Ive got a miniramed 383 in my 85 vette with a custom done prom for the setup. The car runs a little rich it seems all the time (fuel smoke out back until warm, then still has a little) When you give it alot of gas or try to rev it over 3000 rpm it stumbles very bad and will backfire out intake and exhaust. Like its out of fuel or like its flooding. I would guess flooding from looking at the plugs. what could cause this? I cant even drive the car because its so bad

 

i really dont know too much about anything, but if its so bad you cant drive it, it might be worth making sure all your plug wires are plugged onto their correct posts on the distributor cap. I had mine switched once and it ran kind of like your describing. also check to make sure all the connections to your injectors are tight, i know you've checked everything three times, you usually find the mistake on the fourth check. good luck

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1986 Trans Am
305 TPI
"If it's not one thing, it's another!"
http://www2.hanover.edu/hierlmeier

 

Ive double checked all that several times.

 

sounds like what mine was doing when I swapped my new 350 in place of my 305 4-5 years ago...I remember the day really good b/c I went to test it to see if I fixed it and got a ticket for 112 in a 55...luckily he didn't turn the radr on until I was on the brakes a split second or 2. Anyways, mine turned out to be that I wasn't unplugging the brown wire on the passenger side firewall. I was unplugging another brown wire behind the distributor. You probably already know about that wire but it sounds like timing. Either you aren't unplugging the correct wire sticking out of the wire loom or your distributor isn't in the engine correctly. Is the rotor button pointing at the #1 cylinder when its at TDC? If not the distributor is off slightly...sounds like it's retarded.



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1988 TA 300+hp 350 w/ TBI and Holley TB unit, Holley projection intake,
WC T-5, 3.42 gears w/ Auburn posi. MSD 6A, edelbrock TES headers, dynomax 3" cat and cat-back system, ACCEL coil, polyurethane bushings all around, aluminum driveshaft, Mr. Gasket open air cleaner.

1993 S-10 w/ 4.3L V6 TBI, slightly bigger cam, Mild polish job and 3 angle valve job on heads, Edlebrock TES headers, Dynomax cat back, MSD 6A, ADS chip

2000 Kawasaki KX 125

 

This problem is most likely 2-fold.

First - your custom PROM is from where? I haven't met anyone yet who can get a custom PROM 'dead-on' the first time around. There are just too many factors. You really should look into burning your own PROMs ... its is cheaper and less frustrating. Anyhow - back to my '2-fold' theory....

1) I can almost guarantee that your car is running rich at idle. Bigger cam = less manifold vacuum = less vacuum at fuel pressure regulator = more fuel PSI = more fuel dumped into engine. This creates a lumpy cold start until the engine goes into closed loop. If the BLMs don't bottom out then you'll be OK in closed loop. If they do bottom out (BLMs=108) then it'll still be rough in closed loop.
2) The 'pump shot' table needs to be increased dramatically. A LOT of people experience the dreaded backfire after installing a MiniRam (especially if they bump up the ci too). What's happening is that as soon as you open those throttle blades you get an immense amount of air entering the cylinders. Even though you are running rich at idle you are going to be running lean at just off idle.

Tim

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• Program your own PROMs!. Read my article to get started!
• Research and Experiment before asking questions.
• This is not a chip store. Go to the classifieds if you want someone to sell you a chip or give you a BIN.

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

 

A guy named Craig Marcho burned the chip for me. hes a frequent on the corvetteforum

Basically this is sounding like all chip tuning? I cant afford to go spend huge money on chip tuning. Im trying to figure an inexpensive way. plus i have no knowledge of proms