[T2] ECU and larger displacement

[c.dreike]

Sami,
We also did not check the timing. Sorry I didn't think about that. I do 
have a timing light.
Next time.
We need a check list.

Chris


On 8/9/2016 11:01 PM, Sami Dakhlia wrote:
> Hi Chris,
>
> Yes, it would be wise to check the gauge before I do anything else.
> This being said, when I first turned the ignition key on the cold
> engine, the CHT read 75 F, i.e., it correctly displayed the ambient
> temperature.
>
> CHT at idle seems about right to me, given that my cooling flaps
> should be operating properly (new thermostat).
>
> Best,
> Sami
>
> On Tue, Aug 9, 2016 at 7:26 PM, c.dreike <c.dreike at verizon.net> wrote:
>> One other possibility is a poor calibration on the CHT gage/thermocouple.
>> Next year drop the thermocouple into a pot of boiling water and see if you
>> read 212F. Will have to look up the temp of boiling water at your altitude.
>> Idle temp after 10-15 minutes should top out at around 280. Odd that its so
>> close to cruising temp.
>>
>> Cheers,
>> Chris
>>
>>
>>
>> On 8/9/2016 6:27 PM, Sami Dakhlia wrote:
>>> Quick update:
>>> I relocated the thermocouple, wedging it quite firmly between two
>>> fins. See photo:
>>> https://drive.google.com/open?id=0B3JXI3RTjfDCamQybXVXTHA3anM
>>> (ring-shaped connector is cut off)
>>> I think it's close enough to the spark plug hole and it will have to do.
>>>
>>> Took the bus on a 25-mile test drive from Topanga to Malibu and back.
>>> Here is an elevation map for the outbound journey:
>>> https://drive.google.com/open?id=0B3JXI3RTjfDCN3hKb2lLdjhoM0k
>>> [Start altitude: 420 metres, End altitude: 71 metres, Maximum
>>> altitude: 420 metres, Minimum altitude: 1 metres, Distance: 31.3 km,
>>> Total ascent: 236 metres, Total descent: 585 metres]
>>> (BTW, the elevation map was created at
>>> https://www.doogal.co.uk/RouteElevation.php)
>>>
>>> Pleasant 75 F ocean breeze.
>>> Idle CHT: 365 F
>>> Easy cruising at 45 mph CHT: 370-380 F
>>> Slight 7 deg. incline at 40 mph, 4th gear: 395 F
>>> Same in 3rd gear: 380 F
>>> Return trip, climbing up Topanga: 410 at 30-35 mph, 3rd gear 3-5 deg
>>> incline.
>>> 390-414 F in 1st and 2nd gear at 5-15 mph on 10-20 deg incline.
>>> Throughout, oil temp gauge showed 210-220 F, went up to 240 during the
>>> last half mile up the steep hill.
>>>
>>> So it's still running hot. That's all for now. Leaving California in a
>>> couple of days, so further troubleshooting will have to wait until
>>> next year.
>>>
>>> Cheers,
>>> Sami
>>>
>>> On Tue, Aug 9, 2016 at 12:15 AM, Sami Dakhlia <sami.dakhlia at gmail.com>
>>> wrote:
>>>> Hi,
>>>>
>>>> Fellow list member Chris Dreike offered more than a helping hand
>>>> today. He pulled his wideband O2 sender and gauge from his magnificent
>>>> DD bus and clamped the sender on my bus's '75 exhaust pipe; then sat
>>>> in the backseat, holding the gauge, while I cruised up and down I-405.
>>>>
>>>> The readings' range was between 11.5 and 12.5, even at WOT,
>>>> invalidating my hypothesis that the engine might be running lean. On
>>>> the contrary, it might be running a tad rich.
>>>>
>>>> This also means that there is no pressing need to replace the ECU for
>>>> an early '76 one. The '75 FI system designed for a 1.8-liter engine
>>>> appears to adequately cope with a 2-liter engine, i.e., not cause a
>>>> lean-running condition at WOT.
>>>>
>>>> It appears that I was misled by a poorly installed CHT sender.
>>>>
>>>> Thank you, Chris! Many thanks also to Bob, who offered to send me a
>>>> later-model ECU from his stash. And to Jon, Syd, and Dennis for
>>>> offline conversations and advice. I shall henceforth strive to worry
>>>> less and just enjoy the ride!
>>>>
>>>> Cheers,
>>>> Sami
>>>>
>>>> On Wed, Aug 3, 2016 at 2:15 PM, Sami Dakhlia <sami.dakhlia at gmail.com>
>>>> wrote:
>>>>> Hi Dennis,
>>>>> I had removed the crush washer to adjust for the presence of the
>>>>> sensor ring. Did not hear any unusual noises and did not see tell-tale
>>>>> marks around the hole. :-( Too bad, because I really wanted to believe
>>>>> in the escaping hot gases story...
>>>>>
>>>>> The injectors are the same for the various years. So I'm still
>>>>> thinking it could be the ECU. I wonder if with a 1976 ECU (only the
>>>>> displacement changed between '75 and '76, the AFM did not -- and in
>>>>> particular was of the 6-prong type without air temp sensor, so
>>>>> compatibility with the rest of FI system is more likely), the
>>>>> injectors would fire more often for a given AFM position?
>>>>>
>>>>> With a ECU swap, the AFM would then need to be re-adjusted (adjust
>>>>> spring to make it stiffer), effectively increasing the air flow rate
>>>>> at which the AFM reaches the full open position. In other words, just
>>>>> swapping the ECU would not be enough. And together with the stiffer
>>>>> AFM, the ECU would get meaningful information as the AFM reacts to
>>>>> WOT.
>>>>>
>>>>> Good idea to do a dyno test, perhaps I'll be able to do that on my
>>>>> next trip. A proper diagnostic would make a lot of sense before I
>>>>> concoct more hypotheses!
>>>>>
>>>>> Thanks again,
>>>>> Sami
>>>>>
>>>>> On Wed, Aug 3, 2016 at 1:46 PM, Dennis Gentry <dennis.gentry at gmail.com>
>>>>> wrote:
>>>>>> Did you use a crush washer plus the sensor ring, or just the sensor
>>>>>> ring?
>>>>>> If you left off the crush washer, the plug might extend into the
>>>>>> cylinder a
>>>>>> tiny bit more, making it run hotter?  If hot gases were escaping, you
>>>>>> should
>>>>>> have been able to hear it, plus it would leave tell-tale marks around
>>>>>> the
>>>>>> hole.  (Try running with a spark plug only screwed in a couple of turns
>>>>>> to
>>>>>> see what I mean. :)
>>>>>>
>>>>>> I like your hypothesis about it running lean, since too lean will
>>>>>> definitely
>>>>>> cause high CHT.  Are you thinking that the injectors meant for a 1.8 L
>>>>>> engine are failing to keep up with 2 liters of displacement at high
>>>>>> RPMs?  I
>>>>>> don't think that's the cause, since (I think) the injectors were the
>>>>>> same
>>>>>> from 1975 through 1979, when the stock engines became 2.0 L in 1978 or
>>>>>> so.
>>>>>> You could check for too-lean and for reasonable vs. too-low power
>>>>>> output by
>>>>>> putting it on a dyno and measuring the CO/O2 levels in the exhaust, but
>>>>>> I
>>>>>> imagine there is an easier way to do it that I'm not thinking of right
>>>>>> now.
>>>>>>
>>>>>> Good Luck!
>>>>>> Dennis
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Wed, Aug 3, 2016 at 11:46 AM, Sami Dakhlia <sami.dakhlia at gmail.com>
>>>>>> wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> I'm back in California for the month, my annual pilgrimage to the US
>>>>>>> to work on my '75 bus (and see family, too :)
>>>>>>>
>>>>>>> I must admit that I'm just not enjoying the bus as much as I used to;
>>>>>>> it's just a big headache. Too much time spent on fixing things, not
>>>>>>> enough time spent traveling. Last year I installed a Dakota Digital
>>>>>>> head temperature gauge and the temp readings went through the roof!
>>>>>>>
>>>>>>> We suspected that the O-ring crimped on the thermo-couple didn't allow
>>>>>>> for a proper seal of the sparkplug, allowing hot gases to escape and
>>>>>>> cause the high temp readings. I've now relocated the sender, wedging
>>>>>>> it between the fins, not under the sparkplug. Not perfect, but a
>>>>>>> better solution will have to wait until the day I have to pull the
>>>>>>> engine.
>>>>>>>
>>>>>>> While the temp readings are no longer outrageous, they're still north
>>>>>>> of what's acceptable, sometimes above 380 F. And the engine is lacking
>>>>>>> power, even by vw bus standards.
>>>>>>>
>>>>>>> Which brings me to a new hypothesis: the engine is running lean when
>>>>>>> pushed to the limit (highway driving at 60mph, or climbing hills).
>>>>>>> It's a '75 model and came stock with a 1.8 liter engine. I have since
>>>>>>> "upgraded" to a 2 liter engine. I have so far assumed that the AFM
>>>>>>> would properly compensate for the extra displacement, but now I'm
>>>>>>> wondering.
>>>>>>>
>>>>>>> BTW, I also adjusted the AFM following the instructions at
>>>>>>>
>>>>>>>
>>>>>>> http://www.itinerant-air-cooled.com/viewtopic.php?f=50&t=7761&sid=26d79b8f4581a7c3219fbb1581ad5523
>>>>>>>
>>>>>>> Thoughts?
>>>>>>>
>>>>>>> Sami
>>>>>>> _______________________________________________
>>>>>>> type2 mailing list
>>>>>>> type2 at type2.com
>>>>>>> https://www.type2.com/lists/type2/listinfo
>>>>>>
>>> _______________________________________________
>>> type2 mailing list
>>> type2 at type2.com
>>> https://www.type2.com/lists/type2/listinfo
>>
>> _______________________________________________
>> type2 mailing list
>> type2 at type2.com
>> https://www.type2.com/lists/type2/listinfo