Local2Ed

I'm trying to track down what feels like a chugging or missing response during normal acceleration.
The car is a 1985 automatic, 104,000 miles.
https://www.corvetteforum.com/forums...-a-1985-a.html

I posted the above results about a month ago and today I rescanned the car. Nothing was done to the car between scans except to put a can of sea-foam in a tank full of gas that I have only used 1/2 of tank.
Here is what I scanned today;

Prom ID- 61
Idle air mtr pos- 21 steps
Coolant temp.- 197.6* F
Vehicle speed- 0 mph
EGR duty cycle-0.0%
Engine RPM-825 RPM
Throttle sensor- 0.56 volts
Integrator- 131
Oxygen sensor 761 mVolts
Manifold air temp- 203.0 *F
Knock sensor- 142
Block learn- 244
02 cross counts- 0
Mass air flow- 7gr/sec
Injector pulse- 1.5 mS
Learn control- Disabled
Rich lean flag- Rich
Loop status- open
Park/neutral- NOT DETECTED ******* Was in park
Power steering PSI High- No
EGR- Off
Fan Number 1- Off
A/C - REQUESTED***** Heat/AC controls were in OFF position.


Some suggested when I scanned last time, in the link above, that I put the wrong Data in the scanner but I double checked that it was correct and rescanned with some different results.

The scanner is a Autoxray EZ- Scan 5000.

I have no idea what all this info means so I'm asking anybody who is well versed in this to tell me what you see going on with the data provided and if you want to explain it to me, DUMB it down as much as possible because when I read posts about programming and/or scanning I really have NO idea what their talking about.

Thanks, Ed.

DanielRicany

Well, there's a few things that I see here but take it with a grain of salt.

The scanner is not properly organizing the readings with the actual parameters. For instance, Knock Sensor should not be 142 because the '85 ECU does not report knock counts to the ALDL. I imagine instead it's probably 142 BLMs (Block Learn Multiplier). Also what caught my eye is that 7 gms/sec MAF seems a little low for 825 RPMs (take this with a grain of salt). And lastly your IAC counts seem a little low for 825 RPMs. They should be around 20 for 725 RPMs I believe (also take with a grain of salt).

Let me explain BLMs. 128 BLMs means NO fuel correction. Any numbers above 128 means that the computer is adding fuel (something is making it run lean), and below 128 means the computer is taking away fuel (something is making it run rich).

So what I can determine from this is a sign of a vacuum leak. Typical for the symptoms you are describing if I am interpreting your description the right way.

So that's the first place I would look if it were my car. Vacuum leaks. And there are quite a few areas where vacuum leaks can arise on TPI systems.

Here's a good video on how to make your own smoke tester.

Cliff Harris

Your block learn should be 128 in open loop mode. That number is held fixed by the ECM so 244 is bogus. Your data would be more meaningful in closed loop mode because then the ECM is controlling the AFR using the O2 sensor. The block learn parameter will then tell you a lot more about what is happening in your engine.

There is no power steering pressure switch on Corvettes, so that parameter is meaningless.

You won't get any O2 cross counts until the ECM goes into closed loop mode. Then you should see the number increment continuously about once every second or so until is reaches 255 and overflows back to zero.

Crazy Scotty Kilmer does a smoke test:

Local2Ed

The open loop mode suprised me. I drove the car for 45 minutes at an average speed of 40 mph. and I see the coolant temp was 197.6* F.
What could keep it out of CLOSED loop mode?