Setting up my TBI

[EagleMark]

I know my status on here is "carb and points" and they're starting to look mighty good about now!

Just because your cars not running right is no reason for profanity!

Look for vacuum leaks... or an exhaust leak. One of the two is causing the issue when you go Closed Loop.

[1great40]

I have searched for vacuum leaks and currently have the vacuum port that goes to my AC controls connected to a vacuum gauge and the vacuum that controls the EGR is pinched off. My exhaust system is 2 inch duals with a crossover pipe in between them and 2 40 series flowmasters. I actually stuffed a rag in one side just to see if backpressure made a difference. It's just a guess but I would say that this truck as little to no backpressure because of the exhaust system, at least at idle speeds. Maybe this is a problem I have created

[EagleMark]

Scan tool will help find it if you know the data to look for, if not it will just tell codes.

Around here we use TunerPRo RT, cable to laptop so we can record logs and help each other with the data.

[1great40]

I got my cable for the Actron scanner yesterday. I'm guessing that i will be able to read data from the various sensors. do I need software like winaldl or tuner pro? Not sure what to look for or how to understand the data when I see it but i really do want to learn, besides, the first cruise night of the season is in less than 3 weeks :(

[EagleMark]

Can't do much else without a data log to look for issues?

Scan tool will help find it if you know the data to look for, if not it will just tell codes.

Around here we use TunerPRo RT, cable to laptop so we can record logs and help each other with the data.

it starts readily and tries to idle normally till it warms up, then the idle goes from almost dying to revving up to about 2000-2500 rpm and then it dies back and almost stalls and then revs up again. It does this for a minute or so and then it settles into a constant high speed and you can hear the IAC port whistling like crazy

IAC port noise is common with air cleaner off but also a sign the throttle blades are closed to far so all air has to come through IAC port. When this happens air and fuel do not mix well because throttle blades are closed to far... did you close throttle blades because of high idle?

Look for vacuum leaks... or an exhaust leak. One of the two is causing the issue when you go Closed Loop.

Without logs we can see it's up to you to read data from Scan Tool and find the issue.

[1great40]

Hi Guys!

I got the Actron scanner hooked up and downloaded a bunch of data from the scanner I'm posting it hereI hope someone can point me in the right direction cause I'm a total noob with this stuff.



1989 Astro/Safari
Z=4.3L TBI


Vehicle Data List




CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.8
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 1000
EXHAUST 02 LEAN
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 127
LOOP STATUS CLSD
MAP(V) 2.04
O2S(mV) 719
O2S CROSSCNTS 246
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 0 Time: 0.0


CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.7
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 1000
EXHAUST 02 LEAN
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 126
LOOP STATUS CLSD
MAP(V) 2.06
O2S(mV) 98
O2S CROSSCNTS 246
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 1 Time: 1.1


CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.7
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 975
EXHAUST 02 RICH
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 127
LOOP STATUS CLSD
MAP(V) 2.08
O2S(mV) 861
O2S CROSSCNTS 248
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 2 Time: 2.3


CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.8
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 1000
EXHAUST 02 RICH
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 127
LOOP STATUS CLSD
MAP(V) 2.04
O2S(mV) 768
O2S CROSSCNTS 251
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 3 Time: 3.4


CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL DIV
AIR SW SOL CONV
BATTERY(V) 13.7
BLM 114
CLEAR FLOOD OFF
COOLANT(øF) 192
ENGINE RPM 975
EXHAUST 02 RICH
HIGH BATTERY NO
IAC POSITION 74
INTEGRATOR 127
LOOP STATUS CLSD
MAP(V) 2.08
O2S(mV) 795
O2S CROSSCNTS 0
P/N SWITCH P/N
PROM ID 9461
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.65
VEHSPEED(MPH) 0
Frame: 4 Time: 4.5

[EagleMark]

All data looks good!

Except one thing that maybe someone as sick as me may notice... since it's my favorite PROM ID... PROM ID 9461 is ASDU which is for an 8 cylinder... but the scan ID can be used in others...

So I searched for your Prom number 16139566 from first post and guess what I found? ASDU which is an 8 cylinder bin/chip.

Have no idea if your smaller chip/netres is correct. Pull the big chip and see if it will run? It should run although not well...

[1great40]

Thanks for reviewing the data. I guess i could put the 6 cylinder prom back in and see what happens. I have the 8 cylinder one in there because that's what painless specified in their manual. Also, since I didn't post every frame that the scanner picked up, I reviewed stuff and noticed that in some frames, the o2 sensor says "rich" with a voltage of about 800 mv and then in another frame, I have a similar voltage but the sensor reads "lean" . should these two parameters correlate? what is the crossover point (voltage) where the sensor goes from rich to lean? not that this might mean anything, I'm just learning. And one more dumb question... If the data looks good why then will theis engine not idle below 1000 rpm and why does it run so rough. I'm reading 15 inches of vacuum at 1000 rpm...it's on the low side but probably OK since the throttle/iac is admitting so much air... I'm stumped

And what does 3rd gear sw "ON" mean... The one time i tried to drive this thing it wouldn't shift out of first and I forgot to mention that all the data i posted was taken with the VSS unplugged.

[EagleMark]

If the Painless manual told you to run an 8 cylinder chip in a 6 cylinder then.... well I don't know, I'm baffled?

O2 sensor voltage is constantly switching past the mid point, in this case .451 volts. Yes it is supposed to switch rich/lean.

Your IAC was in the 70's which is to high, probably a worn or rebuilt throttle body and needs the throttle blade/Min Air Adjustment done.

If the data looks good why then will theis engine not idle below 1000 rpm and why does it run so rough. I'm reading 15 inches of vacuum at 1000 rpm...

My first guess would be it has an 8 cylinder chip running a 6 cylinder?

And what does 3rd gear sw "ON" mean... The one time i tried to drive this thing it wouldn't shift out of first and I forgot to mention that all the data i posted was taken with the VSS unplugged.

Not sure what 3rd gear switch is? Mine does not have that. If your VSS was unplugged it should have set an error code? Why it won't shift out of first has nothing to do with the ECM, it has no control of transmission except for TCC lockup which needs VSS. Have you adjusted the 700R4 transmission TV cable properly?

[1great40]

I'm learning a lot of stuff: The VSS in my TH700R4 will notwork with the ECM unless it is used with the speed buffer from the donor truck. It was causing the scanner to report over 200 mph while going up my driveway and the TCC would lock the minute the truck was in motion. Then the VSS was disconnected and now the TCC stays off. I ordered a Dakota Digital SGI-5 Universal signal interface to correct this problem.

While I was fooling around under the hood I noticed that the throttle shaft had lots of play in it. I'm thinking that maybe when I was removing the throttle lever from the donor TBI to install on a better one, I got my "recipients" mixed up and built up the wrong throttle body. Anyway, I found a good one in my junk and cleaned it up.

I assembled the "new" throttle body today and when I installed it, that engine would idle so slow you could hear the individual injector clicks! I set the minimum air and idle speed according to the GM procedure and since this is an OLD (1989) pre-Vortec, pre-balance shaft engine, I had to find a sweet spot where the idle was as smooth as it was gonna get without just plain running it too fast. I know there weren't the smoothest idling engines in the world but I think it doesn't make much difference when the truck is parked at a cruise night :). I still need to put the scanner back on there and look at my IAC count but I'm confident that it is in the correct range now.
Once I get the SGI-5 set up, I should be able to reconnect the VSS and not have the scanner tell me I'm doing 200 MPH crawling up my driveway and the instant TCC lockup should go away too. Then I need to get it to the guy who did the transmission to see why it wont shift correctly despite having set the TV cable according to the GM procedure. Thanks again to all who helped!