Running Very Inconsistently

[rondofj]

Hey there, just thought I'd ask for suggestions. Since getting my car(R34GTT, PTE5558, 286rwkw) back from the tune in Dec its been running inconsistently as in sometimes its feels smooth, sounds nice, requires less throttle and goes hard. Most other times (mostly always during first 10-15mins) it drives crap- sounds loud/groany/rough, requires more throttle, is lazy and doesnt feel fast, below 4k rpms feels like a boat. Running rich???

But then after turning it off then goin for a drive again while still warm it goes and sounds like it should, light on throttle, noticeably more down low and fast, sounds smooth/purry too. I had sime boost leaks (wasnt boosting to 18psi, which I fixed and now it does). But still think there might be a leak which gets sealed once warm which explains it always running crap for few mins during first startup. This is my main issue.

The other thing is first cold startup is always cough cough cough shudder shudder for 5-10secs with idle hovering at 300-500rpms then it goes up and it starts fine. This always happens. IAC i have cleaned before. But if the engines warm after a drive and I start it again theres less cough n shudder and it starts somewhat easier. Not wirried about this startup prob as its probably something minor needing a tweak.

All these probs happened after my turbo upgrade n tune (Nistune) so could it be tune related/ afm/ boost leak/ thermostat or what??

Have a slipping clutch as well which will be replaced asap.

[rondofj]

Or even crank angle sensor/timing?

[Dose Pipe Sutututu]

Bad tune by the sound of things, do you have a wideband O2? I've seen a few tunes from different workshops and most of them don't even touch the temp vs. injection table because they're lazy (Power FCs)

[rondofj]

Thanks guys, I dont have a wideband and laptop unfortunately, Johnny you could be onto something, I do think its temp related- both the starting and running shit initially. Might want to see what the workshop says

[GTSBoy]

What you have is probably the ignition timing problem that has plagued a few Nistune owners. I can't remember the details...perhaps shmooze the Nistune forums (in the type 4 section) for people with cold running issues. The problem is to do with the way the Nissan ECU pins the timing at a fixed value (like 15 deg) until you reach a threshold coolant temperature. This is adjustable in some ECUs, not so much in others.

The problem with Nistune is that many people think they can tune it because they see the fuel and ignition tables and adjust those, and don't realise that when you have injector size changes and AFM changes there are often a lot of other things you need to tweak, like some of the TP limits and cold start settings and so on.

[rondofj]

What you have is probably the ignition timing problem that has plagued a few Nistune owners. I can't remember the details...perhaps shmooze the Nistune forums (in the type 4 section) for people with cold running issues. The problem is to do with the way the Nissan ECU pins the timing at a fixed value (like 15 deg) until you reach a threshold coolant temperature. This is adjustable in some ECUs, not so much in others.

The problem with Nistune is that many people think they can tune it because they see the fuel and ignition tables and adjust those, and don't realise that when you have injector size changes and AFM changes there are often a lot of other things you need to tweak, like some of the TP limits and cold start settings and so on.

Thanks man you sound like a pretty knowledgeable bloke in all areas of mechanical / tuning and car stuff, I've seen your comments in a few posts, will definitely pass your suggestions to the tuner and see what he says, but one thing with this tune, the car has returned amazing fuel economy of 13.4L/100kms (did a nice long drive plus numerous short ones last fill-up) compared to previous stock turbo with tune was always 19-20L/100kms which is really bad. Driving style unchanged.

[rondofj]

Hey guys do you think my thermostat is likely to be knackered? From what I read its gotta be the engine thermostat not the ecu one?

[Dose Pipe Sutututu]

You mean the temperature sensor? there's two near the plenum. 1x is for the ECU and 1x is for the dash. Best to drop the car off at JEM and leave it there overnight or till it cools right down and ask them to have a look with the nistune package opened and see if the temp sensor is reading correctly..

Also I can't find the thread, but I remember reading about 6 months ago STATUS mentioned that R34 GT-t had some issues with reading the ROM.. best to shoot him a message

[rondofj]

Ok thanks mate, JEM offered to keep the car for a week, to go through the issues, I asked them if they can do a couple days, so hopefully they will find something wrong in the tune and fix it... Tomorrow my NPC HD Organic is going in so a little woohoo lolzz..

I will shoot STATUS a pm