85 928 engine cut out
09-28-2013, 01:26 AM
#32
Rennlist Member
A little more development. Been going through and re-cleaning some more connections in an effort to eliminate all possibilities I could think of. Got everything put back together and went to see if it would run. As soon as I turned the key on I could once again hear the rapidly clicking injectors, so I knew it wasn’t right. I tried jumping both the EZF and LH relays, but neither made any difference.
In an effort to try to figure out what was going on I did a quick hookup of my Innovate LM2 to the EZF so I could see the RPM signal. With the engine off but the key in the run position I was getting a ~450 RPM signal. I then switched it over to the LH to see if it was seeing the same signal as delivered by the EZF. Again engine off key in run and I got ~450 RPM. I cycled the key on and off several times when connected to the EZF and LH just to see if anything changed. After messing around a bit I cycled the key off and on and suddenly no more clicking and the LM2 read 0 RPM. As the fault had seemed to have corrected itself I cranked the engine and it fired right up and idled smoothly. I then went back to the passenger side and with the engine idling I reach down and rapped on the side of the EZF with my fingers. As soon as I did this the engine shut off.
Conclusion: there was a connection inside the EZF computer causing erratic RPM signal. I disassembled the EZF and inspected all the solder joints. In general they looked pretty good but there were a few questionable ones for the connection from the harness connector to the PC board. I went through and rewet all the associated joints and reinstalled the EZF. Engine fired right up and continued to run even when I tapped on the side of the computers.
Again this could all be circumstantial sand I may not have resolved this yet but my confidence is much higher this time.
In an effort to try to figure out what was going on I did a quick hookup of my Innovate LM2 to the EZF so I could see the RPM signal. With the engine off but the key in the run position I was getting a ~450 RPM signal. I then switched it over to the LH to see if it was seeing the same signal as delivered by the EZF. Again engine off key in run and I got ~450 RPM. I cycled the key on and off several times when connected to the EZF and LH just to see if anything changed. After messing around a bit I cycled the key off and on and suddenly no more clicking and the LM2 read 0 RPM. As the fault had seemed to have corrected itself I cranked the engine and it fired right up and idled smoothly. I then went back to the passenger side and with the engine idling I reach down and rapped on the side of the EZF with my fingers. As soon as I did this the engine shut off.
Conclusion: there was a connection inside the EZF computer causing erratic RPM signal. I disassembled the EZF and inspected all the solder joints. In general they looked pretty good but there were a few questionable ones for the connection from the harness connector to the PC board. I went through and rewet all the associated joints and reinstalled the EZF. Engine fired right up and continued to run even when I tapped on the side of the computers.
Again this could all be circumstantial sand I may not have resolved this yet but my confidence is much higher this time.
09-28-2013, 01:34 AM
#33
Nordschleife Master
A little more development. Been going through and re-cleaning some more connections in an effort to eliminate all possibilities I could think of. Got everything put back together and went to see if it would run. As soon as I turned the key on I could once again hear the rapidly clicking injectors, so I knew it wasn’t right. I tried jumping both the EZF and LH relays, but neither made any difference.
In an effort to try to figure out what was going on I did a quick hookup of my Innovate LM2 to the EZF so I could see the RPM signal. With the engine off but the key in the run position I was getting a ~450 RPM signal. I then switched it over to the LH to see if it was seeing the same signal as delivered by the EZF. Again engine off key in run and I got ~450 RPM. I cycled the key on and off several times when connected to the EZF and LH just to see if anything changed. After messing around a bit I cycled the key off and on and suddenly no more clicking and the LM2 read 0 RPM. As the fault had seemed to have corrected itself I cranked the engine and it fired right up and idled smoothly. I then went back to the passenger side and with the engine idling I reach down and rapped on the side of the EZF with my fingers. As soon as I did this the engine shut off.
Conclusion: there was a connection inside the EZF computer causing erratic RPM signal. I disassembled the EZF and inspected all the solder joints. In general they looked pretty good but there were a few questionable ones for the connection from the harness connector to the PC board. I went through and rewet all the associated joints and reinstalled the EZF. Engine fired right up and continued to run even when I tapped on the side of the computers.
Again this could all be circumstantial sand I may not have resolved this yet but my confidence is much higher this time.
In an effort to try to figure out what was going on I did a quick hookup of my Innovate LM2 to the EZF so I could see the RPM signal. With the engine off but the key in the run position I was getting a ~450 RPM signal. I then switched it over to the LH to see if it was seeing the same signal as delivered by the EZF. Again engine off key in run and I got ~450 RPM. I cycled the key on and off several times when connected to the EZF and LH just to see if anything changed. After messing around a bit I cycled the key off and on and suddenly no more clicking and the LM2 read 0 RPM. As the fault had seemed to have corrected itself I cranked the engine and it fired right up and idled smoothly. I then went back to the passenger side and with the engine idling I reach down and rapped on the side of the EZF with my fingers. As soon as I did this the engine shut off.
Conclusion: there was a connection inside the EZF computer causing erratic RPM signal. I disassembled the EZF and inspected all the solder joints. In general they looked pretty good but there were a few questionable ones for the connection from the harness connector to the PC board. I went through and rewet all the associated joints and reinstalled the EZF. Engine fired right up and continued to run even when I tapped on the side of the computers.
Again this could all be circumstantial sand I may not have resolved this yet but my confidence is much higher this time.
Hope it holds for you.
Excellent, thoughtful maneuvers.
09-28-2013, 12:57 PM
#34
Inventor
Rennlist Member
Rennlist Member
I then went back to the passenger side and with the engine idling I reach down and rapped on the side of the EZF with my fingers. As soon as I did this the engine shut off.
Conclusion: there was a connection inside the EZF computer causing erratic RPM signal. I disassembled the EZF and inspected all the solder joints.
Conclusion: there was a connection inside the EZF computer causing erratic RPM signal. I disassembled the EZF and inspected all the solder joints.
If a EPROM is removed a bit too forcefully, one or more pins can be loosened.
Stuttering over bumps, hard or no starts are the symptoms.
Problems may appear to be temperature related. (May be hard to start when cold.)
Thumping the side of the (steel) case while idling will often duplicate the problem.
It's easy to fix, just heat up (reflow) the 24 solder joints of the EPROM holder.
I had two EZs that were bad from constant chip changes - boy did that make it hard to diagnose!
09-28-2013, 01:03 PM
#35
Intermediate
Thread Starter
Join Date: Mar 2004
Location: Lincoln Il
Posts: 27
Likes: 0
Received 0 Likes
on
0 Posts
Good to hear. I'll be cleaning grounds tomorrow and testing the results. I to believe my issues also
are in the the lh/ezf. But like you eliminating other possibilities first. Plus cleaning more grounds wont hurt anything. My next issue will be getting up the guts to get the soldering iron out. I did my cruise unit only after an electronics shop was unsuccessful twice. Thanks keep posting if it is still running.
are in the the lh/ezf. But like you eliminating other possibilities first. Plus cleaning more grounds wont hurt anything. My next issue will be getting up the guts to get the soldering iron out. I did my cruise unit only after an electronics shop was unsuccessful twice. Thanks keep posting if it is still running.
09-28-2013, 01:28 PM
#36
Intermediate
Thread Starter
Join Date: Mar 2004
Location: Lincoln Il
Posts: 27
Likes: 0
Received 0 Likes
on
0 Posts
The constant chip changes makes sense. I have changed out chips 4 or 5 times I can think of. If it turns out that way. " yep fixed it till I broke it". David
09-28-2013, 08:48 PM
#37
Rennlist Member
Took the car out for a few short drives today. Ran flawlessly. I'm confident re-soldering the EZF pins have cured it's ills. On mine the cold solder joints were actually on the pins that connect the 25 pin plug to the PC board. Didn't have to touch the pins for the chip socket, all those were good. Reflowed the 25 pin connections on one on the very corner of the board near the MAP sensor. Feels great to finally running reliably again.
09-28-2013, 09:02 PM
#38
Inventor
Rennlist Member
Rennlist Member
Good to know!
09-29-2013, 06:45 PM
#40
Intermediate
Thread Starter
Join Date: Mar 2004
Location: Lincoln Il
Posts: 27
Likes: 0
Received 0 Likes
on
0 Posts
Update; Removed ezf and lh brains. Rewetted ECM and connection pins on ezf. 4 pins on the ECM and 3 pins on the connection pins didn't even have enough solder on them to Rewet. Additional solder was added. I disassembled the lh brain, some corrosion was present on both sides of the board. This was cleaned. All solder points were inspected and were much better than the other brain so they were left alone. The Brains were hooked up and a test drive was conducted. After 40 miles I pulled back in the garage having experienced. NO ISSUES !!!!!!!!! Yeah. I'll take her out again later and hussle down I 55 But I anticipate a smooth experience. Thank you everyone for your input Simon is yours still running today? David
09-29-2013, 08:58 PM
#41
Rennlist Member
Didn't drive it today but it ran great all day yesterday. Glad yours is up and going well again too. I know what a relief it is to finally diagnose and fix such an elusive problem. Don’t know how long I spent chasing grounds, power and relays, and intensely studying the engine management wiring schematic, but I know it took me a while to finally determine the cause. Once I figured it out and even before fixing it I felt so relieved. My wife was making fun of me at the 928s on 9-28 breakfast yesterday, telling everybody how I kept running in and out of the house working on it and when I finally figured it out she was saying how she could see my whole demeanor change and how I couldn’t help from smiling. As I came in she nonchalantly says, “So, how’s it going out there”, knowing obviously I’d made some progress and was feeling better about the whole situation.
Of course while having it up on lift bars chasing the power feed from the battery forward I grabbed the front wheels for a quick shake just to learn that my driver’s side inner tie rod is now due, so off to the next project. Guess it’s good to have a small success every once in a while to keep you motivated.
Of course while having it up on lift bars chasing the power feed from the battery forward I grabbed the front wheels for a quick shake just to learn that my driver’s side inner tie rod is now due, so off to the next project. Guess it’s good to have a small success every once in a while to keep you motivated.
09-29-2013, 09:11 PM
#42
Intermediate
Thread Starter
Join Date: Mar 2004
Location: Lincoln Il
Posts: 27
Likes: 0
Received 0 Likes
on
0 Posts
Ditto on the wife. The last bill from Roger got the "good thing you don't say anything about all the shoes I buy". I am not allowed to play with her CTS V. All stock no touchy. Borla exhaust would be great on that car. It is one quick car! I did all the suspension etc 2 winters ago on my 928 Was planning a top end refresh this winter. Good evening
09-30-2013, 06:23 PM
#43
Track Day
Join Date: Aug 2013
Posts: 16
Likes: 0
Received 0 Likes
on
0 Posts
Hello all,
Special thanks to "Mrmerlin", this weekend the firts item that I checked found the problem. The battery had been replaced recently and the terminals were tight and the cable was nice and clean, but there was two red wires attached to the positive terminal (don't know what they are) they were loose and as soon as I tightened them the car runs nice and no issues so far. The car starts and runs to get to the normal temperature, the electric fan kicks on, at this time you would hear the fuel pump relay click and it would die, not anymore, now when the electric fan kicks on there is no click and no change to the engine rpm, and if not for looking at the fan you would not notice that it kicked on. I have test driven the car sunday night and all is well so far. Also I don't see the battery gage in the dash jumping anymore. Will report if any issues come up. Thanks everyone for your time and advise.
Special thanks to "Mrmerlin", this weekend the firts item that I checked found the problem. The battery had been replaced recently and the terminals were tight and the cable was nice and clean, but there was two red wires attached to the positive terminal (don't know what they are) they were loose and as soon as I tightened them the car runs nice and no issues so far. The car starts and runs to get to the normal temperature, the electric fan kicks on, at this time you would hear the fuel pump relay click and it would die, not anymore, now when the electric fan kicks on there is no click and no change to the engine rpm, and if not for looking at the fan you would not notice that it kicked on. I have test driven the car sunday night and all is well so far. Also I don't see the battery gage in the dash jumping anymore. Will report if any issues come up. Thanks everyone for your time and advise.
11-18-2019, 02:49 PM
#44
