I just finished getting a fairly good tune on my 350tbi, It runs pretty good except for a slight bog off idle at WOT and a loss a low end torque 2500 RPM and below, i think that's because of the 670 tbi i installed. I figured with the l31s, cam, headers, 3" exhaust, 1.5 full rollers, it could use the extra air. But it has so little torque, it cant even break the tires loose anymore. But other than that, the plugs show a mid grey, isn't perfect, but better then straight black. I just thought i'd shere my .bin with the experts of thirdgen in the hopes of some in sight to my torque problem. AE maybe? I noticed that at idle, exhaust gasses spew out of the tail pipe as if it were under heavy load with a miss, but found that advancing the timing to 30 deg. it seemed to stop it. Never knew timing could cause such a big change in exhaust. i hope its not this poor 700 R4 dying...again


Have a look if its not too much trouble, I'm running the old 7747

 

what are you running for fuel pressure, injectors, an regulator? thanks

 

15psi with 86lb/hr injectors on the built in regulator on the holley tbi and i have a 112 BPW in the .bin. I hooked a fuel pressure gauge to it, and noticed under the load of a quick rev, it drops by about 1/2psi. Could it be my fuel pump? or too low pressure? What would be a good pump that can support 420hp or so? I tried bumping my pressure up to 30 like fast355 but even the smallest movement in throttle caused it to drop to 16psi but come back as soon as i let off, the 454 pump cant cut it, the bosch "Upgrade" tbi pump is what i have now, and it looks like it cant get the job done, so i'm stumped. a vortec/LT1 pump maybe? being that this was a budget build, i didn't think it would make anything over 400, but i could be wrong

 

A TPI or a Walbro 190 fuel pump will work better.

 

the car im workiong on we just put in a walbro 255 i think a 454 throttle body with injectors its running just over 30psi of fuel and it runs pretty well

 

How about this: http://cgi.ebay.com/ebaymotors/ws/eB...d=250497225584


If that could fit in the tank, i'd be happy with it because ots cheaper than the tpi, and has more flow for future mods. Could it be tune related? it is a self tune, and i'm not the best at it, Have a look if you would, i don't want to get the new pump only to find that it doesn't solve my problem

I look forward to >

 

Quote: I noticed that at idle, exhaust gasses spew out of the tail pipe.

Possibly the FP and injector size cannot reduce the PW of injectors sufficiently at idle. Do you idle CL? If so are you seeing CL at idle? Can you or do you idle asynch?

As far as AE with those injectors you do not have much resolutuion in AE tables. I believe AE is multiples of 61 usec... I bet you are fat in AE unless you really dropped the values there. I have 80 injs at 19.5 LBS and for AE in MAP PW I see today from low kpa at 61 usec to 122 at 80 kpa. At TPS AE I am 61 in all TPS%. AND that is just about right. I do pull AE at over 2400 rpms by 10% up to 4800 rpms at 40%. 7747 may not support that modifier.

Edit: I do use a VAFPR which modifies BPC across MAP. so that may play a role in values.

30deg SA at idle may burn all the fuel on the compression stroke and adding heat to the piston and oil-coolant.