sounds like over fuelling?

Well its isn't super economical but the AFM isn't that old and is adjusted correctly. Basically everything came off my old car when I put the EMS in and that ran like a dream so I can't see it being sensor related. Did the ECU diognostic test and it all showed up fine too.

it was a crud afm in the end, i switched a few before i found one that worked.

more than likely afm, the car will run but in certain spots it over fuels mine does it real bad until it gets hot, if it really bothers u buy a brand new one i haven't bothered caus my afm is in the cooler piping adn the guts of em just get blown out

yeah mine was over fueling and backfiring sounds same as what you got but no tacho jumping hope that helps but probly confuse you more.

boys i had this problem. took me a **** load of time to work out. Tacho will reach approx 3 grand and then jump up 500rmp or so for no reason. You would accelerate really slowly untill it did it and the engines rpm wouldnt change at all, only the tacho, and obviously the computer thinks it does as well so it changes spark and fuel. It was the power transistor( THat thing that hovers in front of the distributor) Replaced it and problem was solved straight away Good luck

overfuelling and backfiring minus tacho jumping erratically is usually crank angle sensor.

i would be checking leads, plugs, afm, cas plug and afm plug, look for corrosion on dizzy insides and scrape it off oil change it, might be the plugs leaks in the feul system try and ecu diagnostic check try 98ron feul too as it might be retarting timing on boost if you got a knock sensor

I am getting the same **** in my non turbo 5 speed. tacho bouncing round like crazy at 2400rpm bouncing to between 3000 and 4000rpm like mad... car does feel to missing but goes like a dog.. (false signals like twinvl said) did 2 x afm, coil, leads, dizzy plugs, temp sensor and plug, then it completely died.. then was told cas did that and it was fixed for about 3 months max then slowly but surley came back.. now its ****house Changed plugs and oil for regular service that was 1400kms over due the other day cause it was geting undriveable and it was ok for like a day then slowly came back and is ****ed again now.. it drives me insane i just wanna get out and smash the f.uckin car.... so thinkin i will try this power transistor \ fu.ck it makes me angry just typing bout it...

Same thing has happened to me in 3 different vl's. Crank angle sensor on the way out.