Engine cutting out/ hesitation

[F355GTS]

Car is a 98 SLR with a Minister VHPD derived engine, std Rover Throttle bodies, SLR cams and Rover Mems ECU

 

At Donington today the car suffered momentary power loss, not like a misfire but as if the whole engine dies for maybe a quarter of a second or so, it was only apparent when on a balanced throttle between 6k and 7k revs, when under full throttle it works fine and at all other revs it is fine. I could recreate the fault at will based on the above revs etc. All HT, coil, ignition wires seem fine.

thought it might be fuel pickup but same problem persists with 1/4 or 3/4 tank

 

Only thing changed on car since last run on Friday last week when car was fine is fitment of a new Redtop Battery, All connections checked and appear fine.

 

Any ideas?

 

Mark

[Peter Carmichael]

Can you revert to the old battery to eliminate the cause. I know at least one owner who has given up on a Red Top with a MEMS, but that was mostly to do with starting. When running, the alternator should be assuring 14.4 volts.

 

It might be worth checking the spark plug gaps and making sure the HT leads are clean (use meths and cotton woolbuds) and there is no crud on the insulator of the spark plugs. All of this will minimise RF interference.

[F355GTS]

Peter

 

 

thanks for the advice, Alternator is spot on 14.4v, I can try the other battery although it doesn't want to hold a charge hence the change. Will do a complete clean of all the HT's and check gaps etc

 

is the gap 31 thou?

 

 

 

Mark

[Julian Thompson]

Mark - you should have said - you could have tried my Emerald for a few laps..... then again if the map wasn't quite right - ouch. Perhaps not.

 

It won't be the battery. You are keeping it on a conditioner, yes?

 

[F355GTS]

Julian

 

yes, I don't think it can have anything to do with the Battery, more likely a plug,HT or fuel problem as Peter suggested

 

Mark

[Julian Thompson]

Sounds about right - it's just a pain to check it with the problem occuring so high up the range!

[EFA]

Mark - Change the fuel - completely. I had similar problem on the Rumble with BP SUL.

 

Fat Arn

Visit the K2 RUM website

See the Lotus Seven Club 4 Counties Area Website here

 

[Jason Plato]

I had a similar problem with my K , it felt like the engine went flat for a fraction of a second under load , try checking the inside of the dizzy cap to see the condition of the contacts , I had burnt contacts due to the spark jumping . The problem was solved by removing and reseting the cam drive plug to TDC on 1 .

Since then I have changed to wasted spark , which has proved reliable .

 

Dave

[F355GTS]

thanks guys, fuel was brand new Optimax but could have been a bad batch I suppose, Dizzy cap was new 400 miles ago but will check

 

 

 

Mark

[Wallbanger]

The only time I've had a similar problem it was traced to a cracked HT lead. However, it felt just like fuel starvation, espically as it only happened when going around Gerrards at Mallory Park.

 

[F355GTS]

Wallbanger

 

I've cleaned all the HT leads and will run it up in the dark tonight to see if I can see any arcing and then test it at Rockingham on Sunday. Interesting though as I only noticed it on the last part of Craner (I know I should be taking it flat!) and Coppice, just assumed these were the only places where I happened to be at those revs and on a balanced throttle, Dizzy was quite oily although no evidence of tracking and HT leads generally a bit grubby with oily film

 

Mark