M6 idle slightly "lopey"--- normal or worth addressing?

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GAflyer
Posts: 47
Joined: Sun Mar 10, 2013 5:27 pm
Location: Peachtree City, Georgia, USA

M6 idle slightly "lopey"--- normal or worth addressing?

Post by GAflyer »

My 1988 M6 has about 135,000 miles. I've put all of 4,000 or so on it in the decade or so I've owned it. (Yes, I know...I should drive it more). Like all of you, I enjoy improving my car where I can. I also subscribe to the philosophy of "if it ain't broke...."

As long as I can remember, it has idled about 600 RPM with a slightly lopey or burbly idle. It starts readily and doesn't stall out. It pulls smoothly through the rev range (as far as I push it anyway-- I'm an old pilot who by habit doesn't push old machinery to anywhere near limits). MAF is stock, chip is Dinan (according to PO). I've never driven anyone else's M6 to compare idle or acceleration. I did run a couple cans of Lubri-Moly fuel system cleaner through it several years back, with no noticeable change.

No indication the injectors have ever been serviced. I've read relevant posts here, and wonder if it would be worth the effort to pull the fuel rail and send the injectors off for reconditioning and flow matching. Balanced against the risk of breaking something, or dropping a small part down into a combustion chamber. #-o I've also read about the Mantis Manometer and matching of the ITBs, but hesitate at the cost of a tool I'd likely use once, if ever (although the gent's surely entitled to profit from his labors).

Am I likely to see any benefit? I prefer to be proactive and improve my cars where I can, but don't want to waste time/money or, much worse, create a problem where none exists. Or should I just focus my effort on fixing the mediocre air conditioning and inop cruise control?

Any thoughts on this from you experts out there? :-k

Many thanks. Everybody stay well!!
Rob Welch

1988 M6 Black/ Lotus
2000 528i Orient Blue/ Tan
1981 911SC Targa Wine Red/ Gray
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hornhospital
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Re: M6 idle slightly "lopey"--- normal or worth addressing?

Post by hornhospital »

I'm no expert, don't own an M6, but I think your philosophy of "ain't broke/don't fix" is a good one. You _might_ improve the idle. Then again you may spiral out of control (flying reference just for you) and end up with a great, non-lopey idle, but running worse overall...or not running at all.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
GAflyer
Posts: 47
Joined: Sun Mar 10, 2013 5:27 pm
Location: Peachtree City, Georgia, USA

Re: M6 idle slightly "lopey"--- normal or worth addressing?

Post by GAflyer »

Thanks Ken.

The last thing I want to do with a decently running car is make anything worse. I spent many hours "correcting" my paint until I finally saw some primer peeking through. Dang! Note to self- doing nothing is sometimes the best option!

I'll get a consensus, but if there's not a big upside to the injectors, I'll tackle something else.
Rob Welch

1988 M6 Black/ Lotus
2000 528i Orient Blue/ Tan
1981 911SC Targa Wine Red/ Gray
brickwhite
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Re: M6 idle slightly "lopey"--- normal or worth addressing?

Post by brickwhite »

have you synced the throttle bodies?

I just bought this to sync mine, I'll let you know now it works...

https://thedigisync.com/product/the-digisync/



How old is the Fuel?

If she isn't ran much I'd check the plugs too, they like to foul when not ran much.
- 12 535i
- 92 325ic
GAflyer
Posts: 47
Joined: Sun Mar 10, 2013 5:27 pm
Location: Peachtree City, Georgia, USA

Re: M6 idle slightly "lopey"--- normal or worth addressing?

Post by GAflyer »

Fuel is fresh. Plugs have been in a while, but don't have a lot of miles. Good idea to check them though.

Let me know how the sync device works. I think that's kind of what the Mantis Manometer was supposed to do, but I haven't read anything new about that in a while.

Thanks
Rob Welch

1988 M6 Black/ Lotus
2000 528i Orient Blue/ Tan
1981 911SC Targa Wine Red/ Gray
emac
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Re: M6 idle slightly "lopey"--- normal or worth addressing?

Post by emac »

Mine has a similar idle. I have replaced plugs, wires, cap and rotor. That helped. I may remove the idle control valve and check/clean it out if I get bored one day. I think the OEM ICV is NLA so be careful with it! Check all hoses for air leaks.
GAflyer
Posts: 47
Joined: Sun Mar 10, 2013 5:27 pm
Location: Peachtree City, Georgia, USA

Re: M6 idle slightly "lopey"--- normal or worth addressing?

Post by GAflyer »

All good things to check. Thanks. At the next Sharkfest I go to, I might ask a couple other owners to crank their M6 and let me listen to the idle.
Rob Welch

1988 M6 Black/ Lotus
2000 528i Orient Blue/ Tan
1981 911SC Targa Wine Red/ Gray
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