Re: J N's MiniRam backfire

[rrauscher@nni.com]

Don't be afraid to add too much. On a TBI system (I know yours
is port), I had to add more than 7 times(!) the pump shot. I
started with 20%, nothing, another 25%, nothing. 

BobR.

>Hi,
>
>    Some answers to your questions.  Car is an 89, 165 ecm $32B.  I have a

>chip from fastchip that I have been playing with that has modified MAF
>tables for a ported MAF.    I also tried my stock timing map and other
>various things.  I have been concentrating on my pump shot.  I called TPIS

>and they knew right away what my problem was.  They said I bet your getting

>a big backfire through the intake.  They told me to modify the pump shot
>tables and that should do it. I increased the pump shot by 45% and that did

>nothing.  I plan on increasing the pump shot more and experimenting.  Fuel

>pressure is set to 50 psi line off.  If you blip the gas, the pressure
>spikes to 50 like it should.  TPIS suggested raising the pressure to 60 psi

>and I explained to them that for whatever reason, my multecs seem to start

>locking up at pressures over 50.  With that in mind, they suggested going to

>a 24 pound injector.  I have a set of 30 pounders that I have been saving
>for the 396.  I figured that they were too large for a 350 with ported heads

>and a slightly hot cam.
>
>Thanks,
>Jason Norris
>----- Original Message -----
>From: <timsiford@hushmail.com>
>To: <gmecm@diy-efi.org>
>Sent: Thursday, November 09, 2000 9:14 AM
>Subject: J N's MiniRam backfire
>
>
>> Jason sent me an XLS spreadsheet with data from a scantool that shows a
>> backfire happening when he blips the throttle.  Car = 1987 Vette w/
>MiniRam.
>>  Its pretty interesting.  (Jason, I am posting here because I can't find

>> your e-mail, thirdgen appears to be down, and I also want to share this
>> info with others here).
>>
>> The data clearly shows Jason 'blipping' the throttle from off idle.  There

>> are 4 data points on the throttle blip and you can clearly see the O2
>volts
>> going from the switching behavior at idle (TPS=0.53V) to 0mV on a Throttle

>> blip.  The data is below.  This appears to be a fueling issue (expecially

>> when viewing the SA in relation to the throttle blip and LV8).  Its
>undetermined
>> as to whether or not it is a PROM fueling issue or a mechanical fueling
>> issue.  What do you guys think?
>>
>> RPMs,TPS, O2, AFR, Knock, SA, LV8
>> 875, 0.530, 836, 14.7, 0, 25.4, 57
>> 875, 1.630, 712, 11.7, 0,13.8, 189
>> 875, 3.310, 292, 11.7, 0,15.9, 177
>> 1300, 2.94, 0, 11.8, 0, 28.2, 175
>> 1725, 0.90, 13 ,14.7, 0, 45.5, 124
>>
>> Jason - quick question for you.  The MiniRam has ZERO provisions for EGR.

>>  What PROM are you running?  Are you running $6E code, $32B code?  Is your

>> PROM image based off an original TPIS image or did you start with the
>stock
>> image as a base?
>>
>> A separate issue is that IMHO, knock -should- be detected and isn't.
>>
>> Tim
>

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