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Discussion Starter #3
I found the site right before purchasing my '94. Seller said CEL was on, but didn't know why.
Used it to scan for codes and monitor it on the test drive.

After I bought it, I was able to flash the pcm to later calibration, and correct the speedo.

Will be using it to tune as well.

Very nice tool to have for 94-95 LT1 owners!
 

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I spent a lot of time beta-testing that tool over Christmas, and it is by far the best OBD1 LT1 logging/flashing tool in existence. Among the dozens of cool features in that tool are real-time spark timing adjustment, idle speed adjustment, AFR adjustment, and tune uploads up to twice as fast as Winflash. No those aren't typos. It literally reduces LT1 drivability tuning from days to a few hours. Several folks on that forum have made tremendous progress cracking the LT1 code, which you can read about here. I think a custom LT1 OS is not far off.

That said, tuning done right takes a lot of understanding of combustion dynamics, sensors, fuel injector nonlinearities and characterization, and computer hardware and software, and if you don't have the time/energy to learn that stuff, it's far better to pay someone who does to tune your car for you. And DON'T go on there asking for a free tune. That's rude.

FYI - Greg Banish's books are a great starting point and massively helped me get going.
 

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Stumbled across $EEHack a couple of months ago, and will echo the previous posts... Great application! Saw a newer release was out, and loaded it. Haven't taken a deeper look at it yet though.
 

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I downloaded this easily and it does look like a very nice easy to use tool, but I can't connect! Any suggestions? I know I have a good connection because tunerpro connects, but in EEHack I get a perpetual "connecting..." and no data.

I hope I can get past that because this looks great!
 

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I assume COM ports are the same. Also, don't have any other data logging app open simultaneously.
 

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It occurred to me that since winflash will not work in my RMW or my FWB, but WILL work in my 9C1, I should try EEhack in my 9C1 and see if it works in that, and as I suspected, it worked flawlessly for the few minutes I had it connected.

Just for grins I went back to the RMW and tried again. It did connect, but almost immediately disconnected, reconnected, on and on constantly reconnecting and disconnecting. Within a couple minutes I had an error count of about 1000 where I had 0 in the 9C1.

I also noticed a "debug" feature that allows me to email the results to eehack for some advice, so I will try that.

I love that cylinder strength test feature. That is cool! All about even on the 9c1 and I'm looking forward to trying it on the RMW as I suspect my #8 cyl in that one is not pulling its weight.
 

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Running on Windows 10

Finally got this to run on my Windows 10 laptop. I saved a log but cannot open it. Getting an error message: Could not open definition file, file does not exist. Do I need to download a definition file> Can anyone help me open the data log?

I did run the cylinder test and was able to open it since it was a text file. How can I interpret this?
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CYLDROP Memo ::
(Higher is better...)
CYL1=22.4 CYL2=24.3
CYL3=25.3 CYL4=26.5
CYL5=27.2 CYL6=26.8
CYL7=26.9 CYL8=27.2
 

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Is there own for 1996 Caprice Caprice LT1? I believe it's OBDII... I know the 96 differs from 94-95.... I can't find a tuner in NJ. Can anyone help?
 

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Discussion Starter #11
Cheap DIY ALDL cable OBDI

You can buy small converter boards off eBay.
Not as pretty as the $60+ cables, but it is the same type of hardware they use.
If you want pretty you can also buy the ALDL plug + pins online.

Very simple hookup, and been using them for years w/o any issues.

 

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I'll ask the NOOB question since I plan on doing this with my ride, but the question: Can this be done on a bench with the PCM out of the vehicle?

Thx.
 

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I'll ask the NOOB question since I plan on doing this with my ride, but the question: Can this be done on a bench with the PCM out of the vehicle?

Thx.
Looks like it can be done as I stumbled across this video the other day doing some reasearch. It does not really explain how or what pins used. I would think you could look at this video and the Schematics for the PCM circuit to figure out how you need to hook it up.

 

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Discussion Starter #14
where is the 3rd wire going ?
ALDL wire, Tx/Rx on board are tied together.

Ground on board goes ALDL ground.

This is OBD1 ONLY! No need to confuse folks by mentioning OBD2.
If doing on bench, use a 1amp 12v power supply for pcm.
 

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[SNIP]

As for confusing OBD2 LT1 , the question was brought up
My only point was ,
If you are going to build an LT1 bench top programming harness, the plugs are the same, why not make it do both ?

I am sure I am not the only one who messes with both "obd1" and "obd2" LT1s
As far as the OBD1 & OBD2, this is my understanding that the only differences that I'll have to take into account for when I tweak mine (OBD1 PCM Installed in OBD2 vehicle) is as follows:

With the connector off the knock sensor, check for 5v on the harness terminal with key ON. Continue if that is good. If not good, check at pin C8 (1993), D22 (94-97) on back of computer. If voltage is ok at the back of the computer, repair the wire from the computer to the sensor.

Key OFF. Connector off at the knock sensor. Measure the resistance between the KS terminal and ground. Resistance should be between 3300-4500 ohms (OBD-I) or 93k-107k ohms (OBD-II). If it is not, the sensor is faulty or the sensor is not making good contact with the block. Try another resistance reading from the sensor terminal to the outside metal of the sensor body.

This from the 4Th Gen LT1 webpage

if anyone has any more information regarding this, I'd like to hear
 

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A 96 "B" bbody OBD2 , the left and right knock sensors are separate circuits , as opposed to 94-95 where they are tied together.
To run a OBD1 PCM in a 96 without hacking the wiring , or changing the Knock sensors ( this so you can pop the OBD 2 PCM back in at any time), you have to bridge the L+R knock sensor circuits inside the PCM and add a resistor to ground.

I have done this to a couple cars way back but when OBD2 tuning became available, it was pointless ,to me.

Plus with an Impala, you have to deal with the tach output being different ( think you might be able to do with software now , as opposed to the little circuit that was added.

Where I live, the 95 cars had to be sniffed and dyno'd for emissions, the 96 were just plug in test.
Another Huge reason to leave OBD2 intact, for me.
Just thinking out loud here based on what you described about the knock sensors on a 95 bbody. Since the l and r sensors are tied together and assuming no mechanical engine issues, is it possible to remove 1 of the sensors and plug the hole in the block. I believe the Fbody cars only use 1 sensor.

Also, if wanting to remove them completely, could a resistor of the same value of a good KS be used to just fake out the system into thinking its there? The reason i ask is if doing headers or other engine mods like roller rockers, these if I understand correctly, can cause noise which the system interprets as knock and retards the timing. I think this is one of the reasons that the LT4 knock module was so popular but they are a hard/expensive find now.

If these concerns happen from engine mods and no lt4 module is available, would static resistors even work or do the KS actually vary and the system needs to see these changes for other functions?
 

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Discussion Starter #17
NO 3rd wire is NOT power.
Tx & Rx pins on board are simply tied together to ALDL data wire.

If an individual wants to do both OBD 1&2 that's fine.
This thread was simply info for folks on EEHACK and OBD1.
 

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Discussion Starter #18
Understand now .



Ok, I will delete my of track posts and answer others questions offline

No need to delete, I just like to keep threads on topic is all.
Nothing wrong with adding info, but since the thread is on '94-'95 OBD1 cars, adding or discussing OBD2 stuff may just confuse some folks.
 

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@babywag - is that just a TTL to USB adapter?

I probably have 2 or 3 of those laying around here. My car is in storage but I could easily pull one of my spare PCM's to play with.

I have like 2 spares with the one in my car having the LT4 module.

I have a serial ALDL cable but heck if they are THAT simple those TTL - USB adapters are like $5 all day long.

The issue with the Serial to ALDL adapers were that the actual ALDL data speed wasn't a perfect serial baud match up. You would use 8192 baud and it would be close but could cause data errors. if you can just use a TTL - USB adapter that should no longer be an issue.

Do you have a link where it is explained? Thanks!

Rodney
 

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Discussion Starter #20
Yep, that is exactly what they are.
Super cheap & reliable.
Out of the half dozen or so that I've bought, only one has ever given me trouble.
Most (probably all) of the commercial $40-$60 cables utilize them as well.
FTDI chipset, couple I own are even chinese clones, and they work fine too.
 
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