing system is operating (i.e. reducing timing when knock is detected) then the knocking is also robbing your GT of 10%-15% of power.

Wiggle room you ask? Well, the doctor has told you that you have high blood pressure. Left untreated it can lead to far-more serious issues like heart disease and early death.

What do you want to do? You can leave it as is for a while or forever.

Note that I'm not admonishing you to stop driving your GT this instant. I AM telling you that it is NOT normal and that is IS an indication that your GT is unhealthy. The longer you let the knocking go, the lower the lifetime of your engine will be.

If you can't deal with it now, then stay away, as much as possible, from the operating conditions that cause the knocking until you can deal with it.

If you know you need an intake refresh...

Knocking on a 928 with a stock tune (i.e. no after-market chips or shark tuning) is a symptom of:
- poor air-fuel ratio control
- poor ignition control
- poor engine temperature control (e.g. poor engine cooling)
- too-high static compression (e.g. carbon build-up on pistons).

There are dozens of easy reasons for the first two on 928s:
- dirty injectors
- false air
- bad o2 sensor
- out-of-spec MAS
- bad plug/coil wires, coils, plugs, rotors, caps, coils, coil amps
- fuel pressure problems

In these categories, it is generally too little fuel / too much air that leads to engine knocking.

For S4s and GTs I've never found just one thing wrong, when everything else was near-perfect, that caused knocks. If your 928 hasn't had it's "20 year" service with almost-all of the above dealt with then it is likely several of those constructively combining to produce the knocking.

siscogts

www.bergvillfx.com, go in download section, there is the kts manual....

Knocks:looking at various sites, very good car should not exceed 25 knocks, a good car not more than 50, more than 50 means accurate check.