Torture testing the PCM

Hi Guys:

A few months ago, I downloaded a stock V4P tune (tow pack, 3.42 gears) from a trusted source. I am converting my current 94 Cadillac FWB to tow pack specs and after I changed out the gears, proceeded to load up the V4P tune. TC did all the things it was supposed to do, (have done this before 20+ times so know it works), turned off ignition when prompted, did my disconnect and on restart, engine went wild. Reconnected and the dreaded "no communication" came up. The PCM was dead.

Replaced the PCM with spare (thanks Jay), did a speedo recalibrate on my original tune (2.93 gears) and was back in business. Can't immediately point my finger at the file I downloaded but it did come as an "LT1" file and I converted it to a "bin" file. I would really like to try out an original V4P tune, modified for fan temps to see if there really is much of a difference but as you can imagine, I'm a little gun shy now (no longer have a spare PCM). To this end a few questions:

1. Can you load an LT1 file directly or must you convert it to a bin file?
2. Could I have corrupted the file by saving it as a bin file?
3. Is it possible for a bad file to knock out the communication capability of the ECM?
4. Is it possible to resurrect the original ECM?
5. Is there a utility in TunerCat (or an add-in) that can check the integrity of a file?

As I said, I can't really point my finger at the file as there is a possibility that something else happened during the upload. Have been playing around with the tune for a few months now and this is the first time I have had any problems. The only thing I can say I did differently was this was the one and only time I did this on the laptops battery alone. All the other times it was plugged in. The battery still showed 98% after the fact but maybe something happened in the background that didn't show. TunerCat acted normally during the upload and terminated normally.

Sorry for the long post but could really use some advise. Going to also post on "that other site". Any help would be appreciated.

Bill

why are you stuck on this vp4 thingy file?
if you have lt1 edit,. then modify your own program,.put your fan temps,. shift points etc,.T/C lock up unlock where ever you want them,.
done deal,.
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Nick
always keep the laptop plugged in,. screen saver, power saver, etc,. all things that'll skip the laptop and fubar the pcm, if the laptop is wireless and it decides to automatically update,. or there's a trojan in it,. thats reporting back,. it could interrupt the program ,.

phantom 309 wrote:

why are you stuck on this vp4 thingy file?
if you have lt1 edit,. then modify your own program,.put your fan temps,. shift points etc,.T/C lock up unlock where ever you want them,.
done deal,.
[You must be registered and logged in to see this link.]

Nick
always keep the laptop plugged in,. screen saver, power saver, etc,. all things that'll skip the laptop and fubar the pcm, if the laptop is wireless and it decides to automatically update,. or there's a trojan in it,. thats reporting back,. it could interrupt the program ,.

Nick:

Just wanted to start off with a clean slate and work from there. From what I have heard the General did a few tweaks to the tow pack tune. Just trying to verify.

Don't have LT1 edit but am using TunerCat and Datamaster for logging. Did everything you suggested, turned off the wireless, security, screen savers etc. The only thing I didn't do was plug it in. Was running on battery (raining like hell and didn't want to get out of the car).

Have gone through the procedure a bunch of times before and since with no issues, but not with this particular file. All I really want to know is there some way a corrupted file could fubar the PCM? Don't care if it screws up the programing (though it comes up with all the right numbers) as long as I can still communicate with the PCM to correct it if it's bad.

Bill

just buy another used PCM and keep going. last time I checked, the going rate was $65 shipped for a used pcm and you should be able to find one at that price pretty quickly.

I agree with nick - there is nothing in the V4P tables you can't generate yourself by tweaking.

Well just an update. Replaced all the injectors yesterday and then found a clean V4P tune from a guy over on the TunerCat forum and bit the bullet this morning. With all appendages crossed, the puter set up to run TC only and it loaded cleanly. That was a relief.

Did a run with it and used Datamaster to log the trip. Not really happy with the long term trims but that could be caused by a number of things, not discounting the engine does have over 1/4 million miles on it. They are reasonably even and better then the original injectors but still could be closer to 128 (they tend towards 110-115). Regardless, they should do to get me by an Etest, which was the original intent.

If anyones interested, the V4P is different in almost every table from the stock Caddy ECM I got from Jay. Yes I know I could have plugged in the correct tables but I am still very new at this and want to be more comfortable with the process and the methodology before I do anything serious. Remember I'm still a diesel guy. Blowing up an engine because of a stupid mistake is not my idea of a good time. I still need to drive this thing on a daily basis.

Thanks for the suggestions.

Bill

If they are running rich in general as stated 110-118 BLM's. You might simply run a scaler across the whole or part of the fuel table(s) Last time I did (* X 0.97) and got a three percent cut in fuel across the board. I did that on the lower table. did not touch my upper table.

I admit to using a totally different program, but if available in yours, it beats making individual entries to the whole fuel chart.

I'm not a fan of lowering the overall fuel pressure to do the same thing.

You saved the old tune from my (your) car, right?

jayoldschool wrote:

You saved the old tune from my (your) car, right?

Oh yeh. Still way too uncomfortable with this tuning stuff not to have a reference point, ergo my desire for the V4P tune. At least now I have a starting point.

Bill

lakeffect wrote:

If they are running rich in general as stated 110-118 BLM's. You might simply run a scaler across the whole or part of the fuel table(s) Last time I did (* X 0.97) and got a three percent cut in fuel across the board. I did that on the lower table. did not touch my upper table.

I admit to using a totally different program, but if available in yours, it beats making individual entries to the whole fuel chart.

I'm not a fan of lowering the overall fuel pressure to do the same thing.

There is a bunch of stuff still left to check out/replace before I dive into this. As long as it passes it's Etest and I get it re-licensed that will do for now. Even though the long terms seem out of wack, the short terms are flucuating around 128 as they are supposed to which is an improvement over the old injectors.

Changed the sparkplugs last summer and picked up about 3 MPG but I still need to do the opti thing. Vent harness is missing on the intake side so it is sucking air from behind the damper so at the very least I am going to have to clean it up inside. The wires should be replaced on spec. Replaced the O2s when I first bought the car and sealed up an exhaust leak on the drivers side. Have cleaned all the normal suspects such as the MAF, throttle body, egr etc.

Without spending a ton of dough, this should get it passed it's emission test. Once I get all the other things done, than I will look into playing with the numbers.

It may very well turn out that I will be building a replacement engine and tranny for it over the winter. The current powertrain has over 1/4 million miles on it and as been said before, you can't polish a turd. If the gods of financial benevolance shine upon me, I'm still toying with doing another 6.5 turbo diesel/700R4 swap.

If I stick with the gasser my hope is to have two tunes. One for daily highway use for mileage and one specifically for towing the RV. Might even take Sherlocks advise and get a couple of ECMs to swap back and forth. The list continues to grow.

Bill

You know where to find PCMs and lower miles LT1 ;-)

Well it looks like i will be diving into this sooner than later. Failed the Etest this afternoon.

HCs at 543 ppm. supposed to be 312
noxs over as well.

The guy refused to do just a high idle test (as per Jays advise) and it would have passed this way. Now I have to pull the EGR, check again for vacuum leaks, swap out the O2s for the old ones (didn't need to replace them in the first place) and pull a few plugs. What fun.

Oh well its off to the license bureau to get another temporary permit.

Bill

how about I just give you a pcm ?

If you take it to Oil Changers on Innes in Orleans, they will do a two speed idle test. Make up something about ABS sensors or your trailer hitch.

Personally, I think it is time for new cats.

Jason:

Thanks for the offer but I don't think its the PCM. Everyting seems to be tracking correctly when I do the data log. As Jay suggested though, I might be hitting you up for a couple of cats. By the way, thanks for the injectors.

Jay:

Now that its been run at another facility, the Province now has it on record. If I go to another place and pay for a new test, not a re-test, and the perameters for the test are changed, that could very well flag an inspection of both garages. These guys have already been screwed by the Provincial government with the new legislation. Don't want to add to their problems.

These guys have always done my tests and really did try hard to get it through. I was mistaken in my last posting. The results were:

HCs: 91ppm, limit 46ppm
NO: 577ppm, limit 331ppm

Both are reasonably close but no cigar. The COs were tight on the limit but not over. Everything points to a bad EGR and too rich. Going to swap out the EGR, check again for vacuum leaks, replace the PCV valve on spec and then do another data run. If the longterm trims improve significantly than I will try another Etest. If not, than will re-install the old O2s and try my old injectors and maybe even the original tune. If this all fails to improve things than I guess the cats will be next. Really can't think of anything else.

Anyways, thanks for the help.

Bill

btdt,. you need cats,..


read back on my egr fun,. it makes no difference after a while,.new one f body,. 6 speed,. cleaned up yada yada,.

as for using the same garage,. it makes no difference where you get the re-test,. i went to 3 different garages before i got them to do the 2 spd test because the car was too low for the rollers,.
the provincial government isn't going to waste resources on 1 caddy lt1,.your caddy.
buy a new pair off ebay,. as you said the car has plenty of miles,.
not to mention the ontario government has been tightening emissions standards for the past 10 yrs,. car now needs to cleaner than it was 10 yrs ago,.

Nick