9a Underfuelling

[pumbaa 0]

Hi all,

 

I had my valver on the rollers in Norwich at the charity rr day 2 weeks ago and found out it was underfuelling so they didn't push it beyond 5500 revs.

 

I spoke to Dave (CrazyDave) as i was worried it was the DG map and he said it sounds like its still running closed loop at full throttle. (i.e. its still adjusting from the lambda output, and the WOT switch might not be working)

 

So i went ahead and changed the throttle body for a known working one, and swapped the metering head for another known working one.

 

I then had it rollered again (where the new metering head was setup and the throttle body switches were electronically tested and found to be working) and the results were identical, so they were both fine.

 

I'm going to change both fuel pumps now (they aren't making any bizarre noises).

 

Does anyone have any other suggestions?

 

Please find power run results attached.

 

Thanks,

 

Kunaal

[dannyboy 0]

it does look like the lambda is still in closed loop mode as the fuel starts to lean out after 5000rpm even though it should stay rich if on WOT.

 

Fuel pumps dont have to make noise to be on their last legs,also what state are the mechanical injectors in?have them ever been changed? Vacumn leak somewhere?

 

If youve done some substainial work to your engine it might be either injectors or pumps are working overtime and cant provide enough fuel

[pumbaa 0]

They're brand new bosch injectors and a brand new lambda (well about 1000 miles old now) im going into the garage today to have a quick check over the wiring and any vacuum pipes and them i'll get some new pumps next week.

 

I thought k-jet injectors were good for about 200 horses?

 

Thanks for the help, all other suggestions welcome!

[davidwort 0]

Fuel delivery from the injectors shouldn't be a problem as you say, never heard of the k-jet injectors or metering head being a limitation on a NA 16v.

I'm assuming you have had the ECU checked for any faults.

Did you check the balance between the injectors when you fitted the new ones? fuel delivery check is pretty easy to do.

Is it possible that the wiring from the full throttle switch is defective? Not sure if this would cause an ECU fault, but it might be worth checking the wiring for continuity.

I think it was Corradophil that has a similar problem with a modified 2L 16v, they do seem to be limited by the shape of the airflap cone, but then I've also seen 9A's that don't seem to have a top end problem.

Edited May 28, 2011 by davidwort

[pumbaa 0]

I haven't checked the ECU for faults, how would i go about doing that? I spoke to Dave and he assured me the map was fine and he would have enriched it enough at the top end, so haven't done a power run with the original ECU. I will try it after i change the fuel pumps, this rr time is starting to get expensive!

 

I didn't personally check the injectors but i assume dave did when he set up the car. I'll do a test when i get a chance. (I assume this is done by getting 4 plastic bottles on the injectors and trying to start the car a few turns and then checking that the bottles are evenly filled?)

 

I did think about the wiring but it goes into a loom pretty much as soon as it leaves the throttle body. Anyone know of a way to check this? I will try to get it on a diagnostics machine to see if its throwing up any fault codes.

[dannyboy 0]

i didnt mean the injectors dont flow enough, i meant injectors or fuel pump was getting old and not providing enough fuel at top RPMs. Im modding my g60 and as a insurance policy changing fuel pump as its probably in there since it came out of the factory. a 21 year old pump wont be putting as much fuel through as new one especially at top rpms.

 

as the guys said check your ecu for faults. Id also check the intake meter flap to make sure its not sticking near the end of its travel