Setting minimum air & minimum air with AC on

[sosuzguy]

Hi I have an 84 stock hot air car. A friend and I were resetting the minimum air then the TPS. For some reason we still have a slight stumble when I take off in the car in drive after a cold start. This seems to never go away no matter what we do. I will admit we've been using my friends experience to guess the engine is around 500 rpm He's pretty accurate.

I wonder if we are off by 75 rpms would that make that much of a difference? My 84 service manual says to set at 500 +/- 50.

Is there a procedure to set the idle with the AC on? Now when I turn the AC off in PARK the car immediately dies!

Thanks

 

[84GNGary]

My 84 idles nicely at 700 rpms. When you say the minimum air do you mean the IAC (idle air control) if so the only way to adjust it is with a scan tool. The IAC should be around 20 and no higher than 30 at idle in park with a warm engine. After you get the IAC adjusted then set the TPS .40-.44 at idle.
See what your IAC and TPS are set for and post them. The idle is done through the chip and does not have any adjustments. At 500 it must be rough.

 

[sosuzguy]

Hi Gary, yes IAC control, basically making the IAC plunger extend all the way, unplug it and then set the minimum air that will flow through the trottle plate. In the service manual (SM) it's called setting minimum air. When you say adjust it with a scan tool do you mean to use the scan tool to see what the RPM's are? We just use a jumper wire to extend the IAC from the computer port under the steering wheel, then unhook the connector from the IAC and go from there. When you said 700 rpms is that in park or drive? Yeah we set the TPS after that, but the service manual says .4 +/- .05 which would be .35 on the low side and .45 on the high side. I've always went by what the service manual from Buick for 84 said to do. This car has 39k original miles and everything is original, well except for the MAF (looking for an OEM MAF) plugs & wires. Did you find that 700 worked better than 500? Great to hear from someone else who has a stock 84 hot air. By the way I forgot to mention this car is a Riviera T-type not a GN. But from what I've seen in the SM all the settings and componets are the same for both vehicles, just maybe some differences in locations.

 

[84GNGary]

Not at all familar with the Riv T Types, a good one to ask is Turbofish38 (Eric Fisher) shoot him a pm, he will be able to help you. You don't even use the same ecm so everything is going to different. On GN's and Regal T Types we adjust the IAC through a set screw on the back of the throttle body. It's setting can be seen using one of any types of scan tools with a laptop or it's own display screen made for these Regals, Power Logger, Direct Scan, Scan Master, Turbo Link, OTC 4000. The first two connect directly to the ecm the others connect to the ALDL under the dash. The 700 rpm's was in drive, in park I am around 825 and I have absolutely no control of the idle, it's all done through the chip. We do not have a minimum air setting on our cars so unfortunetly most of the guys here are not going to be much help

Good Luck

 

[Turbo Riviera]

Not at all familar with the Riv T Types, a good one to ask is Turbofish38 (Eric Fisher) shoot him a pm, he will be able to help you. You don't even use the same ecm so everything is going to different. On GN's and Regal T Types we adjust the IAC through a set screw on the back of the throttle body.

Good Luck

This is NOT true. The Riviera does use the same ECM as the turbo Regals. It's adjustments are also the same as the turbo Regals. Everyone with Hot Air Regal knowlege will be able to help a Riviera T-Type owner.

 

[sosuzguy]

Thanks, I'll have to double check my setting info in the 84 service manual but I believe the settings I quoted in the earlier one are correct. Thanks

 

[sosuzguy]

I just check my 84 and 85 Buick service manual. It says on both G body and E body Turbo engines set the minimum idle to 500 +/- 50 in drive then set the TPS to .4 +/- .05 Since some of you are setting your minimum idle higher in drive are you finding that setting worked better than the factory suggested setting?