[Guest]

Since taking my car for its 18k service I've been having a very odd problem, when cruising in 5th gear I floor the accelerator and the car accelerates as usual, during the acceleration I sometimes, but not always, experience a very minor reduction in acceleration for a second or 2 and then things are back to normal, its almost as though I'd lifted off the gas a little for a second (as you would do when you reach the speed you actually want, not as in when you are about to brake).

If I keep my foot down on the accelerator this lag goes away on its own (I don't have to lift off and then put my foot back down again). This only seems to happen in 5th under the circumstances I've described and has only started to happen after my service (although I can't think why the 2 should be connected at all) while I was driving round Europe, possibly in colder temperatures (although I wasn't paying attention to the actual temperature at the time it happened so I can't be 100% sure they are linked)

The car is a stock E6 GSR, the only idea I've had it that this has really only been happening in low temperatures and could possibly be very minor fuel cut? with a few mods I could understand fuel cut in the cold but on a stock GSR? tell me it ain't so!

I'm off on a dual carriage way tonight so I will see if its still happening in a warmer climate

Ta
Ryan

 

[Guest]

hardly call cambs a warmer climate?...

 

[Guest]

Ryan,
Sounds very much like the dreaded fuel cut to me.
Have a look at your wastegate actuator and make sure that it's still there and not stuck or missing. This would cause the wastegate not to open and hence the fuel cuts from overboosting.
I had the same thing happen on my standard car and the actuator was replaced under warranty.

Andy

 

[Guest]

Ryan,

it could be low quality fuel too. The detonation sensor could sense more det at
certain revs and hence (the ecu could) retard the advance and decrease the boost.

Why after the service ??? I simply don't know ! Was your tank low on fuel before the service ?
Could the service people added any 95 octane fuel (long shot, I know).

Did you ask the people who serviced the car about the new symptoms ?

Good luck,


Alex.

 

[Guest]

Rob,
Campared with -3 yes its warm!

Andy,
Ok I guess this is what I was expecting to hear, I'll have a look tomorrow when its light

Ta
Ryan

 

[Guest]

Alex,
I always run with Optimax and only once while in Italy did I use 95RON and then its was only a 1/4 tank with octane booster, I'll see what it runs like tonight and if there is still a problem I'll have a look at the actuator

As I said I don't see how it could be linked to the service and I've not as yet talked to ralliart about it
R

 

[Guest]

Could also be the secondary air system, particularly if you have your foot down.

 

[Guest]

Anyway to tell if its the SAS Blade?

R

 

[Guest]

Spose the key hint is after the 18k service , so wot have the garage monkies done then?
Check connections after the airflow meter , also the fuel pressure reg 2 inlet manifold air connection (small diameter rubber tube) and anything else they may have disturbed and not refitted correctly (skeptical................who me , 2 bloody right )

 

[Guest]

I was going to give them the benefit of the doubt until I know

 

[Guest]

Mmm, sorry, missed that. Evoboy is right. Too suspect. If it didn't do it before, and it does now ... get the picture?

 

[Guest]

hmm, just drove 80 miles and couldn't re-create the problem, ponder

R

 

[Guest]

ok this stupid thing is still here and seems to be more noticeable now I've had the air and zaust done.

I now get real fuel cut so I know this isn't the same thing

what I also get now is a kind of reverb going down the new zaust, seems that it must now be amplifying the symptoms.

Blade you mentioned the SAS, can you explain a little?

I also remember someone else saying they had a similar problem but I can't find the thread.

R

 

[Guest]

Ryan,
The SAS were formed during WWII to go behind enemy lines and disrupt communications. They have since been involved in covert operations all over the world including the Falklands War, the Gulf War and the storming of the Iranian Embassay in London. http://www.lancerregister.com/graphics/tonguewink1.gif border|EQU| 0 align|EQU| absmiddle >[img]http://www.lancerregister.com/graphics/tonguewink1.gif border|EQU| 0 align|EQU| absmiddle >

Alternatively, the SAS is the secondary air system on the Evo that acts very similar to the dump valve but dumps air into the exhaust manifold rather than back into the intake system. This setup is used by the WRC teams as part of the anti lag system. The SAV (secondary air valve) only opens after 3 seconds of full throttle followed by lifting off with the revs still above 4,000 rpm.

I doubt that this system would be causing the problem you describe. Have you checked the condition of your spark plugs recently or were they changed at the service? It could be that they are fouled and are causing the engine to misfire at that particular load and rev combination. It'll be worth taking them out to have a look at the condition of them.

Andy

 

[Guest]

Andy,
I think I would notice if I had a small army of men wearing black under the bonnet so I'll go and check the spark plugs, the load conditions do sound about right for the SAS causing the problem though, hmm I wonder

R

 

[Guest]

Ryan,
The thing with the SAS is that it's only supposed to open on throttle off i.e. not when you're accelerating as in your case but we'll see.

Andy

 

[Guest]

I've just read my 1st post, I think its actually when I'm cruising and coming off throttle that I think it happens, I'll investigate later

R

 

[Guest]

for what its worth and may be totally unrelated but there was exhaust carbon in the inlet so its opening when it shouldnt , i vaguely remember having a similar problem, yeah certain now it did use to do that, once its been tripped doesnt it stay open for 3 minutes or something?

typical non mappable problem, you havent got a clue what is going on

andrew

 

[Guest]

Had a similar problem on my 'standard' RS Sprint - whenever I floor it, the response is spot-on http://www.lancerregister.com/graphics/tongue1.gif border|EQU| 0 align|EQU| absmiddle > However, if I put my foot down, lift, then floor it again it occasionally hesitates, (almost a flutter sound for a couple of seconds so it sounds a little like Ryans description of reverb in the exhaust) before picking up. Not sure what the revs are at when it does it.
How do I check the wastegate actuator?

Not noticed any difference with different fuels but always run it on 97 (Esso or Optimax lately)

[any of you going to John Noble rolling road at the weekend?]

 

[Guest]

My 6 has always done this and I'm pretty sure it is caused by the secondary air sytem operating as it only does it above 4k and when coming off and back onto the throttle after being on full throttle for more than a few seconds. There is a slight hesitation while on part throttle and a strange resonance sound from the exhaust which is hard to explain!
It's definately not fuel cut and not caused by a faulty wastegate actuator.