car bogging down when setting off
Turbo Mini Forums

Hi,

I have a 1293 with a t2 on mirage manifolds, dizzy and rebuilt hif44. I have a problem that when setting off the car bogs down, and leans out until I let off the throttle and feather it back in until I get going. Once rolling it's fine and I can put my foot down. Even if I set off at high revs it usually bogs.

I've timed the dizzy in 6 degrees less than stock in order to limit my advance at high boost, I have 20w40 oil in the dashpot. Full throttle my AFR reads between 11 and 12.5, part throttle anywhere between 12 and 14. When it bogs it shoots up to 17-18 until I get off the throttle.

It's making it a real pain to drive and I can't work out what's going on. Any help would be really appreciated.

Cheers

Try blanking off the part throttle lean off pipe if you haven't already.

Has the fueling been setup on a rolling road?

Lean off pipe is blocked off, not been rolling roaded yet, in waiting until I can afford megajolt/nodiz.

Well you may be needing to afford a new engine if you keep driving it at those afrs!

I'd really get it done as soon as possible, even if you try and fine tune the needle yourself on the road. With a wideband you should be able to get it somewhere close

Dashpot oil?

Very fair point Kean, I could do without melting anything. Would it be as simple as filling a bit off the base of the needle? It feels as though it's something more drastic than that.

Plenty of 20w50 in the dashpot Carl, though I was thinking of doubling up the spring.

the bdd is a very good all round base needle, the t2 will spool faster than a t3 so there will likely be a lean out as boost builds but should be safer that what you have got

Yes i moved to the darkside

Instagram @jdm_brett

I would go with dash put oil. Try see if you can get some heavy r/c car silicon shock oil 50wt or heavier.

Own the day

20w50 should be fine, thats what I used with no issues. The base of the needle may just need a tickle.

Whats the history of it? Is it a new build, what needle, has it just started doing it?

Thanks for all the replies, Kean; the engine was built around 600 miles ago by the previous owner, it has a piper 270 cam, omega 10cc pistons etc. and I had a head built by Benross. Not ported but the chambers opened up and a few other bits. Steve reckons it's good for 14psi and I'm running it in at 8psi max for a while.

I rebuilt the carb, and it has always done it. This being my first turbo A series I wasn't too sure how it should drive, especially with the 270 cam but now I'm sure it's not right.

I don't know what needle is in it tbh, I can check tomorrow evening or maybe the morning. I'll report back.

If it's not a BDD brett, i'll get one ordered as a base.

Cheers

also check if you have the right gasket between the carb and the plenum, you need the one with the extra hole in for the plenum to the carb,

give me a ring Jeff if I can help you buddy

Cheers Steve, I'll give you a bell tonight if that's OK.

I got up at the crack of dawn today to have a look. I doubled my dashpot spring up and filed my needle (a BGB) a bit. It's cured my problem except I took too much off. If I just lightly touch the throttle when cruising my AFR drops to 9.5-10. The car doesn't lean out out bog down at all now. Runs around 11 AFR most of the time.

But the needle is a bit rich pretty much everywhere really so no great loss. Does anybody know the best place to get BDDs? They seem to be up around a tenner most places.

Cheers

Edited by thejefinabox on 13th Aug, 2013.

Try reinstating the part throttle lean off pipe.

In the 13's at last!.. Just

if its now rich every where ,just unscrew the mixture screw a little?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Sorry for not ringing steve, i've spent an hour or two with the bloody thing and have had enough for the night.

On the way home from work the mini started missing, I nursed it home on 3 cylinders. I figured because it was running rich it'd have sooted the plugs up. It had, so I cleaned them up and set off for a test drive.

Straight back to missing. Shit.

Cleaned the plugs up and tried them against the block, they all sparked well with the spark jumping about an inch to the block. Set off again and it's still missing exactly the same.

So I have no idea what's up with it now, going to do a compression test tomorrow.

ffs

the joys of turbo..ing minis
jeff there's no such thing as problems only solutions.

Cheers Steve, in looking at it as a challenge. A challenge I don't understand yet lol. Bloody thing won't beat me though.

Well, I swapped the plugs to the BP6ES from my van into the turbo car and it runs fine. The plugs I took out were nearly new BPR6ES and the van runs fine on them.

No idea what the craic is, going to look into testing the coil tomorrow. Needle is way out though, going to start with a bdd.

stick at it jeff, your nearly there

I usually find that plugs are bin fodder once they a subjected to a shit load of fuel/oil.

In the 13's at last!.. Just