15 replies to this topic

[dan1zo]

Hey peeps

 

Last week i went to take Coop out for a drive and as i went up the road it felt like he was really low on power, and holding back.

A blip of the throttle and it was ok for a bit, then sounded like he was on 2 cylinders every time i put my foot down. Burbling from the exhaust.

 

Today thought i'd finally get around to taking a look. Pulled the spark plugs and they were BLACK, caked in soot. So i figured that must be it. Just to check i gave them a quick wire brush (i've got a new set coming). Idle was better and seemed ok while stationary. Revved normally and was fine idling until it warmed up. So i tried driving again and same thing happened. This time i hardly had enough power to back on to my driveway! Had to take a run-up. Its only a tiny slope.

 

What do you reckon? First things to check?

Bear in mind, i only have the simplest of tools, so once it starts getting complicated, its going to have to be a tow to the local garage.

 

Cheers

Dan

[Steve220]

When it gets worse, pull the ht leads in turn to see which cylinders have dropped. The ones where it doesn't make a difference when the ht lead is pulled, swap the lead with a good cylinder and see if it's improves.

[genpop]

or buy a new coil block

[Steve220]

or buy a new coil block

Or diagnose it before buying random parts? Could be ht leads.

[dan1zo]

Leads are fairly new. Only done about 600 miles since replacing. But I will give it a test.

[dan1zo]

or buy a new coil block

 

 

When it gets worse, pull the ht leads in turn to see which cylinders have dropped. The ones where it doesn't make a difference when the ht lead is pulled, swap the lead with a good cylinder and see if it's improves.

Cheers for the feedback chaps

 

My suspicions were with the coil pack. I had a look at the terminals attaching to the ht leads and they are corroded.

In fact #1 and #2 leads dont even 'click' on like the other 2 and so feel a bit loose.

 

Could it be that those 2 are coming away from the terminals far enough that they can't produce a strong spark? 

 

I started up, didnt want to annoy the neighbours too much as its properly loud! So only ran for a little bit. It did take a bit of effort to turn over.

Went along each plug and pulled the lead as it was running and there were definitely sparks arcing to the block from each lead (as well as up my fingers!) so that rules the ht leads out right?

 

Could it be as simple as needing new plugs? But strange it only happens when i start to drive, or when warmed up.

Will see once i put some new ones in. Maybe a couple of them have died.

[Pete - W.Sussex]

But what was the difference to how the engine ran as you pulled each plug lead?

[dan1zo]

OK guys, so i fitted new plugs today just because the others were looking shot and to start fresh.

 

Pulling the leads and swapping them about, i found that its #1 plug not firing properly. Leads are fine.

I made sure by pulling the plug out and it was black again. These are supposed to be new shiny plugs.

 

So does that mean coil pack then?

I may have to see if the head gasket is going too, there seemed to be a bit of oil residue on the plugs too. And that distinct puff of smoke when it starts up.

[dan1zo]

Today I pulled the coil pack as I found a pinned post about testing it.
Looking at the terminals, not the wired connector, they are corroded.
Think is so bad I couldn't always get a reading on my multimeter.

When I did get a reading it was OK, but has to be down to bad connections right?

[dan1zo]

So the coil pack is now replaced, it definitely needed it and fires up nicely. It doesn't appear to have made any difference though. It is OK for a little bit, but as soon as I start driving it starts missfiring.

This time I noticed a bit of a clunk just before it started. So that's new plugs and coil pack. At a bit of a loss now.

[pete l]

You're clutching at straws on this. An MPI needs a code reader. It will tell you lots of what is going on.

[dan1zo]

Yeah probably right there. I'll look at finding one. In the meantime I might have to swing into a garage and see if they can find out.

[pete l]

I doubt many garages have a code reader that will connect to the mems2j ecu on the mini.
I got one from chi'a that does. A T300 for £65. It's great for the mini.

[dan1zo]

Thanks for the advice Pete. Looks like they can be picked up fairly cheap.

I assume that i'd need a different connection lead /dongle for the Rover mems2j?

 

I have found another issue, the plastic elbow on the IACV has snapped off again.

Ages ago my top engine mount sheared a bolt and couldnt get it out of the engine block, so got an engine steady that connects to the water pump side instead. This snapped the IACV elbow on the bulkhead.

I suspect i didnt adjust the steady bar far enough forwards and its hit the bulkhead again.    This probably hasnt helped.

 

I've got a new one on order from minispares. I reckon i need to have about 10 of these as spares but they arent cheap!

[pete l]

With the IACV broken, it shouldn't affect the engine. as long as the air is controlled by the stepper motor. But it will be suckng in unfiltered air, so not good for the engine.

 

The plug is the standard diagnostic plug, but it is not OBDII compliant.

 

You might have some broken wires around the throttle body if your engine has been moving a lot, this is a known problem, and has even happened on mine, the wires going to the MAP sensor were broken.