Anyone have the TPI system running off of an LT-1 computer?

The thought crossed my mind while thinking about doing a 4L60E swap for the computer controlled shift points and line pressure, but there could be the added benifits of sequential fire injection and MAF and SD capabilities (I think I remembered reading that somewhere)

Any thoughts on this? Benefits, drawbacks?

Any complications that I might run into?

The big thing I'm not sure of is the optispark, but all the other inputs should basically be the same. Right? 5v reference, mechanical throttle, thermistors for cts, iat, etc... If I can find a good way to mount up the crank sensor, I may even be able to get the optispark to work on the gen1 sbc.

Can I still use my pp2 and tuner pro with new ecu and bin?

 

Ive thought about this one also and it appears that the optispark is the stumbling block. If you can get around that, then the rest is pretty easy. The early LT1's had a memcal much like the TPI system and if you can come up with a definition file you can program with TunerPro and PP2. Otherwise TunerCat has a configuration file for the early LT1. The later LT1's used flash programming (no removable eproms) which you can do again with TunerCat.

The other simpler (in my opinion) option is to use a pcm running the $0D mask. Check out the "$0D ecu file" thread.

Steve

 

The trick is the Optispark. I've heard of two people who have transplanted the Opti "guts" into conventional distributor housings, although I haven't personally seen one. Looking at the Opti innards, it doesn't look like it'd really be all that hard to do.

Other than the Opti, the other sensors are essentially the same.

The SEFI LT1s ('94-'97) were all FLASH, so your PP2 is essentially useless, unless maybe you were to modify the PCM to use a socketed chip or something. Right now, TunerCat works with FLASH. TunerPro doesn't, at least not yet.

Earlier '92-'93 LT1's were batch fire, and used a memcal like the P4's, but those were ECMs, not PCMs, and won't control the 4L60E transmission.

SEFI may not necessarily be an advantage over batch in many circumstances. Grumpy has posted some interesting observations in the past on that subject.

The LT1 MAF is a gigantic improvement over the TPI MAF, but I'd still rather use SD.

I'd be inclined to run a separate PCM just as a TCM instead, unless you have enough cam to be able to make good use of the sequential injection, or have some air distribution problem where the LT1's individual cylinder fuel trim might come in handy, or some other special circumstance. But, if the idea of using an LT1 PCM makes you happy, by all means go ahead. This is a hobby, after all, and sometimes it's worth doing things just to see if you can.

Anyway, HTH

 

Stevie, I'll look into the thread. I swear I've seen the thread listing at least 100 times, but have never clicked it.

This is more of a curiosity thing than anything, and if I end up doing anything it will probably be using it as a trans controller as you suggested Dave. Any idea what inputs the secondary ECM would need to see for trans control?

 

I hope to eventually. Haven't had much luck in getting the information that I need to actually implement it, though. I've got a port monitor log of a PC uploading and downloading from an LT1 PCM, but haven't had much luck in disecting just what is going on.

If someone can point me to documentation on what commands to send the PCM to support this, I can probably implement it in an hour or two. =)

 

All the transmission controller needs is TPS signal, distributor REF, VSS, pwr and gnd. I've been running that setup (ecm and pcm) for almost a year now and it is great!

Steve

 

So it doesnt need the high resolution 360 deg. signal like the opti generates, just the low resolution 8 pulse module signal? If so that's great news

 

Exactly. Cause the pcm's which run the $0D are batch fire so they dont care which cyl is coming up.

Steve

 

Just to be clear, Steve is talking about using one of the later TBI PCMs, not an LT1 PCM. LT1 PCM may in fact need the Opti signal for the RPM input; I don't think the '8051 would be my first choice to use as a TCM.

 

That does clear things up, thanks I thought we were still talking about the LT-1 ecm.

Stevie, do you have one of the $0D bins you could send to me? All I can find are the definition files for it. If you find the time, my email is quiktrp@netzero.net.

Thanks

 

Ok, you have mail. The bin is from a 95 astro van (I think) but I changed the transmission shift points and line pressures. I cant speak for the part of the bin concerning the fuel injection cause I'm only using it as a transmission controller.

Steve

 

FWIW, I got an email from a guy some time ago, I forget his name, and he'd said there are some switch operations that are inverted between a 4L6E, and 4L8E. So according to that, you'd want like a 8625 for a 60, and a 7060 for the 8E. Unless of course someone knew the different flags, that's assuming there're flags for inverting the operation, to be able to cross use them.