Kangarooing M40 - Now with video

Post Mon Jul 04, 2011 6:16 pm

Hi chaps,

On my way home today the car started kangarooing and then it went. I carried on and planned to look when I got home. This happened a couple of times until the kangarooing didn't disappear.
On idle the car is fine. When I rev it, it is lumpy and unappreciative. I know all the plugs are recent but when pulling leads out and plugging them back in again one was dodgy. Changed that and it's the same.
Been checking for air leaks etc but to no avail.

Can anyone help?! I'm currently outside some old chaps house who probably doesn't like the idea of a broken down old car being started up and revved every 5 mins!

Thanks in advance chaps.

Post Mon Jul 04, 2011 6:17 pm

Oops, the car is an '89 manual m40b18

Post Mon Jul 04, 2011 6:17 pm

fuel pump mate .. thats what my money is on

Post Mon Jul 04, 2011 6:29 pm

Bugger. It was/is quite noisy...

Post Mon Jul 04, 2011 6:32 pm

im 99.9% sure mate..

Post Mon Jul 04, 2011 8:14 pm

Took it out, had a fiddle and it seemed to get it's act together. Managed to drive it home and it only kangarood once.
Got home, swapped it for a spare I had and it's the same... The new one hasn't been used for a year though.

Anyone anymore ideas? Tried swapping the AFM and no change.

Post Mon Jul 04, 2011 10:39 pm

Changed the fuel pump relay and then DME relay and no change.

Crank sensor?

Anyone got anymore ideas?

Post Mon Jul 04, 2011 10:51 pm

Check the distributer cap pete?

Post Mon Jul 04, 2011 10:53 pm

injector cleaner/carb/throttle cleaner, or as above inc rotor arm or coil ?

Post Mon Jul 04, 2011 11:35 pm

Yea, could be the crank sensor...measure the resistance on the pins of the connector, where it connects to the loom just under the throttle body (opposite the pulse sensor from lead 4)

Should be between 500 and 600 ohms...

Post Tue Jul 05, 2011 6:41 am

Thanks for the tips chaps, I'll give it all a go this evening.

Post Tue Jul 05, 2011 7:59 pm

Update.

Changed the dizzy and it was the same. Then changed the TPS and it was backfiring and cutting out like a mofo so changed the dizzy back. Now idles and revs like a dream. Took it for a spirited drive and it ever so slightly juddered at very high revs (probs the limiter kicking in

?)

Post Tue Jul 05, 2011 8:19 pm

False alarm.

Back to square one.

Post Tue Jul 05, 2011 9:36 pm

Thats weird, do you have a code reader?

Is the AFM cable connected fully and not at all damaged?

Post Tue Jul 05, 2011 9:39 pm

No i don't. And i haven't checked the resistance either because I've lost my volt meter.
Yeah it seems to be. Im going to have another go tomorrow though. Tracing the wiring back etc.

Doing my head in, seems too intermittent to be serious. Can only be a dodgy sensor/loose connection or something. So irritating!

Post Tue Jul 05, 2011 9:44 pm

i had the same problem, is your head gasket okay? after my car conked out i changed turns out my head was cracked also.... cleaned out the injectors, obv oil change, dumped injector cleaner into it new fuel filter and took it down the a3 for a little blast, it sorted the problem,

Post Tue Jul 05, 2011 9:46 pm

Yea, not great is it!

Whilst your at it, see how it runs with the ICV unplugged...it should push the rpms to up (aparently to around 2000), it could be wiring there, or possibly dodgy ICV.

In what way did it judder and at what rpms?

Post Tue Jul 05, 2011 10:03 pm

Bloody well hope it's not a cracked head! Surely if it was the injectors it wouldn't be intermittent though?

Well it started off only a high revs. Then yesterday when it got to it's worse the car could barely move. So now anything above idle. I live on a hill so when freewheeling down today I banged it in 2nd and the revs went right up so I can only think it's and electrical throttle problem. I also changed the throttle body and cleaned it.

Where can I find the ICV?

EDIT: is the ICV the silver cylindrical thing inbetween the bulkhead and inlet?

Post Wed Jul 06, 2011 1:45 pm

ICV looks like this: (nicked it off magpies for sale ad

) !

Post Wed Jul 06, 2011 2:02 pm

Hole in the intake rubber or any of the tons of vacuum tubes?

Post Wed Jul 06, 2011 5:26 pm

@Coops90

Yep it is!

@Schnaarf

Good thinkin!

@Coops90

I was checking my whether my ICV was to blame for my lean misfire today and swapped in one from a working 318i M40 engine, worked the same, but when I did the above test on his it just stalled! But I think his motor might have a problem or two! Besides it's a test suggested in the haynes manual....FYI...

Post Wed Jul 06, 2011 8:04 pm

Cheers broseph.

Ratch: I've checked the intake hoses and any others i can find. Did find one small split in the end of the one which joins the underneath of the AFM hose but its covered by the circlip.

Soul4t: I swapped the ICV this evening and gave some other bits a clean too. changed the Throttle body yesterday too.

Just this second tried your ICV unplugging trick and yes, the revs went up. However, when i plugged it back in the car stalled...

Many thanks for the tips chaps, very much appreciated

Post Wed Jul 06, 2011 8:08 pm

Back at square one?

Post Wed Jul 06, 2011 8:23 pm

schnaarf wrote:Back at square one?

Yep! And if anything its getting worse.....

Post Wed Jul 06, 2011 10:42 pm

Hmm...

Well it could still be the fuel pump/pressure regulator, I don't suppose you have a fuel pressure gauge?

I bought one for about a tenner from ebay...it was a bit messy...but cheap and it worked!

Still thinking....

Post Thu Jul 07, 2011 6:53 pm

I'm on the look out for one now on eBay.

in the meantime I took a video of what happens when I try and rev it....

[youtube][/youtube]

Post Thu Jul 07, 2011 7:36 pm

who'd you buy the engine off Pete?

Post Thu Jul 07, 2011 7:45 pm

A well known fella on Retro Rides called Dez...

Post Fri Jul 08, 2011 7:57 am

Sorted! Change the crank sensor and it's ok now, just seems to stall on idle sometimes instead.

Post Fri Jul 08, 2011 7:59 am

Swap back the parts you changed! Apart from tps

Post Fri Jul 08, 2011 4:46 pm

Good news...

I hope it stays more sorted and is at least drivable!

Keep us posted!

Post Sat Jul 09, 2011 10:42 am

The stalling now seems to be ok.

So, thanks for all the help chaps!

Hope you sort yours out soul4t.

Post Sun Jul 10, 2011 12:42 am

Excellent!

Thanks! Me too!

Post Fri Jul 19, 2013 12:56 am

hi i have a 318 m40 engine and am having exactly the same intermittent fault - when it starts to shudder badly if i stop unscrew the plug from the air flow sensor while its running screw it back in and that seems to get it back for a bit then it starts to loose it again.

any ideas??