V8 Astro TBI

[falconvan]

Hi all,

I'm new to the forum and still kind of a newbie to FI. I've done a few FI swaps but don't know much on the programming side or making changes from factory settings.

I recently put together a small V8 for my 86 Astrovan. I re-ringed a 68 307 shortblock, added a set of 305 HO heads and a TBI intake. Exhaust is stock manifolds with a 2.5 x 2.5 crossover going into a 3" single all the way out the back with a 3" turbo muffler and no cat. This is the cam I used:
Chevy 283,325,350,400 Cid Small Block Chevy Hydraulic camshaft,
1500-4000 RPM Range,
278 intake/288 exhaust Adv Dur,
Duration @.050 204 intake/214 exhaust,
Valve lift 420 intake/443 exhaust,
Lobe C/L 112

For the FI, I used everything stock off the 4.3. Throttle body, injectors, and ECM are all stock to the van.
It actually runs pretty decent with no check engine light on which surprised me. I does seems to idle low once the engine is warm; about 600 rpm. I'm thinking also with the extra cubic inches and more aggressive cam, I'm probably running lean once I hit highway speeds. My thoughts were to change the injectors to the larger 350 TBI ones and swap to the 87 and up model 1227747 ECM with a performance chip programmed to take advantage of the cam profile. I heard that the 86 model ECMs are too old and shouldn't be used. Any thoughts on the best route to take?

[dave w]

I think the 1227747 ECM is a good TBI computer with good aftermarket support. I think there is a HUGE difference between a "Performance Chip" and "Tuned Chip". For a modified engine like you have, I favor a "Tuned Chip". You can "Tune" a chip for yourself with TunerPro RT software. There are several options for programming chips, one possible option is to convert the 1227747 to a "Flash Chip". Here is a link to a post I did on converting the 1227747 to a "Flash Chip" :http://www.gearhead-efi.com/Fuel-Inj...-%2827SF512%29

dave w

[falconvan]

Wow, that's really inexpensive. Can you do things like remove the EGR functions by going this route, too?

[dave w]

Wow, that's really inexpensive. Can you do things like remove the EGR functions by going this route, too?

You will have "Full Throttle Access" change any chip parameter you WANT ... you are the programmer!

dave w

[falconvan]

You will have "Full Throttle Access" change any chip parameter you WANT ... you are the programmer!

dave w

Sounds cool; I'm sold.

[Six_Shooter]

First thing you will need to do is get an 8 cylinder CALPAK (the little removable chip under the access cover on the ECM) and program an EEPROM for 8 cylinder mode or find one. Right now, your ECM things that the engine RPM is a little higher (about 33% higher) than it really is, due to the 8 cylinder running on 6 cylinder programming of the ECM. It may be easier to just buy a complete ECM that is KNOWN to be from an 8 cylinder application, than finding just the CALPAK on it's own.
Both chips/ICs need to be changed in pairs, otherwise you get a cylinder count discrepancy and a CEL to go along with it.

Without setting the ECM to 8 cyl, the RPM dependent items will not trigger at the correct times, and can be difficult to tune around.

Going to larger injectors will definitely help. You can make yours adjustable, but then knowing the flow rate will be a guess at best, but is a budget way to increase injector flow.

[falconvan]

Great advice, thanks. So if I find an 87-91 TBI Chevy pickup in the boneyard and it has this ECM#, I should be OK?

[falconvan]

OK, I'm making progress. I swapped in a used 1227747 ECM today. It ran like crap for about 5 minutes but as I drove it around it got much better. Now it's idling normally and the shift point feel like they are where they should be. Under easy acceleration it picks up fine but if you floor it, it falls on its face for a few seconds. I'm still running the 4.3 45lb injectors so I sent off a pair of 5.7 60lb injectors to have them ultrasonically cleaned and checked. Once I get them back I'll swap them and install a fuel pressure tap to see where I'm at.

[dave w]

The attached spreadsheet is what I use to calculate BPW, see attached .zip file and screen shot examples.

dave w

[V8Astro]

Looks like the technical help is here. I just popped in to say this project is dear to my heart

[falconvan]

Looks like the technical help is here. I just popped in to say this project is dear to my heart

I can tell by your screen name. What's your setup like?

[V8Astro]

I can tell by your screen name. What's your setup like?

I don't have one anymore. I put a stock 350 in my 92 Astro back in the summer of 2000. After that I had a couple more I converted to small blocks. One with TPI from a Corvette. Another on was 4wd with front axle and transfer case lifted from a 92 S10 Blazer. Good times

[falconvan]

I don't have one anymore. I put a stock 350 in my 92 Astro back in the summer of 2000. After that I had a couple more I converted to small blocks. One with TPI from a Corvette. Another on was 4wd with front axle and transfer case lifted from a 92 S10 Blazer. Good times

Sound like some cool rigs; I really like the 4x4 idea. I got my refurbished injectors back today and will probably swap them in this week. It's 16 degrees here so not today.

[falconvan]

Still working out the bugs; I swapped the injectors and set the initial timing at 0. Now it starts quick, idles great but feels like the 1-2 shift is too early and at highway speeds doesn't have much power. There no ECM trans control on this; just a basic 700r4 so I'm going to go back and readjust the TV cable. As far as the power issue, maybe I need some more initial advance on the timing. Everything I've read said to set it at 0 but this isn't exactly a stock setup. I haven't checked to see if the distributer is advancing on increased RPMs; guess I need to look at that.

[falconvan]

Well, looks like everything is working but just running really rich. So I ordered the chip burner along with the socket adapter and some chips; time to start seeing if I can learn this stuff.