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Old 07-29-2011, 12:01 PM   #1
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Default Ecm resetting upon start up

I have been chasing my tail for a while trying to get to the bottom of this. Long story short is an ems 4 was installed in my car by someone I paid to build a harness now my car won't start. This was not the case before the ems was installed. So what ever he did (which he won't tell me) has caused the ecm to reset intermittantly while cranking. It will crank fine for a while, but not fire. Then it will crank and reset and try to fire. When the Ecu resets all the lights on the dash go out and the starter cranks slowly. I have a new battery in the car and have it on a jumper. Here and there there will be a pop noise in the intake.

I have installed a MS now. The imobylizer unit shows a code of 24 which is the signal to the ecm from the unit. I checked and have continuity so the unit has taken a ****. Not a problem with the MS now.

The factory computer has a code for the cam sensor. I have checked the wires and have power 12v, ground and signal 5v. The book shows B+ at the signal wire but I only have 5v. Is this a problem?

I have spark and fuel. That is not a problem. I pulled the cam cover all timming marks apear to be on.

Any thoughts or sugestions please help. I am at my whits end and about to push this car off the edge or just burn it up. Also if I think of any thing else I will add it. I am thinking that there is a fed up wire some where.

Have a great day,
Jared
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Old 07-29-2011, 12:38 PM   #2
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Sorry can't help much with the EMS4, but the CMP sensor +5V that you are reading comes from a pullup in the ECU. It is not provided by the CMP sensor--the sensor output is basically a switched ground. You should be able to turn your motor by hand and watch the output on the signal wire change between 0 and 5 volts (easier with a scope of course).

Maybe you have more than one problem, but if your stock ECU is telling you that the CMP sensor is no good, well at least there's a starting point.
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Old 07-29-2011, 01:58 PM   #3
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Does the reseting still happen with the MS? Can you capture a datalog?
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Old 07-29-2011, 02:53 PM   #4
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Reverant, yes it does. I just have spark. Where with the stock it did not. I will try t get a log this after noon after work.

As gas as the CAS goes I replaced it with a good one and the same thing happened. Also with out cam and crank signals my understanding is that it won't fire. Since there is no indication of TDC.

I checked all fuses they are fine. I did blow the 30amp efi fuse awhile back. Replaced it and has not blown since.

Have a great day,
Jqred
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Old 08-05-2011, 11:53 AM   #5
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Thank you all for your help. I have been very buisy lately and the car is at a friends shop. I got my car to start last night on the MS. It was only for a few seconds. Much better than before. I went back to the basics and while checking timming found that the triger wheel was on backwards.I can't tell you how lame I feel.

I have been unable to duplicate the resetting problem as of late. I will update with any other info if it happens again.

Have a great day,
Jared
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