flinx

Posted this at corvetteforum.com. They recommended I ask you guys. Apologies if this is re-asking a bunch of common stuff. I know alot about some things, this just isn't one (yet).
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I just got my cable from AKM today (great guy to work with--highly recommended), and promptly downloaded the trial version of Datamaster to see what I can see on my 1990 automatic Corvette. It has been hesitating and sporadically running hot, so I wanted to take a peek.

Computers I know, but some of these terms on datamaster I don't know. If any of you gurus out there would want to take a look and tell me what you think, I'd be much obliged. Or if anyone knows any good tutorials/documentation, that would be great too.

Here's what I'm seeing:

"LTerm-C Counts" is flagged pink at 118. The help section doesn't really say what this is so I don't know what to make of it.

"STerm-C Counts" gets down to 114. Ditto on the help files here.

"Inj BPW" briefly gets below 1. From what I've read this isn't cause for alarm.

EGR DC goes up to 100% during high RPMs. CCP DC also flickered occasionally. My info is limited but I haven't seen anything to indicate that this is a problem.

Now, here are the biggies (from what I know). During the 6 minute recording, the knock count got to 40. Also, the spark retard got over 5 several times. This happened during the hesitating acceleration that caused me to get all this stuff in the first place. I'm using good gas (have used several types to try to eliminate the hesitation), and can't hear anything strange while this is going on. The engine was relatively cool--between 10-150. Could this be a bad knock sensor?

The only other thing I can see is on that histogram view. There seem to be an awful lot of red (rich) blocks.

I'd really appreciate any commentary or good references.

Thanks
-Mike

Grumpy

[QUOTE][B]

"LTerm-C Counts" is flagged pink at 118. The help section doesn't really say what this is so I don't know what to make of it.

Sounds like what the rest of the world calls Block Learn (and hte term GM uses). 118 means your running rich, and the ecm is leaning things out alot. Optimum number is 128.

"STerm-C Counts" gets down to 114. Ditto on the help files here.

Again, in the normal world would be Integrator. and again running rich, normal being 128.

"Inj BPW" briefly gets below 1. From what I've read this isn't cause for alarm.

Less then 1msec., and the injectors *can* start being erattic

EGR DC goes up to 100% during high RPMs.

Odd, why would you want EGR at WOT?.
Usually on at light cruise conditions only.

CCP DC also flickered occasionally.

**Often** runs about the same logic as the EGR.

Now, here are the biggies (from what I know). During the 6 minute recording, the knock count got to 40. Also, the spark retard got over 5 several times. This happened during the hesitating acceleration that caused me to get all this stuff in the first place.

Not good.
Need to look for acoustic sources of noise, the knock sensor isn't a detonation only devise. Anything of the right sound and it trps it's trigger. Exhaust rattles, serpentine belts, A/C bearings are all possible bad noise generators.

I'm using good gas (have used several types to try to eliminate the hesitation), and can't hear anything strange while this is going on. The engine was relatively cool--between 10-150. Could this be a bad knock sensor?

About the only way to kill a K/S is overtighten it. It's basically a chunk of quartz type rock.

The only other thing I can see is on that histogram view. There seem to be an awful lot of red (rich) blocks.

Common for stock cals.

I'd really appreciate any commentary or good references.

Try the links at ww.tunercat.com, and browse around DIY_EFI.org.

Bobalos

Prolly the simplest thing to do would be to go buy a new knock sensor & see if that fixes the problem. if it does then problem solved. consider that the car has some miles on it, things wear out & brake.

if the motor is hot, it will be more likely to knock, if there is a cooling issue, address that first.

One way to test to see if this is the knock sensor (albiet a kinda dangerous way) is to unplug it & go for a drive. the problem here is two-fold, the obvious one is that if the motor is knocking & you have unplugged the sensor it is not going to retard the timing, not a good thing. knock = bad on motor

The second is that the motor might test the knock sensor when you turn it on. My understanding is that there are cal's that will induce a slight knock to see if it is there. if that is the case then unplugging it might not help you determine if it is knocking or not.

Grim Reaper

I am still doing my tests of my new knock sensor and I do not want to start making statements before I have completed my testing.

I will say that IF you are finding inconsistencies between different operations (ie. it appears more sensitive when the engine is started "cold" versus "hot", etc), then yes, a new knock sensor might give you more consistent readings.

But if you are getting knock readings and expect a new knock sensor to eliminate them, you will be sadly disappointed.