TB'd C16XE misfire under load

[dhdev (Oli)]

My Nova has developed a misfire under load. On partt throttle the engine seems fine, and will accelerate through the rev range. However as soon as I apply a more generous helping of the go pedal, it splutters so badly I have to back off. So far I have checked:-
Plugs - BCP7EVX (SBD recommended) all gapped properly and showing only slight carbon fouling (as a result of the problem as opposed to the cause I believe)
Leads - Magnecore blue silicon 8.5mm jobbies, all in excellent condition
Throttle pot - Good stable reading at idle and seems to be linear and stable right up to WOT (tested with multimeter)
Throttle body balance - Checked the bodies to ensure that there was no imbalance.

i don't believe it is due to under fuelling (bad injectors, pump on its way out etc) due to the carbon fouling of the plugs (excessive fuelling)

Between myself and Lee303 we have narrowed it down to possibly the coolant temp sensor being dodgy and tricky the ECU into thinking its cold all the time.

Does anyone else have any likely causes of failure? The misfire is not rev related (so unlikely crank sensor).

Engine spec is basically throttle bodied C16XE (taper bodies), SBD ex manifold, Omega pistons, cream injectors, ported head (std valves), hyd lifters, mild cams.

Any help greatly appreciated, thanks. http://www.migweb.co.uk/forums/images/smilies/beer.gif

[MC]

Plug it into a PC.

[dhdev (Oli)]

Would love to if i had the cash to buy or make a mapping lead :cry:

[Lee]

I would say yours and lee's diagnosis is a good starting point olz. Does sound like CTS to me, although my first guess would have been fuel pressure if you didn't mention the plugs were wet.

[dhdev (Oli)]

I'm gonna get up early and dip the CTS in a mug of coffee and check the readings. If its unchanging I guess its fubared, and I'll have time to nip to vauxhall before they close and steal one :thumb:

[Lee]

I'm gonna get up early and dip the CTS in a mug of coffee and check the readings. If its unchanging I guess its fubared, and I'll have time to nip to vauxhall before they close and steal one :thumb:

LOL @ highly technical fault diagnosis, involving a cup of Nescafe lol

[Will F]

rather than coffee, I would go for camomile... MBE loves it.

;)

[Will F]

PS if you were any closer, I would provide a lead and laptop!;)

[Saloony]

Pfffttt.. weres your earl gray man.. christ!!

[trackdaynova]

Oli - I have a laptop with MBE Easimap if you need to sort something tomorrow, and the leads :thumb:

I'm on my car all day tomorrow prepping for Sprint and need to do some miles on it to bed the brake pads in - do you want me to drive to you and bring my laptop etc?

[MC]

We have a lead or two also and a Laptop if you need assitance.

MC

[dhdev (Oli)]

Crikey guys, thanks for all the offers of help, really appreciate it :thumb:
I'm going round to check the CTS now, if I'm still stuck I'll give you a call later Olly.
Thanks again!

[dhdev (Oli)]

Well the CTS was checked using a multimeter and heatgun pointed at the Stat housing lol All seemed dandy, so a call to Mr Hewitt and an hour later there were two trackday novas on the drive :D
We plugged in the laptop using his £2 ebay comm lead (bargain) and straight away spotted that Easimap was telling us everything is fine :wtf: Which meant the likely candidate was DIS pack, so whilst his back was turned I stole the one off his car and it appears to have solved it! unfortunately he noticed and asked for it back, so I need to buy a new one :( Where is cheapest, and which is the best type? Cheers everybody!

[Paul]

Genuine siemens/valeo one.

Fiesta zetecs are good, vectra x20xev are £46 from vaux brand new.

Not a pattern one IME.

[ck]

what coil pack are you running? the corsa gsi one or a DIS xe type one? i should have a couple corsa DIS packs if u need a cheap one..

[meritlover]

is your TPS voltage calibrated?

[Paul]

what coil pack are you running? the corsa gsi one or a DIS xe type one? i should have a couple corsa DIS packs if u need a cheap one..

Why would you want to run a DIS XE one?

It came only on the DIS Xe's therefore making it very very hard to come by and very expensive?