Mk 3 Power steering issue

Technical Area Steering & Suspension
1

I have a 2006 MX5 2.0 sport

I have posted this before, but I am still having the same problem, I have added dome more details inc the fact that the engine rpm does not increase when I turn the wheel and what i hve done in a failed atemt to rectify it
The steering is heavy whilst doing manoeuvres, but not that noticeable while driving, this started off being sporadic but is now like this all the time, at also does not self-centre as effectively as it used to
The car has done 54,000 miles, I have owned the car for over 5 yrs and only use infrequently
This is what I have checked or fitted over the last 4/5 months: -

The brakes are not binding
The 4 tyres are matched premium brands at the correct psi
I have changed the entire P/S fluid not just the reservoir
A new P/S drive belt correctly tensioned
A low guaranteed low mileage P/S pump and steering rack fitted
With the track rod ends disconnected the wheels turned L&R freely

If I turn the wheels the rpm does not pick up, New genuine Mazda P/S pump pressure switch fitted - I have tested the voltage to the switch - 11.67v. When I ground the wire from the P/S pump pressure switch the engine revs do not increase

I did have a warning light, that when I plugged a reader in came up with P0550 Generic - current - power steering pressure sensor switch circuit, I erased the code and it’s not shown up again. My reader is a generic one not Mazda specific

The only part of the engine bay that has been touched is - I replaced the erg valve solenoid a few years back so I can’t see a reason why anything could have been disturbed.

I know the function of the pressure switch is so the ecu can raise the engine revs whilst manoeuvring the can at low revs, however when I increase the engine speed the power steering doesn’t get any lighter, so can this electrical fault be the issue - is the ecu more complex than I am giving it credit

The power steering is working but it’s not assisting as much as it did esp at low speed manoeuvres.
I am not totally pi55ed off after investing so much time, effort and money without any progress. I must be overlooking something obvious but what?

Any input will me gratefully received

Thanks Ian

2

Not saying it could be the answer to your problem but I had a go in an NC a few months back, that definitely didn’t self centre on the steering. Coupled with a sticking front caliper (not your problem I know) it just didn’t feel right.
The cure for that particular car, it had the alignment checked and adjusted, it was out. Ok they fixed the caliper as a separate fault but yes the self centre much improved.

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3

Hi MickAP

Thanks for your suggestion, saddly 4 wheel alignment done twice, once early on on my saga and again after changing the steeing rack .

Ian

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4

Well you have done all the obvious stuff. You could carry on and faff about forever.
Looks like a trip to the garage (independent perhaps) for a professional diagnosis. :+1:

5

Hi

I have to finally accept defeat and send my car into a specialist, can anyone suggest a repitabel garage near ‘ish’ to me. I live in Saddleworth which is inbetween Manchester and Leeds

6

If you think Sheffield is near enough, Roddisons on Shepcote Lane, he’ll put you right. Ring first maybe give advice on the phone, ask for Paul. :+1:

7

That’s great thanks
Ian