Slow To Build Boost

[Godzillr]

OK. Ever since I have had my GTR it has been slow to build boost and it also has a misfire both hot and cold and not isolated to idling.

Background info.

RB26 with consistent compression across all cylinders. HKS 2530's, 550cc injectors, aftermarket fuel pump, Z32 AFM's, Apexi PFC, pods, HKS exhaust (no dump pipes), HKS EVC.

I recently replaced the standard AFM's and reprogrammed ECU with the Z32 AFM's and PowerFC which made no difference. I have also cleaned the coilpacks and replaced the sparkplugs which made little difference as well.

Symptoms.

Positive boost reading starts just at about 2100rpm's and then climbs at a linear rate until it peaks at 1bar just under 5000rpms. Ideally I would like the boost to come on stronger down lower so that I don't have to flog the engine to get responsiveness.

Some forum articles suggest that gutting the Cat (if it has one) can help the boost build more quickly. I have also heard that cleaning the inlet manifold can help too.

I am at a lose and am really wanting to sought this stuff out. Any help would be hugely appreciated guys.

Cheers.

[GTRsean]

Cam gears, if you have stock cams.

Or replace stock cams, and look at maybe getting some dumps.

[Strik3r]

i'd say dumps too.. running bigger turbos on stock dump pipes is going to severly limit your boost building.

on the down side i dont think that would be causing the misfire.. double check coilpacks if uve replaced spark plugs.. maybe spitfires are in order ?

[Godzillr]

Thanks guys

I know dump pipes would help but there are many other examples with similar mods that don't have dump pipes. If it reaches full boost could it still be a turbo leak?

Is there any tests that I could do to identify the cause?

[black sky]

Hi

I have the same problem in my r32 gtr with r34 N1's (the .6 series turbo's) it start's making boost early, bout 2300rpm but it builds boost very slowly after that. i have a metal cat and standard dumps with a full 3" zorst behind that with all the supporting mods.

i am really looking at fixing this problems so if any one has any ideas please let me know

Cheers

anthony

[Godzillr]

I haven't found the cause yet but have some possible ways to minimize the problem:

1. Install dump pipes

2. Install CAM gears

3. Possible exhaust gasket leak.

My thoughts are that the first two would only mask the problem and they are quite pricey. I am not convinced about the third one as surely there would be excess exhaust noise from the engine bay.

[BAMR33]

Sounds like more wastegate issues.