Installed TPI on a GM crate motor with Vortec heads. The idle is all over and running rich.
What is the best practice to tune for idle with lower than ideal vacuum signal 30 to 40kpa. What should i adjust and in what order if any.
Installed TPI on a GM crate motor with Vortec heads. The idle is all over and running rich.
What is the best practice to tune for idle with lower than ideal vacuum signal 30 to 40kpa. What should i adjust and in what order if any.
30 KPA is pretty decent for idle, 40 KPA is not extremely low either.
Are you using a Vortec base (lower intake)?
The man who says something is impossible, is usually interrupted by the man doing it.
yes expensive little bugger
The 401 in my jeep idles at around map 49-50. No ammount of fuel or timing adjustment has been able to get it any better. But it idles just fine.
Have you checked for vaccume leaks?
79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy
93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver
99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.
This is how I did my Camaro. Go to your spark advance table and make all the cells that it is idling in the same, so as to get the timing rock solid. Then go back and forth between SA and Idle VE adding or removing, to get the highest vacuum (lowest Kpa) while watching the IAC counts to make sure you haven't bottomed it out. If you do get to 0 IAC steps, then close the throttle blades a little, and restart the process. Once you reach max vacuum bring the timing back 2-4 degrees. Lastly try adjusting VE to get around 14.7 on a WBO2, if the engine likes it cool, if not put it back to what it likes.
Last edited by gregs78cam; 05-26-2012 at 08:45 PM.
1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
1981 Camaro Z-28 Clone, T-Tops, 350/TH350
1981 Camaro Berlinetta, V-6, 3spd
1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s
No vacuum leaks just trying to tune for the vacuum i haveOriginally Posted by JeepsAndGuns
I have locked out the timing but i am still having trouble with it idling in gear or park. It is not telling me for certian it wants more or less fuel just yet.
I am using a 1 wire alt and i find i should adjust injector PW correction VS battery voltage to help with idle surging. any thoughts?
Replace the 1 wire alternator with a proper externally excited alternator. You will most likely have idling issues using a 1 wire alternator, due to large changes in charge voltage.
What are you using to monitor fuel? You should be able to get the car to idle around 14.7:1, if not a little leaner. USually using a rich idle, while wasting fuel, and possibly washing down the cylinders, will provide a more stable idle. If you need to richen it up to around mid 13 AFR or so, and start adjusting timing to get get it to lean out and smooth idle, while slowly reducing idle VE (fuel), to get everything to work together, going back and forth on VE and spark. You may also need to make adjustments to other parameters, to get other items, such as IAC or error correction to be less or more responsive.
You may also need to adjust injector comp tables, if you are using different injectors than the ECM was using stock.
What ECM and mask (code) are you using?
The man who says something is impossible, is usually interrupted by the man doing it.
730 with $8d This a howell unit that i purchesed for my dads street rod used. The car had the 1 wire alt allready. i am using TP for datalogging and burn. 22lbs injectors i think.
Ok, so you're using the NBO2 sensor to monitor fuel ratio? If so, it's not real reliable, since the transfer function is not a linear slope, there's little change at either end of the range with a sharp drop (or incline, depending on your perspective) between rich and lean.
I would swap out the 1 wire alternator, in every EFI application I have seen the 1 wire alternator proved to be an issue.
There is a battery voltage compensation table for the injectors located at 0x3FA, if you are not using the GM injectors, you may need to adjust this table for a smooth idle. It adds pulse width to the base PW, dependent on battery voltage. Some injectors will be slower to respond at lower voltages and so more PW has to be added to compensate to get a smooth idle. Ford injectors seem to be particularly sensitive in this area.
Vortec heads also seem to be very sensitive to timing. There should be a bin or two around here, that have been tuned for use with Vortec heads, that could give you an idea of what changes are needed.
What are you using for vacuum hose to the MAP sensor? If it is really soft, the hose can actually collapse under vacuum, and cause an erratic signal, that can cause all sorts of problems, especially idle issues.
Where is your coolant temp sensor installed?
Can you post any pictures of your set-up, sometimes seeing how something is installed can help pinpoint any possible mechanical issues, to be corrected before they cause tuning issues. It's nearly impossible to tune around mechanical problems. Believe me, I've tried. lol
The man who says something is impossible, is usually interrupted by the man doing it.
I have also increased the injector pulse width correction vs battery voltage i seen a big change with that while looking at BLMS. Yes i am using a NB O2
The Map is attached with 2" of hose direct to the port not much chance of sucking close. I have been able to get a idle but it will still die sometimes when put in drive. It also dies when i come to a stop unless i 2 foot it till it takes over. I have taken all the timing out for when throttle is closed and think that will help the stop issue.I also have knock at about 2000rpm. i have only lowered the complete timing table to try and help the idle100_2365.jpg100_2366.jpg
Last edited by Rtcat9; 05-28-2012 at 08:31 AM.
Ok i have got it to idle pretty good in gear and out but now i cannot scan the computer with my scanner for some reason. i can still data log with TP. Is there a way to clear codes with TP?
I think there is a mode you can set in the adx to clear codes. not 100% on that though. nice looking setup btw.
87 4Runner, 15" spring lift, 3" body, chevy vortec 355, 5.29 gears, 38.5x15.5x15" Boggers, 280hr, 16168625 running $0D
93 S10, 36x12.5x15 TSL's, custom turbo headers, 266HR cam, p&p vortec heads, $0D Marine MPFI with 8psi boost.
05 Silverado, 2' lift, 4" exhaust, Bully Dog programmer,
If the ADX was built completly you can edit definition and cahnge a setting to clear codes, if not disconnect battrey.
Just some ideas for you with this purdy engine conversion.
1. One wire altenators suck for EFI.
2. is that tha correct MAP for this engine?
3. I did not see CTS, is it in proper location?
4. Where's the coil? Spark plug wires near EFI wires are a bad thing and can not be tuned out...
5. Do you have a VSS hooked up?
You should not be having this much trouble making this run with that vacuum. Have you checked fuel pressure?
Did I mention one wire altenators suck for EFI?
Look at log when engine is started and running cold, what is voltage? POOF! One wire altenators suck for EFI. Now rev the piss out of engine till altenator starts to charge, does it run better? Is it still charging? EFI likes steady voltage!
Nice looking engine bay, when you get er running right lets see rest of the rod!
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
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