Is there a difference?

between the 3AM and the 5AM MAF?

Trying to solve erratic idle/surging on my '93 LSE which currently has the 5AM unit, and the local scrapper has a 3AM unit for £20. Looks identical although it's off a G reg 3.9 ('89?).

They're both marked Lucas, Hitachi, etc.

Does the 4.2 have differing fuelling requirements to the 3.9?

TIA - Alastair

Id stick to the 5AM one . like for like to engine model. if you unplug the MAF and its the same then get it replaced, if it has trouble starting after you have unpluged it then its ok. check the air filter too and check for leaks in the air intake piping

I have a problem with my 3.9 classic. Starts up OK, runs for 5 minutes then stops. Won't start again until everything is stone cold (generally the next day). If I remove the plug to the MAF, it will keep running but if I switch it off, it won't restart again with or without the MAF plugged in. It's a 3AM that's fitted but I haven't been able to get one. Just for a laugh, I rang Land Rover. They told me the 3AM was superceded by the 5AM and then superceded again by a later one. According to his information, the later one was listed for mine (1990). Not sure whether they're forwards compatible but it'd be worth a try at £20. Otherwise, give me the name of the scrappy and I'll buy it
The later ones are still available from Land Rover by the way on an exchange basis - absolute bargain at £1139! (Yes, I mean one thousand one hundred and thirtynine). They're having a laugh.

worth a try >>>
LAND ROVER/RANGE ROVER HITACHI / LUCAS 3AM AFM MAF on eBay (end time 11-Nov-10 15:18:47 GMT)

odyssey said:

between the 3AM and the 5AM MAF?

Trying to solve erratic idle/surging on my '93 LSE which currently has the 5AM unit, and the local scrapper has a 3AM unit for £20. Looks identical although it's off a G reg 3.9 ('89?).

They're both marked Lucas, Hitachi, etc.

Does the 4.2 have differing fuelling requirements to the 3.9?

TIA - Alastair

Click to expand...

Yes, from distant memory you can use a 5am on a 3am car but NOT a 3am on a 5am car.
Its very unlikely that the surging is being caused by the airflow meter,its more likely poor base sttings,a vacuum leak or inactive oxygen sensors.

dougdotcom said:

worth a try >>>
LAND ROVER/RANGE ROVER HITACHI / LUCAS 3AM AFM MAF on eBay (end time 11-Nov-10 15:18:47 GMT)

Click to expand...

Might just give that one a bash - Cheers

Found a post on discoweb that suggests the 3AM is for non cat and the 5AM is for catalysed motors, (but also found a post saying that they were completely interchangable as long as both were from LRs.)

Given that the car I took it off in the scrapper had no cats, I'm inclined towards the first suggestion . . .

A