School me on TBI/OBDII vs Old stuff

[dudeiwin86]

As some may have seen, I recently purchased a 1990 K5 (350/700R4). its pretty stock, with a lift and tires. Ive mentioned some of the things im posting in this thread, but without much response so i wanted to make a thread dedicated to it.

i bought it because i spun a rod bearing in my toy (daily driver too-- heavily modified Dodge Charger) and needed a good daily.

I want to hang on to it as a long term project for some part-time off road, full time daily driver. which has now got me thinking.....

If i ever want to throw a cam in it....
If i ever want to swap the engine (im thinking 12v Cummins...)

Right now my intentions are to fix up some minor issues on my 1990 while i repair the Charger.. and once the charger is up and running ... im thinking about selling this 1990 to get an early 80 or late 70 model to replace it. (if i can ever find one without cancer)

I know the 1990 stuff isnt as complicated as what im used to (2006 dodge), but doing any kind of swap.. even throttle body porting.. head porting.. mild cam...
it requires a good re-tune (often on the dyno) just to make sure the engine is still SAFE.

How easy or hard is it to do work like this to a 1990 TBI model?
My understanding that so much as a re-tune is not easy
(im used to a handheld flash tuner...)

I feel like having an old car with a carb and no OBDII would make life a boat load easier.

Ive already ready about TBI being superior for high angle offroading, But any offroading i do will mostly be low angle if any angle at all. and not very often.

Im really not sure what all to ask, so any thoughts and experiences would be greatly appreciated.

Thanks,
Miles

 

[bigred88]

Nope, hand held tuners definitely don't work... you have to burn new chips. Some guys get into doing it themselves, I never have. Just had one done for me after a few mods. If I ever do anything more serious, I'll need another. Mine's an 88, by the way.

I don't know about the dyno-tuning, I ported my throttle body (mildly), and never saw anything about needing a dyno tune. I've had it that way for 6-7 months now, no problems.

Next truck I get will be older and carbed (and preferably pre-emissions regulations). I have an AMC Spirit, and that's pretty straight forward to work on. I'm getting used to the electronic controls, and I know they can produce more power, more efficiency, and just general better results, but I like the simplicity of the older stuff.

 

[Russell]

A ported throttle body, aftermarket intake, dual exhaust with longtube headers and an Edelbrock EFI cam in my buddy's 89 K5 runs great on the stock tune!

Even if it does come down to needing to work on the tune a bit, it costs less money to get set up to do your scanning / programming than it does to buy a hand held flash tuner for a newer truck. Less than $200 shipped up to me here in Canada when our dollar was worth $.60 USD.

Actually doing the tuning is easy too. If you scan using free software like WinALDL, it'll often generate a chart for you which includes the recommended values to correct any problems with the lower volumetric efficiency chart (mixture). Setting the timing is no different than setting the timing curve on a old mechanical HEI, if there is a certain timing curve you'd weight / spring the distributor for, program the same thing into the tune. Once your timing is bang on, get your O2 monitored mixture bang on, then smooth out the upper VE chart to be slightly richer than the lower chart (there are usually graphs to visually see what the chart looks like as compared to the lower chart) and you're good to go.

If you know anything about programming, and have built the engine to be EFI friendly, then you won't have any trouble with tuning the TBI's chip. I used to be able to get my chip better than factory within 10 chips (1 chip per drive). After that, it was just tweaking as I encountered MAP vs RPM situations that are uncommon to normal every day driving (high RPM up the side of a hill, low RPM under heavy load etc).

I would say there is more forgiveness in the factory programming than you think there is. If your mixture is so far out that the engine is lean enough to burn itself up or rich enough to foul itself out, you'll get a code long before any damage occur. Not only that, but if you are running really lean, you'll hear it popping through the intake, heat the pre-detonation, and see your temp gauge rising rapidly. If you are running rich, you'll hear it popping in the exhaust, and smell the rich mixture. A simple pull of a spark plug will tell you a lot about how the engine is running. Keep in tune with your engine (which I think you are) and you'll know if something is wrong long before you cause any damage.

 

[dudeiwin86]

big "duh" by me on the timing.
im used to computer controlled spark combined with EFI.

makes me feel better about it all since the only thing you need to adjust fueling. i know a good bit about tuning and how it works, and seen it done by a skilled LSx tuner....
but ive never done it myself.

so for ~200$ you can purchase all the equipment needed to burn the chips? and just use an editing software to tweak it and re-burn it?

that doesnt sound so bad. maybe this truck will be a keeper after all

any recommendations on where i can do some reading about tuning the TBI stuff?

thanks so much for your input

 

[tRustyK5]

There's enough FI info in the fuel injection forum to cross your eyes and make smoke pour from your ears...at least that's what it does to me.

Rene