16197427 Power Steering Pressure Switch

[notime2d8]

I'm thinking of adding in a pressure switch on my swap. It'san 83 El Camino that came with a diesel originally so it has the Hydro boost system that uses the power steering pump for the brake booster. When i had a carb i could stall while braking and turning.

Does anyone know how the switch is mounted? I’m hoping I can put it on the low pressure line…but I know that’s not right. I don’t want to mess up my new high pressure lines. Should I just test it out and bump my idleby ~50 rpms?

I don't have my a/c in yet but i do have that wired to feed the pcm 12v when it's engaged.

[1BadAction]

I don't think the idea is to increase the idle speed when there's pressure at the switch, it's to add a bit of airflow to maintain the commanded idle before it starts to drop out, similar to how the A/C input functions.

[one92rs]

it is mounted in the high pressure line to get a signal. the low pressure is just return.

[steveo]

I don't think the idea is to increase the idle speed when there's pressure at the switch, it's to add a bit of airflow to maintain the commanded idle before it starts to drop out, similar to how the A/C input functions.

that's usually the idea - it has a target idle it's trying to hit, unless the program alters that commanded idle speed or whatever.

i'd try without it. the iac reponds pretty quickly to the extra load; it wont necessarily act like it did with a carb (which has no real idle governer).

even on a hard slow turn, power steering load doesnt come on all at once like an a/c clutch does...

[Fast355]

that's usually the idea - it has a target idle it's trying to hit, unless the program alters that commanded idle speed or whatever.

i'd try without it. the iac reponds pretty quickly to the extra load; it wont necessarily act like it did with a carb (which has no real idle governer).

even on a hard slow turn, power steering load doesnt come on all at once like an a/c clutch does...

I never really understood the gm logic for the p/s pressure switch. They used it on some TBI and TPI cars but none of the trucks.

[steveo]

due to ratio, i dont think truck power steering works as hard as you think.

you throw manual rack or just tie the lines together on a truck and it's alright, but on a lot of cars you can barely steer the damn thing.

even so, my f-body has TONS of load on the power steering pump, and it wont even bounce the tach when i crank the wheel with a flat tire or whatever, so i dont get it either.

[EagleMark]

I never really understood the gm logic for the p/s pressure switch. They used it on some TBI and TPI cars but none of the trucks.

steveo has a good point I never thought of... but Trucks usually have enough motor that it does not matter.

Cars on the other hand have less motor and the PS cramp is noticed, turn wheel while sitting still and motor load increases and RPM may decrease with just IAC Idle logic. Anything noticed is worked on so customers buying cars have no bad feedback from car. It's all about sales.

The logic behind tuning PS cramp, AC on, or even fans on is to keep idle same. Not to increase and do not let decrease idle RPM when system, like PS is put under load.

Years ago I played with the AC RPM on my Suburban and realized first hand why when AC comes on you just want idle stable, not an increase.... I was at a traffic light and stopped, AC came on and truck started to creep away into car in front of me! I had to apply more brake to compensate.

Now on my newer PCM truck, 98 with 0411 swap I have idle tables for In Drive and Park/Neutral. So while in P/N I do raise RPM when AC comes on. Keeps alternator charging better, oil pressure higher, coolant flowing better and most importantly AC stays colder!

[steveo]

it all seems unnecessary to me, but that's nothing.

my last 80s mazda 4 banger (and this thing had as much torque as a 305 chevy, it was a really stout little 2.2l motor) was a hybrid fi system, it was port fuel injected, it had a full on long runner high pressure multiport fuel system with a bigass monoblade throttle body. but it had a vac advance distributor......

anyway this thing had a bank of a half dozen vacuum solenoids and sensors mounted on the firewall, with all these crazy vacuum lines going everywhere, with tees, check valves, hard lines, totally nuts. probably 20 feet of vac line.

this crazy squid-looking device was linked to every damn system either electrically or pneumatically.. steering, hvac, distributor, egr, a/c, headlights, whatever. there were at least 6 vac lines running just to the throttle body for both pre and post throttle plate air control.

anyway i only found out when i started having issues with it, that the entire point of this system was to stabilize idle by allowing extra bypass air when an accessory of any kind, either electrical or parasitic on the rotating assembly, was turned on.

each solenoid even had a knob on it to adjust the amount of air that was added for each accessory bank. you could tune this thing so it would respond to the defroster being turned on by raising idle 1000 rpm, or not at all.

the funniest part is it had computer controlled IAC too, so all this stuff was totally unnecessary, if they just would have put some damn contact switches in place.

crazy stuff....

[1BadAction]

Years ago I played with the AC RPM on my Suburban and realized first hand why when AC comes on you just want idle stable, not an increase.... I was at a traffic light and stopped, AC came on and truck started to creep away into car in front of me! I had to apply more brake to compensate.

Now on my newer PCM truck, 98 with 0411 swap I have idle tables for In Drive and Park/Neutral. So while in P/N I do raise RPM when AC comes on. Keeps alternator charging better, oil pressure higher, coolant flowing better and most importantly AC stays colder!

One of the reasons I dug into the XDF for the 7060 is the "Initial IAC counts added when A/C turned on", the factory had it set at 15, which was enough to make the RPM surge higher when the A/C kicked on. I changed it to 10, kept the max/min counts added the same and now it cycles with zero effect.

[notime2d8]

Thanks for the info guys. I just tried stalling it moving it out and back into my garage and it didn't die. And i doubt i'll be in a situation where i'll be braking hard while turning. I'll have to test again once i add a/c.

Now I have to relocate my coolant temp sensor, because i just realized it's making me run rich until the thermostat opens since i got lazy and stuck it in the therostat housing along with my temp sensor which i also need to relocate...

[one92rs]

seeing as my 1992 Camaro has one I can say it does do something. I have tried it with and with out. very little but it does do something. would actually like to have something compensate for my electric fan coming on more.