My car (MY98) has quite a lot of breathing mods including a VF23, HKS EVC4, decat, ported manifolds, K&N panel filter in original airbox with resonator removed, Walbro 255 litre fuel pump, FSE fuel pressure regulator, etc etc. I run it at 2 boost levels of 1 and 1.2 bar. I find that on acceleration at 1.2 bar the engine starts to 'misfire' once it exceeds 6000 or so revs (not always exactly the same) which disappears on backing off slightly. The same happens at 1 bar but at higher revs. The AFR meter shows the richest green light on at the time and the EGT is well under 800 so I don't think that it's fuel starvation (which is what it feels like) - is this some sort of fuel cut? Any suggestions gratefully received as it's becoming annoying!!

 

Depending on where your egt sensor is I would say its too rich, the Walbro pump also ups fuel pressure a bit in its own right, dependant on what you have set your FSE reg to try lowering the fuel pressure setting to see if that helps. What afr meter are you using ? Richest green is a minimum value and you could actually be reading well over without knowing.

 

Bob,
Thanks for your reply. The EGT sensor is in the up pipe just below the turbo and I don't think that it has ever exceeded 800 degrees. The FSE regulator setting has not been touched from standard. I had this problem before fitting the pump and regulator and they were attempts to solve it as I thought that it was running lean in spite of what the AFR meter (which is a Lumenition) was saying In fact, I think that I first noticed this after fitting the EVC, which came before the VF23, but it has become more noticeable as more mods are carried out. The ECU is bog standard, by the way, and also I'm getting 28 mpg average as long as I don't cane it too much.

 

Ignition problem?? Coils packs? Plugs ? Leads? Id check the plugs first, and replace if necessary, gapped to 0.7mm

 

Plugs are PFR7B's gapped at 0.7mm and changing them made no difference. Can the coil and leads be checked on the road with a Select Monitor and, when I think about it, can the mixture be checked the same way?

 

Select Monitor never registered the plug lead when it caused a prob on my '98. Eventually cured by dealer, after 3 tries, when an "expert" from IM had a look.

 

That sounds promising...The difficulty is in checking things while the engine is under load and at high revs which you obviously can't do in the garage unless you have a dyno handy.Will the Select Monitor check the mixture on the road? Anybody?