Topic

Hey all, I'm new to this great forum, an amazing resource of experience here. This is my first query, second post. See my intro at Welcome.

Since I got my MGF Mark1 1997 registered I've travelled about 3000 km. The last 400 km or so it developed an inconsistent rough idle or intermittent miss, more noticeable with the A/C running. However, upon cold start it always idled beautifully, when warmed inconsistent rough idle would develop.

When driving in 1st or 2nd under very slight acceleration, an infrequent brief fraction of power loss would occasionally occur. Also, cruising under load, say a hill in 5th accelerating sudden power loss would occur, where 4th gear would need to be engaged with less peddle higher revs to have the engine run normally. Fast acceleration high revs through1st to 4th gear, that power loss may or may not occur. The power loss has always been intermittent throughout that 400 km driving. Until yesterday!

I thought the problem might be plugs or leads. Start with low cost and problem solve along the way with each change. So yesterday I installed new plugs and leads. When engine warmed the idling actually became worse, consistently, than it was before. So, I put the old plugs and leads back in, no change. Again put the new plugs and leads back in, no change. I wondered if when I was pulling and pushing plugs from and into the distributor cap it may have worsened a fault already there, since that was the only other component I'd handled. I don't have a spare distributor to replace to problem solve the issue.

I took the car for a drive down the road and it was frequently intermittently losing power, stalling, shuddering, through all gears. When I stopped to turn around and return home the engine stalled, it stated ok but driving back home was just as terrible.

Next I removed the distributor cap, rotor and back plate. Cleaned the brass components and the rest of the internals, then reinstalled. Started easily and the idle was good and consistently smooth. Another very brief test drive, it was just as before, terrible and I felt lucky I got back to my garage.

Is it electrical?
Is it a problem with the distributor? Made worse since that's the only component I've handled, disturbed a worsening fault, other than plugs and leads.

Could it be fuel?
Anyway, later since I don't have a distributor rotor nor back plate to change, I replaced the fuel filter. The old one seemed fine nevertheless. Another test drive down the driveway and again terrible. Undrive-able!

I've since pulled apart literally every electrical connector in and around the engine and sprayed electrical component cleaner there. I've pulled apart the Idle Air Control Valve and cleaned it, reset it. Tested the brown temperature sensor, as working. None of those things improved how the engine is still failing.

Nowhere within a few hundred kilometres and probably further, have a parts store with a distributor for sale. I'll have to order it online and wait...

I do also have an 1997 VVC (I bought having a failed engine) that should have a good fuel pump and a load of other working components, sensors. Like a parts shop in my garage, less a distributor. LOL

Now, from a cold engine, the engine starts easily, idles perfectly, for a while then begins to shudder and firesup again to an stable idle, shudders and again stable idle then stalls.

I'm open to all advice and suggestions as to the where the fault may be.

First guess, engine temp sensor. Not the gauge sensor.
Second guess, idle air control valve.

Here’s a list of stuff to check:

Temp sensor and idle air control valve as per David’s recommendation.

Fuel pump, these can just die suddenly or intermittently over a long time.
Fuel pump relay

Rotor arm and dissy cap

Ignition coil……. test both primary and secondary resistance

Test the resistance of your ht leads……even the new ones!

Check the throttle position sensor

Check for vacuum leaks, hoses and manifold

Check the catalytic converter isn’t blocked

Get back to us with your findings.


Some other things that unrelated but are must haves of these early Fs are:

You need to bin the silly plastic 48mm throttle body, these can distort and create a intermittent high idle replace it with a proper alloy 52mm throttle body, the engine will be a little smoother and more responsive with one of these fitted.

Fit a low coolant alarm, I use and recommend the Browns & Gammons kit, but there are alternatives.
It is utter stupidity not to have one of these fitted, your parts car would probably still be a goer if it had one of these fitted.

You also need to get your grubby arse scratchers on a Pscan OBD diagnostic unit, you can get one via this forum…..can’t recommend these enough

Best to get your nose pick’n fingers (especially after recently scratching your arse) on the workshop manual, either paper or from online…….. paper is best.

Another thing that will make life much easier is internal covers for the taillights, with these fitted you can actually carry things in the boot without the bulb carriers being knocked out of the taillights and damage to the wiring.

One thing you might have started to learn about T-bar is that your Uncle Cobber has an uncanny knack of diagnosing faults at a distance,being rude about a lot of things & complementary about others. His command of the backwaters of the English language is without peer & if he lived in Sidney he would be seen regularly taking his thylacine for walks around Circular Quay.
A good bloke
I've never had an f or tf with a distributor but I guess it will still be wasted spark & you'll have a couple of plug top coil packs, see if your VVC has plug top packs & swap them over if it does. I changed over from the coil packs on the rear of the engine to plug top packs & the improvement was significant.
M

Gday,

Hopefully today I can get time to busy myself at the MG, I might pull the fuel pump out and have a look. Though, no way I can check if pump is producing enough flow/pressure. I could swap the pump over from the VVC.

Thanks for all the advice so far and things to check.

Yesterday as I mentioned, I checked the "brown" temp sensor (the green gauge sensor is also working) and Idle Air Control Valve. With engine running I pulled the brown connector and checked for fans operating in front, all good. Is that a good enough check? As normal previously fans were coming on when A/C was running.

Yesterday, the Idle Air Control Valve, the stepper motor was moving in and out when I turned the key on. It wasn't gummed up before hand, was just a thin carbon coating, I cleaned it anyway, reset it. Yesterday, I didn't fully describe what I did with temp sensor and stepper.

The throttle body valve was good, didn't need cleaning.

So, no improvement of engine from either of those checks, and all the other things I did, as it was yesterday.

Damn it, I wish I had a spare distributor...!

Rather than pull the fuel pump out, I thought I'd try this for the moment. I disconnected the inlet pipe to the fuel filter (a new filter installed yesterday) connected a hose and a drain bottle, to see how much volume is pumped to the 600 ml Pepsi bottle.

The smaller amount in the bottle is from only turning the key to second position, could hear pump working and stop. Took photo.

Then, I went back and turned over the engine for about 2 seconds, which shows the larger amount in the bottle, combined with the first amount. Took photo.

How is this useful as an indicator of the pump functioning adequately?

That should be enough fuel flow to maintain a decent idle

Thanks Cobber That's good to know, hopefully rules out the fuel pump. That pipe has a lot of kinks of flattened out pipe so I guess the pump has pressure too, to get the fuel to the bottle. I've not checked any fuel pump flow pressure or volume before so I didn't really know. So, thanks again.

Yesterday I tried to order online Lucas branded distributor and rotor, from a company Ive not dealt with before, the store had a fault and the transaction failed...
The other online parts stores I search for and browsed through don't indicate what brand they are selling...
Not sure who to buy parts from. I'm waiting for replies from two stores as to the parts manufacturer.

Try

British Auto Parts in Melbourne.
https://www.britishautoparts.com.au/ignition_system___1_8_4cyl__petrol

Or

Pickard’s of Melbourne
https://www.pickardsautomotive.com.au/

And

British Car Components
http://www.britcar.com.au/

As well as

Heritage Mg
www.mgspareparts.com.au

Hey Cobber, thanks for those links.
Ordered parts already. The top link has the best prices I've come across and they appear to be original parts, part numbers. Maybe.

Look out lads we've another antipodeen to contend with. Looks like this larrikin's not shy of a bit of hard yakka either, all dressed in his daks & flannies. Ripper !
My nephews marrying a Sheila at Chrissie & I've had to learn another language just to communicate, & it's defo far out. I'm not going, it's a long way to go to meet a load of borgans & drongos that aren't even true blue & all for a few words a curly sanger, a snag & a warm stubby. I'm not all that good with others relies so I'm staying at home, I'd like to bet for the cost of the flight I could buy a really nice 160.
Translation available on request.
M

My wife has correctly pointed out that hard yakka wouldn't be undertaken in daks & flannies. As she has also swatted up on Afferbeck Lauder excellent book on Strine, she pointed out that like over here overalls would be warn. I put forward Overies as a possible diminutive; she wasn't all that impressed.
M