jtgli

iTrader: (13)

question for any of you guys here with f/i Ever since Ive gone f/i with the vortech Ive had hot start issues when its above 60 degress outside and the car had been running for more than 20 min. Im running a Utec and deatsh werks 650cc injectors. Anyone else on here have this problem? Now that Im greddy tt Im still having the issues so it rules out the vortech being the problem. Im looking at it either being the injectors themselves as the reason or maybe the fact that I dont have aam's or some other reflash with the utec? My buddy has a aam tuned greddy tt and it starts up ever time but hes also running rc 750 cc injectors. So any have any ideas?

Jay'Z

iTrader: (118)

I have rc 750cc but it starts only with throttle help.. = massive failure

I have no idea wat the **** is the problem.. I know there is a ****ing fix besides changing utec to fcon etc..

wannabuy350z

iTrader: (27)

its your ems

Hexxum001

iTrader: (3)

Yup. UTEC is known to have hot start problems. You just gotta give it some gas and it should start up.

350 Rookie

iTrader: (29)

Whats hot start mean?

Jay'Z

iTrader: (118)

Thats not entirely true.. Some people on here have the same problem with haltech..

JonnyC

iTrader: (19)

Yeah, my 650's with UTEC have no chance of starting w/o any throttle unless the car has been sitting all night (real cold). I usually have to give it like 75% throttle, then see some nice smoke blow out the back :-/ It starts up super rich.

wannabuy350z

iTrader: (27)

Most EMS's will create that problem, especially with bigger than average injectors 600+cc. thats the bottom line.

Nexx

iTrader: (41)

but its 100% with the utec, the tuner should be able to get around this with the standalones.

350Z400rwhp

iTrader: (4)

I have a Utec and DeatschWerks 600's and my car had hot start issues for about 2 weeks after I had my car tuned at Forged. Sharif said that the Utec would sort this out after some time and has since learned and starts like stock now with no throttle blip needed. Guess I got lucky.

KPierson

iTrader: (1)

I have the dw 650s and a UTEC. I used to have major issues with hot starts and then I lowered my base fuel pressure quite a bit. With the lower base fuel pressure I all but eliminated the problem. If I run the car hard then shut it off and try to restart it within 10 minutes it won't start without some throttle, but if I'm driving normally it isn't an issue.

Basically, by lowering base fuel pressure you'll be able to run longer injector duty cycles at start up - which is what the OEM ECU wants to do.

Hexxum001

iTrader: (3)

I have the HKS FCon iS and DW injectors and I never have any hot start problems. It always starts up right away without having to touch the throttle.

KPierson

iTrader: (1)

How big are the injectors?

SpoilsofWar

iTrader: (39)

I have a UTEC and 650cc RC's, and at worst the car requires just a quick blip of the throttle to start when hot. Most of the time it starts fine without any throttle.

Like Kevin mentioned, I am running a fairly low base fuel pressure as well, ~45psi.

Old School

iTrader: (28)

I step on the gas if I'm doing a warm start....no biggie.

captj3

iTrader: (1)

Bottom line it's the utec. The utec doesn't control your injectors until after the car is started. This is the one feature that turbo xs f**ked us on. They never fixed the injector rescaling the way they promised.

jtgli

iTrader: (13)

hmmm since its the utec, could a reflash help with this then?

KPierson

iTrader: (1)

Its possible - the OEM ECU uses open loop fueling during cranking. If they offered the ability to reduce injections during cranking and for the first few seconds it may fix the issue.

Of course TurboXS hasn't released a firmware upgrade for 2 years or so, so I wouldn't hold your breath that they will be proactive and fix this.

Drop your base fuel pressure and tune around it and this really isn't an issue.

jtgli

iTrader: (13)

base fuel pressure is around 49-50psi. How low should it go to possibly fix this?

Dynosty

iTrader: (27)

We have no problem setting the Haltech to start perfectly - immediate and no throttle required, just like factory. If anyone needs help, please let me know.

As for UTEC, that is one of the limitations when you move to a bigger injector unfortunately. We have had a handful of customers come in and make the switch from UTEC and that is their first comment - "omg, I don't have to use the gas pedal to start the car?!" haha

jtgli, yes a reflash for the larger injectors would help since the utec is not controlling the start. you can lower base fp to ~40, but the change will not be 20% less fuel as one may think, but rather only the square root of the change Lowering fuel pressure will require a retune because everything will be leaner after that.