Won't start in the damp

[Jasper2019]

This has been a longstanding issue with my '98 MGF but now I would like to really resolve the issue as the will it-won't it uncertainty is presenting a problem for the morning commute.

If my MGF if left out in the rain overnight under no cover, it is very 50/50 if it will start in the morning. It turns and ever so nearly fires... but doesn't. Eventually I can try and try until the battery runs flat and it just groans until the clicks that signal, yep, it's gone. If I don't take it that far it turns over but doesn't fire. Very occasionally, it will fire eventually and off we go.

Sometimes if it's damp, but no rain, it won't fire. If it's under cover like a car port, it struggles, but most of the time it will fire after a bit of a struggle.

I replaced the leads, that had no effect. Since being under cover seemed to help, I've covered the air vents by the boot overnight to stop rain coming in to even see if that helped - but that doesn't make any difference.

Any idea what I can do? Various garages I've taken it to don't know the answer and have always just said "change the leads", which I've done.

[Geoff.F]

Low Voltage. Cables or Battery. Buy a Voltmeter.
Geoff.F

[Neil Rushton]

I usually start with cleaning & tightening any earth connections.

[Jasper2019]

The battery is only 3 months old. Replacing it has made no difference. New leads have made no difference.
Which cables are you referring to Geoff.F?

Neil Rushton - I'm not mechanical, what should I be doing and where (and how!)?

Thanks.

[Rob Bell]

Is this a VVC or MPi?

If an MPi, it'll most likely be a problem with the distributor cap/rotor arm. If relatively new, be aware that the quality of aftermarket replacements is appalling. Buy genuine MG Rover or Land Rover parts.

If a VVC, it is likely to be a problem with the long HT leads from the block-mounted coils. These have always proven somewhat problematic, as they can get damp directly from rain etc entering through the boot deck cooling vents. Good quality HT leads are the answer, and Magnecore are extremely good in my experience. Have these on both my MGFs

[Jasper2019]

It's a VVC. So I replaced the HT leads about a year ago. At the time I'd heard good things about the Magnecore leads but couldn't find them anywhere, so I bought a set from Halfords which were supposed to be good quality (ie. not the cheapest/most basic).

Like you say Rob, I feared damp was coming from those cooling vents just behind the boot. Yet when I've covered those vents completely when it rains, it still has the same problem.

[Rob Bell]

I'd still be suspicious of the HT leads, but being new, hopefully that is not the problem.

Coil fault? The VVC has two, both mounted on the back of the cylinder block, under the inlet manifold.

[Jasper2019]

Can I check the coils myself? Like I said, I'm not familiar with the technicalities of MGFs. Used to know a bit about what I was doing with old MGs, but it's a black box of seemingly unreachable stuff with the MGF! Step by step please, how do I get to the coils and if I get to them how do I know if they're the problem by sight?

[Mykel]

The coils on a Mk1 VVC are one of the more awkward parts to get to. They are riveted to a carrier bracket which in turn is bolted to the engine block with two (iirc) M8 bolts. And they sit right beneath the coolant pipe, thermostat and its hoses, so one would think they’re easy to get to from underneath. There, sadly, sits the exhaust flexi pipe.

A replacement coil pack ist about £75 and with it being such a massive pita to swap, I would suggest the following as a permanent fix:

Leave the old coils where they are, remove all their wiring (including the LT ones). Get a MEMS 3 rocker cover incl the plastic coil cover, a set of coils from a Trophy or TF/TR160 plus the wires (LT – long enough! – and HT) to connect them. Remove old rocker cover and replace with the MEMS3 one. Connect the LT wires for the old coils to the MEMS3 ignition wiring loom, the colours are identical: brown-pink is the +12v supply for both coils, white-orange is for coil 1, white-black for coil 2. You might want to trace the original wires back to the ECU connector block to make up a proper wiring loom.

Fit new coils and connect them to the newly made wiring loom and the HT cables for cylinders 2 and 4, bolt in coils and try to starte the engine. If everything works as it should, fit the plastic coil cover and have a cold one as reward.

btw it’s not important if the rocker cover is off a VVC/160 engine. The only difference for the MPI is the hole for the cam shaft sensor above the exhaust cam, which is not needed on the VVC. You can simply leave the old sensor in as a plug.

[Jasper2019]

Thanks Mykel, that is certainly step by step, but I don't think I can do that, I'm just not familiar enough with it all to identify the parts, let alone be sure what I'm doing with them. How did you even begin (top or under?)?! Nevertheless, I'll have a good read and re-read of it, and if I have some tips on how to start, I'll have a good go.

[BodgeItAndScarper]

Double and triple check the earth connections first! Best rule out the easiest things before moving into things that are hard

[Geoff.F]

I might agree with Mykel but he assumes that you have his experience.
1st. Spray all the ignition system with WD40 Dewatering Fluid.
2nd. I have a cigar lighter plug to connect to a Voltage Multimeter. A quick check for possible connection problems albeit not definite.
Geoff.F

[AndyH]

All valid comments.
Had these problems. Solved with new HT leads, a new distributor cap and rotor arm and I think very importantly new spark plugs set to the lowest possible setting of 0.8

I have had no problems since.

[Rob Bell]

Any updates Jasper?