3x00 cams

[FORTEEN3GT]

Originally Posted by tejohnson

Myself, I am pushing 10PSI, and seeing at most 1.2° KR.

different topic and thread...... but how's it running... do you have a thread on this?

[tejohnson]

Originally Posted by FORTEEN3GT

different topic and thread...... but how's it running... do you have a thread on this?

Not really, 15° of KR is the highest our PCM will command. Point being, there is no reason it should be going that high. Even with a relatively untuned turbo setup like Donny's (1SickGT) where he is running stock timing and an 8lb spring, with very low KR. I don't understand how it could be "false".

As to mine, I am scanning and scanning daily now, and slowly taking care of my fueling: http://groomlakelabs.com/grandamp/scans/

[xonelith]

Well, Overclock this from GrandsOntario helped me figure out my tuning and the kr (he's the one who has been helping to this point). It was torque management.

Apparently, the PCM is sending kr when too much power is being produced in order to adjust timing to save the crappy parts GM put on my car I guess some sort of PCM generated knock (at least this is my understanding).

Basically, we changed the torque management in my PCM and in a worst case scenario I get like 3.8 degrees of kr.

pretty cool... we are going to work on the last bit of kr tomorrow evening... i gotta get some scans now

[AaronGTR]

Thats all fine, but just a word of warning, once you get the cam sensor working again you'll probably have to re-do all this tuning. Even if you use a wideband right now, the A/F will probably change when the injector timing changes, so it will throw you off. As long as you don't mind doing it right now though, it will probably help getting the practice with the tuner to make it easier later.

[tejohnson]

Check to see if the knock occurs when you take your foot off the throttle...

You can tell by logging:

TPS %
MAF Raw Hertz
LTFT
Engine Speed (RPM)
Vehicle Speed

I use DHP's LogColor program. Not sure if it is free at this point, or what...

You should be able to tell using the "Graph" interface of the VCM Scanner utility though...

If this is the case, you may want to take a look at Engine -> Fuel Control -> Fuel Cutoff, DFCO to see if there is anything you can change... ALthough, I can tell with a relatively newer version of HPTuners that there isn't much you can do with a 2000 GrandAm. Looks like HPTuners needs to map more of the parameters for this area...

Edit: Yep, DHP LogColor is free:

http://digitalhorsepower.corphelp.ne...&nav2=LogColor

[xonelith]

Originally Posted by AaronGTR

Thats all fine, but just a word of warning, once you get the cam sensor working again you'll probably have to re-do all this tuning. Even if you use a wideband right now, the A/F will probably change when the injector timing changes, so it will throw you off. As long as you don't mind doing it right now though, it will probably help getting the practice with the tuner to make it easier later.

Ya, i'm expecting this, but it's friggin cool. Tuning is fun (and a little frustrating) since I'm still learning, but once stuff is working and the right guys are helpin out.....

I dont' mind tuning now and later as this is my daily driver (waiting for words of warning and disbelief from you ) and I didn't feel comfortable driving at WOT on the hwy with KR.

Practice is what I need. There are an awful lot of parameters that are a mystery to me.

[xonelith]

Originally Posted by tejohnson

Check to see if the knock occurs when you take your foot off the throttle...

You can tell by logging:

TPS %
MAF Raw Hertz
LTFT
Engine Speed (RPM)
Vehicle Speed

I use DHP's LogColor program. Not sure if it is free at this point, or what...

You should be able to tell using the "Graph" interface of the VCM Scanner utility though...

If this is the case, you may want to take a look at Engine -> Fuel Control -> Fuel Cutoff, DFCO to see if there is anything you can change... ALthough, I can tell with a relatively newer version of HPTuners that there isn't much you can do with a 2000 GrandAm. Looks like HPTuners needs to map more of the parameters for this area...

Edit: Yep, DHP LogColor is free:

http://digitalhorsepower.corphelp.ne...&nav2=LogColor

Knock went away when my foot was off the throttle... All the parameters you have listed I have in my scan, but appreciate the info.... never sure what parameters to have. For example, in order to decipher if the KR is real or generated by the PCM to avoid damage, it would help to have the Sensor Voltage. There are 4 to choose from and I don't know which one to look at:

Knock Sensor Voltage:
In Range - Front
In Range - Rear
Out of Range - Front
Out of Range - Rear

I attached the only table in the section you referenced. I did modify it, but these are the stock numbers:

[tejohnson]

More my point was to correlate KR with other parameter values to determine if the engine "could" be the source. Too much spark advance, loss of fuel, etc.

[MilzyZ34]

Originally Posted by kubiache

If that's the case then the injectors could be firing too late, resulting in being way lean in the cylinder but appearing rich in the 02s due to unburned fuel.

it wouldn't go too lean. lets say you're right, and the injector pulses right when the valve closes ... then it would have to wait until the next opening to escape. the thing you're forgetting is that this injector pulse is essentially constant at the same rpm, so a split second before that last injector was blocked by the valve, the previous charge mixture was waiting at the valve, it opened, and it went in. so it's not like he's not getting fuel. this is a continuous process. the older engines ran multi-port fuel injection which fired multiple injectors at once, when only one was needed out of those pulses at the time. so running without the cam sensor is no more dangerous than the multi-port car.

[MilzyZ34]

Originally Posted by xonelith

Well, Overclock this from GrandsOntario helped me figure out my tuning and the kr (he's the one who has been helping to this point). It was torque management.

Apparently, the PCM is sending kr when too much power is being produced in order to adjust timing to save the crappy parts GM put on my car I guess some sort of PCM generated knock (at least this is my understanding).

Basically, we changed the torque management in my PCM and in a worst case scenario I get like 3.8 degrees of kr.

pretty cool... we are going to work on the last bit of kr tomorrow evening... i gotta get some scans now

sorry that we added too much torque to your car, and caused you all this trouble

[xonelith]

Originally Posted by MilzyZ34

sorry that we added too much torque to your car, and caused you all this trouble

Ya, that's too bad.

[Sprucegagt]

Originally Posted by MilzyZ34

it wouldn't go too lean. lets say you're right, and the injector pulses right when the valve closes ... then it would have to wait until the next opening to escape. the thing you're forgetting is that this injector pulse is essentially constant at the same rpm, so a split second before that last injector was blocked by the valve, the previous charge mixture was waiting at the valve, it opened, and it went in. so it's not like he's not getting fuel. this is a continuous process. the older engines ran multi-port fuel injection which fired multiple injectors at once, when only one was needed out of those pulses at the time. so running without the cam sensor is no more dangerous than the multi-port car.

Problem is the charge is being blocked by the valve. During acceleration rpm is not constant so injector timing is not constant. It will allow the fuel charge to puddle and not ignite, instead it will cause an excessive rich condition on O2 yet the engine is really running lean.

Bottom line, If the cam sensor was not needed, it would not be in the car period.

If the cam sensor is used for fuel injector timing then you can have periods when the car runs fine and then goes to complete ****. That sensor is needed to match the engine and computer timing sequences. Also I am sure it is screwing up the O2 sensor readings since the computer cannot correctly correlate fuel timing adjustments versus O2 response and change in rpm.

If the car is left running the way it is, it will burn a piston or valve. Bank on it.

[bszopi]

You can't compare it to an old MPFI system. The MPFI system fired all the injectors every time (although it was said to be a bank system, if you looked at the wiring, all the injectors were tied together). So sure, it fired the injectors when the valve was closed, but it also fired the injectors when the valve was open. So the cylinder was still getting fuel when it needed it. Here, with the heat of the engine and such, there is a good chance that a significant portion of the fuel that is fired early/late is evaporating or not atomizing correctly for when it finally gets into the combustion chamber.

[AaronGTR]

Brad is right. If the injector fires when the valve is closed, some of the fuel will evaporate into a gas (instead of a proper fuel "mist"), which doesn't burn the same and will cause the engine to run lean. This is the basic principle behind the new direct injection engines. Fire the fuel charge directly into the cylinder instead of the intake runner which eliminates any evaporation and gives better atomization so you can get a more complete burn with less detonation and at leaner mixtures. That equals more power with more fuel efficiency. The current and most common engine setup has the fuel injector fire as the intake valve is opening. With the outside air pressure, and the suction from inside the cylinder, you get a sudden burst of air movement into the cylinder that pulls the fuel in and helps atomize it. If the injectors fire while the valve is closed, the fuel is sitting in a hot intake runner behind a hot valve and it's going to evaporate and throw your A/F ratio way off.

[xonelith]

OK, but I think I will be ok for another week or so without the sensor. Looking forward to it though so I can get tuning more aggressively... well kind of, the tranny is still stock

Once I get this and install the upper intake manifold, I will be going to the dyno for a wideband AF. Hope this to be complete within the next 2 weeks!! I'll post these results when I get them.

Next purchase is headers, then work on the tranny (maybe a TB).

[bszopi]

Semi-OT...

Just wondering why the cam is listed on the website as being for 96-05?

[FORTEEN3GT]

457 posts and 23 pages??!!!

[MilzyZ34]

Originally Posted by bszopi

Semi-OT...

Just wondering why the cam is listed on the website as being for 96-05?

my web-builder had a slight typo, should read '94-04 . thanks for the heads-up.

[bszopi]

It COULD actually read 93+, since the 3100 was first available in 1993 in the A-bodies (ie, Century). But most people still consider 94 to be the first year for the 3100. So that should suffice.

[FORTEEN3GT]

for right now it really only should say 2003! thanks to this trigger / sensor mismatch issue!