Author Topic: G40 Problem, Serious lack of power? UPDATE WITH PICS/VIDEO  (Read 9444 times)

Offline LeonL

  • Members
  • *****
  • Posts: 453
G40 Problem, Serious lack of power? UPDATE WITH PICS/VIDEO
« on: July 19, 2009, 11:24:25 am »
Hi there,

I bought a G40 the other day and on the way home i realised it has a serious lack of power. The acceleration from standstill was pretty slow and i only mananged a top speed of around 85mph-90mph.

The car is on 89k miles, tottally standard apart from jabba sport induction kit. I have taken of a few of the boost pipes to check for cracks aleady but have been unable to find any.

I am a total noob when it comes to a problem like this so any advice, ideas, experience etc... would be greatly appricated.

What should i check/test and how should i go about it? Could it be something very serious?

Thanks

Leon
« Last Edit: July 22, 2009, 07:41:56 pm by LeonL »

Offline DKnight

  • Administrators
  • *****
  • Posts: 1426
Re: G40 Problem, Serious lack of power?
« Reply #1 on: July 19, 2009, 11:32:59 am »
howdy

erm, your best bet is to check to see if you do have boost, if you look at the throttlebody there is a little plastic control arm (looks like something off a remote control car)

prize that off the ball joint it connects to, turn the car on, now if you clasp the boost pipe that comes away from the radiator, squeeze it, now shut the valve that you have released from the control arm, and you are now pressurizing the system, doing this will cause the pipe you are squeezing to expand.

WARNING Do not close that valve for more than 2 or 3 seconds, as it will try and pop a seal somewhere

if the pipe expands then you have boost, if it doesnt, it has a leak and you will be able to now source the leak

im 99% sure it will be a leak

Offline PeteG40

  • Administrators
  • *****
  • Posts: 4010
  • Housewives heart throb
Re: G40 Problem, Serious lack of power?
« Reply #2 on: July 19, 2009, 12:55:20 pm »
if its not a boost leak (probably) or the BRV not closing properly, or then its looking at the charger!

Offline LeonL

  • Members
  • *****
  • Posts: 453
Re: G40 Problem, Serious lack of power?
« Reply #3 on: July 19, 2009, 04:26:40 pm »
Well i done the above and the pipe expanded...Meaning i dont have a boost leak, right?

So what now? :(

Offline PeteG40

  • Administrators
  • *****
  • Posts: 4010
  • Housewives heart throb
Re: G40 Problem, Serious lack of power?
« Reply #4 on: July 19, 2009, 05:45:05 pm »
well if there is no leak, then it might be best to plumb a boost gauge in to see what pressure you are getting out of the charger.

Offline LeonL

  • Members
  • *****
  • Posts: 453
Re: G40 Problem, Serious lack of power?
« Reply #5 on: July 19, 2009, 10:15:37 pm »
It an easy enough task putting a boost gauge on?

Offline g40chris

  • Members
  • *****
  • Posts: 529
Re: G40 Problem, Serious lack of power?
« Reply #6 on: July 19, 2009, 10:49:53 pm »
i would also have a quick check to see how tight the charger belts are

how does it sound when driving? maybe a loss of power through a cylinder not firing or a lead not linked up correctly. i done this the other day when i was fiddling. took the car for a spin and it was pants to drive. sounded ok ish but no power. pulled over and realised that i hadnt pushed one of the leads all the way back on the spark plug. maybe it could be something simple like that. hope its simple for you anyway

Offline LeonL

  • Members
  • *****
  • Posts: 453
Re: G40 Problem, Serious lack of power?
« Reply #7 on: July 19, 2009, 11:01:22 pm »
Car drives fine, sounds fine also. Just not G40 power...

Tried different plugs from another G40 today, took for a drive and it was still the same. Played about with the timing a fair bit taking it for a test drive each time it was changed, didnt affect it at all.

Could it be the actual leads?

Any other ideas?

Offline g40chris

  • Members
  • *****
  • Posts: 529
Re: G40 Problem, Serious lack of power?
« Reply #8 on: July 19, 2009, 11:16:42 pm »
are you getting a spark through each lead

Offline LeonL

  • Members
  • *****
  • Posts: 453
Re: G40 Problem, Serious lack of power?
« Reply #9 on: July 19, 2009, 11:25:00 pm »
How would i check?

**Complete noob to cars really**

Offline PeteG40

  • Administrators
  • *****
  • Posts: 4010
  • Housewives heart throb
Re: G40 Problem, Serious lack of power?
« Reply #10 on: July 20, 2009, 08:53:52 am »
if its idling ok and driving without hesitation, then it would suggest that the ignitiion/fueling is ok, but you have a boost leak or lack of charger pressue.

1. check for boost leaks in pipes/joins
2. check the brv on the throttle properly closes to build up pressure.
3. check the charger belts are tight and its actually spinning
4. hook a boost gauge up (t in to the fuel pressure regulator vacuum hose line)

if all these are good - its time to get your charger looked at I would suggest. - Has it ever been serviced?  what size pulley are you using?

Offline jez1272gt

  • Members
  • *****
  • Posts: 686
Re: G40 Problem, Serious lack of power?
« Reply #11 on: July 20, 2009, 09:51:08 am »
To state the obvious it has to be a problem with one of the following - Fuel (pumps, filter, fuel lines, regulator or injectors), Air (filter, air box, supercharger, intercooler or throttle body ) or Spark (coil, distributor, leads or spark plugs).

-The more accurate a desciption of exactly how the car is behaving often makes it easier to narrow down the problem!!
How is it driving across the board? Is it a complete lack of power or intermitent.
Have you got a lack of power throughout the whole rev range or just some of it?
Does it struggle to get up to the higher revs when stationary?
How does it sound under load and revving freely?
Etc etc..

Some suggestions,,

Is there air leaking from any of the pipes including the intercooler, exhaust and manifold?
Is there enough fuel to the engine, any fuel leaks at the back of the car (ie smell of fuel by the pumps) or blocked lines maybe?
Do the HT leads or ditributor look worn?
Are all the connectors plugged in around the engine bay and bulk head...

Before concentrating on any one component just stop and try and go through the car logically, fuel air spark,  part by part to see if there is anything that might be easily missed and is actually quite obvious. It might not be some thing that you need to be an expert mechanic to spot. Hope this helps a little - good luck

Offline dannyb.G40

  • Members
  • *****
  • Posts: 126
Re: G40 Problem, Serious lack of power?
« Reply #12 on: July 20, 2009, 03:04:37 pm »
sorry to thread hi-jack, but what would cause a seal to pop when pressurising at idle and not when under load?

i.e. what changes to make it ok at high revs?

Will this highlight all boost leaks, even ones that may only present themselves at high pressure (10psi or more)

Offline PeteG40

  • Administrators
  • *****
  • Posts: 4010
  • Housewives heart throb
Re: G40 Problem, Serious lack of power?
« Reply #13 on: July 20, 2009, 03:13:57 pm »
when its under load then air goes in the engine and so you get a max of 1bar which the system can handle - the rest goes into the engine.  Pressurising it by taking off the brv and closing it will just back up the pressure as it wont be returning by the brv, neither will the engine be using the air.

Offline dannyb.G40

  • Members
  • *****
  • Posts: 126
Re: G40 Problem, Serious lack of power?
« Reply #14 on: July 20, 2009, 03:38:19 pm »
but surely providing the system sees no more than 1 bar it should be able to cope?

n.b. i'm probably completely wrong, i was just contemplating pressurising the system with the engine off using an air compressor which would probably have a similar affect, im not trying to be argumentative lol