RetroTed

My new S1 has a massive fault under boost
The car splutters and bogs down under load and pops and bangs, it smells of fuel and carbons the plugs up really quickly. I've replaced the metering unit. fuel ecu plugs etc


Has anyone got any ideas pls, car isn't fully built so I can't take it to anyone atm to get them to look at it
It starts and ticks over fine and will trot along as long as it isn'tfoot to the floor
Any ideas

stevo123

Hi,

Check plug gap, make it slightly smaller than spec. If your ignition system is weak the spark may not be up to the jumping the gap under boost conditions.
Also how old is the fuel in the car?

RetroTed

fuels new, gaps are all good,

jonfoc

I had this on an S2. Turned out the metering head was faulty. I'd changed it too, both were duff!

mentalasanything

Inlet MAP feed to the ECU?

Chopshop85

iTrader: (4)

Just throwing out another idea.
Check the vacuum pipe that goes to the ECU.

Had similar symptoms on mine a while back and somehow the vacuum hose had got squashed behind the heater box.

mentalasanything

That's the one I meant. It provides manifold pressure to the MAP sensor in the ECU.

Lee

Chas

If it were me I'd look at three potential culprits:

1) Trapped MAP hose
2) Ignition issue ; I'd say it's either a rotor arm issue, especially if it is a pattern part and not an OE brand or it is a spark plug issue. They may be new but I'd throw some NGK BCR8ES plugs into, and only from half decent motor factor (and ensure they are made in Japan).
3)TPS issue. Check it is working as intented. IIRC it has a switch in for full throttle operation and idle.

Regarding the plugs I would check them. On an old Triumph Stag I changed just about everything on the ignition. On normal driving it was fine. When giving it the beans it would splutter, misfire and backfire out of the exhaust at 3.5k and above. After a while the problem came and went. People said the engine was overfuelling. The day I changed the spark plugs a year later the problem went away completely.

The first set of plugs I got from Halfords and another motor factor. They were NGK BP5ES' but they could be fitted according to NGK. I checked the gaps a few times as well. The second time around I used BP5Es from a known Triumph Supplier. It never idled so good and it passed the emissions first time on all counts.

s1cosse

Do the basics and check compression. It's more than likely a bent conrod.

Karl @ FPT

Sounds like the metering unit could be out of tune (rich) and/or your timing is retarded.