Dodgy alternator?

[Myles1ZZ]

Hi!

Not sure if I have a problem or not... Got the car back on the road yesterday after replacing leaking power steering pipes and managed to stall my MR2 for the first time since I've had it.
Normally when warm it idles at the usual 750 - 800 but the more electrical stuff I put on the lower the idle gets. The weather was bad yesterday so I had the lights, blower, rear demister, and wipers on. When I got it back in the garage I did a little experiment and it seems when I put the lights on the idle drops a bit, turn the blower up and it drops a bit more. The rear demister really drops it down and when I add the wipers and radio the engine is threatening to stall.

I had an old 1989 Audi 80 that did the same thing and was just told that it was possibly a voltage regulator? I would like to correct the problem if possible but I'm pretty sure I can live with rationing the amount of juice I'm pulling.

Do any of your MR2s have the same issue?

[m1tch]

What voltage is the alternator putting out when the engine is running?

[Myles1ZZ]

Haven't had a chance to check yet. I'll need to try and find my multimeter when I get a chance.

[Carolyn]

The electrical systems off the battery.  The alternator replaces the charge.  It could be low voltage from the alternator not topping up the battery properly.  It could also be a battery struggling on voltage.

[Myles1ZZ]

Sorry, forgot to add the battery was new about 3 months ago. Bosch Silver. Should still be good.

[theredone]

i think what you are describing is fairly normal. the greater the load on the alternator, the more engine power is required to drive it. when the engine is idling it cannot produce more power so the alternator drag on the engine reduces the revs. I doubt the mr2 electronics are smart enough to cope with the situation.
be thankful you don`t have air-con   s:D s:D

[Carolyn]

My understanding is that the ECU sets the idle regardless of load.  I do know it turns the idle up a bit when the aircon is switched on.

[Myles1ZZ]

When engine is off voltage across the battery is 12.54V. At roughly 2000rpm it reads 14.16V which seems to be within the norm for these engines. Guess I've just been spoiled by modern cars   s:D s:D    I'll just be more mindful of how many volts I'm using.

be thankful you don`t have air-con   s:D s:D

I've always wondered why they bothered to put air-con in a convertible? surely if its too hot you just put the roof down...

[Carolyn]

For hot days on the motorway.  When I got mine, I had the same thought as you.  After a few miles getting battered by the wash from the heavies and all the tyre noise (from other vehicles) on the motorway, I saw the value in roof up and air on.

[beavisrules]

Sounds like a Idle control valve issue to me. it should throttle the engine to match the load.

[Myles1ZZ]

Found out what the issue was in case anyone is having similar problems. Had the same problem emerge last week just after heavy rain (same as last time.) Car stalled and I got a CEL for a misfire in cylinder 1. Removed all the coil packs and found cylinders 1 and 2 were full of water up to the tops of the spark plugs!
Dried them off, took it for a long run and now its working great again.

Could this be because I don't have the plastic cover that bolts on top of the engine? I assume the water is coming in through the vents in the engine lid.

[Tomo70]

I think you have sorted your problem there, definitely water coming through the lid.  s:D s:D