Ideas for troubleshooting TBI issues?

[shimniok]

I've been fiddling with TBI tuning to keep my mind off something (for another post)

EDIT: 7747 ECM, $42 ASDU was the starting point. Duraspark distributor modded per BinderPlanet faq disabling mech & vac advance, and correct phasing.

Issue #1 - twice today I saw the BLM numbers drop to < 120 "across the board" (like, 112-119) or at least in the normal city driving range. Normally the BLM numbers are running between 126 and 130. Ever see this? It's unusually warm today. It seemed only to happen after driving for a very long time. Obviously I have to find out more... I wonder if it has to do with elevated coolant temp.

Issue #2 -- off the line bog, popping through throttle body... happens off the line when really slamming the throttle down to nearly WOT. It seemed like a lean out condition to me but then again I fixed a similar bog with less throttle by increasing timing a bit. I've bumped timing in that area a little, no luck yet.

Was hoping someone might have some thoughts about either issue. There's no VSS or knock sensor and knock retard is disabled (along with a few other 'features'). I'll post the bin if anyone wants to dig deep.

On the upside, I've gotten most of the normal driving range feeling really good. The truck has a lot of part throttle get up and go in city and hwy. It cruises around requiring very little throttle input at 65 and below. Basically, it drives like it's fuel injected, which is to say it drives loads better than any carb FSJ I've ever encountered. In most of the normal city and hwy driving range, it drives like I'd always hoped I could get it too. I'm quite happy.

If I can sort these remaining issues it should be pretty well good to go. Any words of wisdom are most appreciated.

[babywag]

For #2 have you added any AE yet?

Both mine liked AE increases.

[FSJ Guy]

Dunno RE the BLM #'s. But 120 isn't TERRIBLE. It's not good, but it's not real awful, either, IMHO. Set up TP to show you coolant temp and BLM # on the graph and see if there is a relationship.

X2 on increasing AE. There is a delta TPS and a delta MAP table. I was told to add more to the delta MAP table. Use the multiply function it TP to increase the AE by a percentage (50%, 100%, etc). To me, it seems more logical than adding an arbitrary # to the setting.

[Bill usn-1]

#1-was it during steady cruise or when accel or decal?

#2- did you correct the rotor/reluctor phasing from the stock setting when performing the conversion?
Popping is from lean fuel and incorrect timing. If phasing is not correct you could be arcing over to the previous cap terminal.

Assuming you have fuel and timing control.

[shimniok]

#1-was it during steady cruise or when accel or decal?

It was in the cells for 20-60 kPA, 800-1600 rpm. Basically, all the in-city driving cells. I'd been driving for awhile with BLM numbers in the 126-130 range, spot on, all of a sudden, all the numbers were running in the 112-119 range in the cells mentioned. It seemed strange that there would be an across-the-board change like that. I know it isn't a lot to go on so I'll try to get more data collected to correlate the change to something else.

#2- did you correct the rotor/reluctor phasing from the stock setting when performing the conversion?[/quote]

Yes. I followed your procedure for rotor/reluctor phasing for the Duraspark distributor.

Popping is from lean fuel and incorrect timing. If phasing is not correct you could be arcing over to the previous cap terminal.

Ok, that gives me something to go on, thanks. It may well be both lean fuel & incorrect timing.

Assuming you have fuel and timing control.

Stupid me should've posted I'm running the '7747 with timing control using a Duraspark distributor configured per the binder planet faqs you put together. I'll edit the OP and give more info.

[AwesomeJ10]

Summer blend gas?

[shimniok]

The change in BLMs occurred within the same tank of gas within a period of about an hour of driving around. One minute BLMs looked fine, next minute, they were all low.

[Bill usn-1]

Are you using tunerpro or tuner cat to setup your chip?
Tunerpro has many errors in the temp related settings which is probably why so many AMC guys on here were having poor results tuning their 7747 system instead of sticking with the basics pointed out in the tuning FAQs on the BP. Then they jump ship and have better luck with the 7427 pcm.

You may be turning the EGR on if you set the enable temp with tunerpro.

[AwesomeJ10]

Then they jump ship and have better luck with the 7427 pcm.

Do you have a good write up complete with pinouts for the 7427 pcm?

[Bill usn-1]

I would have to look Blake.
I think the better tune with the 7427 was due mostly to the errors in the tunerpro XDF's for the 7747.
The XDF for the 7427 was written by someone a little more versed in code.
I did my first ECM to PCM conversion about 6-7 yrs ago with the guys on thirdgen.
We worked up all the pin cross over sheets and I know I have all of them.
But the tunerpro and datamaster files back then were really sparse.
So I'm not sure if I posted all I had in a thread.
I remember posting a write up on my adapter to just swap an ECM for a PCM without needing to repin.
I think jeeps and guns or someone on IFSJ did the same.

If it's something you need I can did them up.

[FSJ Guy]

Gearhead-efi has the most up-to-date TunerPro files for the '7747. They have fixed a bunch of things that were wrong (and had been wrong for years).

Just goes to show, you can't believe everything you read on the internet.

Blake, Gearhead-EFI also has excellent writeups on converting to the '7427 ECM.

Back On Topic, to the OP, I'd go grab the updated XDFs and see if that helps.

[Bill usn-1]

Just goes to show, you can't believe everything you read on the internet.

Guess it depends on who you listen to.

I and others on thirdgen have mentioned it for years that the temps do not convert properly from tunercat to tunerpro but some guys just said everyone else was doing it wrong.

I'm glad things are getting fixed. Tunerpro is a good program, unfortunately the XDF and ADX files are written by guys with questionable skills that just interpret the code the way they think it works.

[shimniok]

Well... Since I have a degree in computer engineering and do embedded programming to build self driving 25mph robot rc cars for jollies maybe I can look into this and verify a bit more and make sure things are right.

I will see what I can dig up on the forums. Do you have any threads you can point to? If not no worries. Google is my friend.

6811 assembly is generally familiar to me having done a smattering of VAX-11, x86, 6502/10, AVR and PIC assembly over the last 30 years. It reminds me most of 6502.

So far I am pleased with the 7747 and I don't even have knock, vss, speed sensors yet and still have a ways to go. In other words it is good and will probably get even better. I was just thinking this morning that I have little reason to go with the more complex PCM. More frequent data updates would be nice but I'd rather hook up a micro controller for real time data collection on all the analog lines than hassle with converting to the PCM. The former would be trivially easy and give far better data logging resolution.

[FSJ Guy]

Here you go! All the info you could ever want or need!

http://www.gearhead-efi.com/Fuel-Inject ... rmation-42

[shimniok]

Yes, good resource!

I just switched over to the V5.1 XDF last night; I'd been using the 4T

I started with the posted ASDU bin. It's been a good starting point thus far.

Once I get closer to "done" I'll post up bins, charts, everything.

[FSJ Guy]

Yes, the ASDU bin is my fav for the AMC 360. You can almost leave the fuel table the same and it will run well. But of course, that's not what we do, is it? You can never just "leave it alone."

[shimniok]

What fun would that be? Yeah mine ran ok on the stock bin. But definitely better after tweaking.