LET Engine miss fire

[richardspeed]

I took the car out this morning, filled it with V power, it was booked in at Halifax for a rolling road tune up, typed the postcode into the sat nav then set off, pulled out of the petrol station put my foot down and it started missing, thought that was funny, changed gear still missing then it cut out, started it back up struggling then turned back home, had a look under bonnet check HT leads they were not loose, looked under the car, there was petrol leaking from one of the back lines passanger side, fixed that, then took it out and it was still missing, I had another leak, it must have been when I pulled it to get a bit more rubber line, I have been messing round with it all day, just took it for a final run, its OK when it comes on boost pulls right round with no missing when pottering round it misses, it dos'nt miss as bad as this morning.

Any idea:confused: :confused:

[let_nova]

make sure there are no more leaks on the pipes to the engine . then change rotor arm,cap and leads and take it from there.

[craig green]

make sure there are no more leaks on the pipes to the engine . then change rotor arm,cap and leads and take it from there.

Throwing cash at it willy nilly... :roll:

[richardspeed]

If the pipes are leaking would it cause it to miss?

[let_nova]

if the engine wasnt getting enough fuel yes

[let_nova]

Throwing cash at it willy nilly... :roll:

didnt mean all at once ffs.

anyway thats what you do when you own a LET

[richardspeed]

The pipe that was leaking was the pipe that goes back into the tank at the top, 6-8mm thick. Not any of the fuel pump pipes, is that not the return pipe, for excess fuel?

[craig green]

I'm more than aware of how tempermental LET's are. But buying a new set of leads & finding the fault is still present isnt what I'd call good advice. More like an expensive mistake tbh.

IMO Richardspeed, I'd suggest registering on MIGweb & trawling the search function for archived threads about LET misfires & running problems. The best UK advice is on there.

[let_nova]

iirc yes. wip out the plugs and have a look at them. how long is it since you changed the plugs?

[craig green]

Plug gap is something that is often overlooked. Too wide & the spark will generate too much voltage trying to jump the gap, thus missing under load & placing too much load on the coil.

[richardspeed]

I changed the plugs about 150 miles ago, I put the RS turbo plugs in that people told me to use, BCR8ES, I dont use the car much, its been fine up to know, I have used it a couple of days a week so I could iron any problems out before I hit the track with it.

[richardspeed]

A question if anybody can answer, the return fuel pipe which comes from the engine bay to the top of the tank, when I replaced it and fitted the clip, if I over tightened the clip could it have squeezed the pipe so excess fuel that comes back to the tank which it should do dose not and stays in the fuel rail and makes it over fuel, when I pulled up a few times and got out the engine was missing and chucking black smoke out which is un burnt fuel.:confused:

[let_nova]

but if you tighten it right up it shouldnt close it over as you would of had hard pipe off the tank going into rubber pipe from rail?

[richardspeed]

Thats what I am saying mate, the clip was to tighten rubber pipe to the hardish plastic pipe that goes inside the rubber one, just wonder if the unused fuel was not passing through enough and backing up in the fuel rail making it miss fire.

[let_nova]

but you shouldnt be able to tighten it that much that it causes the plastic pipe to close over.

[richardspeed]

I only mean it could of been squeezed a little bit, would that not make a differance?

[let_nova]

could the air flow meter possibly be faulty??
you checked for any air leaks round that area?

[richardspeed]

No I hav'nt, I will check, its funny why it dos'nt miss at high revs, what I was saying about the crushed pipe would be right because when under heavy load its using that fuel so its not going down the return pipe as much.

[let_nova]

i hear you also if the AFM was faulty and causing it to fuel more at low revs but its fine under load. get me?