Tails

Rob,

OK, how do you know that all the renewed sensors are actually work correctly?

Suggest that you get a diagnostic check done on you car to see whether there are any faults being recorded (not all new sensors work or even work correctly). If you find a faulty sensor you may need to get an oscilloscope test done to view the wave forms generated or measure the resistance of the temperature sensors over various temperatures.

Do you have a copies of the booklets titled 'LH & EZK Diagnosis / Troubleshooting' , 'Dianososis of the Instrument Cluster '89' and 'Test Plan EZK-Ignition and LH - Jetronic' 87'? These booklets will take you through a step by step trouble shooting, check procedure and repair procedure to eliminate any faults.

When you have everything working correctly then carry out a knock sensor test to get a knock count to ensure that all is well and when you return after this test run undertake an adaption set up with the engine at operational temperature, so that the control units can be tuned to the design curve stored in the control unit.

Tails 1990 928S4 Auto

Tails 1990 928S4 Auto

Tails

Rob,

Posted #16 before I read your #13 in reply to my #8, so a couple of item will now overlap.

Tails 1990 928S4 Auto

928 at last

As far as the sensors go, I don't yet know if all is well for sure, but the way the car is running would seem to indicate that there's no truly major issue. I will get the error codes checked out once I get the car running to the point where I can drive it to the test.

Spoke with Imre today (Imo000), and he seems to think as I do that there's perhaps a sticky injector and or a problem with a plug, so that's where I'm checking first. Bear in mind that with a huge vacuum leak, a completely siezed ISV, fried knock sensors, and a questionable hall sensor, the car was running really pretty well and idling stable although a tich high before I started this job.
And, although I hate to admit it, for 20 thousand miles prior to my starting the job whle I looked after a number of other issues...(Timing Belt/Water Pump, Motor & Trans Mounts, etc., etc.), So I really doubt there's something happened over the last 3 months that would dramatically effect the engine operation. (Other than my screwing around with all the critical sensor units and cam timing)

Once I have a chance this weekend to stethescope the injectors, heat scan the exhaust manifolds and noid light the injectors, check the plugs etc. I'll report back.

Thank You for the input!

Bill Ball

How did the MAF plug look? In refreshing the intake, the harness gets manipulated and wires inside the plug boot can get chaffed, etc. Same for the other plugs, like the throttle switch and ISV plugs. The injector plugs are troublesome as well when manipulated. The wire bales have a habit of falling off and releasing the plug. Check that all the bales are in-place. They are retained by a small bit of melted plastic that often chips off so nothing holds the plug on the injector.

928 at last

OK, Today's Discoverys!
Audio check indicates some issues with the injectors firing......
#4 was where we started.....at start-up good pulse to the injector, and then after about 40 secs, noid light stops flashing and the car runs really rough.
Next check and it seems that the red light on the bottom of the brains comes on at the same time the noid light stops.....
So, it seems that it's going into error mode and shutting down some injectors....
Any thoughts on why????
TIA!

928 at last

Search was my friend!
I'm going back out to check the rest of the Injection Circuit #1.

Bill Ball

That system shuts off half the injectors and would make the car run like crap, although I drove for a few miles once after it tripped wondering why the car seemed a bit down on power. Red light means it is detecting that cylinder 4 is colder than 8 and, suspecting it is an ignition problem, it kills the injectors to 1,4,6,7. Often this is a false signal due to faulty themocouples in the system. I disabled the system with a bypass, although generally this is ill-advised. I'm counting on detecting an ignition failure myself.

You can do some investigating. and determine if one of the thermocouples is faulty. Of course, make sure the ignition to 1,4,6,7 is OK. I know you checked plug wires, etc. And if the car runs well in that 40 seconds before the system trips that is some evidence it is probably OK and the system tripping is false.

928 at last

Thanks Bill!

928 at last

Found It!
Now I need suggestions as to how to "unstick"
Hopefully without pulling the rail again, but if that's the way it's gotta be.......

928 at last

bump!

928 at last

This thread carries on under the "Stuck Injector" thread.........
Thanks to all!

928 at last

Now Closed...