POPE

Here's the scoop. I recently rebuilt my 350 but I put it all back stock. The only thing that isn't stock is that it's now been bored .30 over. The truck runs, but it runs RICH!!!! Here's the list of things I've changed:
ECM
Knock Sensor
Coolent Temp Sensor
Coil
Plugs
Wires
Cap
Rotor
Coil Pickup
and Fuel Filter

There was a small issue with the wiring on the O2 sensor that I corrected.

All of this, with no change. I downloaded WinALDL and made myself a cable and it's giving me TONS of info, but none that can help me troubleshoot my problem.

I'm getting NO codes, just black smoke

SOMEONE PLEASE HELP ME!!!!!!!!!!!!!!!!!!

Pope
89K5

kevm14

Not giving you info to help troubleshoot the problem?

How about: does the ECTS show a smooth increase of reported coolant temp (also corresponding with the guage)? And does the reported temp pass your does-this-seem-right test?
Does the truck ever get into closed-loop mode?
When/If it goes into closed loop mode, what do the block learn values show for various throttle positions and loads?
Or what is the MAP voltage during warm idle?
What kind (if any) of O2 cross counts are we talking about here during closed loop cruise?
Make sure to test the TPS to make sure you re-installed it properly. With the engine off but ignition ON, monitor the TPS output voltage (or throttle opening percentage) and make sure it varies smoothly and linearly. The idea here, specifically, is to prove that it reads low voltage (~0.6v) when the throttle is closed, and 4V+ when the gas is floored.

and so forth...

POPE

I'll see if I can answer your questions.

#1: I'm sure it's giving me MORE than enough info to find my problem, I'm just not sure how to read it
#2: The temp looks to be coming up fine. I watched it for a while yesterday, mainly out of curiosity.
#3: It does go into closed loop mode.
#4:
#5
#6
These last 3 questions get me. I'm not real sure of the info your asking for. This is part of the deal where it's giving me some killer info, I just don't know how to read it. If I didn't think it would tie up the rest of this BBS, I'd post the log files I've got.

What should I be looking for? Would the fuel enrichment problem cause the O2 sensor to go bad, as well as the plugs? It's running rich to the point that I don't think just changing those two factors would be a difference maker.

Thanks in advance for all your help.

JPrevost

What are your o2 volts at when in closed loop and what are your BLMs? BLMs will tell you what the ecm is doing as far as fuel delivery is concerned. If the BLMs are near 108 or 150 then you've got issues. If they are around 128 then you're alright.
Are you getting knock/spark counts? If so you'll notice the number counts up to 255 and then resets, this will cause the ecm to pull out a LOT of timing and you'll run really rich.
How about you datalog with winaldl and attach the log file to your reply, then I'll look at it and tell you what's going on with the ecm.

POPE

I'll see if I can attach this stuff so you folks can take a look.

I really appreciate all the help.

Here's one run

POPE

and here's the other.

kevm14

Seems to me that your fuel pressure might be set too high.
What is it on now?

Also, try running 93 octane if you aren't already. Then try pulling some timing because your knock sensor is a tad overactive.

POPE

I hope you folks are patient

I don't know honestly what the fuel pressure is set to. I'm really stumped here. Could a large vacuum leak be causing this? It's pretty tough to find leaks on a TBI what with the injector noise and all, so I'm really not sure on ow to go about this. Computer control is really pretty new to me.

kevm14

It looks to me that your engine may be a candidate for a vacuum compensated fuel pressure regulator. Your BLMs are smack on 108 during what looks like light load and they increase to the good region (mid 120s) during more load. Therefore, if you obtained and setup a vAFPR, you could reduce the light load fuel pressure, bringing that 108 up to the mid 120s and keep the WOT fuel pressure where it's at.

Do you get black smoke when near WOT?

kevm14

Does anyone know what units WinALDL reports the MAP reading in? Is it a percentage? I'm used to my XP240s voltage readout.

Anyway, I made the data look a little nicer and put it in an Excel spreadsheet and zipped it...here it is for all to see.

POPE

THANKS FOR THE SPREADSHEET!!!!!!!!!!!

That makes things a LOT easier to read.

Yep I do get smoke at WOT.

What is this VCFPR that you speak of, and where are they to be found?
Would this be a bandaid fix or a legitimate fix?

Thanks again for the help.

BTW, where would I go to find out more info on what the BLM is/means? Same for some of the other info?

JPrevost

Replace your TPS sensor. It's definatly out of adjustment!
EVERYTHING else looks perfect. The IAC steps are a little high but I know for a fact that it's effected by the TPS sensor.
Gotta love winaldl .

POPE

You got that from reading the data? HOW??!?!?!?!?

I'm on it, I'll change that little bad boy first chance I get, how can you tell that that is the culprit though?

This is as much a learning experience as anything for me. I WANT to know how this stuff works. Hunger Mode ON!

JPrevost

It was simple. Just look at the TPS column, that's your throttle position sensor. It should be in the single digits, not in the 30's. The only time it would be in the 30's is if you're passing somebody because 30's = the pedal a third of the way to the floor.
The BLM (block learn multiplier) is just a fancy way of figuring out if your computer is pulling OUT fuel, or adding IN fuel ontop of it's programmed fuel maps. A BLM less than 128 means the computer is pulling out fuel because the o2 sensor is showing too rich and anything greater than 128 means the o2 sensor is showing a lean condition. The INT (integrator) is a fine tuning BLM and should be ignored in just about EVERY TBI tuning application .
O2 volts are updated too slow to even matter, just make sure the values are going up and down bouncing around the .450 mv average. Knock counts are BAD BAD BAD. This means you're timing is too much or you've got some nasty mechanical problem which sounds similar to somebody banging on your engine with a hammer. I find that timing is 99% of the time more at fault. Back off the timing a little until those knock counts stop adding up. You might get a couple knock counts when you first start the car but that's just your starter making noises, not to be confused with real detonation. So yes, 15 to 20 knock counts is normal, it isn't normal when it keeps going up.
That's the basics, to learn more you should do a search and check out diy-efi.org , it's a good knowledge base on EFI tuning, especially GM stuff.

POPE

THANK YOU VERY MUCH for the explanations.

I think I found one of the knock problems. I crawled under the truck hunting an exhaust leak (broken bolt, busted doughnut gasket) and heard a clanging that was pretty rythmic. The weight that was welded to my flywheel to balance it is pretty good size, with the larger than normal dustshield that is on the 4 wheel drive models, it was banking and rubbing. Thats the *semi* bad news. The good news is that it has just about clearanced itself. I'm thinking I'll go in with the grinder and clearance the dustshield a little more to make it work.

I'm also thinking I've got a small leak at the back of the intake. I noticed a little bit of oil on the backside of the motor that by now, should be gone. I got oil everywhere when I ran the valves, but that should really be gone after a few week, at least I think it should be.

You guys have been ROCKIN with the help. I REALLY appreciate it, even though I'm not a thirdgen guy, more like a second gen Blazer

Thanks again.

POPE

Okay fella's. I changed out the TPS and put Premium gas in this thing. It's STILL running bad. It's running BETTER, but still pretty poor. I got an email from another guy that I sent this info to. He said that I'm getting some crazy info from my MAP sensor. Here's his email reply to me.

"It is definitely running rich. It could be a lot of things but check these
out first.

You have low vacuum (high MAP) which is making the engine add a lot more
fuel. It appears that you are giving it more throttle than what I think it
needs for the speeds you are getting.

Did you change either the chip or the injectors since it was running ok?

There are three things I can think of beyond the chip or injectors causing
this. Very late timing, a significant vacuum leak, or the cam is not timed
correctly causing low vacuum. The data looks a lot like a hot cam on a stock
chip. Are you sure the cam is stock and not something else?"

How's this for help? Does this give you guys any more insight? I'm hunting what might be an intake leak, but it's gonna take a while to track it down.

Thanks for the help