ptc92rs

The whole reason I started burning chips was to fix my spark knock problem.

I assumed the problem was simply due to a lean mixture condition and could be fixed in the VE tables.

Its been a few weeks now and I've got the VE tables so close I can't stop patting myself on the back, but I'm still plaiged with awefull ping\knock.

It doesn't matter which gear I'm in, when the engine is hot it knocks under light acceleration. Any time I add just a little throttle(light acceleration), it pings, but just a little more throttle and it stops, and I'm not talking flooring it, just a smidgen more.

When it starts to ping, I can see the spark retard on the scan tool, sometimes 10 or 12 deg. worth, but it will just keep on knockin until I either let up or push down the accelerator.

Something is going to to bust bleed or bend, and with fear of layoffs I can't afford any.

I have read as much as I can find but still feel clueless when it comes to the spark tables. Can anyone spare some advice to this situation? I have looked thru the tables and just dont know where to start.

Currently my .bin is based on a '92 305 5spd 3.08 rear. I found a .bin for a 90 350 5spd and tried importing the spark tables thinking this would help since I have a 350, but it made things worse so I guess the best starting point is the one I already have.

I'm a bit confused with this situation so I'm open to suggestions.

------------------
'92 RS 350 Big Mouth TPI 5spd 2.73 lmtd slp Daily Driver with "ISSUES"

V8Astro Captain

iTrader: (1)

Try backing your timing off. Also, a colder plug might work, something like an ACDelco CR43TS. I think the stock ones are CR45's, correct me if I'm wrong. Set the spark bias up to retard the overall timing. The spark bias is a number that the computer subtracts from the timing somehow or another, so by increasing the spark bias, you retard it overall.

------------------
'92 Astro, GM crate 350, Performer TBI intake, MSD 6AL, 3.42's, 2.5" exhaust, Flowmaster 40 2 chamber, B&M 2nd stage shift kit, 255 60 R15 tires on AR-727's, Polished & Bored TBI, Custom EPROM in progress

[This message has been edited by V8Astro Captain (edited October 21, 2001).]

hectorsn

You have a mechanical problem. You either have a slipped damper giving you false timing readings (your base timing is not what you think it is)or you have a bad egr valve. Try disabling the egr by bringing the operating temp to 255. The ecm adds timing when the egr is open and if it isn't opening you get all this extra timing without the leaner mixture and then ping happens.

ptc92rs

The EGR valve and control module are new, also I have used a vaccume pump to open the valve at idle to assure it operates and it does.

As for the damper, it's ok unless it has slipped while on the car. I personally put this motor together and the damper mark was on "0" then with the timing gear marks aligned.

I will try your suggestions though and will respond.

Thanks!

Grumpy

Can you cut and paste your timing table?.
Bruce

ptc92rs

"Can you cut and paste your timing table?."

I did. I opened the table in Tunercat then selected import table and chose the .bin I wanted to import from. It seemed to work. The numbers changed.

Grumpy

I meant cut and paste them to a reply here, so I can see what you have.

ptc92rs

19.0 19.0 19.0 19.0 17.9 13.0 13.0 11.9 6.0 0.0 0.0 0.0
19.0 19.0 19.0 19.0 17.9 13.0 13.0 11.9 10.9 6.0 0.0 0.0
20.0 20.0 20.0 20.0 20.0 19.0 19.0 19.0 16.1 11.9 6.0 6.0
19.0 23.9 23.9 23.9 22.8 22.8 22.1 21.1 19.0 16.9 10.9 8.1
19.0 26.0 26.0 26.0 26.0 23.9 23.9 22.8 21.1 19.0 11.9 11.9
19.0 29.2 29.2 28.1 27.0 27.0 26.0 24.9 22.8 21.1 16.9 16.9
19.0 29.2 32.0 30.9 28.1 28.1 27.0 26.0 23.9 22.1 22.1 22.1
19.0 29.2 32.0 30.9 29.9 29.9 29.2 28.1 28.1 22.8 21.1 21.1
23.9 29.2 32.0 32.0 32.0 32.0 32.0 29.9 29.2 24.9 21.1 21.1
29.2 32.0 32.0 32.0 32.0 32.0 30.9 30.9 27.0 22.8 22.1 22.1
29.2 32.0 32.0 32.0 32.0 32.0 30.9 29.9 26.0 22.1 21.1 21.1
29.2 32.0 32.0 32.0 32.0 32.0 32.0 27.0 22.8 20.0 20.0 20.0
29.2 32.0 32.0 32.0 32.0 29.9 27.0 22.1 20.0 17.9 16.9 16.9
29.2 32.0 32.0 32.0 32.0 28.1 24.9 21.1 19.0 16.9 14.0 14.0
29.2 32.0 32.0 32.0 32.0 29.2 23.9 21.1 19.0 16.9 16.1 16.1
29.2 32.0 32.0 32.0 32.0 29.2 27.0 22.1 21.1 19.0 17.9 16.9
29.2 32.0 34.1 34.1 34.1 30.9 28.1 23.9 22.8 22.1 20.0 20.0

Main spark v RPM v Load


29.2 32.0 34.1 34.1 34.1 30.9 28.1 24.9 22.8 22.1 20.0 20.0
29.2 32.0 34.1 34.1 34.1 30.9 28.1 24.9 22.8 22.1 20.0 20.0
29.2 32.0 34.1 34.1 34.1 30.9 28.1 24.9 22.8 22.1 20.0 20.0

Main spark v RPM v Load(EXT)



[This message has been edited by ptc92rs (edited October 21, 2001).]

ptc92rs

I disabled the EGR valve but it still knocks. I also increased the Max Knock Retard Vs. MAP values and this seemed to dampen the problem. It still knocks but not as loud and not as much, though the max retard is not maxed out. At times I'm getting 15-17 deg retard.

I'm guessing the spark table values need to be decreased. Can this be done effectively the same way as the VE tables?

I figured I would isolate the info in a spread sheet per RPM Vs. Load and make corrections based on the retard. This sounds to simple.

Suggestions?


------------------
'92 RS 350 Big Mouth TPI 5spd 2.73 lmtd slp Daily Driver with "ISSUES"

fast_broker

iTrader: (1)

That table does not have too much advance in it... Sounds like your balancer is off or you are setting your initial advance incorrectly..

Or maybe you have rod knock??? Or an exhaust leak? Both can sound like engine knock...

Or, you have an EGR Spark problem (too much EGR advance) and/or PE Spark Adder problem (too much PE advance).

BTW, if you disconnect the EGR valve so that you get no EGR effect but keep the EGR spark active, you will get more knock than with the EGR conneced and operative!!! Be careful

and diagnoe and fix the problem without driving with that knock. I assume that your knock sensor is hooked up and a scan tool shows KNOCK COUNTS??? If you are getting abusive knock with an active knock sensor and active spark control, you have some major probs...

[This message has been edited by fast_broker (edited October 22, 2001).]

Grumpy

I couldn't attach it so the list could see, but try something along the lines of what I emailed you, and report back <g>....

ptc92rs

When I said I disabled the EGR, I meant that I disabled the EGR by adjusting the Min MAT for EGR Enable to 255.

GRUMPY - I'm feeling Quite ILL today but if I can make it out later I will try your changes and let you know. Thanks!

------------------
'92 RS 350 Big Mouth TPI 5spd 2.73 lmtd slp Daily Driver with "ISSUES"

ptc92rs

First I want to thank everyone for all of their great input. The problem is fixed!

I tried GRUMPY's fix today but unfortunately it was no help. While backtracking my attempts to fix this problem I decided to take one more look at my new knock sensor. I wrote down the part # and called my local GM dealer. It turns out the sensor that Auto Zone sold me a while back not only had a valid GM part # but was the wrong one, it was for a 3.1 ltr. 6 cyl. Auto Zone seemed happy to do an exchange for the 10456549 sensor I needed(can't believe Auto Zone sells Knock Sensors with GM part #'s at less than half price). To make a long story short, the problem vanished with the correct sensor.

The odd thing is that the old (wrong) sensor reported knock, the computer appeared to register it and innitiate retard, but obviously it was either not enough or the computer was some how being tricked.

Well, that's one less "ISSUE"!

------------------
'92 RS 350 Big Mouth TPI 5spd 2.73 lmtd slp Daily Driver with "ISSUES"

fast_broker

iTrader: (1)

phew