i know this question has probably been asked but i would like for some of the head honchos to reply if you could.my sig says it all with all these mods going as slow as i was i thought it would be the chip now that the ed wright chip is in it runs 10x better than the old chip but i'm losing my mind trying to iron out the idle no matter what i do it wont settle down.so the question i have is who has used dfi before would it make my life easier(keep installing new chips as opposed to plugging in my laptop and changing the values) than getting the equipment to burn my own proms.the chip runs great under load but lumpy as hell at idle once and a while stalling.i have 3 weeks to return the chip and go with dfi if i'm gonna do it.also is it as hard as everyone says to program?

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87 trans am,gm crate 350(4 bolt mains 10to1),L98 aluminum heads,LT4 hot cam,slp runners,slp 1 5/8 headers,3in.y-pipe,edelbrock base,hi flo cat,air foil,afpr,as&m ported plenum,gutted airbox,t-5 tranny w/centerforce clutch and a 3.27 9bolt(11.9in. brakes),ed wright's fastchip,relocated iat sensor,160 fan switch,tb bypass,accel supercoil,cap& rotor,hollowed maf,slp 3in. catback,a/c delete.

shooting for 13's!!!!!!!

14.10@97mph w/2.01 60'(auto ET)

slp catback is finally on!!!
fastchip prom is in.OH!MAN!
FLOWMASTER S.U.C.K.S

 

What you are experiencing is part of the problem with MAF and "lumpy" cams. It's primarily caused by the reversion through the MAF. You probably could "tweak" it a fair amount, but these are "driveability" issues that require a LOT of hands-on tuning us DIY'ers talk about.

And this is my biggest beef with "formula" eproms from custom eprom writers...they concentrate on the WOT, but because they don't have the time to work on part-throttle and idle for the "unique idiosyncrasies" you REALLY have to do it yourself.

If you are seriously considering DFI, why not look at converting to SD? The cost of the conversio is a hell of a lot cheaper. I think SD is easier to modify and SD is fully emissions compatible IF you must be concerned. Lastly, if your DFI should die, you will have to wait to get a new one and it will be damn expensive to replace if it is not covered by warranty...and your model may not even be covered.

With SD, you can pick up the ECM from any 3.1 Cavalier for about the cost of a case of beer. There is PLENTY of information available about the conversion, so it is not uncharted territory. The tools needed (eprom burner and editor) are readily available and just over $200.00, and Craig Moates has a freebie scan tool available for SD if you don't feel like buying a scan tool.

A Flash Prom can be installed on the SD so you don't need a UV eraser and it takes only seconds to reprogram. In all honesty, this "programming on the fly" is overrated. When you get into "tuning" you want to see the results of your scan data before you just start "playing" with settings. And if I go the track, it takes me less than a minute to pull my eprom, insert it into my burner and reprogram it with my Laptop (thanks to an DC/AC Power Invertor powered off the cigarette lighter).

One final note, I have seen a few DFI guys come to the DIY PROM Board seeking assistance, and there isn't much help. Not that DFI guys are shunned, but because there just isn't that much knowledge about them...so you are REALLY on your own. With SD, you have a ton of guys on the DIY PROM Board that can help you .... not only for max performance, but for driveability and (my personal favorite) better gas mileage. How does 30 US MPG with an L98 grab you? That's what I get and my car runs GREAT for a 175,000 mile engine.

 

Oh, one more thing...no more Code 33s. And SHOULD you need to get a new MAP sensor (they seldom do though) they are only around $10-20.

If you MAF sensor is still good, you probably can sell it to one of the many guys who have problems with their MAF sensor/burn-off relay and reduce your costs for the conversion and all the tools you'll need to burn your own eproms. Plus, no more 255 gm/sec limitation.

 

Although Glenn's answer makes sense, he didn't even mention the hollowed out MAF as a possibility for why it doenst run right at idle/light load.

Yet another reason to convert to SD. It is a very real possibilty that you are out a $400 sensor.

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Ed Maher - Moderator @ The TPI & Carb Boards
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

 

I never even noticed that one in the "sig" Ed. I was just speaking from all the experiences from "former MAF - born again SD users" have stated on the SD (I mean DIY) PROM Board.

 

Basically I agree with Glenn in getting into your own prom burning.
But as for the hollowed out MAF? What was hollowed out? The fins and screen? If that is all that was done it won't have any affect on the idle just because I have that done to mine and the idle is good. Also I don't have the LT4 hot cam but the ZZ9 is simular.
First I would check for any vacuum leaks.
Then what made my idle real bad was that I did not tighten down the hose clamp from the MAF rubber hose to the throttle body. Air was getting into the throttle and not being registered through the MAF. When I tighten that the idle settled at 700rpms instead of bouncing from 400 - 800 rpms!
I am not saying this is YOUR problem but it is something to check.
As for Ed Wright, I heard alot of good things about him but it can only get you so far.
Burning your own will get you to best level of performance for YOUR car.
If you don't want to swap over to SD there are still alot of guys programming proms for their MAF cars. And the SD guys still know alot about the MAF systems too .

Bottom line is you have to decide what you want to do and how much money to spend.

Good Luck!

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89 IROC 350 Auto
MSD 6AL
Custom DUAL Exhaust
Edelbrock Performer 6085 Aluminum Heads
ZZ9 Cam
TPIS Level 5 Chip
And Free mods.
(stock intake, runners and suspension)

13.879 @ 98.90 mph (with 2.77 gears!)


Moderator of http://www.iroczone.com

Member of JFA Crew


[This message has been edited by Ski89Z28 (edited July 19, 2001).]

 

I have a setup which is pretty similar to yours;

'86 Camaro SC

'89 350 2 bolt block
Factory crank
TRW forged pistons

'86 Corvette aluminum heads (fully ported)
9.5:1 compression
'86 Corvette TPI Manifold (ported to match runners)
Air Flow Research "Hydra-Rev" kit
1.5 Crane Gold roller rockers

Comp Cams hyd. roller cam
Lift ; .520I/.540E
Duration @ 0.050 ; 236I/242E
L.S.A. ; 110

MSD 6AL ignition

Ported plenum (also matched to runners)
24# injectors
52mm throttle body
K&N filters
A.F.P.R.

SLP Runners
SLP 1 3/4" Headers
SLP 3" exhaust (cat. back)
Random Technologies Cat.
Completely emissions legal

R.O.D. 6 speed trans.
B.W. 3.27 rear
South Side Machine lift bars
Complete '89 Iroc suspension and steering

I have done both the custom prom with the MAF sensor (stock ecm), and I also have a DFI.. I have played around with both systems to see which one would give me better results. Both systems perform excellent for me with VERY similar results. Both systems give me a GREAT idle too, doesn't wander at all.

One good thing about the DFI is that it uses a MAP sensor instead of a MAF sensor so you are able to remove the restrictive MAF sensor. The DFI is also great if you plan to install nitrous or a supercharger because they have built in fuel/spark compensation for both. I have also found the DFI easy to program and you can program it “on the fly” to see your changes immediately. One thing about the “on the fly” tuning is that while you are tuning the DFI you can see exactly where you are in the fuel map (real time), so if you see that you are running lean or rich (there is a real time bar graph which is displayed under the fuel map to show you how lean/rich you are) you will know exactly which cell or area of cells on the fuel map need to be changed. The same holds true for the spark table and all of the other menus which you tune the DFI with. And of course, you do not need to remove the prom, burn, install, test, and then remove the prom again, burn again……….

Of course there are advantages to the stock ECM with PROM burning. First of all the price. It is a lot cheaper to burn your own PROM vs. buying a DFI. If you do decide to burn your own PROM than you can convert to speed density (MAP) also to remove the restrictive MAF sensor, but you do not have to. I have had good results with the custom prom using the MAF sensor.

I guess the most important thing to you here is that either system can give you a great idle, even the stock system with a MAF. If you look at my cam specs you’ll see what I have and I am able to get a GREAT idle with both systems, so you should be able to also so it might be something else causing your poor idle, or it might be the chip.


[This message has been edited by TunedPort350 (edited July 20, 2001).]

 

i know it's the chip i was running an ads(crap)chip both 3305/t-5,350/auto itt would idle like it came from the factory with the 305 chip but the 350 would make it stumble.also i only have a problem with it during warmup after it reaches 160 it stays there and idles great so i'm thinking of using ed's chip as a base cause the wot is phenomenal it just needs a little work thhhe other thingi don't wanna switch over to sd and render this chip useless i'll see what happens.

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87 trans am,gm crate 350(4 bolt mains 10to1),L98 aluminum heads,LT4 hot cam,slp runners,slp 1 5/8 headers,3in.y-pipe,edelbrock base,hi flo cat,air foil,afpr,as&m ported plenum,gutted airbox,t-5 tranny w/centerforce clutch and a 3.27 9bolt(11.9in. brakes),ed wright's fastchip,relocated iat sensor,160 fan switch,tb bypass,accel supercoil,cap& rotor,hollowed maf,slp 3in. catback,a/c delete.

shooting for 13's!!!!!!!

14.10@97mph w/2.01 60'(auto ET)

slp catback is finally on!!!
fastchip prom is in.
kicks you in the A.S.S at wot.
FLOWMASTER S.U.C.K.S