Rb26 Unusual Power Delivery, Slight Hesitation

[RB335]

Hi.

On my R33 GTR which has done 100,000km, I have noticed it has a very unusual power delivery mostly when cold, it seems as if the power curve flatlines for a bit, and then surges suddenly, I can feel/hear very feint misfiring, but most of the times it seems like somethings holding back, you can notice it when you hold the throttle at say 40% in 1st or 2nd gear. It get's better as car warms up.

Now I'm thinking first thing most people would say is Coilpacks, am not sure how they play up on these cars but I'm thinking those would cause severe misfiring under high load all the time, which I don't get, could it still be coilpacks?

2nd Issue I have heard could be AFM's, I have opened them up before to add solder the the joints which is a common problem. The elements on the AFM's appear clear with no buildup.

Igniter is recently changed off a car that had no problems.

I had it in at a GTR Specialist and they said some of the injectors may be dirty which is causing a bit of a rough idle and coming onto power badly.

I would appreciate any feedback or experiences you guys have had with an issue like this.

Cheers.

[niZmO_Man]

Could be a combination of those things. More details about your car? The mods.

[KiwiRS4T]

Had new plugs lately?

If its not your daily it would probably be worth sending your injectors off to be cleaned and tested.

[blind_elk]

If it only does it while the engine is cold, then I wouldn't worry about. You really shouldn't be using "power" on a cold engine.

Edited August 29, 2015 by blind_elk

[djvoodoo]

Cold enrichment below 50 deg Celsius. You running standard ECU or aftermarket?

[RB335]

Standard Engine, Standard ECU

Boost restrictor removed, Fujitsobo Mid-pipes and exhaust.

It's almost like power delivery flatlines in small split seconds then comes back on.

[Gus Baby]

Have seen afm's that look practically new and be no good...not saying this is ur problem tho as it probably wouldn't change hot r cold...could be fuel delivery alrite...what work have u got done recent or how long I this happening?

[RB335]

It happens 80% of the time when cold. I have not had any work done on the car recently.

It definitely doesn't feel right.

On rare occasion when cold the revs would play up a little bit, slight misfire, but most of the time it's unusual jerky power delivery.

Edited September 29, 2015 by RB335

[GH05T]

[img4]http://i.imgur.com/reqcct we x[/img]

2

My 32 gtr daily has just had the exact same symptoms, did you find a cause?

When cold the power is hesitant. Not on boost just on gentle power then it sudenly releases and its smooth again.

I now and suddenly get it occasionally when crusing allong, it feels like it starves for fuel or air sligtly then releases. No issue at all on boost or wot.

Im running stock ecu, stock engine rb26 and although i have had no issues prior and no change and i daily the thing so i know, something has deteriorated. What should i check first?

Plugs or coilpacks, even injectors pumos and so on would have to give me issues on wot i would have thought?

Im guessing something more electronic like cas or afms, can i trouble shoot these somehow when its such an intermittant and specific issue?

Edited October 15, 2015 by GH05T

[RB335]

I could not find the issue.

I notice that also when the car is fully warm on a midly hot day, it can be slug when you put your foot down in 1st gear, but if you let the revs sort of build then punch it, it goes better. I have no idea if knock sensors are detecting pinging or going off randomly and pulling the timing or not.