running a bit rough

[methodwares]

the cerb started running a bit rough a few days ago, its fine at idle, but seems a bit lumpy and hesitant at 2k to 2.5k rpm, a definite funkyness at 2100, fine below and fine above. i hooked it to a computer and one tpot was at 19.4 and the other at 15. i adjusted the 15 one to 19.4 and the both hold steady at 19.4 with the ocassional flicker to 19.8. the other thing was one map (the 19) was running at +2% and the other -20%. after i adjusted the pots, they both ran at -12%... at least this was consistant. the only other thing i noticed was the lamdas real time graph is really jumpy. i gave it a decent run after adjusting the pots, it seemed a bit smoother, but i'll hook it up to the computer again tomorrow. it had a service about 2 weeks ago, should the pots go out this quickly? and also, would the adaptive maps cause the lumpyness at 2k rpm? and should i try and fix that or have a pro with a dyno look at it?

[GreenV8S]

The lambdas are supposed to be jumpy (that's how narrow band lambda systems work).

The behaviour of the engine management system is complicated. Some problems are fair game for a competant DIYer but others will require a thorough understanding of how it works. Clearly you're willing to have a go and good for you, don't underestimate the complexity of the system though.

[methodwares]

hopefully i'll have time tonite to look at the leads and coils. being a 4.5, its probably a pain to get all that intake stuff off the top. i have notice the ht leads have tvr written on them, do i need to get new ones from tvr or a decent set from demon tweeks or halfords?

[trooperiziz]

Mine is similar at the moment and I've got a new set of leads to try when i get a chance.

It's very annoying to reset the maps and have everything perfect for a few weeks, only for it go to a bit screwy and need resetting again. I need a "keep this setting and don't adapt" option until i can get round to trying to sort out the problem properly.

[dannylt]

Probably worth having a spare set of leads - if they don't cure the problem, you can use them at the next service anyway. I had this several times, though was usually a misfire at higher revs.

[methodwares]

i'm thinking the same, get a spare set... should i go for the magnacore that ACT do? was thinking the 8.5 but that may be a bit overkill. or should i stick with good old tvr replacements?

[redleicester]

I went for the Magnacores a couple of months ago when mine was running very rough indeed. Certainly did the trick, and about £85 for the set IIRC.

[dannylt]

Given you're best off replacing them every service (they never seem to make it to two) you may as well just get the usual TVR ones. IMHO.

[trooperiziz]

dannylt said:

Given you're best off replacing them every service (they never seem to make it to two) you may as well just get the usual TVR ones. IMHO.

The magnecors come with a 10yr guarantee though?

[methodwares]

trooperiziz said:

The magnecors come with a 10yr guarantee though?

i'd be very surprised if they'd last that long!