Fuel Cut, Belt Slip Or Boost Leak?

[edeath]

Hi Guys,

Some times when I accelerate (mostly when I floor it) i get a pause when the engine is at about 2.5-3k rpm. It feels like the traction control has just kicked in, but obviously without the light coming on. If I lift off and then on again slowly the engine speed will increase and I get power back.

Problem is that I'm not sure what is causing this - could be fuel cut or belt slip. The FCD is on 9 and engine revs all the way up to the limiter. The tensioner is all the way to the right if looking toward the car from the front, so cannot tighten any more but the belts were 2nd hand and ive just taken delivery of 1 5pk800 and 1 5pk780 belt.

If it helps the power loss seems to come in more often the more people i have in the car. Sometimes the car judders as well. Anybody have any pointers/ideas?

Hope that made some sense. Cheers,

Ed

[sparkystav]

Sounds to me like your leaning out the engine a tad, which is a problem with the FCD cause it gives a percentage right through the range, rather than just a ceiling like the black box,

I'd suggest trying setting 10 first, and if you dont hit the fuel cut at the top it should be better,

[Bazza]

sounds a bit like a clutch !

[aaronabbott]

yeah sounds like your clutch silpping

[edeath]

Stav - i had the FCD on 10 and moved it to 9 to try and fix the problem.

Bazza - i was also thinking clutch but the revs don't rise when i feel like i've lost power. It just kind of sits at 2,750ish (when torque starts to come in) untill i lift off and then on again. If i lift off and then floor it, it does it again most times. I am planning a new clutch soon as the pedal is v high.

When the car judders it feels more like power surge - power loss - power surge - power loss: which was why I thought it could be belt slip I:e boost - no boost - boost - no boost etc.

[Steviewevie]

You don't have that boost gauge connected yet, do you ?

[Asi]

have you fited the 5pk 780 belt

[Rob]

Hi Guys,

Some times when I accelerate (mostly when I floor it) i get a pause when the engine is at about 2.5-3k rpm. It feels like the traction control has just kicked in, but obviously without the light coming on. If I lift off and then on again slowly the engine speed will increase and I get power back.

Problem is that I'm not sure what is causing this - could be fuel cut or belt slip. The FCD is on 9 and engine revs all the way up to the limiter. The tensioner is all the way to the right if looking toward the car from the front, so cannot tighten any more but the belts were 2nd hand and ive just taken delivery of 1 5pk800 and 1 5pk780 belt.

If it helps the power loss seems to come in more often the more people i have in the car. Sometimes the car judders as well. Anybody have any pointers/ideas?

Hope that made some sense. Cheers,

Ed

I get the same sometimes and i have the silver ecu from TTE, the pause happens at exactly 3k and the shudder is more towards WOT.

it is not clutch slip

[Asi]

sorry to hijack the thread edeath. when i had mines fitted when ever i change gear it makes a short dump valve noise, just wondering if thats right?

[edeath]

Asi - Not fitted the 780 belt yet literally took delivery of it while writing orig post.

Rob - WOT = Wide open throttle??

Steve - Boost gauge not fitted - was thinking of fitting it on Saturday (or maybe that not the done thing at shows? )

[P.Lindblom]

My car does the same thing sometimes and I’m pretty sure it’s caused by the slipping belt. I think it only happens when the rpm is low and the bypass valve is completely shut.

I tried closing the bypass valve by hand, in idle, and the belt is obviously slipping a bit before regaining grip.

Please wait a few seconds for Video to Load!

Yesterday I picked up a 790 belt but I wasn't able to fit it. I will get an 800 belt tomorrow and then I'll use some anti belt slip (no idea what it's called in English) on the pulley. My current belt is 803 and the tensioner pulley is all the way to the right.

[Steviewevie]

Steve - Boost gauge not fitted - was thinking of fitting it on Saturday (or maybe that not the done thing at shows? )

Yeah, course it is, if a charger can be fitted at JAE (last year) then I'm sure a boost gauge should be no problem !

[edeath]

Asi - IIRc dump valve noise is boost pressure releasing due to the bypass not opening quick enough when you lift off. As the SC is running and the throttle is closed the boost pressure has nowhere to go so escapes out of the hoses i think - hence the dump valve noise. I only get it when at full throttle in too high a gear and then lift off.

I'd suggest giving the bypass vlave a good oiling.

I'm assuming the sort of grinding noise at high revs when you change is normal as a few Youtube clips have this too.

[edeath]

Patrick i think you may be right i'm going to try and fit my new 800 belt (which then leaves the assumtion that these belts strectch if it works) before Japfest and see if it helps - otherwise another job for Saturday lol along with fitting new IK22s and boost gauge.

[Asi]

right thanks. it always happen when i change gear when at high revs. i have 5pk788 belt and 5pk800 so will fit once i get my new engine in.

[edeath]

Asi is it dump valve or grinding noise? At high revs the SC sounds like its grinding when you change gear - well mine does along with a few youtube vids i've seen

[P.Lindblom]

right thanks. it always happen when i change gear when at high revs. i have 5pk788 belt and 5pk800 so will fit once i get my new engine in.

Mine did that as well. I thought it sounded great until I let my girlfriend rev my car with the bonnet open, then I realized it was actually a sqeek when the throttle was released. I tightened my belt as hard as I could and the sound disappeared :)

[Asi]

thanks guys will let you know nve i get the car up and running.

[Rob]

when fitting the belt remove the tensioner put belt on the compressor and then refit the tensioner with the belt on it already then install the mounting bolt - it is so much easier and takes less time