Timing Advance On 87 R10 TBI - The 1947 - Present Chevrolet & GMC Truck Message Board Network

eddieeddieg · 10-09-2004, 09:52 AM

Decal under the hood states initial timing should be set at 0*.
Question is:
Would it help my gas mileage(about 11mpg) increase
if the timing is bumped to 8-10*btc.
(Right now WinALDL reports very few knock counts.)
And I just installed a new O2 sensor.

Thanks
Eddie

87 R10/TBI/5.7/Auto/3.42/10x31"AT's

*1972C10* · 10-09-2004, 02:42 PM

Doenst matter where you set the timing the computer will compensate automatically.

Jason Spears · 10-09-2004, 06:19 PM

They usually say 4 degrees are safe for a stock engine and you can advance up to 6 with some performance mods. I tried 4 on my stock truck and it knocked badly when the engine was hot and I stepped on the gas.

Jason

Jason Spears · 10-09-2004, 08:27 PM

Quote:

Originally Posted by 1972C10

Doenst matter where you set the timing the computer will compensate automatically.

Yes it does!

The ecm does not actually know what the base timing is. It assumes the timing is set to 0 degrees and advances or retards the timing according to the input from the various engine sensors. If you advance the base timing too much you can end up with too much advance during normal operation resulting in detonation. When this happens the ecm will have to retard the timing to where it does not knock. What you end up with is a driveability problem.

eddieeddieg · 10-10-2004, 10:11 AM

Jason: thanks for the info.
I've adjusted the timing to 4*btc.
So far no pinging.

Eddie

Jason Spears · 10-10-2004, 11:14 AM

Try this forum for more info on tuning TBI engines.

http://www.thirdgen.org/techbb2/foru...php?forumid=17

These guys know just about everything there is to know about GM TBI.

Grim Reaper · 10-10-2004, 07:24 PM

Unless your going to go through the trouble to get a real time set up so you can see how much timing advance, and the knock count the ECM is alowing or you dyno the car your are not going ot know if you are improving or screwing up. If you start tripping the knock sensor its going ot retard MORE then the 4 degrees you advanced it and acully make less power.
\
A lap top comuter and some sharware and a cable and you can do it.
http://www.customefis.com/ Sells the cable and has a link to the site that has the Shareware and be a pall and slide the guy $10 on the pay pal for the software. That site also has a good library on how to customize the FI and will burn custom chips off of the data logs off the software.

eddieeddieg · 10-10-2004, 09:26 PM

Quote:

(Right now WinALDL reports very few knock counts.)

Although getting a new chip may be the only way to get better mileage.
Eddie

greg0380 · 10-11-2004, 07:48 AM

Eddie,
I recently coverted over to TBI on my 85 and have been looking at things with Winaldl. Just curious, what numbers are you getting for knock counts? I was getting quite a few like 40 on the highway in a certain RPM/vac range, then hooked up EGR and went down to like around 3 over a 20 minute ride.

eddieeddieg · 10-11-2004, 08:33 AM

greg0380:
I get about 30 knock counts a week. This includes
about 75% city and rest on the hwy. And usually
under 100 miles per week.

Intersting thing in WinALDL shows entering closed
loop at 120*. Are you seeing the same?

One other thing - I'll be installing a single exhaust
in the next month or so (removing the non-cat true duals)
and considering moving my O2 sensor from the drivers
exhaust mainfold to a spot somewheres right after the
merging in the y-pipe. This might help get a more accurate AF reading

Eddie

greg0380 · 10-11-2004, 09:21 AM

I'm not 100% sure but I think the stock location for the O2 is on the drivers side about 4 inches below where the stock manifold connects to the Y pipe. That is where I put mine.

I have never pinpointed when it goes into closed loop related to temperature, but I don't think temp. is the only factor. I think if the computer sees that the O2 sensor begins to send valid voltages (.3-.9 volts) then it will go into closed loop. Are you running a stock chip?

10-09-2004, 09:52 AM	#1
eddieeddieg Registered User Join Date: Sep 2004 Posts: 10	Timing Advance On 87 R10 TBI Decal under the hood states initial timing should be set at 0. Question is: Would it help my gas mileage(about 11mpg) increase if the timing is bumped to 8-10btc. (Right now WinALDL reports very few knock counts.) And I just installed a new O2 sensor. Thanks Eddie 87 R10/TBI/5.7/Auto/3.42/10x31"AT's

10-10-2004, 07:24 PM	#7
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	Unless your going to go through the trouble to get a real time set up so you can see how much timing advance, and the knock count the ECM is alowing or you dyno the car your are not going ot know if you are improving or screwing up. If you start tripping the knock sensor its going ot retard MORE then the 4 degrees you advanced it and acully make less power. \ A lap top comuter and some sharware and a cable and you can do it. http://www.customefis.com/ Sells the cable and has a link to the site that has the Shareware and be a pall and slide the guy $10 on the pay pal for the software. That site also has a good library on how to customize the FI and will burn custom chips off of the data logs off the software. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

10-09-2004, 02:42 PM	#2
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	Doenst matter where you set the timing the computer will compensate automatically.

10-09-2004, 06:19 PM	#3
Jason Spears Registered User Join Date: Dec 2002 Location: Stoney Creek, ON Posts: 89	They usually say 4 degrees are safe for a stock engine and you can advance up to 6 with some performance mods. I tried 4 on my stock truck and it knocked badly when the engine was hot and I stepped on the gas. Jason

10-10-2004, 10:11 AM	#5
eddieeddieg Registered User Join Date: Sep 2004 Posts: 10	Jason: thanks for the info. I've adjusted the timing to 4*btc. So far no pinging. Eddie

10-10-2004, 11:14 AM	#6
Jason Spears Registered User Join Date: Dec 2002 Location: Stoney Creek, ON Posts: 89	Try this forum for more info on tuning TBI engines. http://www.thirdgen.org/techbb2/foru...php?forumid=17 These guys know just about everything there is to know about GM TBI.

10-11-2004, 07:48 AM	#9
greg0380 Registered User Join Date: Dec 2003 Location: CT Posts: 454	Eddie, I recently coverted over to TBI on my 85 and have been looking at things with Winaldl. Just curious, what numbers are you getting for knock counts? I was getting quite a few like 40 on the highway in a certain RPM/vac range, then hooked up EGR and went down to like around 3 over a 20 minute ride.

10-11-2004, 08:33 AM	#10
eddieeddieg Registered User Join Date: Sep 2004 Posts: 10	greg0380: I get about 30 knock counts a week. This includes about 75% city and rest on the hwy. And usually under 100 miles per week. Intersting thing in WinALDL shows entering closed loop at 120*. Are you seeing the same? One other thing - I'll be installing a single exhaust in the next month or so (removing the non-cat true duals) and considering moving my O2 sensor from the drivers exhaust mainfold to a spot somewheres right after the merging in the y-pipe. This might help get a more accurate AF reading Eddie

10-11-2004, 09:21 AM	#11
greg0380 Registered User Join Date: Dec 2003 Location: CT Posts: 454	I'm not 100% sure but I think the stock location for the O2 is on the drivers side about 4 inches below where the stock manifold connects to the Y pipe. That is where I put mine. I have never pinpointed when it goes into closed loop related to temperature, but I don't think temp. is the only factor. I think if the computer sees that the O2 sensor begins to send valid voltages (.3-.9 volts) then it will go into closed loop. Are you running a stock chip?



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