Hi,

I have an 88 Daytona Shelby Z TII (Turbo / Intercooled) I have picked up a scanner and wrote a program to data log from the scanner to my laptop. Over the past 10 months that I have been data logging I have noticed that I record knock. The knock can show up in all cylinders but mostly cyl #1. The timing is at 12 degrees and I have triple checked the cam timing. Backing the timing to 10 degrees, I think made some difference, but it has been a while since I did that and my notes in my logger are not good enough for me to tell for sure. Boost is set only to 10psi.

The knock can show up with 0volts from the knock sensor, can also show up in vacuum, and of course shows up while in boost. O2 readings can be rich or lean or in between.

I can export the logs to CSV format if anyone would like more information.

A little history on the car. It has been rebuilt, .20 over, wiesco forged pistons, the deck and head were maybe shaved .10thou, if I remember the head was CCed at 52. 3" SV and full exhaust, no cat, no PCV system, boost controled via g-valve.

Thanks for looking
Scott

 

What's the throttle position?

 

TPS voltages varies it has been up to 3.68 with O2 around .96 and as low as .54


Here are two new logs, in CSV format. Lotus, Excel, etc will be able to open them. If you do not have anything that will open them, then my datalogger can be downloaded and the logs imported in.

http://www.sheenconsulting.com/car/ToTheCity.csv
http://www.sheenconsulting.com/car/CleanTB.csv

 

I forgot to mention, it is possible I put in an 88 2.5 TBI cam instead of a 88 2.2 TBI cam. There is a 4 degree difference between the two. The stock TII cam has the same specs as the 88 2.2 TBI. My orignial was destroyed.

 

It's doubful that your cam is the problem, even though I wouln't frankenstein somthing together with parts from other engines.
All of the knocking events are pointing to your #1 cylinder.

Besides that, it could be a host of things that is making #1 go "Boom" too early. Carbon, mechanical, EGR, FUEL.......

My guess would lean towards EGR sticking or fuel quality due to the fact that it is worse under moderate acceleration at mid RPM's.

But, that is a pure guess that is worth next to nothing without being able to put my hands on it.

 

Are you actually getting a MIL on?

 

+/- 4 degree difference in what?

 

this might be a bit in the outfield, but it's worth a little thought.

you've rebuilt the engine with new and more stout parts. sometimes these parts make a bit more noise and clatter than stock parts and that can be fooling the knock sensor at times into thinking the engine is knocking, thus causing the knock.

sometimes it take a reposition of the knock sensor to get things back in order.

if I'm wrong about this then I'm wrong, but it's just a thought.

 

The cam is the same for a 88 TBI and TII. Except I do not know 100% for sure if I picked the cam from the 2.2 or 2.5. It was before I knew enough to check.

The Intake Centerline is 118 on a 88 2.2 tbi cam and 122 on a 88 2.5 tbi cam.

Not sure what you mean


I have logs back from Feb showing this, most likely no carbon then as the car was on the road for only 2 months since the new rebuild. No EGR, I have tried different fuel. Higher octane (93), lower octane (89) makes no noticeable difference.

I have thought about that too. Not too sure about it though, it still does not explain the 0volts pulling knock retard. I do have 7 extra knock sensors, I am thinking of hooking up one not touching anything except the wire to the SMEC and see if it records anything then.

 

Web page for the car is

www.sheenconsulting.com/car