Missing under load at 4.5k

As title really  

It's ok if I don't press the pedal down too far, but under 3/4 load or more it struggles at 4.5k, then clears up, then again at 5k, then I daren't go any further.

It feels like an ignition cut rather that fuelling, sort of similar to a rev limiter feeling really.

Any ideas before I go spending loads of money on random bits which won't cure it?  :dontknow:

Thanks

If it feels ignition related check the rotor arm, some have a spring that's supposed to cut the spark at a certain rpm

not had this problem myself but worth replacing for one without a spring as they're cheap enough

also check the HT leads,spark plugs and maybe even coil, or even the TCI unit (little thing the plugs in on the scuttle area with a heatsink attached also known as the ignition amplifier)

if it's not those I can't think of any other ignition related problems that'd cause your problems (although there's probably a few things I've forgotten)

could be fuel related but that's a whole other load of things to check (fuel pump, injectors, metering unit etc..) so I'd start with ignition first  :wink:

Hope that's of some help

Right, well it's had a new dizzy cap and rotor arm this year, and spark plugs in the last week, the fuel filter is new too.

Looked for some HT leads earlier in Halfords but they didn't list them, only ones for the Mk2 8v (wasn't sure if they're the same or not, so left it)

BUT, I drove the car today and the misfire wasn't there, it was 100% fine :?

I'll check the rotor arm is one without a spring anyway, but I think it's 90% likely to be the leads (I hope anyway, as I have no clie at all about the KJet system and how to fix it

Does anyone know where I can get HT leads from, or if mk2 8v ones are the same?

Mk 2 8v are the same.

Glad to hear your misfire's gone.  How many miles has the engine done?  If a lot, then check out your air filter to see if there's an oil build up in there.

I hope it's not what it was with mine some years back…..

Al

It's not gone gone, it just wasn't there yesterday, can't say that it's cured though, I'm sure it'll be there tomorrow or something.

It's done 115k, but was recently serviced.

I'll check the air filter (if I can work out where it is  ops: )

What was wrong with yours?

Oh, and thanks for the confirmation with the leads, I'll get some tomorrow and see if that helps.

RobinM said

What was wrong with yours?

My first GTI many years ago.  A 1600, it was unfeasably QUICK.  There's a long hill on the A55 in North Wales, quite a big hill, and this blessed car would RED LINE IN TOP all the way UP (when everyone else got out of the way, that is…..)

And then I started to get the fault that you are describing.  And it started to get worse.  Then one day it happened just after I'd managed to get past an idiot in a Mk4 GTI who was in love with the outside lane.  He finally moved over, I powered past, revs rose to the 5000 'danger zone', power disappeared and looking in the mirror I could see I was laying down loads of white smoke, such that visibility for the guy in his brand new Mk4 had gone down to around 3 feet!  I doubt he could even see the end of his bonnet!  So funny looking back at it….

Anyway, what happened was that the bores had got worn (Engine was on about 180k at the time) so compression (only at full throttle, high revs, maintained over time) would find it's way past the rings and into the crankcase.  Lots of exhaust gas pressure in the crankcase would force oil up through the breather tubes into the airfilter box, and then through the manifold and into the combustion chamber.  Where the oil was duly burned, reducing power and laying down thick white smoke.

Was a knackered engine, mate, well past it's prime, in need of a rebore.  Needless to say the cheapest way was to slot in a second hand engine, which is when I went up to 1.8 and discovered that although it was no more powerful, the extra torque absolutley transformed the handling of the car.  (Which is why I now drive a 2.0!)

And I guess the reason it was so damned quick was because the engine had got so loose there was almost no internal friction……

I hope, my friend, that with your mere 115k your engine hasn't reached this point.   One word of encouragement……  I did a further 10,000 miles in mine before I finally swopped the engine.  I just drove less above 4.5k rpm and spent more on oil…..  i.e. I still had transport, if not the full GTI experience.

Here's hoping there's no sign of oil in your air filter box.

All the best,

Al

Well, there's actually no airbox bottom on it, but the filter is really dirty (as you'd expect, with no protection) and is therefore starting to fall apart.

The thing above it was caked in crud too, so I've cleaned it with petrol and a rag, going on the theory that petrol wouldn't damage it as it's an engine part  :? Anyway, I'm not going to drive it 'til I get a new filter on there, and an airbox bottom, if I can find one.

If the worst comes to the worst and I can't sort it, I'll ABF it with some decent management, saves messing around with K-Jet and reconditioned 8v engines

It's only an engine at the end of the day, the car is solid, so if the engine is terminal, hey ho, worse things happen at sea and all that.

Nice story anyway Al, up until the point of death. They always say engines are at their finest just before they let go, which is a bit depressing really  

So it could just be lack of air….

Let's hope so.

Changed the air filter, and it's worse  :cry:

Won't even take 1/2 throttle now without misfiring constantly, whatever the revs.

No smoke though, not even black :? I'm confused, if it was an ignition cut, there should be black smoke, right?

The car is still driveable, it's just not very fun as you can't actually accelerate

New leads are on order, but I can't see that curing it either TBH, and if it doesn't, I'm stuck for ideas.

I'f you've changed the air filter and its worse, it sounds like it could be the mixture. Best to get it checked properly and adjusted. Another thing it could be is fuel delivery rate at pressure (credit to Phill for this one!)

Where can I get that done? Will any garage be capable, or do I need a specialist?

You need a garage with a gas analyser - most of them have one (or purchase a gas analyser yourself).

Good good, my mate works at a garage, he'll be able to help hopefully  8)

They do a lot of work with Escort RS Turbos too, which, if I remember right, have K-Jet?

mk2 gti leads are different. they have the pin type ends. you can tweek your fuelling manually to see if it helps.
 where are you located?

….but it's all ok unless you give it welly?

Have you done a compression test?  I've known head gaskets on these engines to be fine except when pushed.

(Why am I always thinking the worst?)

Al

Wooders, I'm near Wellingborough in Northamptonshire, and the leads I've ordered are definitely mk1 ones.

Al, I've not done one yet, but I will do.

Fitted the new leads today, the old ones were terrible, one of them came apart when I removed it from the plug, but it's still doing it.

I've got it booked in to Jamsport in Northampton on Monday, my mate works there and reckons it sounds like it just needs tinkering a little to get the fuelling right…

Hopefully that'll sort it out without costing me too much.