Whats the link here ???

[mr_grumble2010]

At first glance at the title I admit it looks like I have absolutely no idea what it is I'm talking about, obviously the aircon makes a difference to engine performance

However, my issue is a little more involved than it first appears.....

I have a 2001 1.3 echo that has now 160k on the clock. It is such a beaut little car, runns well and costs bugger all really.

I do all maintenance myself since 80k and seem to have a pretty good handle on what the car needs, but I find that occasionally, every 1-2k, economy reduces slightly from a tank average of 5.5l/100km to about 6.5-7.0l/100km and at the same time, acceleration is a little rough, with slight flat spots across the rev range, particularly at low rpm, ie 1500-2000rpm.

Additional to the normal servicing I carry out, I have tried the following to narrow down the cause without success.

- Plugs

- air filter

- cleaned the MAF sensor

- cleaned the throttle body

- checked for air leaks

- injectors serviced

- in-tank fuel filter replaced

- injector cleaner

- swapped out all (4) ignition packs with another echo

I had given up on finding the reason why when I began to notice that after my wife drives the echo, it seems to be ok again.

I quized her on what it was she was doing different, she doesn't drive it all that often, prefers the Aurion ZR6 to take to work and the only thing I could come up with was that she uses the aircon often, where I rarely use it.

Noting this, I then waited until the poor running started again and hit the aircon for 30 min on the way home one day. The next day, all was good again. I've been able to reproduce this time and time again for some time now

My question is, what link is there between engine performance and the post effects of having the aircon on for a while.

I personally can't see it, I originally thought that the clutch on the aircon compressor may still be engaging occasionally, thus effectivly having the compressor load on the engine all the time and by cycling the aircon on / off, possibly disengaging the clutch, but from what I've checked, it seems to be ok. It feels as though the engine runns better after having the aircon on ??????

Any thoughts ?

Steve

Edited August 3, 2010 by mr_grumble2010

[rob323]

In theory, the AC should make no difference to the problem.

But maybe the ecu notices the air con being on and advances timing a little to help compensate?

Could it be related to random batches of fuel?

[mr_grumble2010]

In theory, the AC should make no difference to the problem.

But maybe the ecu notices the air con being on and advances timing a little to help compensate?

Could it be related to random batches of fuel?

I was thinking of the fuel issue for a while.

Although this vehicle seems to be very sensitive to fuel types, I can reproduce the aircon fix with almost any mix of fuel.

Esentially, I agree, AC should have not part in the engine performance, however, I cannot make the ecu link after pouring over the schematics