90 roller

[rufrob]

I’m always the “only one” in my neighborhood, even around Toronto, so I know how to tune out the noise. To their credit they are polite and say great job, but I know they say indoors, ‘filthy gaijin, bringing their dirty habits to our clean country.’
That’s ok so long as I can enjoy my whips.
Here no one bothers me. In Toronto neighbor and cops were forever in my business. Once I was stopped 3 times in 1 week for a spot check. My mechanic in Toronto no longer drives customers cars because of the attention. In Tokyo the vulgar display of wealth on the roads here was truly astonishing to me. Daily I see McLarens and Lambos.
So long as there are no dead bodies hanging in front of my house I think I’m good.


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[stepson]

Did you take the engine out the bottom?

P.S. I was kidding about the neighbors and the Bonzai tree.

Hopefully you were kidding about the bodies hanging outside your house.

[rufrob]

Yup. From the bottom.
No worries. My skin is quite thick. Unlike my poor attempt at gardening. That shrub refuses to grow any more than that. It was supposed to hide my tool box, parts etc. Man putting it back together takes a lot more time. Checked valve timing, installed injectors, alternator, ps pump, radiator, painted valve covers,


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[rufrob]

Cam and ignition timing, oiled pistons&cylinders and cams, vacuum hoses, vinegar soaked and cleaned fuel rails, cleaned and painted injectors, heat resistant painted valve covers( scratched on installation), radiator flushed and cleaned, suspension torqued, spark plugs and ignition wires, fresh oil all done. Engine rotates smoothy, timing marks line up on second rotation
To be done are destroyed power steering low pressure line, crank bolt torque, hall sensor connector, coolant refill.
What am I missing?


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[JK McDonald]

Hey Rufrob - You are making good progress - It sounds like you are closing in on firing the motor up soon. It is always nice to see when the Cam Timing Marks all line up. About all you need next will be a few more of the basics - gasoline will probably be important pretty soon now.....

Michael

[rufrob]

I discovered I didn’t install the lower timing cover properly so I need to remove both top ones too. The thing is both my 10mm sockets have disappeared to do whatever.



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[stepson]

Originally Posted by rufrob

I discovered I didn’t install the lower timing cover properly so I need to remove both top ones too. The thing is both my 10mm sockets have disappeared to do whatever.

I hate when I goof something like that up. It seems like it take forever to remove everything you put on afterward to get to the piece you goofed on.

My 10mm sockets always have a way of jumping down underneath the intake into the "V" when I least expect it. Must be a helluva socket party down there

[rufrob]

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[rufrob]

The Fat Lady started but ran very poorly. Stalled soon after.
Careful wiring inspection found a disintegrated green blue, green white wires in the main harness.


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[rufrob]

Wiring harness swapped but still it starts fantastically but soon stalls. I’ve checked all connections and relays.


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[Danglerb]

I don't know the S4, so I can't point at anything, but most of it is working, not many things do the starts fine and stalls.

[JhwShark]

I don't know the S4 either. Does it have two Ballast resistors? check them...

[JK McDonald]

Hey Rufrob - From your description of what is happening after your car starts - it sounds like you have all the basics (Gas-Air-Spark). This means your computers are both up and running. Perhaps your engine is stalling out from being over fueled. There is a water Temp II sensor that can cause starting and running issues. The S4 928 Temp II sensor works a little different than our S2 set up but have the same function during the warm up cycle.

To test the Temp Sensor II there are two separate temperature sensors housed in the one sensor body. Prong 1 is the sensor for the Electronic Ignition and prong 2 is the sensor for the LH fuel injection. The resistance reading from each prong to the sensor case should be in the range of -

0 C / 32 F: 4.4 to 6.0k Ohm
15 - 30 C / 59 - 86 F: 1.4 to 3.6k Ohm
40 C / 104 F: 0.9 to 1.3k Ohm
60 C / 140 F: 480 to 720 Ohm
80 C / 176 F: 250 to 390 Ohm.

You still can drive the car if the temp II sensor is defective - just disconnect the sensor. The S4 model brains notice that the connector is off and use a pre-programmed warm-up time to adjust the mixture upon start-up. Starting might be a bit harder but once warmed up, the mixture will be correct.

Good Luck, Michael

[rufrob]

It’s like you are here with me. I just noticed the slight fuel smell from the exhaust. Thanks I’ll try that.
Honestly I’m loosing my patience.
I checked the timing, cold start valve connection , the fuel pump is running when the engine stalls. When the idle drops below 1000 it won’t stay running.


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[rufrob]

I disconnected the temp sensor and Hall sensor. Same condition. Now I notice the green diode flash on the clear relay. No doubt it’s running pig rich


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[JK McDonald]

Hey Rufrob - You might try resetting the O2 sensor readings captured in the fuel computer memory. Disconnect the battery - disconnect the O2 sensor - reconnect the battery and start your engine. When the computer sees that the O2 sensor input is missing it will select it's own generic setting. Once the engine is warm - if it now idles and runs OK, suspect the O2 sensor is defective.

There is also a possibility that your "Idle Control Valve" is not adjusting the idle bypass air flow properly. This computer controlled stepper motor type valve is known to fail (no longer open) from contamination. Many times they can be cleaned/flushed out using a spray lubricant.

Good Luck - Michael

[rufrob]

This car is a German spec thus no O2.
While checking the FPR I found the coil to distributor wires had different ends thus not seated properly. So with MAF off it starts and didn’t stall. Rough and still rich. Plugged in a spare MAF is much smoother albeit rich. I guess the plugs need cleaning.

Looks like I found the culprit.
Thanks all so much for your guidance and encouragement. Honestly I was about to give up and dump it. I have time limit of 3 more Saturdays before I’m gone on assignment for 4 months.


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[rufrob]

Oddly the same MAF worked fine-ish on the bad engine...or was it bad...


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[JK McDonald]

Hey Rufrob - I've seen the Mass Air flow Sensor cause some strange (Lean-Rich-Poor Idle-No Power-etc....) symptoms. So they can be difficult to troubleshoot without a known good spare. You were right to try and see what happens with the MAF disconnected. One of the MAF troubleshooting steps is to disconnect it to see if it runs better-worse-no change. The LH computer has a learning curve it goes through when the MAF sensor is reconnected and/or replaced.

Since your S4 doesn't use the feedback signal from an O2 sensor - the Air/Fuel ratio is calculated as a default open loop system. You might try to calibrate your MAF using it's potenimeter adjusting screw on the computer near the electric panel. You'll need an exhaust gas analyzer to try and set the potentiometer for a 1% CO at idle.

All the S4 models I've worked on had catalytic converters and O2 sensors so I appoligize that some of my trouble shooting suggestions are "By Guess and By Golly....

Good Luck, Michael

[rufrob]

Thanks Saint Micheal, patron saint of 928 causes.
Your CE looks different from mine but I know of the CO adjuster there.
What I don’t understand is with the bad engine I didn’t have the problem and all the components are for the most part the same.
I pulled the plugs this morning, which didn’t look too bad. I cleaned and reinstalled them. It no longer stalls but runs only marginally better. Still very rich and or a terrible miss.
I know the wires are weak but again, it ran before.
Now I’m hearing a rattle from the torque tube, which I rebuilt, at low idle.


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