working with accel gen 6 and can't get overdrive to kick in ............also having trouble with stalling after high rpm.........messed with iac counts and tps by pass air....... not helping...... could someone walk me through this..............how high for iac counts and how high for by pass air can I go? Thanks


[Modified by lead foot 85 vet, 3:10 PM 5/29/2004]

 

You should be able to go to ECU configuration, then use the Covertor lock up TPS table to use that output to control your OD engagement. There is a table based on TPS position. Also there is a TCC lock up vs speed but it is engine RPM. This means that the TCC would engage if the TPS was >= (X) and the TCC would engage if engine RPM was >= to (X) There is also a Convertor lock up vs MAP which takes MAP pressure into consideration, this table can be used as well. But I don't suggest it because an ever changing MAP value would cause the it lock and unlock all the time. The G6 ECU does not have advanced control dead band tables or alogorithms that allow for better control

Your GM ECM used its VSS speed input and a OD request switch in order to activate the OD. The OD request switch was probably just a 4th gear switch that would close indicating to the ECM that you were in 4th gear. Then based on the speed setpoint for the OD engagement the ECM would close the OD relay which in turn would supply power to the transmission OD solenoid which would then engage the OD.

You could in theory wire in the original 4th gear (OD Request) switch in series with the TCC output from the Accel G6 ECU to the OD relay. Then when the 4th gear switch closes, and if the TPS and RPM tables say match to engage the TCC then the relay would close and supply power to the OD solenoid.

As for your idle air problem have you tried to adjust the throttle stop screw to compensate? Then after doing that readjust the TPS voltage to spec. Try that and see if that helps you.


[Modified by tjwong, 12:16 PM 5/31/2004]

 

thanks tom.........the converter is set at 800 rpm and tps at 0% ...no over drive........tps is configured at .50 engine idles fine after playing with the program.......the problem is in unloading the engine, usually at light throttle the engine revs down to 5500, 4500 rpm and then somtimes dies........sometime it does this at after high throttle.........I've exhausted the changes of the stall saver and tps follower........one move at a time..but done almost every configuration I can think of ........I can make it worse but not better.......could it be the map signal is causing it? if I go into the Ignition map it changes down to 16 degrees and is always flucuating........hanging around 24 degrees.........I'm lost right now.

 

So what you are saying is that when you chop the throttle at 5000 RPM and its trying to decellerate to an idle it dies? If that is so, check your fuel maps at the "high" vacuum cells meaning look at the cells from 0 kpa to about 40 kpa. If your high vacuum cells have a high pw number in them it could be that you are pouring in too much fuel at those points and the engine is choking. I tuned a 447 CID small block with 50lb/hr injectors and that was his problem. He had some rediculously high numbers in the high vacuum cells where the engine would only hit at high RPM coast down on a closed throttle. Basically he was flooding it out.....so try that and let me know. Good luck......

 

I think I've got it tamed...........at least so far..I noticed the idle control limit vs throttle position total by pass air was 20% so I raised it to 45% and grafted it from there raising the by pass air...........at 20% the closer I got to a flat line the better the responce........I didn't realize I could change the total in the graft. yaahoo.........now if the gen 6 will support the overdrive than something else is wrong with the overdrive........dam you can spend alot of time tunning with these things........at least learning the hard way thanks for the help tom.....I"LL BE BACK.

 

If it were me I would just wire a switch to the O/D relay overdrive request lead. The 4+3 fuctions do sort of piggyback off of the TCC ones, but there are more in there for the overdrive logic to get the whole thing working.

 

Thats right Scorp and the bad thing about the old G6 is that it lacks a lot of complex logical functions. Too bad someday someone won't build a ECU that allows some form of discrete logic functions......I mean it would not be hard to do thats is for sure. I can get small PLC (programmable logic controllers) mail order buy the bucket loads now.

 

Scorp IM'ed you............thanks

still having some stalling but 100% better.....going to try rising the iac counts in the effected area........by the way tom its on the rich side but its a low rpm stall, from high rpms it ok after a quick tb release. does the tps scale determine the amount of iac counts the iac moves....at least up the the tps limit I set? I'm tring to understand the relationship between the two.

 

Ok A7 is the wire coming out of the ECM that triggers the overdrive relay to engage overdrive. It is a Tan wire with Black stripe. When the ECM wants overdrive it applies system voltage to this wire.

Things to keep in mind....

By doing this you will no longer have any of the overdrive logic the ECM originally offered and monitored for proper O/D usage. That being..

1. Proper Coolant Temp
2. Proper Vehicle Speeds
3. Proper Engine Speeds
4. If in 1st Gear or not

The system will become fully manual and it will be up to you to properly use the overdrive. I can attach all of the relavent overdrive wiring schematics from O/D switch to O/D relay if you'd like to see how it works.

 

Brian..thanks for the elec. plans..I beleave the ecm grounds the A7 wire rather than applying system voltage........there's no way the accel ecm is going to look at all that logic for overdrive ingagement...I'll wire in a switch.

 

Bert, you're very welcome. I too wondered if it was a ground, but when you look at the pinout for the ECM harnesses I gave you it says B+ which is system voltage. I know that the O/D switch itself is switching a ground. Test it both ways an see what happens, it shouldn't hurt anything.

 

In the DFI system the TPS does affect the IAC counts somewhat. Be sure to have the TPS around .55 volts. Especially if you have moved the throttle plate stop screw. The throttle plate position has more of an affect on IAC counts t han the TPS does, meaning that if hte throttle plates are open more then the IAC counts should decrease as the controller is closing the IAC in order to compensate for the added airflow through the throttle plates.