I'm trying to find a comparison of all the aftermarket fuel injection systems out there along with pros/cons of each and the stock GM stuff.

I've got a 1988 5.7L IROC that is mostly stock for now. I'm considering swapping to a 730 ECM but the Accel and FAST systems seem tempting also.

Has anyone done a fair comparo between the systems?

 

Ok, I do not understand why more people do not respond to this type of post. I have done months of research and have burned hundreds of chips. Now I am upgrading to a FAST ECM. Here is why.

GM ECMs- You can upgrade to a GM ECM but you are still in the 90s. If you go with a 165 or a 730 you are doing a lot of rewire to again burn chips. The end result is a system that does not have a closed loop WOT computer. To properly tune this car you must Dyno the car and constantly burn chips to get the max HP. Or you can install a wideband O2 sensor and burn chips to get the mixture correct. What sold me on a 3rd party ECM is the fact that O2 sensors only work at 14.7 A/F mixture. Where I want to run my car at 12.7-13.1 O2 sensors simply read rich. In conclusion I saw GM as a lot of work not to solve the big problem. What killed me was when you hooked to the ALDL connector, the timing would be altered. What a joke.

Accel- Everyone who has not installed a Gen 7 that the Gen 7 is the way to go. Well I spoke to about 5 shops and serveral individuals who tell me that the Gen 7 is not there yet. Apparently there is limited support and the software is buggy. The stories were consistant. Finally the price was higher than the FAST unit and the reputation was not there. All said the Gen 6 was a great unit but it is discontinued.

FAST- Everyone tells me this is a great unit. Easy to tune and it is a copy of the Accel Gen 6. Many told me not to go with the FAST because it is a copy of the Gen 6 but many did not do the install of the various unit. They all told me how the people worked at Accell and moved to FAST and this was a bad thing. Well I worked for many corporations and in many cases people leave companies because companies loose focus of quality and tend to hose the consumer. When all is said and done my guess would be that Accel lost focus and wanted to ship the Gen 7. Many thought this was a bad idea and left or got fired. Thats fine. They started their own company and took the good and made it better.

Frank

 

Thanks for the info...I can't believe this topic was viewed over 60 times before someone responded.

I always though the FAST product was Fel-Pro and totally different than Accel.

Anyway some of the details I am trying to work out are things like how much trouble is it to get an aftermarket ECU to control the TCC and the cooling fans and such. I can't seem to find any documents that explain how many "accessory" connections each ECU supports.

The Holley unit looks good also but again no real details that I can find.

Also does anyone make jumper harnesses so I can "plug and play" and not hack up my factory harness? That could be a big factor in picking one unit over another.

John Guynn

 

Lockup converter- This gets tricky- No aftermarket computer will support this as far as I know. I have a 4 speed with the automatic overdirve. I setup my wires to only engage this in 4th gear.

Lockup converters will require you to do what gm did in the mid 80s. Use a vacuum switch to turn the converter off. If If my memory is correctn in 88 you have a th700r4. This has a valve body that controls the engagement of the lockup converter. So you would be fine with a switch.

Fast was Fel-Pro


Cooling fans and fuel-pump are controled by the new ECU. Except the fuel-pump relay needs to be rewired to support a negative trigger verse the positive trigger.

Holley- I did not find anyone who recommended this for drag. Looks like the unit is for TBI.

White racing makes a jumper harness for these systems. I thought of that. I found my harness came out so quickly that if I ever wanted to go back I would just buy a replecement for the cost of the jumper unit. I ripped my harness appart to retain the AC controls, Oil Pressure controls. the Knock sensor controls and the fuelpump relays.

Frank

 

I don't mean to sound like an *** but the research you did was nothing more than hearsay. Someone told me this, someone told me that. Based on those "facts" you went and dropped close to $2K on an aftermarket ecm. Anyone on this board that has been around cars and efi for any length of time and has a true understanding of what they do can tell you that there is a place for aftermarket ecm's but if the application is anywhere near stock, the factory ecm will do the job just great. If you are running naturally aspirated, and not far over 500 hp, you can run a factory ecm. If boosted, you "may" need one sooner than that. What it boils down to is not the software but the injector driver. Factory injectors are high impedance units at about 16 ohms. F-car ecm's with TPI only have one injector driver. When you get to 36 lb injectors and one injector driver, the idle pulse width becomes way too short and the ecm has a more than difficult time controlling the injector. This is where having low imp. injectors come in handy as they can run at a slightly lower pw but the factory ecm driver can't support the low imp. inj's because it'll let the smoke out of the driver. Of course, sequential may be of benefit here also and again, aftermarket ecm's can do that too, but at a greater cost. With that being said, if you run boost or have more than 500 hp there is the SYTY ecm which has two inj. drivers. But since I have never dealt with them I couldn't tell you what kind of heat they can take or if they run better at idle with a bank to bank system and large high imp inj's. These ecm's can be run without boost, BTW. So in a nutshell, this is "my opinion" of when an aftermarket ecm is necessary or a better option than a factory ecm. And if it were my money it would go towards a TEC system. Very small ecm, DIS, been around forever and they can build you a wicked looking individual runner system all in house. At least that's what they said the last time I talked to them which was a few years ago.

As far as the concerns of the stock o2 sensor, again that goes back to trully understanding it. Yes, it is only accurate at 14.7:1. No, there is no closed loop WOT. No, you can't run a wide band into the closed loop part of the software- that is of course unless you are really good at writing code in which case you can pretty much make the ecm do whatever you want- but cars run pretty damn well without it now for far too many years and through today. Although running a different ecm the LS6 still uses a narrow band o2 sensor and it makes 405 HP at 6K rpm. You can however just have the o2 disconnected forcing the ecm to run open loop. This leaves you running off the fuel maps in the prom. Hook up a wide band to the ecm and monitor via the ALDL and tune to whatever A/F ratio you want with confidence of accuracy from the WBo2. The only thing there is that you won't have any BLM corrections. And the timing being altered with the scanner hooked up thing is not entirely true. You must have been putting the ecm in one of its modes of diagnostics which made it alter the timing. You may be sick of hearing people telling you to read the archives at DIY PROM but the fact is that is the best way to learn about the factory ecm's. There is just too many questions about them to be answered one post at a time.

 

The research I did was more than hear say. I personally programmed the 870, 165 and 730 computers (all motors had light mods). I also have friends who have a Gen 6 and am close to a person who is selling a haltech because they can not get it tuned in. Everyone tells me how wonderful the GM ECMs are, that’s great, but how much time do you have to invest in programming one for a 427ci SB. I have a motor with a custom stroked crank, 6 inch rods 220cc AFR heads and a ported TPIS Mini-Ram. I have 30lbs injectors to get this thing started and now will bump up to the 36s to get the horsepower I am looking for. I do not consider this stock and think it’s a joke trying to tune a GM ECM.

I agree if the motor has minor modifications or if even stock you can do a very good job tuning. In fact I have tuned a 165, 730 and ZR-1 computer with tunercats software. These were all stock or had very mild modifications. In my latest project car a 1985 vette, this car had the original 6870 ecm. This is a real junk with a very low baud rate and was MAF. The only way to get the ALDL to output is to put it into a diagnostic mode. In my case I needed a new computer, the choices were clear given the size motor.

Yes a stock o2 sensor does fine after to tune your engine. Lets not forget about the tools and equipment that GM would use to tune the LS6 to achieve 405 hp. I would assure you that they have several wide band O2 sensors as well as temperature sensors on the exhaust pipes. Sensors before and after the Cat and sensors on the intake. When all is said and done then they freeze their code and ship it in a cheap ECM. Why would a production car need a wide band O2 sensor. The program is created and is repeatable. All they need to measure is a specific area in the engine exhaust spectrum to identify if there are any deviations that would cause the check engine light to go on.

When tuning a motor you need this feedback. For example what good is putting you car on the dyno and not hooking up a wide band O2 sensor to it. What good is knowing your car can put 400rwhp when you do not know if this car went rich or lean and by how much during that pull. Yes you can do multiple runs on the dyno but if you add the dyno time up I think it will surpass the price of the wide band capable computer.

DIY PROM- Been there done that. Great posts.

Frank

 

Well I am glad we agree on several things and I am glad that you knew someone with an aftermarket ecm before you made your decision. I do understand the GM ECM is at it's limits for your application but I hardly think trying to make it work is a joke. The guys at GM did put a lot of time in the software and have lots of resources at their hands, just as you stated in your post, and that resource is very much worth tapping into. It's a cliche now but "easier to tune doesn't mean a better tune". All you have to do is look at the tables for TCC and you know they had a lot more thought then "lets just lock it up after fourth gear at 45 mph".

The only thing I disagree with is the dyno tuning. I don't think it's necessary or the utmost authority on how much power and the perfect tune you have. I believe it is a great tool to assist in tuning a car at WOT. It will make things much easier and faster. But all you really need is a performance meter and a desolate stretch of road. Having a wide band makes it faster still and don't forget you can build one of those through the DIY community for less than $300. Having the car actually moving down the road is a much more accurate way of doing things. And of course the 1/4 mile being the ultimate authority.

Hector

 

I agree the TCC should be given more respect but for a street light drag or 1/4 mile race who cares about the lockup. I just need it to get me to and from the race.

Finally, the 1/4mile is the ultimate answer to all this.

 

FWIW, I have the Gen 6 Accel, and it controls the TCC and the fans just fine. I wish I had a bit more control over the TCC, but it works. The fans can be programmed to turn on at any temp (within reason).

 

Do any of these systems have control over the EGR? Building a high HP engine is one thing but having it pass emissions is a must for me.

 

I'm toying with the idea of converting one of the old banks TT systems to work with a TPI L98 and use the FAST system to control everything. After seeing what Monty accomplished, I have faith in the FAST systems.

 

Just remember how swell the aftermarket ecm is when it dies on a Sun night 400 miles from home. AND then a couple hundred bucks, and a few weeks to repair it.
No Thanks.

Yes, the GM ecms are more time comsuming to learn, but that's what makes them so good. Get it right, and nothing will match it.

As for the on the fly, I've seen lots of guys just fly by optimum because they were in such a hurry. I perfer to burn a chip, write my notes, and actually understand what's going on. Maybe just a midwest thing, but I've seen more lousy running aftermarket ecms then oem ones, of course talking about in Hot Rod use.

When you really get to the nity gritty, find out who all was involved in the DFI, Holley, Speed pro, ecms and one guy has contibuted HEAVILY to all of them.

Lots of old Black Buicks running 10s, and 11s with a 1987 GM ECM.