V6Discussion and questions about the base carbureted or MPFI V6's and the rare SFI Turbo V6.
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I tried it, just put a battery in yesturday. It seems to be a little better than completely going without it, but still gives some of the problems which tend to go away in a week or so.
If you have the time allow this step to occur twice:
Let engine run until fan cycles on then off.
Then let it cycle on then off again. I've found that it helps obtain a better idle right off.
If you haven't cleaned the throttle body for a while (or ever), I recommend that to be done first. The EGR is piped in right behind the throttle blade and COATS the inside of the TB & blade with exhaust carbon.
When I clean it I wear heavy rubber gloves, then use paper towels and carb gleaner (GumOut). I nearly soak the paper towels w/cleaner and swab the inside of the TB. Also get edges of the throttle blade. You'll be amazed at how dirty the paper towels get. It's darn near disgusting (hence the rubber gloves!). Can also use a large screwdriver (as a lever) in the TB linkage to help hold the blade open.
Originally posted by Dale Well, it NEEDS a new throttle body as a tps screw is snapped off in it. I have cleaned it, and the IAC is fairly new.
I am getting code 35 with a fairly new IAC.
Oh-boy, looking at the code now. With a code 35 set (IAC error) your idle will go all to @$%^. The code will skip the SA idle correction, and branch around the idle fueling routine (and use the regular fueling routine).
OK, it looks as though malf 35 gets set whenever the desired idle speed and the actual idle speed differ by 500 RPM for more then 22 seconds (these are AZTY cal values, '92 w/auto).
In order to run the test the ECM needs to believe that the engine is in an idle state. This is defined by having the vehicle speed less then 14 MPH and the TPS less then 2.4%. Check these sensors values also.
Hmm, maybe a vacuum leak? That would cause this to happen. The P/S pressure switch is also involved in the diag routine. Could also be an IAC connector problem. Sometimes the pins open up and don't make good contact.
The code was set while we were sitting in a parking lot eating our rallys food. So I can see where the "22 second" thing comes in at.
So do you think "setting the idle" will correct this, or do you think its something else??
TPS is like brand new, ac delco also. IAC is quite new, autozone brand.
car was sitting still so I dont see how it could be the power steering sensor.
Belive it or not, it idles tad rough, but not bad at all.
It is possible that the sensors and IAC are all operational and a vacuum leak is causing the problem. When the code occurred do you recall whether the idle too high or low? Or maybe the idle speed was OK?
The P/S switch becoming active will disable the actual malf 35 test, just as though the engine was not in an idle mode.
If I were to troubleshoot this problem this is the procedure (more or less) I would use:
Check ECM for cal AZTY (this is the latest auto trans cal for your car, if a stick I'll have to check what it should be). If not then get AZTY cal (buy new memcal or burn AZTY into existing).
With a scan tool hooked up check that:
At idle IAC counts are ~ 30-40. If less then, maybe vac leak, if greater then maybe a rich/lean condition.
At idle TPS% is zero, wiggle tps wires and check for jumps. Slowly move tps and check for jumps/dropouts.
Check that PSPS switch is functional. (hitting the steering wheel while sitting still with your knee would cause this switch to become active).
Check that desired idle RPM & true RPM are being reported properly (is the tach also steady?).
Check the O2 reading, should be toggling rich/lean.
From there I would check for vacuum leaks. A low IAC count would be a sign of this. A low IAC count may also be due to the TB idle screw being turned in too far.
The Helm manual diag chart makes extensive use of a Tech1 tool to run the idle speed up and down. If you can do this or have access to a stepper motor driver you can verify operation of the IAC.
At this point (no matter if wires/leaks/whatever was corrected or not) I would reset the ECM and do the idle learn procedure and go from there.
Ahh, here is something interesting: the Helm manual states an RPM difference of 125 RPM for 45 seconds to set code 35. These are not the values in the AZTY bin, maybe you are getting a false error?! The Helm manual is usually accurate in these parameters. The values may have been changed on an updated memcal due to false malf 35 reports.
The rough idle you mentioned is probably because of the SA idle correction being bypassed. On a different engine/vehicle I was surprised at the difference having this function made on idle stability.
HTHs,
RBob.
P.S. Visited your web site. You did a real nice job on the engine compartment. The painted accents and upgrades (valve covers!) are stunning. It really looks good.
Since you are eventually replacing the TB, I would put some glue or epoxy in the torx screw that broke. That broken bolt could be causing a vacuum leak at the TB.
if you tap the gas pedal does the idle go back down. Mine used to do that with the SES light, but I just ent and got a carb spring set and hooked it to the linkage on the outside of the TB and to the Upper plenum, fine now. i think that the spring on the TB is weak, so it doesn't close the plate all the way. Now that it has the exta little umph that it needed, it's fine. kinda ghetto, but can't afford a new TB right now. Don't want to get a bigger one, just want the stock one becuae I'm afraid of what it'll do when i go for smog checks with the bigger TB, don't know if it'll pass. Anyone know where I can get a new stock one (or rebuilt) for a decent price?
Hello, I have a problem with idle speed in my 1991 Firebird 3.1L V6. Should I make "idle learn procedure" after setting up the torx adjustment screw for 400rpm with IAC disconnected?
Because when the idle speed problem have started I done it like this:
Put the jumper to ALDL
ignition on
wait 45 sec
disconect IAC
take out the jumper from ALDL
start the engine
set 400 rpm with torx adjustment screw (I've done it on hot engine)
turn off the engine
connect IAC
and after that on PARK I have 1200-1300 rpm, so I don't see a point of making "idle learn procedure"
something has to be different. if you set parking brake and chuck the tires and put your t-5 in gear, you'll kill the motor. that step would certainly be different but I don't know what it would be.
__________________ highly modded 3.1.....
best 1/8 mile time...9.51@74 mph
2.04 60' on street tires
There is no "idle re-learn" process for a manual equipped vehicle.......
I also have NEVER done the above procedures for an auto, and guess what, they idled and ran just fine. I have known people that have done the above and didn't notice a difference in how thier car has ran.
Which leads me to believe there isn't really an auto tranny equipped idle re-learn either. Almost seems to be one of those engineer jokes... "Lets see how many people we can get to do this...."
Really you have to ask yourself, why would an automatic have this idle re-learn and a manual doesn't?
__________________ If you're not living on the edge, you're taking up too much space.
There is no "idle re-learn" process for a manual equipped vehicle.......
I also have NEVER done the above procedures for an auto, and guess what, they idled and ran just fine. I have known people that have done the above and didn't notice a difference in how thier car has ran.
Which leads me to believe there isn't really an auto tranny equipped idle re-learn either. Almost seems to be one of those engineer jokes... "Lets see how many people we can get to do this...."
Really you have to ask yourself, why would an automatic have this idle re-learn and a manual doesn't?
Trust me, there is an idle re-learn required for the 3.1l auto equip'd Camaros and Firebirds. Along with other 3.1l cars (FWD).
The $88 mask uses the IAC airflow in the idle routine injector PW calculation. The ECM needs to learn this in order to provide a stable idle. If you ever get a chance to work on one reset the ECM by disconnecting the battery. Then start it up and immediately drive the car.
Be alert for stalling while the vehicle slowing down and turning along with surging while stopped in gear (that too gets exciting).
RBob.
[edit: forgot the note about stick cars. Just let it sit and idle in neutral for about 5 minutes. That will do the trick.}
Trust me, there is an idle re-learn required for the 3.1l auto equip'd Camaros and Firebirds. Along with other 3.1l cars (FWD).
The $88 mask uses the IAC airflow in the idle routine injector PW calculation. The ECM needs to learn this in order to provide a stable idle. If you ever get a chance to work on one reset the ECM by disconnecting the battery. Then start it up and immediately drive the car.
Be alert for stalling while the vehicle slowing down and turning along with surging while stopped in gear (that too gets exciting).
RBob.
[edit: forgot the note about stick cars. Just let it sit and idle in neutral for about 5 minutes. That will do the trick.}
I play with 660 cars, and have for a long time, I've owned a few FWD 2.8/3.1 cars, auto and manual, and worked on many that would use that mask, I've still never noticed a difference, and only ONCE, had I ever noticed that a car had stalling issues, just after re-connecting the battery. The rest all started, idled and drove fine.
It is because of my experiance with cars using this mask or cars that should have used this mask, running fine that I have to question just what this "procedure" really does.
