Just for reference here.

On a stock 1989 MAF 350 EPROM (chip) I ran a 14.4 @ 96 as my best time with the motor in my sig.

On a lightly tweaked chip that I burned The same car ran 13.7 @ 99.3 about 2 weeks later. ("Later" meaning getting further into the summer heat.)

So... you are running a 355 mildly built motor that has heads, pistons, etc etc on a stock 305 chip.....

You be the judge if the chip could be the culprit.

If you want my stock 350 TPI cam I'll send it to you for just the price of shipping. Its yours to have or you can get a better cam which I highly suggest.

 

Before you toss teh TPI for a carb becasue of the bad mileage. YOu may want to get a chip for 24 lb injectors before you wash your rings.

 

Thats the thing that always amazes me with computer controlled cars. People know that the calibrations are set for all conditions for a STOCK motor. Then they scratch their head when the mod the crap out of a motor and add 50 cubic inches to it to boot then wonder why the car isn't as fast as it should be.

Bottom line here for the topic poster is I guarantee .7-1.0 second difference minimum with a chip designed for your application. Is a 13.6 acceptible to you? Would it be what you expected? Get some computer work done.

 

Sounds like your shortfalls are the heads and cam. The stock heads will not support good flow numbers and/or good horsepower without significant porting. By the time you put a lot of porting effort into the stock heads and then spend the money on rebuilding them, you might as well step up to some vortecs. The ZZ4 cam was recently put up against a stock L98 cam in a dyno test done by GMHTP or CHP. The only thing changed between the two tests was the cam. The ZZ4 only produced about 4 or so HP and 6 or so TQ over the stock L98. Obviously, these numbers would be greater depending if you had more mods done to the motor but not as good as could be had with a better cam. I am a firm believer in the HOT LT4 cam and its application to a street car. It has decent street manners and performs acceptibly when used with an 86-89 MAF EFI system. It will not work well under a stock speed density system without tuning because of the lack of stock vacuum at idle. However, I strongly suggest running more than 9.5:1 compression when using the HOT LT4 cam to take full advantage of its relatively long duration. Just my $0.02.

 

I'm way too lazy to read everybody elses posts, so I hope that I'm not repeating. I think I can be quite a bit of help, because your setup is VERY similar to mine. I built a TPI 355 for my 85. I've got 461 heads, a decent hydraulic cam, 24lb/hr injectors, SLP runners, Accel base, blah blah blah. For a while I was running the stock 85 computer and the stock 305 chip (which is the same as your chip with more conservative timing). My car ran like crap. The best 1/4 I could muster was a 16.1. The problem in my case turned out to be a bunch of stuff, but the biggest was the computer & chip. The 305 chip is calibrated for 19lb injectors. 24lb injectors are WAY too big. My car ran so rich that it would foul plugs within a few hundred miles. Black crap blew out of my tail pipes and stained the garage floor. I went through an oxygen sensor every few thousand miles. It just plain sucked.

Anyway... this spring I swapped to a 165 ECM and wiring harness out of an 87 IROC. I bought my own PROM burning equipment and I've burned a couple chips for it. I've got a long way to go, but already the car is a night and day difference. Since my 16.1 I also swapped the 700R4 out for a T5 and I've recently upgraded my open diff to a zexel posi. I haven't gotten it to the track yet (damn rain), but I can smoke the tires at will anywhere in first gear, and through 2nd and 3rd it pulls hard. 4th gear will get me up any hill I can find, and even overdrive gets me over anything if I'm doing over 40mph.


So anyway... if I were you I'd concentrate on your computer & PROM. The 85 ECM is junk and in my opinion should be replaced. It cost me less to upgrade to the 165 and buy all of my PROM burning equipment than it would have for 1 custom chip. You can tune the 85 computer, but your capabilities will be limited, and if you decide to do it yourself, you're not going to find very much support. A TON of people are burning for the 165, so there's enough information already out there for you to learn from.

 

165 ECM??

That happens to be what I am running. So if you wanna switch over to a 165 I'll help ya with the tuning as best as I can.

Jim, have you used the 89 ARAP.bin yet? Thats what I am using as a base.

 

redIroc- yes sir right sir I'll get right to it, sir
I just didn't think that only 50 more cubes would be that bigger deal on a MAF car (since the rest is stock (cam/heads) and the other mods are just add ons...if I had 500 lift cam and 230 dur with AFR heads I would understand....) but if you belive I could get to 13.8 by swaping ECM and chip then since I got all that siting in my garage (well except for the chip that is) I'll find some time to convert over. (if it doesn't go anyfaster after that, then I'll come back and yield at you ok? j/k )

Jim85Irocn- don't have that problem, the car isn't running rich like yours at all. But then I have a stock cam (which ever one it could be!) and plugs don't read rich at all either....

Thanks for all your help guys, here's what I'm going to do:

I'll switch to the 165 ecm and see what it'll do (that's the cheapest option right now). I have doubts on which cam is in my motor, it would be difficult to find out withou pulling it out. It is hard for me to belive that a chip will do such a big difference (because my motor is basically a stock L98 running on a 305 chip) but I have friends that do radical combos with LT1's and seeing how "well" the engine runs with a stock calibration (yes I'm being sarcastic, usually they don't even run at all ) I'll go on a belive that the extra 50 cubes will have enough effect to throw everything off.

so that's what I think is the wisest for now

 

Brad, I *sorta* tried the ARAP. A buddy of mine made a bin that was basically an ARAP with timing from a more conservative L98 PROM. The car wouldn't idle worth a crap until it warmed up. It would stall 3 or 4 times until it was warm, even with me trying to keep the throttle at 2k rpm.

I found that the ARAP isn't very 5-speed friendly, so I burned a version of the APYP bin, and the car seems to be a lot better with it. It still won't idle on its own for the first 30 seconds to a minute, but then after that it's real nice. I'm about done screwing with it for this year, but over the winter I'm going to make an ALDL cable so I can start using the Moates software to see what's going on. My auto x-ray just doesn't let me see enough of what's going on, and that's when it actually interfaces with the damned ECM.

 

my 91 trans am went a 14.1 with a 1.94 60'. all i had done at the time was a k&n filter, thunder racing air foil, and a flowmaster. since then i have put a pipe in place of the cats, put a 176 degree t stat in and put on some 1 3/4 headers. i hope to go high 13's at 100 or so mph.


David

 

THose pointing to a mismatch between chip programming and injectors are RIGHT ON THE MONEY!!! A 305 chip is designed for 19lb injectors. You have 24s. You're running fat by about 25% on your WOT fuel ratio.

MAF ENGINES ARE VERY SENSITIVE TO MATCHING THE INJECTORS TO THE CHIP PROGRAMMING!!! Don't discount this. It makes a HUGE difference. The O2 sensor can help compensate for the mismatch at part throttle but at WOT it's going stright from PRM, MAF readings and the programmed "injector constant" variable, primarily. There is very little it can learn if it's running very fat at WOT since it never looks at the O2 readings.

Regarding the ARAP BIN- I don't even think that applies because it's for MAP type systems, not earlier MAF systems. Totally incompatible technology as far as I know.

I'll lay money that if you put your stock 19lb injectors back in you'll instantly run faster. You may max them out at high RPMs, but at least the injecotrs will match the programming, which counts for a LOT.

It's custom chip time or consider upgrading to a later MAP-style FI system with appropriate ECM and wiring harness. FYI- m expereince with MAF systems is that they are FAR more adaptable to modified engines than MAP systems are, until you max out the stock MAF sensor- then all bets are off. You might be close, but I don't think you'll max it out with your combo.

 

Thanks Damon, you said a lot of things that I didn't get to.

If the topic poster were to switch to a 165 ECM then he would be able to use the ARAP.bin though. Although if he has a 9th cold start injector then there is a little work that needs to be done before the system will run correctly. Anyway, I agree about the MAF being easier to tune for radical combos than a SD up until you get to the 254 gram/sec limit of the MAF. Which on another thought, maxing out the MAF without a set of AFR heads and an "opened" up intake would be quite a feat. My car maxes the MAF readings at 5400 rpm with 195 grams/second. I have quite a ways to go to get to the 254 gram limit. My guess would be a mid-low 12 car would be capable of this.

Jim, the reason your car won't idle by itself is either because your IAC valve motor is unplugged ( like mine ) or it doesn't have enough "steps" there to supply the motor with enough "controlled vacuum." Basically thats what the IAC is, a controlled vacuum leak around the throttle blades. (And I know you know that Jim, this was just for reference for those that aren't sure what exactly that thing does.)If there is not enough air getting around there ESPECIALLY at cold start, the engine is suffocating. You might wanna try to add a few steps there at the lower IAC vs. Coolant temp table. Be conservative at first and if it seems to "try harder" to stay running you'll know that you are moving in the right direction.

Thats my experience fellas.

Hope this helps someone.

 

I do have my old 19lb injectors....would it be worth to re-use them and set the regulator at like 50psi, since they probably be too lean for the top end (due to the added cubes)? but then again, I think it would take as much time to swap out injectors than it would take to convert to the 165 ecm....

 

I think you should swap at least to the 165. and as you are hooking up the ECM have a chip ready with the 24 lb injectors programmed.

 

Damon, the ARAP bin is not a speed density (MAP) BIN. It's a MAF BIN used in 89.

Red... my IAC situation is a mess. I replaced the IAC, throttle body, checked all air passages 20 times and tested the IAC wiring a few times. It still won't work. My IAC counts are pegged at 128. I finally had to turn the idle screw a half mile to make the car idle. The IAC is completely non functional and I can't figure out why.