Setup Issues

[andyroo75]

New user after a little advice from someone a little more knowledgeable.

Car is a Mini
4 Cylinder 1380cc
Kent 286 cam
Stage 3 Head
11.5:1 Compression Ratio
Normally aspirated
6000 Rev Limit
MAP Sensor

I have the mjlj fitted and have the car fired up and running.

The problem I am having is the car will not rev properly under load. It seems to be almost missfiring and be lacking power In neutral the engine seems to come up the rev range fine.

The MAP i am using is the Aldon Yellow Mini Map from the library.

At idle (approx 1000 RPM) the load is reading around 65KPa with the advance showing at around 24 degrees BTDC. The vacuum advance hose is attached to the take off on the Hiff44 carb.

I have checked the trigger wheel and VR sensor and there is a missalignment of 2 degrees which I have compensated for. (VR sensor is positioned at 92 degrees)

Anyone any advice as to what the problem may be?

Many Thanks
Andy

[BRUCEROE]

My first question would be, do you have the plugs connected to the right coils & drivers? With a waste fire don't pull a plug wire. Try shorting each plug, and see if some have much less effect. You could also use the timing light on each plug, and see if the mark moves around to the corresponding cylinder TDC. Bruce Roe

[andyroo75]

Plugs and leads are all correct. I had the timing light on it and the figure on the megajolt coresponds with the timing marks.

Could the fact it is a high compression engine be the cause?
I.e the ignition is to far advanced and the problem I am having is engine knock/ping?

[andyroo75]

I addition fired it up again today. Sometimes backfires on cranking.

When driving with your foot hard down pulling at low revs it is very juddery and it sounds almost like a diesel chugging away.

Anyone any ideas?

[Spockie-Tech]

Try unplugging the Megajolt (jult pull the cable out of the socket) and running the EDIS by itself in Limp-Home mode.

This will give you 10 degrees fixed timing and will make the engine feel pretty flat and low on power, but if it takes away the juddering/chugging, then you know the problem is in your megajolt map feeding the EDIS the wrong advance for the conditions.

If it still backfires and chugs in limp home, double check your trigger wheel timing, it must be out.

I am assuming the car ran fine on a dizzy before you fitted the megajolt and theres nothing else non-ignition-related wrong with the engine ? Its not a new engine start since a rebuild or anything ?

Also, I dont know much about mini's, but 11.5:1 static compression sounds like a hell of a lot to run on todays pump fuel unless you have a monster cam with no bottom end (effective compression)

[NITROPIXIE]

How old is your coil pack?? Sounds like one on its way out to me.

[Kerrin]

My mini has been running the 1380 map from on here for a year, luckily for me it has worked great from the start, My motor is a simmilar spec except I have an sw5 cam which is a bit softer.

The Aldon Yellow Map has slightly more advance over the whole rev range than the 1380 map which may not be helping if your motor is borderline pinkng.

What plugs are you running as I put NGK BPR7ES in mine and they seem to foul up in traffic but are great on a good run, maybe the standard BPR6ES would be fine for my motor, I think these resistor plugs are needed for MJ but may be corrected

But I would agree 11.5 :1 compression is pretty high, are you running V-power fuel as the normal unleaded would be a problem.

[NITROPIXIE]

Just reread your post. I also think the vacuum take off is in the wrong place. The one on your carb is located on the wrong side of the throttle butterly. Ideally if you have a vacuum port on your manifold then you should use this.

Ryan

[Kerrin]

Just reread your post. I also think the vacuum take off is in the wrong place. The one on your carb is located on the wrong side of the throttle butterly. Ideally if you have a vacuum port on your manifold then you should use this.

Ryan

So on my MG metro inlet manifold I should use the small vac pipe on top of the manifold casting, not the small barbed pipe on the top of the mount flange itself?

(Edit : I will check in the day light but I think it is already connected to the manifold not the carb, Memory like a sieve.)

Also I cant find the 1380 map I am using in the Map lists must have got it somewhere else, I can post it up if neccessary.

Cheers

[andyroo75]

Thanks for the response guys.

I have the car running on Super unleaded which had been fine when on the old point distributor system. The compression ratio had given no problems previously and it did seem to give it some good low end torque.

It does have a tendancy to blow head gaskets every now and again though and on investigation this weekend I have found that it has gone again between number two cylinder and the water jacket. While the head is off I am tempted to knock the compression ratio down slightly to see if it helps with setup.
As it was, even with the basic default map with reduced advance figures I couldnt get it to stop pinking.

Also double checked the vacuum pipe take off on the carb - it is on the manifold side of the throttle butterfly valve. It is quite close but should be in the correct position.

As for running on the EDIS limp home mode I have wired MJLJ and the EDIS module to a common power source at the minute so if I pull the plug on the MJLJ the whole system will power off. Probably an error in hindsight(But it made my wiring loom nice and tidy).
The plugs I am using are the standard champion ones specified for the engine. Is a different specification required for the MJLJ system?

Cheers

[Spockie-Tech]

Well, a blown head gasket certainly wont help things run smoothly

As far as "pulling the plug", how have you wired it so that you cant just pull the big connector out of the Megajolt (not just cut the power feed to it) ?
Do you have the EDIS power being fed from the Megajolt ?

I cant think of any reason why the MJ would need different plugs.. Plug Heat range is related to combustion temperature and cooling, neither of which the MJ would alter (unless the original ignition was running so badly that the combustion temps were down).

If you cant run it in limp-home mode, then the only other way to check it would be to hook up a laptop while driving, and log or monitor the advance and make sure you're maps isnt putting too much advance in.

[cng1]

The only reason to change plugs is if the ones fitted as standard to the engine are not the resistor type. If they have an " R" in the part number then they have the resistors fitted, which is what you want. So BCP7ES is bad news but BCP7RES are good.

[andyroo75]

Ok well after modding the head this weekend - I have taken the compression ratio down to 10.3:1
The knocking problem has sorted itself out and the engine runs up and down the rev range in all gears from low revs

Everything is fine now except I cant stop the thing from overheating. After a few minutes driving its has already reached hot on the gauge.

Just one more problem.......

[NITROPIXIE]

New thermostat?? lol

[andyroo75]

Its running with the blanking sleeve in i.e. no thermostat.
High flow 2 core radiator. Just ordered an electric fan to see if it solved the problem.

Also anyone know why the KPa value might be so high at idle? Can range from about 65 to 70 odd. Seems quite high compared to others