3800scII 5speed OBD1 or 2? SINISTER!!!

Sinister Fiero · Post by **Sinister Fiero** » Mon Sep 24, 2007 2:11 pm

Jinxmutt wrote:Slightly on topic here, the OBD2 guys are running 60# injectors and able to tune for an acceptable idle/part throttle. Do you see any problems running a 60# injector on the obd1 setup?

Nope. I have tuned the OBD-1 PCMs to run larger than 60lb injectors no problems.

The Dark Side of Will · Mon Sep 24, 2007 2:59 pm

But with any production ECM built for Hi-Z injectors, you'll need a driver box (or hardware mods to your ECM) to run Lo-Z injectors to their full potential.

Sinister Fiero · Post by **Sinister Fiero** » Mon Sep 24, 2007 3:21 pm

The Dark Side of Will wrote:But with any production ECM built for Hi-Z injectors, you'll need a driver box (or hardware mods to your ECM) to run Lo-Z injectors to their full potential.

True, but nowadays you can get Hi-Z (hi-impedance) injectors that work with stock ECMs that flow 65lb/hr or more.

Jinxmutt · Post by **Jinxmutt** » Mon Sep 24, 2007 3:21 pm

Well I found a mustang guy with 60# for sale, now that I know they'll work, i think I found my next purchase.

Thanks Sinister!

Sinister Fiero · Post by **Sinister Fiero** » Mon Sep 24, 2007 4:11 pm

Jinxmutt wrote:Well I found a mustang guy with 60# for sale, now that I know they'll work, i think I found my next purchase.

Thanks Sinister!

Make sure they are HI-Z; some older 60#'s are LO-Z and won't work with a stock PCM.

EarlBarnes · Post by **EarlBarnes** » Wed Sep 26, 2007 3:34 pm

If you go with OBD2 do not go with a 97,

The 97 computer does not like to have it's line pressure increased (computer program) or it likes to throw a 1811 code, I find out this when it threw it and I went through all of that to replace the pressure control selonoid, I found this out when I put a stock pcm back and saw the problem go away, And it runs fine with the stock pcm with no 1811 but as soon as I put the programed back in it throws the code again.

It also needs a case learn or you will get knock (even with a intercooler) After scratching my head and wondering why I still get knock, And fixing stuff that was not broke, A caselearn cures the problem grrrrrrr

The 97 pcm pisses me off and blows.

whipped · Post by **whipped** » Wed Sep 26, 2007 7:59 pm

Line pressure meaning transmission or fuel pressure?

p8ntman442 · Post by **p8ntman442** » Wed Sep 26, 2007 9:02 pm

thats a tough question since the fuel tank has a pressure control selenoid.

/sarcasm.

whipped · Post by **whipped** » Thu Sep 27, 2007 1:02 am

Touche. Didn't read that part.

I know a lot of late model fords and imports have fuel pressure sensors. GM's got them on the diesels.

darkhorizon · Post by **darkhorizon** » Thu Sep 27, 2007 4:41 pm

Ironicly enough, 97's didnt use fuel tank pressure sensors....Only 98+'s did...

Strange...

PervertedHamster · Post by **PervertedHamster** » Thu Sep 27, 2007 10:15 pm

I think I just learned more here in this single thread then I have in 5 years on OLD EUROPE! Thanks guyz! :salute:

Sinister Fiero · Post by **Sinister Fiero** » Fri Sep 28, 2007 12:06 am

darkhorizon wrote:Ironicly enough, 97's didnt use fuel tank pressure sensors....Only 98+'s did...

Strange...

Correct, but 97's did use a EVAP vacuum diagnostic switch mounted between the EVAP purge solenoid and the canister so the computer still could see if the EVAP system was purging.

EarlBarnes · Post by **EarlBarnes** » Sun Sep 30, 2007 5:40 pm

A 1811 code is a transmission code guys

I should of stated line pressure for the transmission, I did not mean fuel line pressure I ment transmission line pressure.

Jinxmutt · Post by **Jinxmutt** » Tue Jan 08, 2008 9:25 pm

Sinister Fiero wrote:
Nope. I have tuned the OBD-1 PCMs to run larger than 60lb injectors no problems.

I picked up a set of ZZP Rails and I want to install my 630cc injectors when I install these. I know the injectors are huge for my current levels, but I want to play with the tuning now before the turbo is on there.

Just looking for some info on where to start. Should I first adjust the summer/winter Injector Flow Rates and go from there?

Sinister Fiero · Post by **Sinister Fiero** » Thu Jan 10, 2008 12:25 am

Jinxmutt wrote:
I picked up a set of ZZP Rails and I want to install my 630cc injectors when I install these. I know the injectors are huge for my current levels, but I want to play with the tuning now before the turbo is on there.

Just looking for some info on where to start. Should I first adjust the summer/winter Injector Flow Rates and go from there?

Yes, I would start with adjusting the summer/winter injector flow rates to compensate for the larger injectors you are using. You will find on the OBD-1.5 PCM programming you are limited to the amount of adjustment you can make in each MAF table; so get overall fuel trims close to being right by adjusting the injector flow rates first before you start messing with the MAF tables.

Not to get sidetracked here, but that's why I like the 94-95 OBD1.5 PCM. The winter/summer injector flow rate constants are very nice for forced induction applications. Anyone that is making a lot of power on a forced induction engine usually notices that engine tends to run leaner (and require more fuel) during colder weather. I've set up my OBD1.5 PCM's injector flow rates to compensate; basically I tell it I have smaller injectors in the winter than I do in the summer. There is also a constant (parameter) in the programming that tells the computer what Intake Air Temp threshold this switches from one table to the other at. If you don't have that in your tuner program let me know and I will dig up the memory address for it so you can adjust it yourself.

-ryan

Series8217 · Post by **Series8217** » Thu Jan 10, 2008 12:27 am

What's the difference with the 97? Can you just put later code in the 97 ECM?

Sinister Fiero · Post by **Sinister Fiero** » Thu Jan 10, 2008 3:29 am

Series8217 wrote:What's the difference with the 97? Can you just put later code in the 97 ECM?

Nope, 1997 3800 PCMs are all by themselves; just like the 96's. The 98-01 model year PCMs are the ones that seem to be interchangable.

Jinxmutt · Post by **Jinxmutt** » Thu Jan 10, 2008 12:30 pm

I do have the thresholds in place. My WOT AFR with the N* TB is now up to an 11.8-12.0 average throughout the range on the stock injectors. These are my current values:

Summer temp: 20* C
Winter temp : 5*C
Summer IFR : 5.65 g/sec
Winter IFR : 5.60 g/sec

The flow rates are a little larger than actual, but they seem to work fine with the dialed back Power Enrichment Trim. (Set to 9.38 in the higher rpm range)

Series8217 · Post by **Series8217** » Thu Jan 10, 2008 7:53 pm

Sinister Fiero wrote:
Series8217 wrote:What's the difference with the 97? Can you just put later code in the 97 ECM?
Nope, 1997 3800 PCMs are all by themselves; just like the 96's. The 98-01 model year PCMs are the ones that seem to be interchangable.

Do they still have memcals?

Sinister Fiero · Post by **Sinister Fiero** » Thu Jan 10, 2008 8:03 pm

Series8217 wrote:
Do they still have memcals?

No, 1995 was the last year removable mem-cals (chips) were used in GM computers.