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Have one remaining 928. 1984 USA.
I pressed it back into service after a 6 year nap.
Things were going well. It's a very strong runner.
Took a rip at lunch one day. East Tennessee I-26N, just about to hit ramp for I-81 N.
Total loss of power, rolled to the side. 6 miles home on a flatbed.
For second time, seems to need a replacement computer.
Did all the diagnostics, fuel pump running fine, green wire new, distributor swapped with known good, AFM too, relays good, swapped, also bridged...all good.
Is there a straightforward engine management system I could adopt that recognizes reluctor disty, o2sensor, temp 2 and temp 1? That is, early bosch ljet replacement?
Or does somebody have a known good surplus old LJet box they'd sell me reasonably?
Really want to drive the old girl again.
Resting during the long nap in Elkhart Indiana.
Guy going other direction saw the 928 on side of road and came to help me in Tennessee.
(That was a very kind action on his part)
Need a plan on this one.
Asking the braintrust about straightforward system replacemen? or, availability of a donor controller?
No spark, no injector flash Ken
Resistors ohm correctly.
Coil needs to be checked. Swapped out spark box previous time this happened, 2017, when it was similarly dead as doornail...when we swapped in this current computer for the instant fix.
Could bad coil result in no spark, no injectors?
Any advice, ie leading me back thru diagnosis, could help me solve. Thanks.
Chris,
It's a US version, but has Euro markers on the front fenders? That's not the norm. Usually, the Euro fenders have been replaced with US fenders.
I think I have a L-jet computer that is functional, and I have no L-Jet cars.
PM me your address.
Ah, green wire failure unlike the previous switched wire flaw back in 2010 time frame were iIIRC a porsche vendor swapped leads. Will try to I'd it. But came from 928sRus circa 2017. I say new as it has about 150 miles on it. That time it was solved with computer change after months of tracing and inspection.. Like a switch was fipped.
I traced all wires back then. Will recheck maf plug and go thru whole wire inspection process and tracing process again if needed. Last time traced every wire. Soontobered 84 is mailing a computer. Will trace all again in meantime. Have off this week. And check green wire origin...will 928 own have markings?
NOTE the URO green wire will require the distributor connector to be forced into position.
this can either short the wires inside the connector or damage the pickup coil in the Dizzy
I do like your creative car lift approach.
So on the pre 85 cars, the spark is a separate system from the fuel injectors. Spark originates, in the distributor, thru the green wire to the coil driver. Do you have spark?
Fuel comes from the AFM controller to the injectors. do you have injector pulse, when cranking?
Alan
No spark, no injector pulse. Checked that after rolling it off flat bed. Went doornail dead at 80mph. Rolled to side of road. All injectors ohm 2.3. It will be warmer here today and saturday so I will start the trace/ohm of every single wire again, as back in 2016. And check coil. Have spare distributor. Spare AFM, but will look for shorts in boots on connectors. Last time this happened it was solved instantly, after weeks of trying things, including oscilloscoping distrib, by swapping in known good controller, on purpose handling/touching nothing but the plug itself.
If John can find his spare, I'll try that. But it wont do me any harm to trace all wires and test all components, I do like troubleshooting these crazy cars.
This one car has been a bit of a nemesis over the years.
Thought we'd finally solved years of intermittent problems when finally swapping contoller in 2017, right before we put it into storage. Darn car runs so strong, and shifts so smooth with S4 auto...when it runs.
My 1984, has single distributor. The single distributor is powered by separate circuit from the ignition, circuit 15. Looking at 1984 schematics, show two distributors, which appear to have power originate with the LH computer. Do you have one or two distributors?
These cars can be frustrating with the yearly changes to the electronics. So it looks like separate ignition power was thru 83ish, as my 84 has one distributor.
12-04-2023, 02:51 PM
LJet controller, need another. Help
