I have 91 5 speed 355(orginally 305) with mimi ram,AFR 190 heads 10.23:1cr 52mm TB 24# injectors, AFPR,MSD 6al.I'm using ECM 8d I programmed my first chip last nite.I set it for the bigger injectors,and cubic in.Tried it and it runs very rough.wont stay running on it's own.doesn't rev very good.plus is backfiring .Running a bit rich according to my A/F gauge.I know I should have a scan tool looking in to getting one.But does any one have any pionters on something I could do till I can get a scanner.Thanks for any help.I'd like to be to get a few breakin miles on motor

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If those are SVO injectors than you have to set the injector constant to 26 or 26.5. second what bin are you starting with? And as you stated you really need to see whats going on with a scan tool or equivalent or else you will just be guessing. Have fun.

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355 10:1 , AFR 190 heads, LT4 HOT cam w/ 1.6 roller rockers, complete Superram intake, 58mm BBK TB, 24# svo injectors, screens out of MAF, MAT relocated, March underdrive pulleys, Streetdampner, Crane HI-6 ignition, 160 thermostat, K&Ns, TES headers(Jet hot coated), Mufflex 4' cat back, B&M shift Kit, 2500 converter, and 3.27s. Chip is custom(doing it myself). 2 1/2 Harwood and just painted.

 

yes they r svo's I have it set at like 25.I know it should be a little higher but want to have a little insurance so it wasn't to lean.I went with the 90L98man8D.If I did it right.I download it from ftp://ftp.diy-efi.org/pub/gmecm/bin_lib/1227730.then opened it on tuner cat then made the changes lsted in earlier post.I fugered the bin would get closest to my set the going with a 305 bin I'm I correct on this.

 

I assume the backfire occurs when you are getting into it right? If so monitor your fuel pressure at higher fuel flow rates (heavier throttle/higher rpm). Leaning out can often cause this. Could have a plugged fuel filter or bad pump. Could be running lean at heavier throttle because of programing too. Check your timing as well. Maybe you already did this, but I figured I throw that out at you. Could also be ignition problems.

good luck.

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82' Z-28. 327" w/ flat tops. 216/228/112LS. Pocket ported 041 heads 1.94/1.50 SS valves. World Class T-5 from a 91'. Best run? Runs with 2001 vette to 150mph! Soon to be converted over to TPI w/ supercharger.

 

When mine did exactly that, I had two ignition wires crossed. Double check that you have all the wires hooked up in the proper firing order.

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92 Z28 5.7
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Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.

Click here to see pics of my car !

 

I don't have a miniram so this suggestion isn't from personal experience.
Once all of the other good suggestions has been taken into consideration, check your pump shot. It may not be enough thee all mighty miniram.
I remember Tim, and some others having alot of problems with it being too lean when you "got on it", yes, just for that split second and then would richen up.

Do a search for minirams and pump shot info on this prom board. I am sure you will find Tim(traxion)'s post about the pump shot info i'm referring to.

Brendan

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1987 IROC-Z L98,SR,EB 6085's,LPE 219/219 SR Cam, Crane 1.6RR, EB TPI Base, 58mm TB, Stock T5, 30lb SVO, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, Aluminum DS, 94 Disk Rear, Adjustable Prop Valve, Precision 3.73 Gears, Weld in Sub-Frame Connectors, Hotchkis LCA's, KYB Shocks/Struts, Poly Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm, Big stereo, 730SD Conversion.

To see the ROC, Check out the webpage Here

 

Yeeeeeup. I had to boost up my Pump Shot table in order to take care of that off-idle lean tip-in. That stopped the backfire.

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

 

Thanks for the ideas I'll check on the fuel pressure in the morning

 

Thanks I did the search and found just that. I will give it a try and go from there.while reading one of the posts.came across this something about(EST SIGNAL is disconnected)for setting the timing what is this exactly.


[This message has been edited by chiefz28 (edited July 26, 2001).]

[This message has been edited by chiefz28 (edited July 26, 2001).]

 

You must disconnect the brown/tan EST wire to set the timing. Not sure where it is on an F body. On the Vette its new the brake booster. What I do is after its warmed up, I disconnect it, set the timing to 6 degrees BTDC, turn the motor off, reset the ECM and then fire it up and your set. This could be part of your problem. I had major problems with the Miniram on my Vette with the 165 ECM. I switched to SD and now I can run all stock AE fuel enrichment tables (pumpshot) with no backfire. I have slight hesitation off idle if I goose it but that's it. I think a minor adjustment in the Pump shot for me will get rid of it. I'm putting on a 58mm TB soom so I'm not worried about fine tunign right now. I'm expecting the 58 to require alot bigger pump shot value. The miniram is one tough mother. Now that my 396 is singing to 6300, I think it was all worth it.......I think. I still am having some problems with either being too rich or too lean in non PE accells to 6000 or so like 60-70 KPA range. Never did get it right. I have an unusual looking upper VE curve where I need more fuel in the 2500-3000 area, less in the 3000 to about 3800 area and more in the 4000 to 4500 area. I have a slight double hump effect if you will. The only way to get it to run normal (and mightly powerful I might add) is to lower the PE enable to 30% 3600 RPM and up. I guess I'm covering up the problem but I want to enjoy my car awhile for now.

On the pump shot, after you get your timing correct assuming its not, add fuel in 10% increments until the stumble is gone.
Good luck and keep us posted.
Jason



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89 Six Speed FX3 coupe
7730 SD Conversion
More Performance 396cid specs:
Callies 4340 crank 3.875 stroke
Lunati Pro-Mod 5.85" rods
SRP Pistons 14cc dish
Comp Cams Custom cam 550 lift 220/229 duration
10.8:1 compression
AFR 195 competition ported heads
Miniram and TPIS 1 3/4" headers

 

hey thanks.just so you know the EST is located behind passenger side valve cover(F-Body).to reset the ECM you disconnect the battery correct.I know when I tried to set it before i'd set it at 6 then if I kept the light on it for a moment after setting it the mark on my balancer wasn't there only for the brief moment that I was turnig distributor.About that mini ram being a mother.with you on that. Seems thats about all you hear about it.If you come across any more pointers for tuning the mother I'd be glad to listen.your refering to the PUMPSHOT vs DIFFERANTAIL TPS



[This message has been edited by chiefz28 (edited July 27, 2001).]