[Diy_efi] Motronic fuel cut on excess boost??

[Chris Wilson]

Friday, August 30, 2002, 8:30:41 PM, you wrote:


> Quoting Chris Wilson <chris at formula3.freeserve.co.uk>:

>> AFAIK it doesn't have a MAP sensor, works of AFM
>> (swinging gate type)
>> throttle pot and RPM, with normal temp trimming.
>> If it HAS a MAP sensor
>> I haven't found it! UK spec 1988 Volvo 740 turbo
>> intercooler, on
>> Motronic, the one with 2 flywheel sensors, one
>> counting ring gear
>> teeth, the other about 90 degrees BTDC ( a metal
>> tab on the flex plate,
>> it's an automatic). Cheers.


> Oh! And I meant to repsond to this because being a 
> Volvo guy I actually know what you have to do! lol I 
> got talking about sensor scaling and missed the point. 
> Wouldn't be the first time. 
> Anyways, there is a pressure switch that is set to 
> about 14psi usually that cuts the fuel (simply called 
> an overboost switch), no map sensor, just a "hobbes" 
> switch thta triggers if you lose the wastegate control 
> line. It is near the center console, almost near your 
> feet somewhere on the driver's side of the car (oh, in 
> north america anyways, hmm, may be pass side for you). 
> Anyhoo you can track it down by pulling your boost 
> gauge out and following the vaccuum line attached to it 
> to the firewall. The fuel cutout switch is "t"'d from 
> this line. So basically hunt around for vaccuum lines 
> coming in through the firewall, there's a switch 
> around. There is an adjustment on the switch, but it's 
> filled with glue. Melt out the glue and tweak it, or 
> buy an adjustable pressure switch from a parts store 
> and wire it up in place of the stock switch (normally 
> closed.
> Hope that helps. You can be glad to know it's not 
> related to the ecm at least. 
> -Kenny
> AKA Captain Bondo

Ahh! Pressure switches, I can handle those :-) Good man, this question
has been asked several times on the Volvo turbo "Bricks" list, to no
avail. I think you helped me when i forgot the orientation of the TDC
trigger on the flex plate a while ago, didn't you? It's now running
fine, thanks, and I am now trying to blow it up <VBG>

All the best!

-- 
Best regards,
 Chris Wilson                           mailto:chris at formula3.freeserve.co.uk
                                       http://www.formula3.freeserve.co.uk


_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi