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Engine Cuts out and stumbles under boost...HELP PLEASE! `

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Where did you connect it? Has to be i4 or i5 which is terminal 5 and 8.



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That was the problem, I was on terminal 4...now I am getting a reading and it baffles me. Strangely though it starts to bleed off almost immediately while the gauge in the car just shows a constant pressure. This is with the engine off though (however I wouldn't think it would bleed off) I will check it when I am out on the road with it running. Should I test the Cam sensor first by unplugging it or just go get a log of the problem and then try the cam sensor unplug?
 
Start the car, then unplug thr cam sensor as ttype6 said. Then drive the car while logging FP

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.
 
Start the car, then unplug thr cam sensor as ttype6 said. Then drive the car while logging FP

No trees were harmed in the sending of this message, however, a significant number of electrons were terribly inconvenienced.

Ok, give me a little time to wrap up this FP sending unit and clean things up and I will go try that and report back with a log. Thank you again guys, I REALLY do appreciate all of your time and effort!
 
Ok guys, same results...the car died on the first log when I stopped to save it and I forgot the damn Cam sensor was unplugged so I sat there for 10 minutes trying to figure out why the damn thing wouldn't start. I figured it out with a quick "dumb ass" comment to myself. Here they are, it did the exact same thing. On the second log you can see that I tried to slowly get into the throttle and it surged but I let off of it after a couple of seconds because I didn't want to lean it out and pop a head gasket again. I REALLY don't want to do that again....
 

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Ok guys, same results...the car died on the first log when I stopped to save it and I forgot the damn Cam sensor was unplugged so I sat there for 10 minutes trying to figure out why the damn thing wouldn't start. I figured it out with a quick "dumb ass" comment to myself. Here they are, it did the exact same thing. On the second log you can see that I tried to slowly get into the throttle and it surged but I let off of it after a couple of seconds because I didn't want to lean it out and pop a head gasket again. I REALLY don't want to do that again....
Look at That erratic engine speed and the corresponding IDC. It gives me the impression of a bad connection that goes intermittent when subjected to vibration. Crank sensor and Ignition module connectors.
 
Look at That erratic engine speed and the corresponding IDC. It gives me the impression of a bad connection that goes intermittent when subjected to vibration. Crank sensor and Ignition module connectors.

I double checked the ignition module connection and it is rock solid and the Crank Sensor is brand new as well. I hear what you are saying and your are right...the erratic behavior is mind blowing to be...I just can't figure out why. If I start the car and then wiggle the connection at the ignition module it should stumble or change in some way if that is the culprit right?
 
I double checked the ignition module connection and it is rock solid and the Crank Sensor is brand new as well. I hear what you are saying and your are right...the erratic behavior is mind blowing to be...I just can't figure out why. If I start the car and then wiggle the connection at the ignition module it should stumble or change in some way if that is the culprit right?
I suspect not the crank sensor so much as the connection at the crank sensor. Contact cleaner/Deoxit.

http://www.parts-express.com/caig-d...source=google&utm_medium=cpc&utm_campaign=pla

First step clean the connectors at the computer,crank sensor,and ignition module. Spray both sides and connect and disconnect a few times.Do one at a time and collect data.
 
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Perhaps in addition to the crank sensor harness, also check the purple / white wire on pin c on the ignition module as well as the corresponding pin on the ECM. Clean with contact cleaner as noted above. If you have the ability to acquire a male terminal it is handy for using as a drag test to test the tension of the female ends of the connectors.
 

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This is the screen shot that contains the most significant evidence. It shows erratic engine speed information being given to the computer and erratic adjustments being made to the injectors based on the erratic input. Until we see fuel pressure fall,we have no evidence of a fuel delivery problem.

I definitely see the issue there. I didn't look at that log as Nero328 mentioned that it didn't cut out in that log.

The RPM acting like that could also be that the reluctor ring on the damper is walking in & out of the crank sensor.

RemoveBeforeFlight
 
After a couple road tests with the owner, a most unusual issue happened which I have never experienced in 30 years of dealing with these cars.

He was driving, and my local friend was logging with the laptop, and during a short burst of power the GN lost all electrical power and died on the street. I do not know if there was a backfire or not, but there was no electrical power from the starter?

I have not ever seen a starter or solenoid fail, and not continue to pass power to the harness?

A replacement starter got the car running again, and is was not running well at all, and he found no.5 cylinder head gasket was torched which I would attribute to pre-ignition some where during the testing.

With the crazy and very unusual issue with the starter, there is a good possibility that the fusible links have been damaged which not allow ample current to be supplied into the electrical system?

Nick has a good point here, the fusible links do deteriorate with age. Could be the one that feeds the ignition switch is bad.

RemoveBeforeFlight
 
I thought fuseible links are either good or they are bad. Isn't the purpose of a fuseible link to be just that...a fuse, when it is bad it cuts all power and when it is good it provides power?

I just found this while chasing down wires again! It is a wire that was run to tap into the MAP sensor in order to get a boost signal to the PL I am assuming. It was touching the header on the passenger side. I will fix it and route it properly but could this be what is causing the issue?
 

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Nick has a good point here, the fusible links do deteriorate with age. Could be the one that feeds the ignition switch is bad.

RemoveBeforeFlight
Nick was wondering how the voltage was interrupted to the car because of the starter. It can't be,because the wires with the links are connected directly to the positive wire from the battery. Knowing this,I don't necessarily suspect the links but I am suspicious of the ignition switch. In his explanation,the engine shut off first. It can't be from a bad starter and we've not seen power go away in any logs since. I would,however,bridge the links to test them.
 
I guess you will be telling us in a few minutes. It probably shares supply voltage with other sensors.

Unfortunately it will be longer than a few minutes. I have to step away from the car for a couple of hours to spend time with my two young boys who have been VERY patient with me for the past 7 days as I have been giving this infernal machine all of my time since I got home from Phoenix. I am going to go take them for a boat ride and let them ski a little and then I will come back and fix this and go out for a test. I don't know if this wire touched after I changed the HG or if it has been there the whole time but I suspect it may just be something I did when I changed the HG...just a guess.
 
Unfortunately it will be longer than a few minutes. I have to step away from the car for a couple of hours to spend time with my two young boys who have been VERY patient with me for the past 7 days as I have been giving this infernal machine all of my time since I got home from Phoenix. I am going to go take them for a boat ride and let them ski a little and then I will come back and fix this and go out for a test. I don't know if this wire touched after I changed the HG or if it has been there the whole time but I suspect it may just be something I did when I changed the HG...just a guess.
What the hell am I supposed to do for the rest of the day. It's 47 degrees and raining here. I'm pretty sure the water temp is even lower,so water skiing is not an option.Of course I don't even own a boat. I guess I could quit drinking tomorrow.
 
What the hell am I supposed to do for the rest of the day. It's 47 degrees and raining here. I'm pretty sure the water temp is even lower,so water skiing is not an option.Of course I don't even own a boat. I guess I could quit drinking tomorrow.

Well, the battery on the boat is dead so there won't be any water skiing today, seems like everything at my house is giving me hell this weekend. The boys are gonna ride their dirt bikes for a little while so I will come back after I watch them...of course they must have Dad watch them so they can show me how good they are. I will be back on it in about an hour. Sit tight...I will keep you entertained a little while longer today. I am very appreciative of the time you have given me already, I am gonna owe you big time if we ever meet in person! In fact I am buying a steak dinner to anyone I meet personally, the help that this board provides is amazing!
 
Well, the battery on the boat is dead so there won't be any water skiing today, seems like everything at my house is giving me hell this weekend. The boys are gonna ride their dirt bikes for a little while so I will come back after I watch them...of course they must have Dad watch them so they can show me how good they are. I will be back on it in about an hour. Sit tight...I will keep you entertained a little while longer today. I am very appreciative of the time you have given me already, I am gonna owe you big time if we ever meet in person! In fact I am buying a steak dinner to anyone I meet personally, the help that this board provides is amazing!

I am having a similar issue with my gn so I am waiting to see if this is the issue as well,my engine satlled when lifting off the throttle after boost.


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Well, the battery on the boat is dead so there won't be any water skiing today, seems like everything at my house is giving me hell this weekend. The boys are gonna ride their dirt bikes for a little while so I will come back after I watch them...of course they must have Dad watch them so they can show me how good they are. I will be back on it in about an hour. Sit tight...I will keep you entertained a little while longer today. I am very appreciative of the time you have given me already, I am gonna owe you big time if we ever meet in person! In fact I am buying a steak dinner to anyone I meet personally, the help that this board provides is amazing!

Dirt bikes are the best tool in the world for curious young minds. I learned so much from all of that tinkering!

Been watching your thread since it started and I certainly do feel for you man. It sucks that you had to bring it home before Nick could get it right for you. I can't imagine your frustrations! Anyways good luck with it, however, you are in great hands here, as the board members here are the best in the world!!

Good luck!!


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I did clean and check the connections at the crank sensor and the ignition module and I couldn't see anything that particularly stood out to me. I am about to go out and test with the MAP wire repaired and re-routed as well as the sensor connections being cleaned. I will log the run again...
 
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