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Virtual Wrench
Virtual Wrench, Chevy Mechanic
Category: Chevy
Satisfied Customers: 14618
Experience:  35 years Master Mechanic
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2004 Aveo, 1.6L engine. No start. Will run on ether, has

Customer Question

2004 Aveo, 1.6L engine. No start. Will run on ether, has spark, 53 PSI fuel pressure at the rail, has 12V to one wire at injector connector. Noid light shows no pulse. Engine replaced with great running 1.6L out of an 06 which was running great when removed
from donor car. Car did run for awhile after replacement about 1 hour total. I kept original intake and transferred to new motor. Car was sitting for almost 2 years with broken timing belt when I bought it. I did security relearn and no change.
Submitted: 1 year ago.
Category: Chevy
Expert:  Virtual Wrench replied 1 year ago.
Hi,
The injectors will pulse when the ECM receives a signal from the crank sensor (CKP). Do you know where this is located on the engine?
Customer: replied 1 year ago.
There are 2 sensors on the block. One on the front and one on the rear. Is it one of those?
Expert:  Virtual Wrench replied 1 year ago.
Thanks,
Give me a minute to pull up some diagrams for you. Be right back
Expert:  Virtual Wrench replied 1 year ago.
Hi,
The link below shows the location.
https://dl.dropboxusercontent.com/u/33691145/ckp%20location.PNG
This link shows the electrical connection for the sensor. Unplug it and make sure all the pins are clean and not bent.
https://dl.dropboxusercontent.com/u/33691145/ckp%20connector.PNG
This link shows the sensor itself at the rear of engine.
https://dl.dropboxusercontent.com/u/33691145/ckp%20sensor.PNG
So, bot***** *****ne is make sure connections are real good and if ok, then replace the sensor. You wont be able to test it though without a lab scope because it produces an AC voltage sine wave.
I hope that i have provided the information you were seeking. If you are satisfied with my service please use the required rating for me to receive credit for working with you.
LJ
Customer: replied 1 year ago.
Ok I will replace the sensor and get back with you,thanks.
Expert:  Virtual Wrench replied 1 year ago.
Sounds good.
Customer: replied 1 year ago.
I replaced the crank sensor and no change.
Expert:  Virtual Wrench replied 1 year ago.
That was fast?
Was it brand new or one you had off another car?
Customer: replied 1 year ago.
It was off of the running engine that I put in the car, I still have all of the parts. It is easy to get to, just one screw and a three wire plug that looks good.
Expert:  Virtual Wrench replied 1 year ago.
Thanks,
Try pulling some codes and let me know what you get..
Customer: replied 1 year ago.
Ok, will do that right now.
Expert:  Virtual Wrench replied 1 year ago.
k
Customer: replied 1 year ago.
PO106
Expert:  Virtual Wrench replied 1 year ago.
Thanks,
That pulls up as a problem in the MAP sensor circuit. Do you have a scan tool that can read live data to test that circuit?
Customer: replied 1 year ago.
No I don't have a scan tool. Will a MAP Sensor keep the car from starting? or keep the injector from pulsing?
Expert:  Virtual Wrench replied 1 year ago.
Hi,
Yes it can. You can try unplugging it and see if it starts in case its shorted.
The TPS (throttle position sensor) also comes into play in this circuit so check all the wiring and connectors for both MAP and TPS.
Customer: replied 1 year ago.
Where does the crank sensor get it's power from? Should't the wires at the plug going to the crank sensor be checked for voltage to make sure the circuit is good? If the cranks sensor is mandatory for the injectors to fire I think we need to make sure the ECM is sending the signal..
Customer: replied 1 year ago.
Okay.
Expert:  Virtual Wrench replied 1 year ago.
Hi,
I assumed you checked the crank sensor for the 5 volt referance??
If not, of course you want to check that. It's the yellow/black wire.
Make sure you have referance volts to the MAP and TPS also...
Customer: replied 1 year ago.
Okay, on the MAP sensor I had one wire with 4.5V, on the TPS I had a wire with 4.5V but the wire on the Crank Sensor barely moved the needle, I would say 1 Volt.
Expert:  Virtual Wrench replied 1 year ago.
Hi,
Sounds like you need to check that wire all the way from the sensor, through that connector i sent earlier and then to the ECM. It has to have that 4.5V.
Here is where it connects to the ECM
https://dl.dropboxusercontent.com/u/33691145/ckp%20wire%20at%20pcm.PNG
I have to leave for awhile so check that wire REAL good because i have seen wires break almost in half but maybe have 1 or 2 strands holding it together....sound familiar?
I will check back later today and see what you come up with.
Good luck bud.
Customer: replied 1 year ago.
I unplugged the large connector at the computer and have 5V at the #5 prong. I then pulled the 3 wire harness all the way from the crank sensor to the computer and it was all intact. I removed the coating about 2" from the computer plug (the yellow and black wire) and still only show 1V !!! But when I test the prong itself it shows 5V !!! So the computer is doing it's job I guess. But how am I losing 4V from the pin thru the plug to the wire? It looks clean but the 5V isnt making it thru the plug!! I have not seen anything like this before have you?
Customer: replied 1 year ago.
Since I still have the car here that I took the engine out of I decided to cut off the plug from the computer. It is a newer car so I can't use the plug permanently but just for test purposes it was adequate. I located the fifth wire from the bottom and stripped it then I plugged the plug into the computer and turned the key on and I had 5V at the wire 5th from the bottom which on the original plug would be the yellow and black wire. So it appears the plug is bad. I there a way to just replace the one wire prong without replacing the whole plug?
Expert:  Virtual Wrench replied 1 year ago.
Hi,
Yes you can remove the prong but it takes a special tool to release the prong from the plug. I think Autozone or NAPA should have it.
http://www.dynamicefi.com/RePinHowTo.php
Customer: replied 1 year ago.
I replaced the prong and now I have the 5V at the plug but still no injector pulse and no start !!!!
Customer: replied 1 year ago.
This morning the car started. I was cranking to check the fuel pressure again and out of the blue it fired up. It ran like it did after the motor was first installed, labored and a little rough, ran for about 5 minutes then revved up and quit, it started right back up then died again and will not start again, I did notice that wile it was running that the needle on the pressure gauge was shaking violently although only going up and down a few lbs. So I don't know what to do next.....
Customer: replied 1 year ago.
It started again and I idled it up a little and the fuel pressure needle smoothed out at 59 lbs. It is in the no start mode again. I tried unplugging the fuel injectors one at a time to see if it would start again and that made no change.
Expert:  Virtual Wrench replied 1 year ago.
Good morning,
Man you sure have a strange one here. I'm stumped bud. Would you like me to opt out and see if someone else has any ideas?
Customer: replied 1 year ago.
yes
Expert:  Virtual Wrench replied 1 year ago.
It's open for others now. Good luck bud.
Customer: replied 1 year ago.
If you are interested I have fixed the car. You might be able to use this information in the future. It turns out that this car has something not many cars have and it is this. The plugs that go to the TPS and the AC Pressure Switch are IDENTICAL !!! and to make matters worse they enter the harness about 8" from the end. It was very easy to swap them upon re-assembly. I switched them and the car started instantly and runs perfect. I am sure that I am not the first person that this has happened too. So you can use my solution at no charge, lol....I doubt anyone could have figured this out for me.
Expert:  Virtual Wrench replied 1 year ago.
I knew you would figure it out bud!!
Good job and get some rest now. I'm sure it had you thinking all night..lol
p.s. i was close when i said the TPS came into play a few posts ago..
Take care.

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