Engine problem

[d6277n]

Had a great time at the Abingdon track day today, but it was spoiled slightly by an intermittent engine problem. Any thoughts would be appreciated as I\'d like to get a handle on it.

Car is fitted with a cat back, K&N panel filter in stock air box and Apexi PFC. Mapped to about 310hp on a fairly rich map with stock fuelling. Boost is at stock levels controlled by PFC, last rolling road showed good, flat boost control.

In second gear, between about 4000 and 6000 rpm, the car kangaroos badly, getting into headbutting the steering wheel territory. I\'ve had it a couple of times on the road, but it seemed to clear after it had happened once or twice. However, it happened last time at Abingdon on a particular right hand off-camber bend. It made second unusable, so it was tricky to drive around. Back on the normal road the problem went away, obviously not driving as hard as on track.

I had the car looked at and there were no obvious problems visible without attacking the rats nest. I didn\'t want to spend the money at the time as I was buying a house. It went away, and I figured if it came back I would have to spend some money getting it diagnosed...

Today I was fine for the morning session then it came back just before lunch on the same corner in 2nd gear. After cooling down over lunch, it was fine for the first three afternoon sessions, then it appeared and got worse, now on several corners and a little on the straights, but always in 2nd gear. No trace in any other gear.

It happened both at WOT and 3/4 throttle, boost was not spiking above normal, but dropping off by a few psi with each "cut" then building back to normal quickly. Fuel was ok as there was more than 1/2 a tank and stock pump, and the PFC knock reading never went above 30 so there was no det.

My best guess at the moment is I can rule out fuel pump issues and ignition. It\'s likely to be a rats nest problem, probably caused by a connection softening and then leaking when it fully heat soaks? Not sure though, and why it\'s only in second is a mystery.

Help

Chris.

[neil_jdmr]

Check your cat mate, ill bet its collapsed partially if not fully. You will need to drop the cat and have a look through it.

[antnicuk]

how can you rule out fuel pump?,  is it fuel surge?

[DR SCHNITZEL]

My car is doing this at the mo on high boost setting. i put this down to the fact i richened my map up alot in those high boost levels for safety.

On low boost .8 bar, the car pulls smooth and strong right to the redline, with an AFR of 11.8 in boost

On high boost 1.1 bar, im getting readings of 10s and 9s, as the mixture is so rich the petrol isnt getting ignited. the car jolts and shudders. You mention your running a rich map, how rich? I know when i lean out my map tomorrow this problem i have which is kind of unpredictable/intermittent will go away. And things will be oh so smooove

hope this helps

[d6277n]

Thanks for the advice guys. Car was mapped by someone who is no longer involved with rotaries, so any mapping investigation will probably require me to re-map it with one of the current tuners. I don\'t know what the AFR\'s are on the current map.

Cat and fuel surge are things I will look into... But do any of these explain the 2nd gear only thing - I tried to replicate the cornering/engine loads in third but got no repetition of the problem. Very odd.

Thanks,

Chris.

[m1tch]

What uprated ignition are you running? Could be ignition breakup at higher boost

[K1HKS arse]

Its not the tune.......... unless something has gone a miss???  If it was too rich it would have done it since it was mapped.

Only in second gear is strange, it sounds like a solenoid/boost issue, 2nd tubby comes in at 4500rpm which is in the rpm range you specify. You would think that it would do that in every gear though ?

If it doesnt do it cold then as you say, something is breaking down when hot.

Im not too familiar with stock turbo set ups and their gremlins, ive always had single turbo\'s since 2001.

Chris give me a call buddy.

G