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just finished final tuning on my mates rebuilt GTR

no real problems as such, but just a minor concern that we'd like some opinions on.

when under full throttle the acceleration doesn't seem smooth, and the engine seems to be leaning out too much, rather than running richer, as it apparently should be. this is especially up to about 3500rpm (no, its not lag), then another somewhat flat spot between 4200 - 4600rpm.

we can up the fuel with the haltech (in those areas, and others if we need to), but obviously, its using 30-40% more fuel than it should be by doing this (depending on how much it is increased).

Now, the tuner thinks this may have something to do with the injectors being slightly lazy (we sourced them from a user that had them in his 34 GTR, were 1000km old - flow fine - def not broken or anything). I know standard 34GTR injectors are different than standard 32GTR injectors, but aren't aftermarket nismo injectors universal??

Or, it may be because the haltech is being used with the standard wiring loom, and not the full haltech loom.

Now I am not a technician or mechanic myself, so I am trying to relay this message as accurately and completely as possible, to see if anyone has had similar problems.

I'll try my best to answer any questions you may have to help...

Any constructive opinions are greatly appreciated.

Regards,

Beau

What makes the R34 GTR standard injectors different to the R32 GTR injectors apart from their body being silver rather than the 32's black?

I had mine flow tested. 40psi 480cc; which is what they should be according to tomei.

Off the top of my head tomei had the gtr injectors down as...

36.5psi - 444cc

40psi - 480cc

46psi - 520cc

Topaz... thanks mate... that info may help a bit... I was sure that they were simply RB26 specific, not different throughout the models!

cubes... apparently the 34GTR injectors are shorter than the 32GTR ones....

My 34 GTR injectors were identical in height and looks *apart from colour* to my Rb20DET injectors.

This was from the Tuner's mouth.. that they are different in height... I cannot confirm it myself.

Did the tuner have a fuel pressure gauge on the car whilst on the dyno, to check fuel pressure under load?

yes, they tested the fuel pressure at multiple places from tank to the injectors... no apparent problems/changes.

hrmm. haltec. similar problems ive heard of. just like my autronic. ps.. is it tuned throttle/map or just map?

obviously the maps can be and I believe are somewhat customised... not 100% sure on the details... I do remember him saying the haltechs are very similar to the autronics in the way they have to be tuned... especially compared to say the power fc that already has base maps to start from.

This was from the Tuner's mouth.. that they are different in height... I cannot confirm it myself.

yes, they tested the fuel pressure at multiple places from tank to the injectors... no apparent problems/changes.

obviously the maps can be and I believe are somewhat customised... not 100% sure on the details... I do remember him saying the haltechs are very similar to the autronics in the way they have to be tuned... especially compared to say the power fc that already has base maps to start from.

Haltech's and autronic are completely different ecu and are tuned in a completely different manner. Not sure if the haltech can be throttle/pressure mapped but it does sound like this could be an issue. Does the tuner have a good reputation?

Haltech's and autronic are completely different ecu and are tuned in a completely different manner. Not sure if the haltech can be throttle/pressure mapped but it does sound like this could be an issue. Does the tuner have a good reputation?

Fuel pressure

Timing

Spark plugs

A/F

Things to pay real big attention to !!!

Haltech's and autronic are completely different ecu and are tuned in a completely different manner. Not sure if the haltech can be throttle/pressure mapped but it does sound like this could be an issue. Does the tuner have a good reputation?

Hmmm... I must have misheard him... I'm sure he mentioned autronic in there somewhere....

I will see what he says about the throttle/pressure mapping.

compared to the tuner that originally had his hands on it, these guys seem to have a good rep.... no bad stories I've heard anyway. (then again, I'm sure all places have good and bad stories)

Fuel pressure

Timing

Spark plugs

A/F

Things to pay real big attention to !!!

I know he tested diff plugs, tried splitfire coils, checked and dbl checked fuel pressure all along the system.

Can't remember what he said about timing.

Its air flow is read thru map sensor, so not sure how this would affect A/F ratios etc

Thanks for everyones help so far!!

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