SC engine keeps bogging down
Turbo Mini Forums

Hi guys,

I asked this on theminiforum but i know you guys will know much more about this sort of stuff.

Quick bit of engine info if it helps:

1275
vmax kit
hif44
electronic ignition in the dizzy
elec fuel pump
Fuel pressure reg
Vmax Scart fully ported/ploished big valve low comp head, Valves are 35.7 x 29or31 cant remember atm, 22cc


I thought the reason for this was the ice on the carb manifold but i now have copper pipe wrapped around the manifold and a heater element in the air filter.

On the way down to MITP i got 50 miles then all of a sudden sudden loss of power. I couldn't bring the revs up for a few seconds then it would come back. This happened a few times before i decided to turn around then the power dropped so much it stalled. I couldn't get the engine started till the next day.

Any ideas? i did nothing to the car to get it started again except for leave it in the garage.

I had the engine tuned up a few days before which ran perfect until this problem on a long run.

Cheers
Nick

I had a problem on my old mini. It would be fine until the engine bay temps git really hot, then it would splutter and die. In the end I had a plug lead that was breaking down. Replaced with new good quality leads and it was fine ever after.

If the engine still runs and all cyclinders are pretty much firing, but it 'bogs down' lacks power but does not 'hesitate' its likely very rich. If on the otherhand it pops farts misfires and hesitates with a jerky motion, its likely very lean

Purchase a wideband O2 sensor. There is no excuse to not have one, they are cheap, good insurance, and will provide diagnostic feedback on issues like this.

As the gents state above, also first check out the coil and all the ignition etc so you have eliminated anything. There.

Ok thanks guys.

Where have you found the cheapest O2 sensor? been looking at a AEM gauge for £148 on ebay

The AEM is a popular one on here. That price seems about the average.

Hi Nick

I run the vmax conversion as well and did have similar issues from time to time. I am convinced most were down to either the carb or its position since going to a weber its been fine. Even with a heater and the copper pipe, don't dismiss carb freezing. A worn carb could also cause similar issues. Are you running a turbo needle valve?
James

James how would i know if the carb is worn? i did replace most of the internals before fitting it.

The needle is what vmax supplied but i cant remember if the tuning company i used reprofiled it.

Carb ice was a nightmare before the heater and copper pipe, but it only happens now on very cold days at speed. I really is a crap position for the carb but i will just have to wait till some sort of blow through kit is available.

Can i ask what fuel pressure you are running? i'm sure mine will be wrong since i never adjusted it from new.

Cheers

Side to side movement on the butterfly spindle.

About 3 psi

No matter what you do, having the carb so far away from the inlet is going to cause you problems. His design although clever is fundamentally flawed IMHO.

Carb icing ?

It isnt exactly winter ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

British weather isn't exactly the best...

Edited by Nick warwick on 12th Sep, 2012.

Tested my fuel pressure, its running at 3psi and i replaced a fuel pipe going from the fuel tank to the fuel pump as it was kinked over restricting the flow quite badly.

Took the car out for a spin giving it some beans and the response was great. No bogging down now at all! I just want to take it on a long run now and see if the problem is fully solved.

Next thing to add is the wideband O2 sensor.

Thanks for the help.