4.9 VATS Bypass problems
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Topic: 4.9 VATS Bypass problems
Posted By: orange
Subject: 4.9 VATS Bypass problems
Date Posted: 25 September 2010 at 4:34pm
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It fires for a couple seconds but then nothing, almost sure
it is the passkey bupass, the one i have i came with the harness when i bought it so im assuming it works. is there a way i can test it? Also the bypass i have was home made and i think they built in the vss speedo converter in the same module to save space or something, the module has black and red and blue wires, but then also a green and yellow (vss is my guess) or are these wires for the bypass and im missing something? Almost sure the computer is a 1991 and i think those were 30hz? Advice appreciated. ------------- Orange 4.9 |
Replies:
Posted By: Dr.Fiero
Date Posted: 25 September 2010 at 9:10pm
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You didn't just bypass it in the PROM? Way easier. |
Posted By: orange
Date Posted: 26 September 2010 at 1:21am
PROM? I have a Rockcrawl chip, and a bypass. Could they be canceling eachother out if the chip already has it programed? ------------- Orange 4.9 |
Dr.Fiero wrote:Posted By: CFoss
Date Posted: 26 September 2010 at 7:43pm
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They can't really cancel each other out. But, if you search VATS, I think you'll find that there was 6 or 8 different resistances they used on the key plugs. If your ecm expects to see one value, and the 'bypass' is inserting another value they may not want to work together. Did this combination ever work? That best way is to get someone to burn you a new chip with the VATS disabled. It's just a enable in the bin file. Rockcrawl should be able to do it; they must already have the bin and the hack if they've provided the chip in the first place. Is the ecm a 1227730? Chay ------------- 86 SE 3.4 |
Posted By: CFoss
Date Posted: 26 September 2010 at 7:52pm
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Ok, there were actually 15 values: http://tpiparts.net/vehicle_anti_theft_system__vats_/ Check the above link. So, you can find the right R value and hope your VATS module is working right, or you can simulate the VATS module output signal. I don't know what it is, but likely it's either +5V, or ground. Chay ------------- 86 SE 3.4 |
Posted By: CFoss
Date Posted: 26 September 2010 at 8:00pm
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More good info: http://www.thirdgen.org/vats_passkey_system Chay ------------- 86 SE 3.4 |
Posted By: CFoss
Date Posted: 26 September 2010 at 8:03pm
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The input is a square wave from the VATS to the ecm. The simple solution is the resistor to the input of the VATS. Chay ------------- 86 SE 3.4 |
Posted By: orange
Date Posted: 28 September 2010 at 5:46pm
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Thanks for the info, and i dont really know what my
computer is. But is there some way i could test the bypass signal, and could i take a frequency generator and hook it up just to make sure that is the problem? Or would the round waves from a frequency generator not be sufficient for the square wave needed? ------------- Orange 4.9 |
Posted By: CFoss
Date Posted: 29 September 2010 at 8:18am
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I think you'd need a square wave gen. Most gens which will do a sine wave will do a square wave.
The trick is to determine the frequency and amplitude. I have no idea what they are.
If someone was willing, you could 'scope a working unit, then build a f gen to match it (555 timer) and you're set.
Chay ------------- 86 SE 3.4 |
Posted By: orange
Date Posted: 29 September 2010 at 4:54pm
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My ECM is 16132240, which frequency would it be, i got a
frequency generator to test. I tested the Bypass module and it seems to be putting a 50Hz frequency out. ------------- Orange 4.9 |
Posted By: Dr.Fiero
Date Posted: 29 September 2010 at 4:56pm
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That sounds right (mind you it's been quite a while). If you've got it disabled in the PROM - this is all a moot point anyhow! The ECM isn't even looking for the signal. |
Posted By: orange
Date Posted: 29 September 2010 at 5:43pm
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What is PROM? And the injectors turn off within 2 seconds
so i dont thing i have it disabled in the PROM ------------- Orange 4.9 |
Posted By: Dr.Fiero
Date Posted: 29 September 2010 at 6:13pm
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PROM - Programmable Read Only Memory. ("the chip") I'd be really surprised if Rockcrawl didn't disable it... but you never know... |
Posted By: orange
Date Posted: 29 September 2010 at 7:45pm
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Well the injectors do turn off after 2 seconds and the
computer and harness came with a Bypass module, so im assuming the PROM doesnt have it disable. But im so confused right now its ridiculous, PLEASE help me trouble shoot this, i need this project done! ------------- Orange 4.9 |
Posted By: CFoss
Date Posted: 30 September 2010 at 9:09am
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It's 50hz, but how big is it (What voltage)? Anyway, if the 50hz output is working at all, I believe it means the VATS module is working. Do the resistor thing on the input, simulating a key. It's the wihte/black, purple/white:
This is the only wiring diagram I can find. Take it with a grain of salt; I don't know what car it's for.
Chay ------------- 86 SE 3.4 |
Posted By: CFoss
Date Posted: 30 September 2010 at 9:11am
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Looks like it diables the starter too....does your engine crank?
If so, maybe it's not the vats! Ok, check that, who knows how your engine has been wired. I'd definatley trace some wires here though! Chay ------------- 86 SE 3.4 |
Posted By: orange
Date Posted: 30 September 2010 at 6:16pm
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I am more confused now, sorry. I dont have a vats module, i
just have the ecm and the bypass module hooked to power, ground, and F 10, the vats fuel cutoff. Yes my engine will crank over and all 8 cylinders will fire once maybe twice, then nothing. The injectors ARE being cut after 2 seconds. My bypass is putting out 50Hz, i know thins for a fact. What voltage should it be producing? 5V or 12V? Thanks so much for you time everyone! ------------- Orange 4.9 |
Posted By: CFoss
Date Posted: 01 October 2010 at 8:47am
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Ok, now we're getting somewhere. Look at the circuitry at the top right of what I posted. The ECM provides the power, at 5 volts. The vats module switches it to ground, causing the signal to go to 0 volts.
So, you should have a square wave, from 5 to 0 volts. It's funny that the diagram above doesn't show the switch being pulsed.
http://myplace.frontier.com/~vze7erz1/id14.html - http://myplace.frontier.com/~vze7erz1/id14.html
Looks like they used more than 1 frequency. Perhaps you are supposed to be at 30hz?
A diy cct for 50hz, you could modify it for 30hz. Let me know and I can build one and confirm values.
Chay http://home.hiwaay.net/~davida1/passkey.htm - http://home.hiwaay.net/~davida1/passkey.htm
Chay ------------- 86 SE 3.4 |
Posted By: orange
Date Posted: 01 October 2010 at 4:38pm
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Ok so I hooked the positive feed of the bypass module to
the 5v reference thinking that would work... it didnt. I am extremely frustrated, and am ready to just buy a whole new module and eliminate this as my starting problem. ------------- Orange 4.9 |
Posted By: CFoss
Date Posted: 04 October 2010 at 8:48am
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I can see that time is becoming an issue for you.
Don't get too frustrated. It sounds like you are on the edge of success!
What you should do is come and coach my 8 year old soccer team. Then you'll know what frustration is! Ha. Actually they were really good the other day. Do you have a frequency generator available to you? You mentioned it before. If so, try the 30hz frequency. Set the F generator for 5V peaks, and 0 volt lows. It should sink current as well as source it, so no problem.
I may have time to whip up a variable oscillator and send it to you. You could set the F with a 'scope or a meter.
It sure would be nice to verify the VATS is still on in your chip, otherwise you are wasting your time with the VATS. Can you/have you tried contacting rockcrawl?
Chay
It would be great if you had access to a 'scope so you could see it happening.
Chay
------------- 86 SE 3.4 |
Posted By: orange
Date Posted: 04 October 2010 at 2:50pm
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I have tried my frequency generator at 30 Hz but i could
not get the right amplification i needed, my physics teacher has one that would work that i will borrow. And i do not know how to contact Rockcrawl and he made the chip proly 5 years ago so i dont know if it would help. Plus if the chip had the bypass then wouldnt it start right up? ------------- Orange 4.9 |
Posted By: CFoss
Date Posted: 04 October 2010 at 3:48pm
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It would start right up if the VATS is your problem. Perhaps you have another problem though. The most dificult problems to troubleshoot are multiple failures with the same symptoms. It's possible this is what you have bumped into.
F generators typically want to go faster then 30hz. I hope the new one will work for you.
I'm trying to come up with some other reason that the injectors would work, then die. On a standard Fiero, this occurs when the ecm or injectors are not powered up (It fires due to the cold start injector). Yours does not have a start injector, but primes via the main injectors. Some engines (Computers) require an input from the distributor in order to keep sending fuel. I had a Chrysler mini van which requires a cam sensor signal or it shuts off the fuel pump. What I'm getting at, without knowing your system, is that there may be a cause besides the VATS holding you back. How is it that you are sure it is the injectors which are not firing, rather than the fuel pump shutting off, or loss of spark? Chay ------------- 86 SE 3.4 |
Posted By: Dr.Fiero
Date Posted: 04 October 2010 at 4:03pm
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Funny you should say the above - I was just thinking about the same thing. If the ignition module (remember it does more than one thing!) goes south, you'll loose the input to the ECM after 400rpm and it'll shut down. It probably wouldn't even run, but you could TRY backing the idle down to sub 400 and see if it keeps going. Try just trickling fuel down the throat also to see if it keeps going (eliminates an ignition problem anyhow!). |
Posted By: orange
Date Posted: 04 October 2010 at 6:02pm
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I am sure it is the injectors because i ran it with the
fuel rail out of the head and i saw that they fired then stopped so then i checked the fuel pump, which i have wired directly to the battery with a switch, and it was on the whole time and after the injectors stopped firing i checked the fuel rail pressure and it still had a lot of pressure. This is how i know it isnt the fuel pump, and for the cam sensor i am unsure, but when i first tried to start it i sprayed starter fluid in and it kept firing so ignition is ruled out. What im wondering about though is the cam sensor, it seems it is missing from the harness, but i do have cam hi and cam lo and i checked the distributor and its all hooked up except the tack. So as of now i still see it being the bypass. ------------- Orange 4.9 |
Posted By: Dr.Fiero
Date Posted: 04 October 2010 at 6:17pm
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If it's the same as Davids setup - the cam sensor is part of the distributor (it WAS quite a number of years ago I did his harness though!!!!). This doesn't rule out the ignition module though. Like I say - the ECM runs without the reference pulses UNTIL 400 rpm. |
Posted By: CFoss
Date Posted: 05 October 2010 at 9:06am
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Good work on the troubleshooting so far. The visual on the injectors is a good answer, the one I was hoping for. Same for the fuel pump. If you have the funds, I'd buy a replacement ignition module. If it ends up not being the module, it's very good to ahve a spare on board anyway, so it's not wasted money. I'd also try the 30hz waveform. Couldn't hurt.
Chay ------------- 86 SE 3.4 |
Posted By: Dawg
Date Posted: 05 October 2010 at 9:38am
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Try to find something called a "function generator". They are more geared for this sort of testing I think. For one, they tend to have a lot of output and will easily go down to below 1 Hz. They also have many different waveform possibilities and tend to have better interconnections available. The Dawg ------------- You dream it up....I'll make it |
Posted By: orange
Date Posted: 08 October 2010 at 10:07pm
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IT RUNS! The bypass needed to be 30Hz and once i got that
right she fired right up... kind of, its got a pretty big cam and it took a bit to start, but it keeps an idle great. ------------- Orange 4.9 |
Posted By: CFoss
Date Posted: 09 October 2010 at 3:09pm
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Sweet! hth! Chay ------------- 86 SE 3.4 |