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Junk I drive



I can watch fuel trims on my own scan tool, but not knock. Buying ANYthing is out of the question atm, but I just got curious about how the thing (GTP) works. Because conversations with a couple dudes who might barter for a tune, y'know? The answer to my question probably lies in the manual with that fancy tool. But if I knew what maximum spark advance is on a stock L67, I'm thinking I'd have my answer. I saw as high as 37.
 
The KR reading is what the PCM retards from the ignition advance. It lines up with our PM's earlier. Stock WOT timing is 15* You had your Cen-Tec showing 11*, so basically at that point you had 4* of KR. If you had 7* of KR, you'd be at 8* (assuming we're talking about WOT).

The fuel trims are the PCM's way of compensating for a rich or lean condition. It has a preset AFR it is trying to achieve, and the fuel trims are the percentage of fuel the PCM is having to add or remove to achieve that AFR. It's a little more complicated than that, but that's the basic gist of the idea. So if you have a rich condition your fuel trims will be negative since the PCM is pulling fuel (closing injectors faster than normal). If you have a lean condition fuel trims will be positive since the PCM is having to add fuel to achieve the AFR it wants.


I'm not 100% sure, but I believe the max advance is 50*.
 
Booba5185 said:
The KR reading is what the PCM retards from the ignition advance. It lines up with our PM's earlier. Stock WOT timing is 15* You had your Cen-Tec showing 11*, so basically at that point you had 4* of KR. If you had 7* of KR, you'd be at 8* (assuming we're talking about WOT).

The fuel trims are the PCM's way of compensating for a rich or lean condition. It has a preset AFR it is trying to achieve, and the fuel trims are the percentage of fuel the PCM is having to add or remove to achieve that AFR. It's a little more complicated than that, but that's the basic gist of the idea. So if you have a rich condition your fuel trims will be negative since the PCM is pulling fuel (closing injectors faster than normal). If you have a lean condition fuel trims will be positive since the PCM is having to add fuel to achieve the AFR it wants.


I'm not 100% sure, but I believe the max advance is 50*.
Click to expand...


OK if the max advance were 50... and I assume thats 90 in tool speak... and the # on tool is 2, the degrees retarded would be about one. Eh? No?

Knowing now how the fuel #s work and that at WOT both should be 0, that helps. But I do need a boost gauge and KR monitor dealy bobber thingy lol.
 
From our previous PMs when you were saying 11*, I'd think it's giving the actual number. Only way to know for sure is to get you a way to scan. I have an old Samsung Moment that I'll mail down to ya once I can get it setup (long story). We'll have to find a way to get an OBD2 to BT adapter for ya, I'm still workin on that. Keep in mind, the knock sensor aren't active (PCM gives 2 ****s of they say) until the coolant is at 170*F, same with the trims.

That scanner just has a 0-90 value to cover their own asses, I'd assume. No car could possibly run with 90* of knock, but a knock sensor could be bad and give an insane reading, so maybe that has something to do with it. That was just off the top of my head.
 
That makes sense because yeah when I was telling you about seeing 11 on the centech I wasn't aware that WOT was 15. The tool manual didn't state if the # was in degrees or what, and if it wasn't then that would well, confuse me. Not hard to do. The insanity level of proprietary engine management computers is astounding, to me. Can't believe theres nobody making simple, tunable aftermarket PCMs. Must be the law. What a joke!
 


So... I run Shell 91 gas and have a 2.5" downpipe with "hi-flow" cat and u-bend delete, all else is stock. Is 2-4 degrees of KR indicative of an issue or normal?
 
I thought it might be. Conditions were nice and cool today but yeah I disregarded everything until operating temps were up and it settles into a nice consistent pattern. My only reference for how good it runs is well, there is none. This one always seemed a little stronger than the 40th was. I think I saw my advance insta-dip to 7 on a 3-1 dshift once before it was warmed up all the way.
 
I wonder if I took one of those big pickup magnets like I saw at HF and sat it on the PCM or coils, if the car would run. lol probably so.

Trying to make a case for distributors ha ha.
 


Yea seems normal to me. The LTFT's being positive are a little high, you might have a small vacuum leak somewhere or it could just be the tune.
 
OK, good. I'm not worried about it blowing up stock lol. In the past, I've always done best by understanding a healthy stocker before trying to make gains. For a miled out pos it still works good.
 
At some point a few months back I got a random OBD2 to BT reader, but since I have my Aeroforce I didn't really need it. If I find it I'll let ya know if I find it

Sent from my SM-G900V using Tapatalk
 


Right now, yes it is. Thats clear across the state too but I'm sure similar deals are around local. Need wifi modem for house before laptop purchase. I don't have mod fever... yet.

Aero, thanks. Those adapters prolly don't cost a bunch.
 
I'm aware of that, what I mean is next buy is wifi router. So I can use PC, phone, laptop and all. Buying stuff to make the GTP go faster would be shooting myself in the foot. It needs other actual repairs, and generally speaking it can outrun traffic. I set out to find a way to monitor KR and did that. At this point I'm just asking questions to gain understanding for future use. Things often take awhile to set in.
 
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