New 73mm MAF-Engine surge at idle

[whlav]

Just changed to a 73mm MAF. Re-set idle per posted instructions. Idles steady at about 850 in park with climate control off. With climate control on idle jumps to just over 1k when compressor kicks in. Cycles on for about 10 second then off for about 30 seconds. Not noticable at all when driving.

Is it supposed to be this way or am I just noticing the difference in sound of the new MAF?

Can't recall the compressor cycling that often before.

 

[BlackOnBlackATX]

depends, are you using "automatic" or setting it to "floor" or "panel" or whatever? side question though, im debating on buying a 73mm since they have mixed reviews, what do you think of yours?

when i turn my climate control on i get an idle surge for a second but it dies and doesnt come back. dunno if this helps. i always set it manually though, i dont use the automatic function.

 

[whlav]

Had the climate control on auto. Will try on manual later. No surge at all on vent or when climate control turned off. Only noticable when the compressor kicks on. Never did it with the stock MAF.

Re your question about the 73mm. Noticed a bit more power at low end. Not much better at high end/

<small>[ January 15, 2003, 06:58 PM: Message edited by: whlav ]</small>

 

[AutoSHO]

whlav:
Had the climate control on auto. Will try on manual later. No surge at all on vent or when climate control turned off. Only noticable when the compressor kicks on. Never did it with the stock MAF.

I would try resetting the Idle One more time per Scott's (Sdpatt's) instructions. Run a search to find them. It should kick the idle up a bit, but not considerably. And it does cycle like that all the time, the computer just hasn't learned the idle well enough yet more than likely.

 

[whlav]

Thanks Chris. I did set the idle per Scott's write up. Also found post on shotimes site and tried that. No change. Will repeat tomorrow.

Does it take the computer some time to "learn" how to read the new meter? Are some WOT runs required?

 

[BlackOnBlackATX]

you know, on auto the compressor will kick on at will. it uses the a/c system to better regulate temps. i dont know why it didnt do it before but perhaps you just didnt notice it. i dont know if this helps at all. it probably surges because the engine is compensating for the drag of spinning the compressor and then regulates itself, i *think* thats the technical explanation. but its definately climate control related. its normal so dont worry. if you start to have alot of problems clean your IAB, but since you said it only does it when the climate control is on i think youre set.

 

[sdpatt]

This "problem" is caused only by the A/C compressor cylicng and not the engine control system including the MAF sensor. This is the climate control system at work and not the new MAF. Also, with the 73 mm MAF, the stock Ford electronics are still being used. The EEC does not know the difference except that the air mass measurements are a little different at higher flows. The big advantage of the larger MAF body is the lower restriction at high flows.

In the cool (cold) air temperatures we have now, you would expect the compressor to cycle much more frequently than during the hot, summer months. Use the MAX A/C setting with the temp set to 60 to keep the compressor engaged longer during the idle test. In that test, did you allow the idle to settle for at least 30 seconds before adding the loads?

 

[whlav]

Finally got around to resetting the idle again. Left the neg battery terminal off overnight and went through the procedure again. Seems to have worked.Notice the idle increase slightly when a/c kicks on but not a surge as before.

Thanks for the info guys!