Curious Stuttering/Power Loss

[ReggieK]

Hey peeps,

I think I know what the problem but would like your opinions.

Scenario....Have just driven length of M40 (and some of M42) so car was well warmed up. The low fuel light came on a little bit before I came off M40, I then joined the A404, a dual carriageway.

I was in tip mode, in 2nd gear, pulled out to overtake, and floored it. Car took off as usual, but when it got to 5500/6000 it started to splutter and jerk, it was OK once I lifted off. I tried this in 3rd gear too, with same results. It was OK for normal driving just happened if I floored it.

Now, I suspect this might have something to do with the fuel tank breather hole being bunged up? I reckon this because when I went and filled up, I took the cap off and got a huge hiss of escaping air.

I haven't had too many opportunities to test if OK since, but the one time I think I got close enough it was OK.

What do you peeps reckon, am I on right track or not. How can I check this breather hole? The car's is due in for a service soon so am not overly worried if it's not something I can do.

Thanks for any help.
K

[Nick VR4]

Riggie these cars don't have a breather hole in the tank
The noise you heard was air rushing into the tank not coming out

As you have stated you had nearly a empty tank
My guess is when you floored it it caused the petrol left in the tank to slosh about
Possible causing the pump to not be pushing petrol to the injectors

Thats my guess anyway :D

[ReggieK]

Riggie these cars don't have a breather hole in the tank
The noise you heard was air rushing into the tank not coming out



How's that work then Nick, is it a self ventilated tank then? It will need to breathe somehow, surely?

[enigma]

My guess is fuel cut, due to a very dense charge of air passing through the Mass Air Flow sensor. The reason you got an abnormally dense charge of air is that it is f**king cold!

[Nick VR4]

I' pretty sure it is something like this

it uses the EVAP system to vent the tank.
Under legislation Hydrocarbon emissions had to be reduced and the EVAP system was introduced (EVAPorative emissions control).
The system consists of a redesigned fuel tank with an area to collect fuel vapour, a vent pipe that runs to the front of the car which connects into a charcoal canister. A purge valve runs from the canister to the intake manifold.
Fuel vapour is vented into the charcoal canister (the canister is open to the air one side) and the HC's 'stick' to the surface of the charcoal molecules so virtually no HC escape to the atmosphere. When the engine is running the purge valve is operated by the ECU which draws air in a reverse direction back through the canister and sucks the HC's off the charcoal molecules and into the intake manifold to be burnt in the combustion cycle.

[ReggieK]

Thanks Nick - I knew I shouldn't have asked :) Damn I thought it would be a n easy fix.


My guess is fuel cut, due to a very dense charge of air passing through the Mass Air Flow sensor. The reason you got an abnormally dense charge of air is that it is f**king cold!

BDA - Well fuel cutting is what it felt like, I just thought it was caused by the tank. Why would it only just start happening then, it was cold all day. It didn't happen this morning - but I'll test it tonight properly.

If it is that, is there anything you can do about it? Bl**dy horrible it was, couldn't get any pace on as it kept cutting in. Would be rather annoying to have a performance car you can only drive fast in summer!!!

[borgan]

Try checking the intercooler pipe that joins to inlet (by the air filter housing) is secure. An air leak will result in your symptoms. Known weak point in Japan where they replace with fabricated pipe. Could be wrong but takes only a moment to check.

[Nick Mann]

I had this a while ago, also on a low tank and a cold day. Could be coincidence? I have never had it since, but don't think I have taken it to high revs with a very low tank of fuel since and definitely not on a cold day. There must be an explanation - BDA's fuel cut seemed to fit with the cold air, but why would it only do it on a cold day?

[zedy1]

ill go with dave on that one cus ive been getting that problem with both of mine recently in cold wheather

[ReggieK]

Thanks for all the replies guys,

I must admit it's weird, it's colder out there tonight but I couldn't get it to do it, and I really, really tried. Maybe as Nick says, with a full tank it doesn't happen...

I might ask Mitsi about it when it goes in for it's next 5 squillion quid service :p

[Kieran]

I might ask Mitsi about it when it goes in for it's next 5 squillion quid service...

Says it all really :laugh: :laugh: :lolz: :lolz: