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acefuture

It won't start - looking for a donor MEFI

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Take this chance and get yourself the Holley set up instead of buying another mefi. 

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3 hours ago, jtmoney714 said:

Take this chance and get yourself the Holley set up instead of buying another mefi. 

Wish that was in the cards. Got 3 weeks to get the car prepped and all I have to do is plug a new MEFI in. Eventually I’ll go that route. In the mean time this’ll work

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1 minute ago, acefuture said:

Wish that was in the cards. Got 3 weeks to get the car prepped and all I have to do is plug a new MEFI in. Eventually I’ll go that route. In the mean time this’ll work

Doesn’t it need to have a specific tune for your motor?

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6 hours ago, jtmoney714 said:

Doesn’t it need to have a specific tune for your motor?

Yep. CBM has a “stock tune” for a stock LS1 that doesn’t need dyno time

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 I'm glad that you seem to of got a diagnosis of your issue. Don't want to stir the pot, but do you have any opinion on what caused the ECM to become faulty?

For those  not familiar with the terminology, ECM stands for engine control module. Similar terms maybe PCM 

voltage test are helpful in basic diagnosis,  and of course you always have to be careful not to short out the ECM. in the process of doing the test. You had sounded like you were getting to the point  where  doing some voltage drop testing would've been helpful in a decision had you not had a known good ECM to swap. Or  another test you could've completed, disconnect the ECM and put it on the bench, and use a jumper wire to ground the fuel pump relay coil  wire in the ECM connector to ground. That is essentially what the ECM does to give the prime sound you were looking for from the fuel  pump. Utilizing the jumper wire would've verified The operation of all the fuel pump wiring, the fuel pump relay, and the fuel pump it self.  Please make note that any time a jumper wire is utilized I recommend that the ECM be disconnected from the vehicle so a voltage surge cannot damage it.

The gentleman was very nice to come to your help and provide a donor unit. However, I would've recommended that you take your questionable ECM and put it in a known good vehicle for testing. If your car has a wiring or electrical problem that took out a ECM you are not risking damage to a good unit by not identifying the true source of the incident  and subjecting  The donor ECM to hthe same conditions that damaged your original unit.  If your original ECM that you suspect is faulty had been transferred to a running vehicle and doesn't reproduce the same conditions, no start, no fuel pump prime, then you know that you need to look elsewhere with your diagnosis.

 By chance did you ever plug the original ECM back in  and try to restart, just out of curiosity? 

A quality ECM  Will have protection against voltage surges and overloads built-in. Keep in mind that this is a balance between  cost and adequate protection to protect from high failure rates.  A connection with high resistance or a broken connection could possibly make contact on a substitute ECM, thereby leaving you problems down the road. In that situation your ECM would've also started a known good vehicle.

Edited by Drdune
Identify

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On 10/12/2019 at 12:08 PM, acefuture said:

Well it was the MEFI. Borrowed another one from @L.R.S. And it started right up. Bummer that I need to get another one but at least it’s easily fixable. Thanks to everyone who chimed in with helpful advice 

My car is still at redline. It got abandoned last Wednesday for the BITD race. I'm glad you found a loaner and got it sorted! 

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6 hours ago, Drdune said:

 By chance did you ever plug the original ECM back in  and try to restart, just out of curiosity? 

Good read. Appreciate it

And yes I did put it back in and tried to start it with no changes. Didn't prime the pump and wouldn't start

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