Neil

When I first installed my Miniram, and with the timing set at 10 deg. BTDC, I was getting massive backfires in the intake! So, I advanced the timing ALOT (to approx 20deg.)and the backfiring stopped. However, part throttle driveability SUCKS! The car feels as if it's got a bad spark plug and that's not the case b/c I checked and replaced almost everything in the ignition system.
Any thoughts on this???

Brent

iTrader: (1)

20° initial is a bad idea IMHO. That's 14° more than the factory setting. By inceasing initial by 14° you have raised WOT from the stock 30-34° to 44-48°. This is a good way to detonate the engine and hurt parts.

Head on over to the Prom board and do a search on miniram. Some folks over there have encountered the same thing.

Chvywolf

Have you checked to see if your running lean. I know that some backfires threw the intake are caused by that. Happend to mine. Just my .02 cents. Laters

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"Oh yeah, well i'm taller"

89 RS Conv 305 700R4
85HO heads
Edelbrock intake
Holley 600
Hedman Hedders and Y pipe
Flowmaster
B&M MegaShifter

Neil

Thanks guys, i'll check out the Prom board like you suggested. Also, I think I found part of my driveability problem, I noticed a slight vacuum leak near the throttle body and it turned out to be the intake gasket, specifically intake port #1.
So, off comes the intake!

Slow Iroc

This is why I sold my LT1 Z28...

The Mini-KaBoom-Ram and LT1 intakes have a design flaw because their small plenum dosen't allow enough air to be stored, which causes the rear 4 cylanders to be chocked for air, cuasing your "Surging" below 1700 RPM in the intake, and well, in my case, a complete LT1 rebuild because of this "SMALL" design problem...

I know this isn't comforting, but unless you are planning to use a blower, the single plane EFI setup is a much better way to go... You should be able to get about 75% of your money back by selling the MiniRam used if you decide to do that, which should just about cover the cost of the single plane, being that's it's cheaper (including throttle body, fuel rails, sensors, and intake). Also, there are some MEAN plate systems you can use this those intakes (500hp I think is avaliable!).

Ed Maher

lol, i'm just curious what the line of thought was on ADVANCING the timing when it was already backfiring through the intake. Backfiring through the intake is a sign of too much advance / too lean, why feed the problem more of it's cause.
As to the fix, as usual in these situations, it would help a lot if you had more of your combo, most importantly, MAF vs. MAP.
...ed

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Ed Maher - Moderator @ The Carb Board
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

Neil

Ed,

I have a MAF system and some of my mods listed below. As for my thought process of advancing the timing when I was getting a lean pop in the intake---it was my last resort and it worked incredibly well!! A few guys on the DIY PROM board have had this problem w/ the Miniram, so hopefully I can tune my chip properly and return the initial timing to a normal/sane setting!

However, w/ my scanner on and when I hit 4500rpm @ WOT, there is about 20deg of spark retard. (I want to keep this motor in one piece for now, so I won't be perfomring anymore WOT runs until I fix the problem.)



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1987 383 cu.in. IROC-Z: TPIS MiniRamIII / GM FastBurn heads/ 10.6:1 compression
Comp cams custom grind: Dur'n 224/236 Lift .536/.555
Strange 12Bolt Diff./ Neil's Home-Built BulletProof 700R4+Vigilante 2800 stall converter
MSD Billet Distributor, Dig 6+, & Blaster coil
Hooker Supercomp Long tube headers

TRAXION

The problem is easily solved in the Speed Density system through use of the Pump Shot table. MAF systems require a lot more tweaking (from what I have heard).

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org