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Old 09-17-2009, 03:01 PM   #1
a143gsxr
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Default Hard to start help

I recently modded my stock injectors by cutting the caps off and had the car tuned by doug at topspeed. Tune is great car runs excellent. a/f's are target on and monitored by aem wideband constantly. But, if you car sits for more than 15 minutes, it starts just as if I had just reflashed the ecu. turns over for bout 10 seconds then fires. while its turning over, doesn't sound like its trying to do anything. I changed the plugs with no change. I also have put the key in on and waited for the fuel pump to prime the system and then tryed, no help. No CEL's whatsoever. I also had my TB ported at the same time as the injectors. The injectors were not tested after the mod. The hard start issue was no affected by the tune. It did this before and after the tune. Doug did not get to see it cause the car was only off for a min to reflash during the tune here and there. I think one of the injectors might be bleeding the line pressure into a cylinder, but I don't smell any gas at start. any help would be appreciated.

stephen
08 STi, ported turbine hot side, ported TB, GS phenolic spacers, TGV deletes, modded stock injectors, mahle pistons, invidia catless DP, 3" midpipe, Gt Spec header/uppipe, Harmon CAI, LFR7AIX plugs, Water/Meth(50/50), opensource tune by doug at TS
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Old 09-17-2009, 03:10 PM   #2
06rexwagon
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I would take it to Doug. I've had the same problem when I was running methanol injection. My theory was that the heat of the motor sitting there not running expanded the meth/water in the lines, making it drip in to the intercooler piping. It would essentially flood the motor with water and methanol. My car would only have a hard time starting within 15-30 mins after turning it off. It would cold start fine. Try removing the methanol line from your nozzle (plug the hole into the nozzle). Go drive around but stay out of boost if you're tuned for the water/meth and get the car good and hot. Then park it for 15-20 minutes and see if it gets better.
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Old 09-17-2009, 03:16 PM   #3
a143gsxr
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excellent idea. going to do that now. thanks
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Old 09-17-2009, 05:40 PM   #4
a143gsxr
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Nope, not the methanol injection. Must be the injectors or the TB calibration. Is there a way to Calibrate the TB??? It just got ported. Maybe it was tweaked a bit during the porting. I'd rather it be the TB than the injectors. The tune is awesome. thanks again in advance for the help.

stephen
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Old 09-17-2009, 07:03 PM   #5
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Use learningview.exe and shoot us a screen shot of that. If your learned fuel trims are way off this would be an indicator that you need some intake tuning.

I realize your hitting targets but in closed loop your car may be making excessive learned adjustment. It won't learn below 5g/s or so, when you try to start it if the intake scaling is way out it can cause this maybe.

We need some more data though to really figure this out.
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Old 09-18-2009, 02:14 AM   #6
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Quote:
Originally Posted by TurboSetch View Post
Use learningview.exe and shoot us a screen shot of that. If your learned fuel trims are way off this would be an indicator that you need some intake tuning.

I realize your hitting targets but in closed loop your car may be making excessive learned adjustment. It won't learn below 5g/s or so, when you try to start it if the intake scaling is way out it can cause this maybe.

We need some more data though to really figure this out.
ok sounds good. yeah i was thinking the maf scaling might be causing this. i'll work on getting the data.

thanks, stephen
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Old 09-26-2009, 11:11 AM   #7
a143gsxr
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Default hard to start help

anyone out there with some input on my issue? I did three things and then this started.....ported TB, APS 50/50 BOV, Modded stock injectors....re-scaled injectors and car runs great once started. everytime you start it after it's set for over 30min it turns over for about 7-10 seconds then fires. I tryed scaling the maf around 15g/s but it seemed to have no effect on the prob.

stephen
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Old 09-26-2009, 11:18 AM   #8
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Sounds like an injector latency problem maybe. Check your fuel pressure as well. Anyhow why have you not taken it back to your tuner? If you don't know what your doing and are just changing things randomly you could end up chasing your tail the whole time if you do to much. You will just create new problems.
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Old 10-09-2009, 12:37 AM   #9
a143gsxr
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Quote:
Originally Posted by dumdum View Post
Sounds like an injector latency problem maybe. Check your fuel pressure as well. Anyhow why have you not taken it back to your tuner? If you don't know what your doing and are just changing things randomly you could end up chasing your tail the whole time if you do to much. You will just create new problems.

I think you right on money, adjusted the latency and the car ran better but still hard to start. I think my fuel pump is next. I ordered the walbro and have the viton 203's on hand. I hope it ends up being the pump/pump assembly. thanks
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Old 10-11-2009, 11:22 PM   #10
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did the walbro fuel pump mod today and the car started perfect all day. I hope i'm done with this issue. I'll post again tomorrow night to say for sure.
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Old 12-14-2009, 11:11 PM   #11
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Update....The car started fine the day i did the fuel pump change then back to same ol crap. I mentioned the aps bov, I pulled that a while back and that did not change anything either. I did notice that since the weather has cooled off it is way better. if it's under 50F outside the car starts fine. which lets me know its a tuning issue of some sort.
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Old 12-15-2009, 12:28 AM   #12
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what did you scale your injectors for. on 06 stock sti the injectors are rated at 550 but scaled to 513.
would you scale the new injectors at exactly what they are or a little less like the factory tune?
im not a tuner but this may be of some interest

or you could go get your tuner to look at it
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Old 12-15-2009, 06:18 AM   #13
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Quote:
Originally Posted by bswilmington View Post
what did you scale your injectors for. on 06 stock sti the injectors are rated at 550 but scaled to 513.
would you scale the new injectors at exactly what they are or a little less like the factory tune?
im not a tuner but this may be of some interest

or you could go get your tuner to look at it
yeah man, it's the maf scale, injector scale, tip in or latency. problem i have is that if i adjust either value my wot a/f will be affected. my tuner is 6 hours away. I have been slightly adjusting things which have yielded no change. i have an aem wideband so I can keep a good eye on things but everything i've done has not made a bit of noticable difference. I modded the stock injectors. 565 to 816 is where doug currently has them scaled. car runs and drives perfect. just the starting......
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Old 12-15-2009, 09:29 AM   #14
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Try using the newest Romraider definitions. Should be able to adjust cranking injector pulsewidth now.
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Old 12-17-2009, 08:20 PM   #15
a143gsxr
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Quote:
Originally Posted by quazimoto View Post
Try using the newest Romraider definitions. Should be able to adjust cranking injector pulsewidth now.
downloaded those yesterday and pulled some injector based on iat. car started good all day. tho it wasnt hot out today. my start prob got alot better as the days got cooler which told me there was a bit too much fuel during starts and as the air intake temp got cooler that too much fuel got more air so it was not so much an excess prob anymore. thanks man and i'll keep the thread updated. waiting for a warm day to fine tune this issue.
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Old 12-18-2009, 02:29 AM   #16
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umm... set it back and drive around with romraiders injector tab up and logging. Log only when you're consistent on the pedal and in closed loop fueling (<~6psi @ low throttle)

see what this tells you for latency and injector scale and compare that to what is in the ROM.

Or do the MAF tab and post the screenshot of that here so we can see what's up.

To do either of those without like 2 hours of driving, you need to keep steady on the pedal, and any time you have to lift off the pedal or accelerate quickly, stop logging. Try to get varied readings across the spectrum (5th gear uphill at low throttle and 3-6 psi, some consistent at 1-3 psi, and some for each gradation of vac on your gauge down to about 15-17 mmHg). should need at least 30 minutes of driving to get good logging of all that.
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Old 01-02-2010, 10:55 PM   #17
a143gsxr
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the car has started perfect since i pulled the fuel during cranking with the new RR definitions. I have only seen about 60F ambient tho. it has been two weeks straight. I have also tried starting in my garage(75 to 80F) during lunch with no problems. If it acts up when it gets warm again i'll be looking hard at the injector scale as discussed in the immediate above post. but for now its all good. thanks guys and gals.

stephen
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Old 01-20-2010, 04:52 PM   #18
a143gsxr
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So I saw 70F other day and it started a little slowly. pulled a bit more fuel based on cranking IAT and today it started perfect all day. I'm finally done looking for answers to this problem. the new 08 RR defintions which include cranking injector adjustments ROCK!

thank ya'll
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