Missing SAW Signal on MS1

[Trys_Hard]

Car Stats:

3.1L

Mustang SVO 32# injectors

Lonewolf Intake

Header

60mm TB

EDIS

Head P&P

Stage 2 CAM MSA

MS1 V3.0 029y24

 

We had the car running fine for 10 months and one day the customer comes in with a bad exhaust leak, he had blown out the manifold gasket when he had a big backfire. We replace the gasket and the car ran but with little power. Like it was in limp mode.

 

Checked the msq and it was the same downloaded new firmware, checked all connections, in fact at this point the entire MS installation was taken apart and rewired.

 

Had the MS1 checked out by a third party MS repair shop and they said it was fine. Still runs like crap, get the scope out and check some things and find we are getting no SAW signal. PIP is there a 12v Square wave but no SAW. What I do seem to get is one pulse when we try to start the engine but none after that. I take the unit out of the car and check it on the bench with a stim. On the bench the MS gives an SAW signal but not in the car. At first I thought something may be suppressing the signal so I disconnected it at the relay board and still no SAW. I checked at the 37pin connector and no SAW even though it was getting a PIP. I did notice one thing, there is a difference in the waveform in the car vs on the bench. On the

bench the PIP and SAW are not a square wave form like it is depicted on the

MS site, they are more of a spiked signal. When the unit is in the car the

EDIS PIP is more of a Square wave like on the MS site.

 

On the bench the PIP and SAW wave forms stay at 0 volts and spike to 12v and 5v each. In the car the SAW sits at 5V not 0, so it is not shorted out to ground.

 

We have tried multiple ECU's and EDIS control units and coil packs with no success. So I decided to throw this out there hoping someone would know why the it works on the bench and not in a car that it worked on for ten months and suddenly stopped. What could cause the SAW signal to disappear, why is the waveform different in the car vs the bench. What should the signal look like. I don't have any other EDIS cars in the shop to use as a comparison, so if anyone does and has a scope could they look at their SAW and PIP and tell me what they look like in a running car?

 

Thanks

Edited June 2, 2010 by Trys_Hard

[Geking]

Car Stats:

3.1L

Mustang SVO 32# injectors

Lonewolf Intake

Header

60mm TB

EDIS

Head P&P

Stage 2 CAM MSA

MS1 V3.0 029y24

 

We had the car running fine for 10 months and one day the customer comes in with a bad exhaust leak, he had blown out the manifold gasket when he had a big backfire. We replace the gasket and the car ran but with little power. Like it was in limp mode.

 

Checked the msq and it was the same downloaded new firmware, checked all connections, in fact at this point the entire MS installation was taken apart and rewired.

 

Had the MS1 checked out by a third party MS repair shop and they said it was fine. Still runs like crap, get the scope out and check some things and find we are getting no SAW signal. PIP is there a 12v Square wave but no SAW. What I do seem to get is one pulse when we try to start the engine but none after that. I take the unit out of the car and check it on the bench with a stim. On the bench the MS gives an SAW signal but not in the car. At first I thought something may be suppressing the signal so I disconnected it at the relay board and still no SAW. I checked at the 37pin connector and no SAW even though it was getting a PIP. I did notice one thing, there is a difference in the waveform in the car vs on the bench. On the

bench the PIP and SAW are not a square wave form like it is depicted on the

MS site, they are more of a spiked signal. When the unit is in the car the

EDIS PIP is more of a Square wave like on the MS site.

 

On the bench the PIP and SAW wave forms stay at 0 volts and spike to 12v and 5v each. In the car the SAW sits at 5V not 0, so it is not shorted out to ground.

 

We have tried multiple ECU's and EDIS control units and coil packs with no success. So I decided to throw this out there hoping someone would know why the it works on the bench and not in a car that it worked on for ten months and suddenly stopped. What could cause the SAW signal to disappear, why is the waveform different in the car vs the bench. What should the signal look like. I don't have any other EDIS cars in the shop to use as a comparison, so if anyone does and has a scope could they look at their SAW and PIP and tell me what they look like in a running car?

 

Thanks

 

I have a multichannel scope and will take a look when I get a chance with my MS2/EDIS setup (mine will be slightly different as it will be a v8)

 

Something that strikes me as odd is, the board holding at 5v. Have you tried removing the megasquirt and see if the 5v is still present on pin 36? What about if you have removed the EDIS module as well, so that you only have the wiring harness? I just get the feeling that it is a problem with ether the configuration in megasquirt so that it is not sending the signal, or that the wire is shorted to a 5v signal.

 

Also, what happens when you bench test the EDIS and Megasqurt modules together?

[Trys_Hard]

I have a multichannel scope and will take a look when I get a chance with my MS2/EDIS setup (mine will be slightly different as it will be a v8)

 

Something that strikes me as odd is, the board holding at 5v. Have you tried removing the megasquirt and see if the 5v is still present on pin 36? What about if you have removed the EDIS module as well, so that you only have the wiring harness? I just get the feeling that it is a problem with ether the configuration in megasquirt so that it is not sending the signal, or that the wire is shorted to a 5v signal.

 

Also, what happens when you bench test the EDIS and Megasqurt modules together?

 

I have disconnect all the wiring to the SAW coming at the 37 pin connector and it is still floating at 5V at the MS. To test them together will be difficult unless I set up a complete test bed like BRAAP did and I think he was just running the EDIS with out the MS.

[Geking]

I have disconnect all the wiring to the SAW coming at the 37 pin connector and it is still floating at 5V at the MS. To test them together will be difficult unless I set up a complete test bed like BRAAP did and I think he was just running the EDIS with out the MS.

 

Ok then, I suppose it has to be a configuration problem. I am not sure what the scope will tell you that the EDIS page in the megasquirt form has not already said(also, I have no time to do it this week). Have you tried reflashing the firmware, then make a fresh msq incase there is a config problem?

 

Here is what we are assuming.

1.Megasquirt is working properly. (you had someone check the hardware out)

2.Wiring is not shorted

 

that only leaves a configuration problem imo unless the hardware tester did not test pin 36. If the signal was too messed up for megasquirt to send a reply signal then MS would not even pick up a tach, thus not firing the injectors.

 

EDIT: Seeing as I run MS2, not 1, I had not looked into what it would take yet. Here is what I have found. Is your LED closest to the serial port blinking when you run the car? If so then chances are your solder connection to the LED has come loose as it looks like it is used to control the EDIS module. If not, then do you have your system set up as http://www.msextra.com/doc/ms1extra/MS_Extra_Ignition_Hardware_Manual.htm#edis describes?

Edited June 3, 2010 by Geking