driftervin

Hi lads car has started to idle a bit mad sometimes like goes up to about 3 back to 1 and up again, hunting like.

Ive done a fault code check and 45 is coming up, pressure sensor.

Would this cause the car to hunt like this.

Cheers in advance lads

Splitpin

Your post reads a little confusingly, in large part due to absence of relevant info. Knowing what type and model year of car you have would be a start.

Fault code 45 can be caused either by the pressure sensor itself or a failed/disconnected pressure source change solenoid. However, a question. Was the check engine light on before you did the code check? If it wasn't, then the 45 error is a historic (rather than current) one and therefore may not be relevant to the issues you are experiencing now.

If the check engine light was on before you did the black plugs, then the engine oddity is most likely caused by the error - but there may also be other causes. If your ECU can't get a stable pressure reading then it could affect the idle - but will definitely affect the way the car drives. You'll likely find it in limp mode with no boost and a lowered rev limit.

As above if you want more specific help, we need some more to go on.

driftervin

Sorry its a 95 wrx

driftervin

No the check light was not on but sometimes when i have started it up in the morning it would be on, so i just knock it off and back on and its fine, but the idle prob has started to get a little worse??

Oh and hasn't gone into limp mode ever car drives 100%

Splitpin

Right, this makes things a little clearer. Sounds like you may have a couple of different problems here.

If your CEL has been coming on, and then going off, given what you've said, the reason for it will be the 45 code you got when you did the black plugs. So you need to either check/replace the MAP sensor and/or the PSCS, or the wiring between them and the ECU.

What this then suggests is that this error is not the (principal) reason for the dodgy idle. In this event, check to see whether you have any air leaks around the inlet tract. Could also be a failing mass airflow sensor, sticking/blocked idle speed control valve, sticking throttle, failing throttle position sensor, and other potential explanations besides.

One thing you could try could be to disconnect the mass airflow sensor and then start the engine. If the idle stability is noticeably improved then this suggests the MAF is the cause of the problem.

Oh, and if someone pops up telling you about a "test" that involves disconnecting the airflow meter with the engine running, ignore them. They're talking (well-meaning) rubbish.

As far as the 45 error is concerned, you should look into that - never a good idea to be driving round on a possibly failing sensor.

driftervin

Thanks for the advice splitpin, il give it the once over this week and do what you have said..