Hello. I've spent most of the day searching the intraweb and this website trying to better understand what kind of induction to shoot for. I have a rebuilt '89 350 (from a truck, now in a Jeep) that has a Compucam 2030, shorty headers, Edelbrock intake, adjustable regulator and soon to be installed second hand Performer centerbolt heads.

What do I need to do to my throttle body to support this? I want a good idle and throttle response (for off roading) with enough horsepower to get around town. Max horsepower isn't a top priority, but I wouldn't turn it down...

Can I do anything with my TBI cheaply? Throttle body upgrades, injector upgrades and chips add up quickly (making multiport look favorable). What do you think?

 

You've basically changed every single component in that engine, and your ecm still thinks it's running a 305 or stock 350 depending on which ecm you have. This is not good, it won't run worth a crap, no matter what throttle body, injectors or mail order chip you put in it. If you want the whole story on mail order chips, do a search. In a nut shell they can sometimes add power on a stock engine, but on modified engines they are useless.

The only way to get this thing to run correctly is to learn how to burn your own chips. There is a whole message board here dedicated to it. Start by reading the stickies at the top. Don't worry about the in depth conversation thats taking place currently on the main message board, it's all going to be way over your head. Your jeep may or may not even start with the new heads. Your gong to be leaving alot on the table if you don't look into tuning. Depending on the specs on that cam you could have a 300 hp combo there, and there just isn't any way a stock tune will support that.

 

That's a good idea. I like the idea a custom prom (then I'd finally get to use that ALDL connector swinging under my dash).

OK. So my computer will need some remedial software training. Even if I burn my own chips, however, I don't want to start with the stock throttle body do I? Then I'd be taking data and burning chips for something that will never get me where I want to be. My question is, "should I fool with the TBI or save some $$ for a multiport." Except for a slightly different cam, my setup would look exactly like Edelbrock's Power Package.

I have a hard time believing it may not start. I've talked to people that swapped Vortec heads without a chip change and it ran OK (just lacked high end power). The Edelbrock heads have very similar, if not slightly lower, flow numbers than the Vortecs. My Jeep idles and drives smooth right now (with everything but the heads) so I'm going to go downtown and get some crawfish while I think about it. I just won't drive as quickly as I could if were tuned properly.

 

Well, not starting is a stretch, but very realistic if you add in a bigger throttle body and bigger injectors. For the HP your wanting to make, you need to get ahold of a big block throttle body, they are the same thing as the holley TB's except most of the GM TB's have big injectors. The BB TB has 2" or 50mm throttle bores and will supply plenty of air, TBI is fuel limited, thats why it's best to get ahold of a TB with big injectors.

Is the vehicle currently running on the TBI setup? I've messed with a couple of jeep FI swaps here locally and most of them don't have a speed signal going to the ECM, this emposes some problems that can be worked around, but not fully cured.

 

As for wheather you should save for a multiport setup or keep the tbi. You going to have about 150-500 bucks in your burning equipment depending on how nice of stuff you want, and about 100-300 in your TB. So that works out to being about 10-30% of the cost of an aftermarket EFI setup, that will still need tuned. Don't even consider TPI you'll have all the same problems as you would with TBI.

 

OK. I purchased an ALDL cable, USB adapter, and downloaded WINALDL. After taking a few datalogs, my computer puked. In the meantime, I installed the Edelbrock cylinder heads on my 6000 mile (rebuilt) '95 Suburban motor. The results are...

Starts and idles OK.
No smoke - the previous valve guides were no count.
Fewer knocks - something in the old valvetrain was noisy. I drove around for about 20 minutes and only got 20 knock counts.
Drastically reduced power - it feels like it just doesn't want to go.
Increased engine temperature.
"Racking off" out the exhaust when I chop the throttle.

I'd like to purchase my own chip burning hardware/software, but am in the dark as to how to judge what's going on now. The O2 reading bounces around quite a bit, so I'm not sure that I trust anything it says at any given time. The BLM numbers indicate a rich condition which doesn't make sense. Anyone know of a thread that steps me through the process in a systematic fashion?

 

https://www.thirdgen.org/techbb2/sho...hreadid=288763

Here ya go. That guide is great. Now you know why I said tuning will be necessary with a big change like you made. It runs, but not that great at all.

Your O2 sensor is doing exactly what it's supposed to, it's switching back and forth over .45 volts. The Narrow Band or NB for short O2 sensor is just a switch that swings at 14.7 AFR. The ecm watches this swinging action and if it sees it staying to one side of .45 for too long it compensates (with BLM) to keep it swinging. This is why we say that the NB is useless for anything but part throttle, then it's perfect for the job.

You say your BLM's are showing rich, how rich? I bet it's peged at 108, this is usually the point at which the ecm can't make anymore corrections. Your new heads are probably not pulling as much vacume at part throttle as the old ones. So now your ECM thinks that your in the throttle more than you actually are. So being rich is perfectly normal. You now need to start working on your VE tables. Once you get this worked out it will run much better.

You also mention "racking off" in the exhaust and running warm. This sounds like your timing is retarded. I'd double check it before you get too involved in tuning. Did you remember to unhook the timing connector and reset the ecm after you set the timing? Either one will cause the timing to be off. If everything checks out, don't worry about it, it's probably just your tune being way off.

Keep asking questions and we'll get you where you need to be.

 

I checked the timing a couple times, but I'll check it again. I also threw in a new O2 sensor.

The fuel pressure is set at 13psi. Since this is the only thing I have to play with right now, I may decrease it a little and see how things run. A sample BLM chart is located here:

Narrow Avg BLM

This is random driving to populate the table. You'll notice my engine doesn't rev above 4000 or so. Is this a fundamental limitation of the stock TBI airflow?

As far as chip burning goes... If I have the standard 747 computer, what software and hardware combination is the easiest to work with? I've searched quite a bit and now my head hurts. My plan of attack looks something like this:

1. Get it running as good as possible for the time being
2. Identify what chip software/hardware I need
3. Spend money
4. Get the Jeep running better (learn process)
5. Consider modifications to get more airflow at higher rpms and repeat step 4.

Misc data => WINALDL data

Please be kind. I'm learning.

 

When I look at BLM, I usually just use Wide avg. I feel the narrow avg doesn't give me a good idea of how things are running.

Your 4000 RPM cap IS NOT because of TBI. I've datalogged 6800 once just to see if it would do it. Your so out of fuel by 4000 rpm your motor just won't pull anymore. I bet if you watch your O2 sensor you'll see it burry itself below .45 volts. Remember what I said about the O2 only switching at 14.7 if the voltage does go below .45 at WOT your way lean for WOT and you should lift imediatly and not flog on it till you get some tuning done. This is where you'll see that chip tuning is so necesary. If you compensate for your part throttle rich condition you'll lean yourself out even more up top, and if you richen it up to compensate for the top end it'll be a pig down low. You can fix all of this in the chip.

Once you start tuning you'll see your going to run out of injector pretty quick with all the mods you have done. I wouldn't go throwing a 454 TB in the mix just yet. I would do some tuning now and get the hang of it, then maybe look into getting a 454 TB with the 90 lb/hr injectors. When you swap in a TB with bigger throttle bores, and bigger injectors it really screws with everything. It's completely tunable, but you don't need to be chasing your tail with a new engine combo and a new bigger TB at the same time.

Edit: Almost forgot, I use tunerpro and just imported the $42.ecu file and turned it into a .xdf that the new tunerpro uses. .ecu, .xdf, and .tdf are different formats of the same thing. They are basically road maps that tell your editor where certain things are located on your chip. As for burners, check out www.moates.net you can use either the 85$ flash and burn or the 350$ autoprom, the autoprom allows you tune real time without shutting off the car to make changes, not necessary, but very nice. With the flash and burn, you can't actually program the stock style 2732's, but moates sells an adapter to use the newer flash programable chips that are more reliable and can be erased electronically unlike the the 2732's that requier a UV light eraser.

 

OK. I've ordered a BURN1, chips, etc and am playing with Tunerpro. Where do I get a good $42.ecu file? I searched the web and tried a couple, but they didn't really work.

Nevermind. Tunerpro kept crashing (and wasn't very intuitive), so now I'm evaluating Tunercat with the supplied $42 definition file.

 

You'll have to convert the .ecu file into an .xdf, tunerpro does this. I have a good one, let me know if you want it. Tunercat is easier to use, but takes longer to edit big tables.

 

Well... I spent a good deal of my Labor day weekend screwing with chips. I've programmed nine so far. My first three focused on getting the BLM numbers close. The engine ran smoother after this, but still didn't have any power. The rest involved increasing advance. At first, I increased advance across the board and noticed a lot more power from 2-3k. I then advanced the timing in high MAP/RPM cells and was rewarded a lot more power up top (which is from 3-4k on this particular engine). At this point, the engine was a complete dog in high MAP/low rpm regions (off the line) so I added some advance there too. It helped, but not as much. I'm trying to keep the factory trend of decreased advance at increased MAP, but where do I stop? I noticed a few knock counts as timing was increased (maybe 25 total for 15 minutes of stop and start driving).

My theory is that the swirl port heads are remarkably efficient at mixing fuel in low rpm regions. The Edelbrock heads need a lot more timing to get good combustion (the temperature also settled back down).

Edelbrock had a TBI performer package exactly like this (except for the cam). I'd really like to see the chip they developed using the dyno and smog sniffer.

 

Glad to hear your making gains, are you seeing the power of chip tuning yet?

Your starting to really see how different heads and cams move your power around. Your not going to get the off idle torque the swirl ports and small cam made, but it shouldn't be a dog either. It sounds like you've got the timing in the ball park. You might want to go back and play with fuel now. You might be way rich right off idle, which will pretty much make the engine feel like a dog, once you get the revs up and burn off the excess fuel it wakes up and starts screaming. Try backing off your pump shot parameters a bit and see if that helps. If so you may want to pull a little fuel out of your VE tables in those areas. I like to keep the pump shot at bare minimum needed to keep from going lean. It just makes for a more responsive engine. Do you see where a WB would be very usefull here? They pay for themselfs in tylenol and time saved. They remove alot of the guess work of tuning WOT fueling. You may also be rich up top too, this won't be quite so noticable to the butt dyno, but can kill 20-30 HP by being in the low 10's instad of the mid 12's. If you don't have the funds for a WB, start paying attention to the plugs, thier your best indicater to whats going on. If you haven't found out yet, the stock NB O2 sensor is useless for WOT.

Don't take anything I say as absolute, these are just trends that I noticed while tuning. Every engine is different.