Hey all, need some help. i just got done building my second motor. after my break in, i went for a tune and the car made NO power. something clearly wrong. Its definitely not engine related, sounds fine feels fine, but maybe fuel/electronic related. we started on a 9lb base tune for drive ability but the car made 300/300 only, and fell on its face (sputtered) as the RPM climbed. fuel was all perfect with in 11-12 AFR. We tried adjusting and adjusting but nothing worked. while in break in i was running rich, so im thinking it may be fouled plugs? or maybe bad coil(s). the only other thing i can think of is a bad MAF. I did get a code P0a03 bank 1 sensor 1 range performance, but we cleared them and it still didnt work. Im so frustrated, its been never ending with this car. what can it be? BTW i left with nothing except a drive ability tune and it drives perfect if driven normally, maybe a bit slugish.

Thank you!

 

Complete mod list please? And what EMS?

-Rob

 

built motor
eagle H-beam rods.
weisco pistons 96mm 8.8-1 compression
stock heads.
turbonetics kit
600cc injectors
walboro fuel pump 255
NGK 7a spark plugs
Utech EMS with map sensor

 

Stock maf? Would the limits of stock maf (4-5psi) affect you or would the utec switch to map? I know it doesn't tend to make that switch very smoothly at least that's what I've read.

If it falls completely Ill as you get on it then is it hitting safe mode? Could that be your problem?

 

yea. if i was running under the maf for tune i would think that would be accurate but its got a map sensor. Also during break in and a little of the tune it was running very rich. we had an issue with exhaust AFR. for some reason the passenger side exhaust had lean AFR readings because there was no exhaust flow so the AFR read lean and kept adding fuel. the numbers werent matching so we switched sides (drivers) and saw that it was SUPER rich from all the fuel he was adding. obviously after a few slow runs driving it so rich may have fouled the plugs... as we began to lean it, it was gradually getting better but was very finicky, hard to tune. we reached a wall at 300/300 and spuddering, hesitation under hard acceleration or past 4500 RPM. That help diagnose the problem?

 

UTECs are notorious for weak ignition drivers, I would recommend switching EMS to Osiris or Haltech. But if thats not in the budget you can try an ignition amp (HKS or Sun Auto) I can price you one if you want. The stock MAF would not a have an affect since the UTEC is basically a standalone when in boost.

Let me know if I can help you with anything,
-Rob

 

I'm trying hard to stay within the boundaries of my own experience so when I see some familiarity I try to put it out there but it looks like your issues are moving beyond what I have seen. I know I'm constantly finding posts with guys who have some trouble with the UTEC map sensor... my original understanding is that it uses the MAF for normal driving and then switches to MAP when you start leaning on it. I seem to recall that it was this transition that UTEC doesn't do very well.

Also- I've read some issues with the MAP sensor callibration so I naturally am drawn to question whether or not something could be wrong with the sensor itself.

The UTECs also very rough on coil packs from what I've read... perhaps this could be contributing to the imblance?

 

Hm. Didn't know this. So an ignition amp, new plugs should help.... ? Rob, please send me some prices of the above ignition amps. Thank you.

 

update: Changed the plugs and still does it. seems that the more fuel that it needs the worse it feels, powerless and sputtering. i think it may be bad fuel injectors or something... this is driving me crazy.

 

Im telling you, i went through the exact same thing on my personal car. On stock ECU (Uprev) at 600rwhp the stock ignition isn't sufficient since you can't increase dwell, sorry I missed your other post. I will PM you some prices ASAP.

 

ok. i took it to another tooner whom is a UpRev advocate and he concluded that it was a bad fuel pump or injectors. I have 570 cc injectors that were at 80% duty cycle! and there it was ok in the AFR, so that tells me that the pump os bad. i am going to by a fuel rail pressure gauge so i can determine exactally. anyone know where i can get the adapter and the gauge? thanks

 

i was thinking. the little black bushing/seal that goes on the fuel pump exit side(side that pumps to rails) to seal it, was a little loose when i took it apart, could it be that it is not sealing and loosing pressure? where can i find one of these little seals?

 

update: I bought a fuel rail adapter and a pressure gauge to test the fuel pressure to see if it was in fact the pump. It wasnt... now im back to square one. the car was at the dyno again, this time tuned with OSIRIS. and still did the same thing. made no power,280whp/280 torque sounds good on the dyno at begining of a pull, then sputters/misfires sounds terrible. the funny thing is i have no codes, and ive checked/replaced everything accept the following, coils, injectors. what else could it be! im super confused and am pulling my hair out.. NOTE: i did ohm the coild and they checked ok, but i then checked if they were igniting the sparkplug and one of the six shocked me when tested. could this be the issue?? In the mean time i just bought 2 coils to replace the suspected bad ones. Any suggestions PLEASE HELP!!!!

 

When the car sputters and misfires does it stop when you lay off it or does it stay like that until you restart the car?

We're looking at fuel... pressure, injectors, pump... etc... Any chance at all this could be a cracked valve or a bad spring? Sorry, shooting at ducks here but thought I'd toss it out there.

 

Just had the engine built, don't think it's that. At least inhope not. The engine doesn't do it enless your under load. When u let off it goes away.