1132cc Mini Turbo - cutting out/missing... help

pristic · Post by **pristic** » Sat Jul 03, 2010 8:28 am

Hi Guys,

Need some ideas.
Mini 1132cc Turbo, running MJ v4

I sold this car 18months ago, was going like MAD... bought it back a week ago.

Problem is this
Driving along, it seems to lose power, ie: wont rev, wont pull, then comes good. Regardless of rev range (sometimes 2000rpm, sometimes 4000rpm) idles fine, unplug MJ and it gets really rough...
Green light is on, no issues with power and earth.

Fuel issue or MJ issue?
Its rougher than before... but it was always a cammy car.

I am replacing the MJ plug (using one from a PC) to see if that helps... the wires are not tidy anyway.
What would a data log show? ie/ what should I look for when it 'misses' or cuts out.

Its like your driving, and it wants to pull but cant. Like its starving for fuel or the timing is way out.

I have to work out a way to check the fuel pressure but its strange that its not at boost or at particular RPM. ie/ If I am cruising and squeeze on the throttle it seems worse (as in happens more) if im at the lights, nail first, nail second it screams through, boost, 7500rpm no problem...

- Ive given it more fuel and I thought it helped, but it didnt
- Ive taken the air filter off turbo and it seems worse (ie/ the colder the air the worse it seems) = fuel in my head...

I have not got the lambda with me to check A/F but will get to it.
Fuel pressure guage is in the engine bay, and cant get to dyno for a few weeks... I might try moving it into the cabin for a test.

Dunno where to check and what to start with...

Thanks,
Peter

Post by **brentp** » Sat Jul 03, 2010 2:31 pm

Try monitoring the engine using a timing light to see if the ignition advance is being correctly controlled by megajolt or if the EDIS module is in 'limp home' mode (fixed at 10 degrees). This might point to the 'flatness' in driving. If the advance doesn't change with RPM you may want to check the PIP/SAW lines. Also, check to see if the ignition map has changed at all, since you last owned it.

pristic · Post by **pristic** » Mon Jul 05, 2010 6:27 am

Hi Brent,

Thanks. Ive datalogged and replaced the MJ plug with a new one, soldered and wired very very well.

Can you help me read the datalogs?
There are 4 all up. I think it was towards the end of the second datalog where I was cruising up hill approx 3000rpm and it was cutting out... does it show up in the log?
If not then obviously I would be looking at fuel... I forgot the key to mark the datalog (spacebar) while I was driving

Log 1 - 1/2 to 3/4 throttle, hit boost first gear, and second gear - short burst.
Log 2 - Longer - boost plus cruising - problem approx 3/4 of the way through on cruise (missing/cutting out)
Log 3 - Trying to replicate
Log 4 - unsure.

Peter

pristic · Post by **pristic** » Tue Jul 06, 2010 8:00 am

Ok, can anyone read the logs? Showing anything??
Tell me what to look for if thats easier.

Also, just noticed that the plugs are FOULED (carbon) pretty badly... they are BP5ES (non resistor type)
I will replace them tomorrow with the BPR5ES plugs...

I also did clean out the dashpot, etc replace oil in there too etc...

Cheers,
Peter

Spockie-Tech · Post by **Spockie-Tech** » Tue Jul 06, 2010 12:33 pm

I just had a look through your logs, but Im finding it difficult to tell where the problem actually occurred without a mark or accurate description of the time when it occurred.

I cant see anywhere in the logs where it looked like you were cruising on a fairly constant ~3000rpm, It all looks to be under 2000rpm or on a wind-up to 5000-6000rpm.

At about -19seconds in the 2nd data log, there is a wild fluctuation in the load (vacuum) and advance curves, but it looks like a gearshift to me rather than a fault. There are no sudden drops to 0rpm or anything that would indicate a communication problem between the megajolt and edis.

I'd try the plugs first, then maybe the leads, or else do some more logs and make sure you mark where the problem occurs. perhaps take some video as well, even if you leave the camera on the seat, or aimed at the tacho or something so we can *hear* where the problem occurs and what it sounds like.

Your decriptions of the 3rd and 4th logs ("trying to replicate" and "unsure" ) dont help much either

- Did the problem occur during them or not ?

Maybe someone else can spot something, but nothing sticks out, other than the huge swings in load, but I suppose that is normal for a turbo boosted engine.

Post by **brentp** » Tue Jul 06, 2010 5:03 pm

I haven't been able to look at the logs, yet- but the first thing I'd be looking for are any fluctuations in RPM, which would indicate the Megajolt losing connection with the EDIS module. If this doesn't appear to be a problem, then perhaps fueling might be an issue, esp. if your plugs are carbon fouled. Did you notice roughness in the engine or just a 'smooth' degradation in power?

pristic · Post by **pristic** » Wed Jul 07, 2010 6:00 am

Hi Brent,

Thanks, just cuts out, engine feels rough all the time. I moved the VR sensor closer to trigger wheel and it made no difference.

Put the A/F meter on it and its LEAN AS @!$#$@#$ only when the problem occurs. So say your driving along fine, then all of a sudden it starts cutting out, the A/F is off the chart!

Will continue to look for the prob.

Peter