Engine stuttering.......... but not at 5500rpm

Hi peeps, had the car for 6 months now, been totally faultless for 7000 miles until wednesday I filled up with petrol (95 Texico) and it was ok for 20 miles then slowed at a junction and the car died on me. Started it up was ok for a few hundred yards, died again. Managed to get home just, it seems hesitant between 2000-3000rpm, and occasionaly I get a popping sound. Seems to be worse on part throttle and is ok with full throttle.
Checked all the leads going to the spark plugs on both ends all good connections and tried in the dark as well but saw no lightning bolts in the engine bay
Any ideas where too look next would be most helpfull.

i dont know bout anyone else but ive a good idea what it may be… do you usually fill up with 97-98octane? If youve been running optimax or super which i feel is essential in the vhpd engine, and then switched to 95 it can mess about with the cars ecu. It will splutter about while it gets ‘used’ to the new octane. Try running it for a few miles and the car should return to normal, however i would only ever run my exige on optimax

I normally fill up with optimax or super but in Bristol most petrol stations seem to have pumps breaking down a bit too often (you go in and have to hunt for the pump without the binliner covering it up) 95 was all they had so put that in.
When it first happened I thought it could be the petrol but have put in 95 before at BP and its been ok. i’ve done 120 miles on it and filled up with optimax again drove another 20 miles and these have been the worst 20 miles ever stuttering everywhere, low down and stalling whenever at standstill. When I parked up on the drive looked down at the stones behind the exhaust and black fuel/oil speks on them never noticed this before.

aha, i had this before… try looking at the small black pipe that goes from the plenum into the airbox unit. Is it loose or unsticking? Sometimes the smallest things like a loose feeder pipe can fcuk up the entire running of the car!! My car had the exact same symptoms, felt like i was running out of fuel, kept conking out and blowing black smoke. Is the idle wonky(more than usual!) too? Deffo the feed from the plenum

Will check the pipes, when its popping it sounds like its running on 3 cylinders its not a loud bang/backfire but sounds like air moving? & the car shakes and rattles.

im pretty adament that the problems your having will be due to a worn or loose pipe! Not a big job at all

Right then checked the pipes all seem ok i’ve got sparks coming through all 4 leads & spark plugs looked ok. Been out in it and it idles ok now but is still stuttering all through the rev range. Worse between 2000-3000rpm, but feels like its starved of fuel.(hesitates when accelerating) and backfiring now and again.
I’m going to order some new plugs & magnecours, anything else to look for in the meantime?.

Don’t order new plugs and leads, if they’re sparking then it’s all ok… You can unplug the injectors on each cylinder to see which one isn’t firing (it’ll make no difference to the running… Otherwsie BIG difference!)…

Then see if the plug is getting wet if it’s not firing… If it getting wet then fuel is all OK and then look at new plugs / leads (you can swap leads and plugs over seperately and make sure)

Otherwise it could be the coil… But then that would take out 2 cylinders, not just one… It’ll take out 1 & 4 or 2 & 3… Good luck!

Also have a read of http://forums.seloc.org/viewthread.php?tid=47726&page=3 to see my recent blocked injector problem

Cheers mark I think you’re onto it there. On cylinders 2&3 if you remove the injectors individually you can hear the change in noise but on 1&4 not as much difference. There is sparks on 1&4 but could they be weak?. Also you can remove injectors 1&4 and it still runs on 2&3 but when removing 2&3 the engine dies cant run on 1&4 on its own. Where do I get a cheap coil pack from looked in the archives and I think you were trying to source one off a Vauxhall.

Yep, vaulhall… But apparently they cost more than the Lotus part but may be more available…

I think my coil is OK so IIRC Mark P has a spare one…

You should be able to see if the spark is stronger

Good luck!!!

Will have a hunt around tomorrow, car is booked in for 30000 mile service in 2 weeks as well.

All sorted took the part to a local Vauxhall dealer, who matched it up with one of their’s. Cost just over �110.
Back on the road again just in time for the rain.

Don’t suppose you have a Vaulhall part no for that?

Sorry mark, my brother went to get the part and they were having trouble with the computers so got a hand written reciept, only says coil on it. I rang my local Lotus dealer today and they said part was �75+VAT so it is still cheaper from a Lotus dealer, but would have to wait a few days.

Ah that’s cool, I just wanted it for the record so to speak… Sorted my problem… Pipe fell off my blocked IACV valves… Doh!!!