Power steering was poor at low RPM. Modified pump by enlarging hole in pressure fitting (50%). Now steering is GREAT but idle is effected. Idle goes high then low, high then low. I want to keep the rig! Can I over ride idle problem?? Is it drag on the motor or some sensor?
There is a power steering pressure switch on the rack.
It signals the ECM that the steering is under load, and raises the idle. You can disconnect this switch, but. I don't know if it will set a code on a 93.
I know it will on a late 94 and later.
Paul,
I STRONGLY disagree with your first statement - a changing load on the engine will affect idle. By enlarging the pressure inlet DB has increased the load of the PS pump on the engine.
I will agree that he needs to verify all the regular stuff like vacuum hoses etc. (did something get disconnected or damaged during the work on the PS rack?) - the "up and down" idle sounds like a air leak (IAC motor is fighting to control air flow and the higher the engine load at idle the harder it is for the IAC to do that if you have an air bypass around the IAC).
It is also important that the PS pressure switch be connected. That switch senses PS pressure demand and triggers the ECM to increase the idle power and cut off the A/C compressor. The switch is either mounted into the PS rack valve body, mounted to a "T" in high pressure line or mounted in the PS pump (been awhile since I've worked on an "N" body with a 3.3 so I'm not sure where it is mounted in that car).
Regards, Bill Bowen Sacramento, CA
The pwr steering won't affect idle. Do the usual: clean the maf, iac, throttle body, look for vac leaks, check the tps and O2 voltages. If that don't fix it, then remove the shift indicator and re-solder each solder connection on it.
I completely agree. However, I was assuming that he meant while sitting still and not moving the steering wheel. BTW, that car does not have a power steering pressure switch.
I did mean while sitting still and not turning the wheel. It started immediately after I rigged it. That's why I'm confident it's the rig. Is there a rack sensor??
See above. I don't see why the pressure would change enough to affect the idle without turning the wheel. It is just sitting there. About the only way to make sure is to undo the belt.
I believe the rig is creating extra drag on the motor (as William said). The system senses it and compensates by increasing the RPM's. Almost immediately the drag decreases at the pump pressure goes high and the systems reduces RPM's. After 2 seconds it happens all over again. Can I adjust the sensitivity of the system or the Idle so it won't do this?? DB
My same car does not have a pressure sensor. Let us know if you find one. You will have to do more diagnosis. I can't help any further. Sorry.
Can I adjust the sensitivity of the system or the Idle???
There is a base idle adjustment procedure:
However, I would suggest some further searching for the power steering sensor switch.
If there is in fact "no switch" get back to me, and I'll send you the base idle procedure.
Allowing the pump to send more volume, by enlarging the orifice, will load the engine a bit, as if you have the wheels partially turned.
The ECM opens the idle air a bit, then if you turn the wheel completely to one side, the A/C compressor will shut down, until the load is removed slightly.
This is totally off-base, Paul. The power steering load is significant on an idling engine, and they have a sensor that picks up on that.
Ok. Likely I am wrong. But I wonder why it would be changing idle speed without a change in steering input? The load should be constant. There is no power steering sensor but perhaps another sensor is picking up a slight change in rpm and over compensating.
I still have my doubts if it is pwr steering related. The only way to tell would be to remove the belt or empty the pump.
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