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Timing advance question

L

LV01gtp

New member
I’m looking for some advice on where to go from here. So back story is car is an 01 gtp with 126k mikes. I bought it completely stock 6 months ago. I’ve replaced all fluids except transmission but I’ve drained and added some back tho. I put on SD long tube headers, zzp fenderwell intake, new oem wires and Autolite 605’s. New belts, couple pulleys, power steering pump and rack and pinion. I’m on stock SC pulley still. I don’t have it tuned so I have cel for the headers.

Anyways i don’t have a way to monitor KR. But I have a little gauge I used to use when I had my ‘11 Camaro 3.6 v6. It shows fuel trims, boost, timing advance and eng. temp. I’ve been using it to monitor fuel trims and timing advance. I’m new to 3800 but I’ve done some wot pulls in 3rd and 4th gear and my timing advance doesn’t go past 9 when Wot. Isn’t it supposed to be 15-16? I don’t drive the car much so after seeing that after a couple pulls I don’t go wot anymore. I did on Friday add some e85 to my 91 to get an e30/ 94 octane blend to see if that would help my timing advance. I took it easy first 35 miles and my trims settled down and were little high but nothing crazy. I just tried another wot pull in 3rd gear and my timing did go up to 10.5 but then dropped to 8.5 and 7.5 so I let off. I know in the Camaro 3.6 we had over sensitive knock sensors and timing advance would be pulled if it sensed kr. Is the l67 the same way? I was deciding between getting a tune next or maybe an Aeroforce gauge to monitor kr. What do you guys think? What can cause so low of wot timing? Btw car feels fast/good when doing pulls. Boost last i looked since headers and intake peaks around high 4- low 5 psi.
 


oops, my bad, forgot Iphones existed for a minute. i'm not sure if there is an iphone app for it seems like someone should make one.
 
My work tablet is an iPad and our tablets at home are kindle fires lol.
So I should get a way to monitor kr before a tune? And is kr prolly why my timing advance is so low?
 


01 gtp stock timing should be about 16º wot top of the rpm range.

if its like 8º you have a boat load of kr. every degree of kr pulls 2 degrees of timing. stock they all have kr. 3 inch down pipe or headers can usually kill that off for ya.

as far at the tune goes, rules are you should be running good, no issues like bad fuel trims or exhaust leaks or it running like crap thinking the tune will fix that.
 
So being that I’m on stock pulley and headers I shouldn’t have much if any kr at all... So since I prolly do have kr is it prolly something false being picked up as kr? what should I do as far as eliminating it? What can cause false kr?
 
it could be a bad o2 sensor cause it, they get lazy and quit working well. see if you can scan the o2 sensor in MV, (milli volts) should hit 930 wot and stay up there, if you see hit 930 then drop off you found your issue. the o2 and maf work together for the fueling, if one is bad fueling goes off.

how low is your timing when your wot?
 
My timing advance when not wot is normal... I’ll see up to I think 30 just cruising. Soon as I go pedal down wot I’m at 9 degrees for timing. It’s hard to find enough space in the city to go wot for long. But it stays at 9 when I’m wot.
 
I checked my crappy gauge I have and I can read “ bank1 02 1 voltage and bank2 02 2 voltage “ and mass air flow 2 g/s” don’t know if any of those would be helpful lol
 


check the o2 voltage, it should dance 1-8 up and down pretty quickly all the time. if its locking up low or high or just not moving swiftly, change it. they are only about 40 bucks for a delco sensor.
 
So I took it for a spin around the block watching both 02 and I saw it go as low as 0.020 up till 0.930. I didn’t go wot...Should I have? It fluctuated a lot just cruising... went low to high and in the middle sometimes.
 
sounds about right. id still try to get that scan in MV. see what its really doing.

i was at the track and got a load of kr didnt notice on the scan that the o2 dropped from 930 ish to 0.79 and stayed there.. new o2 no more issue.
 
What else can cause kr that I check?
Now obviously after I installed the fenderwell intake the intake noise got really loud but it does sound different to me then others sound when I listen to clips of gtps with fenderwell intakes. It’s hard to describe the noise but it sounds like a hollow noise? Lol
 


A worn motor mount of the headers rubbing can be picked up as knock.

Did you have to bash the firewall to make the o2 sensor clear? That was a common rub spot with those headers.


I do want to get a few facts in though. Per the high octane timing curve for a 2001 GTP file, the timing is as follows. ( I'm too lazy to screen shot this).

In boost the cylinder airmass is going to at or above .80 to .90g just about all the time. With that said the timing from say 3,000rpm to 6,000rpm goes from 13 degrees down to 9 degrees. Timing slowly drops away as rpm rises.

The computer also use a timing adder based on the commanded air fuel ratio. That value is 3 degrees at 11.7 AFR and 6 degrees at 10.7 AFR. So range of timing can vary from 9 to 19 degrees. Then you have intake air temps that could reduce the timing. Anything over 104 degrees remove 1 degree and once it's over 120 degrees it removes 2 degrees. So if it's really hot outside or the intake is pulling in really hot air it can reduce the timing.


So timing can vary a little bit but a constant 9 degrees mean something, likely knock retard is pulling probably 5-6 degrees away.
 
I didn’t bash my firewall I had that bung welded shut and a new 02 bung welded little farther down where there is no clearance issues.
It is hot here in Vegas lol my IAT temps are often if not always above 104 lately. Once I’m cruising they are usually 10-15 degrees Above outside temps. And lately the outside temps when i drive are 95-110. It will be dropping to high 80’s next week so maybe I can get a wot pull in the morning. See if there’s any difference.
 
I think you just solved your own problem. A Heaton in 110° weather. If you are staying in it like through 2nd and/or 3rd, especially untuned with headers, I'm not surprised. Doesn't it get cool there at night? Do some night pulls and compare.
 
It’s just now starting to get cooler at night. In summer it “cools” down in the middle of the night to like 95 lol. Wednesday I’ll take the gtp to work and at 6am it should be 70’s then.
I hope that’s it, that would be nice.
 
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