s1 not running well

[mainsy]

Something similar happened about 2 years back, then went away so it was forgotten about.

Anyway, my battery was flat so I jumped started it then went out for a 2 hour run never switching off the engine and the car was going sweet as a nut. I went home then a couple of hours later I decided to go out again but this time the car ran terrible under throttle. Full throttle and it went but but the best way to describe it is the engine went putput but very quickly if that makes any sense

If I was to back off the throttle and just feather it the car pulls as normal, in fact if I just feathered the throttle the car was going as if the pedal was flat.

Jumped in the car this morning and it drove fine. Stopped for fuel and when I restarted it started again.

I tried resetting the tps but its made no difference.

Any ideas

[robin]

Intermittent throttle position sensor is my guess. Examine the wires that enter the TPS plug very carefully and tug them a bit to see if they come free.

Cheers,
Robin

[mainsy]

The wires seem fine, felt to be firmly secured. Does that mean the TPS is faulty? I took the TPS off for a look, nothing to see though. The 3 pins aren't corroded either.

Had a look on elise parts £59.94 inc vat

[mainsy]

I also tried running with the TPS unplugged but its still doing it

[robin]

The TPS is a secondary input to the MEMS; it uses the manifold pressure sensor (integral to the MEMS on K16, bolted to the manifold on VVC and all EU3 engines) as the primary load sense. It needs to see the throttle opening to correctly fuel on fast transients; hence you can coax it up to speed being gentle with the throttle, but if you floor it, it hesitates and bangs (underfuelled). It's very likely that the ECU is not seeing the correct throttle angle. If the wires are all good, then it is very likely the TPS itself. You could try a scrappy for a second hand one ... plenty of K-series engines in there and AFAIK they all use the same TPS, at least '96 onwards anyway. I would also ask a motor factors - they might be able to order you one for a bit less than that!

Cheers,
Robin

[mainsy]

Thanks Robin I'll get one through the week, hopefully its that. I'll report back when its done

[mainsy]

Put the new one on and done the throttle reset and its still the same Should I now replace the manifold pressure sensor?

I should add that the car is running with a decat and s160 throttle body. I don't know if that makes any difference.

[robin]

Maybe, but the MAP is inside the ECU unless you have a VVC or S2 ...

Try pinching off the IACV pipe so that no (or less) air can flow in through the IACV. The car probably won't idle but it will run on slight throttle and beyond.

It's worth checking the integrity of the vacuum pipe from manifold to ECU too ... engine off, pop pipe off ECU and manifold. Suck from the manifold end - you should be able to pull air through the tube. Put your finger over the ECU end of the tube and suck some more ... now you should not be able to pull air through the tube - if you suck hard enough the tube will start to flatten out in some sections.

If the fault is persistent I would take it to MMC and ask them to do the diagnostic on it ... I don't know what MMC charge for the diagnostic, but it may well be cheaper than changing sensors until you run out of money or sensors to change

Cheers,
Robin