The computer said there was no knock and there were no codes... am I just hearing thing? I took a few numbers down, will these help me determine what the problem is?

@ Idle...743 rpm... 0% Idle
Right Intake ~130
Left Intake ~130
Airflow: 5-6 gm/sec
TPS = .58
Right BPW= 2.9 mS
Left BPW= 2.9 mS
Right BLM = 137
Left BLM = 137
L 02 sensor= 71-801
Right 02 = 100 - 744
IAC = 22
MAP "Hg = 9.6
MAP V = 1.24
Spark Advance= 20
Ignition = 13.7
CCP Duty Cycle = 0
EGR = 0
Knock Retard 0

@2000 rpm ...6% Throttle
Right Intake ~130
Left Intake ~130
Airflow: 17 gm/sec
TPS = .76
Right BPW= 2.5
Left BPW= 2.7
Right BLM = 137
Left BLM = 136
L 02 sensor= 71-801
Right 02 = 100 - 744
IAC = 22
MAP "Hg = 7.2
MAP V = .80
Spark Advance= 45
Ignition = 13.7
CCP Duty Cycle = forgot to get
EGR = forgot to get
Knock Retard = 12


So does anyone know if these numbers sound right for a 95 LT1 Automatic? I don't know whats causing the pinging, I don't think knock sensor, because there was no code. Thanks , Suke.


[Modified by C4 Suke, 5:27 PM 11/10/2001]

 

Looks like you picked up some knock counts since you have 12 deg of knock retard by 2k RPM.

Were you at WOT by 2k RPM?

Notice that you have 3x as much air flow at 2kRPM as at idle but the same fuel injector pulse width. That should cause a lean condition that could lead to ping!

 

Damn you know your stuff, I couldn't break all that info apart, I found the air flow info, but whats the fuel info labelled as?

No I wasn't at WOT, I did WOT like for a little bit, but forgot to record the info, but the knock retard I think was around or over 12 for that too.

So is there a problem with my with my injectors? Fuel pressure regulator or something maybe? Thanks a lot, Suke.

 

Fuel is LBPW & RBPW=Left Bank Pulse Width, etc. The ECM should increase injector pulse with as air flow increases, unless the O2 sensor indicates otherwise, in closed loop mode. At WOT you should be in open loop mode and the ECM will ignore O2 sensor readings so will match injector pulse width to air flow and other parameters.

I assume you only hear ping at WOT, maybe near top RPM. Or is it present under load at light throttle? Does the scan tool show knock counts as well as knock retard? My auto X-Ray shows knock counts as well as timing regard and total timing.

We are just beginning to track the problem.

 

I hear pinging whenever I give enough gas to go over 2 to 3rpms or higher, I hear it only when I'm driving. For this reason I have never really given full gas, I'm afraid of messing something up. I'm not sure if there is any under light load, if there is its not audible... When I gave gas the knock retard varied from the lowest being 1 and as I gave more gas it reached 12. I think 12 was at a higher rpm than 2k... I was just giving random throttle at high rpms, I'd say it was at 3000 to 3500 rpm.

I am not sure if it shows knock counts, there was parameter that mentioned I think knock, or may have been knock count, it said "No". If knock count is suppose to be a number, not Yes or No, then that scan tool does not show it.

So are we getting anywhere? Will I need to get some more info? The owner of the scan tool only has the tool, and he said he didn't have the stuff to hook it up to a computer to show all the data at once like in a spread sheet, so that sucks... It would be more accurate that way. Thanks, Suke.

 

Hello Suke, Im new to the forum. I have an 87, had as serious pinging problem and could not figure out what was wrong. After every sensor you can replace was replaced and still pinging, I found that the harmonic balancer had slipped about 30 deg. Hope you find the problem.

 

If you want to purchase a NEW AutoXray XP240, let me know. nriale@hotmail.com

 

Never thought about that, I'll check it out. Thanks.

 

You're Block Learn #'s (BLM) show that the motor is lean and your injector pulse width, though rich, isn't keeping up. Check for a vacuum leak, but considering you have a MAP motor, look for an exhaust leak too, especially at the Headers.

 

Exhaust leak? I'll check that out, how would I pinpoint it?

 

I'm from the old school... set timing by vacuum, then check with a timing light (harmonic balancer), this will instantly reveal bad timing marks.
So,how many of you out here are old :eek: enough to know what a dwell meter is & still have one in the garage (I do)

 

im 26, and i know what a dwell meter is, and an old du-coil distributor, the old OE 298 cam, the 30/30 cam, carter afb carbs, dual quad manifolds, how to set up the old corvette fuel injection units by setting the lean stop and the rich stop by using an exhaust gas analyzer and how to set points with a dwell meter to get the right saturation time, and how to use a timing light! etc.. but i learned it all from my old man :lol: so i suppose if you add our ages together, we are almost 90? this count :D

as far as your readouts from the snap on, i am having trouble understanding, 10 degrees is the max amount of timing the computer will pull for knock retard. your BLM's at 137 are off, would like to see those as close to 128 as possible. as stated earlier, WOT is open loop...or "power enrichment", this is where your cars computer leaves its hunt for 14:1 AFR in search for 12.5:1, it usually gets there by previous values it has recorded so if the info is innaccurate or just not right, it will adjust itself improperly. need target values for the computer to set your injector pulsewidth accurately. with a MAP system, definitely look for intake and exhaust leaks, and how old are your O2 sensors, they can make a difference. also try new plugs, maybe wires, new fuel filter, check your fuel pressure to make sure your pump is keeping up. these usually will work out the problem, if not and everyhting else checks out it could be fixed with programming software and burning another chip for it. but somehting mechanical must be the culprit as the computer from GM are generally tuned well. LT's generally run hot and rich. try the cheaper repairs, chances are the car needs it anyways so its not wasted money. and if these solve it, super, if not, keep chasing leaks, manifold vacuum leakes, exhaust leaks, use an engine stethascope to listen near each of the header flange connections, your looking for leaks between the O2 sensor and the block. these will give the O2's inaccurate afr readings!! make sure O2 sensors are not loose, and tightened good, maybe remove them and use some antisieze, and remove some of the carbon build up from the outside of the sensor. this helps sometimes if the air inlets are clogged. chack for a clogging catalytic converter, this will sometimes cause a lean condition !! good luck and let us know what you find!

chris :smash:


[Modified by lcvette, 9:23 AM 11/14/2001]