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The mkiv Supra Owners Club

Injector upgrade question


Ian C

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It was running rich - black coated interior of exhaust, mileage down to 17-19mpg (same as Brian Duffs who had a failed o2 sensor).

 

I originally put it down to the earth fault wiping the memory of the apexi afc and me leaving the lower rpm range on 0% correction, and the FSE valve forcing too much fuel in.

 

In hindsight, though, how can the FSE valve force too much fuel in at idle, when it's controlled my vacuum/boost pressure?!?

 

So basically it was running too rich before the upgrade, and the most obvious cause of that is a fubar o2 sensor telling the ECU to enrich the mix every time you get a steady throttle. Now I'm fuelling 25% more, it's choking.

 

Sounds plausible so far, anyway - it's the best theory I have so far!

 

-Ian

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Someone has suggested that already, but the car won't go anywhere, it doesn't run long enough and doesn't respond to the throttle.

 

Secondly, I'm a long way away from admitting defeat - I learn best when in at the deep end! The experience I've gained from tackling head-on stuff like turbo swaps, turbo #2 not boosting, trac control not working, this injector upgrade, that godawful earth fault, my MkIII's BHG, and so on, is priceless.

 

I know I get stressed when things don't work, but I also know that this isn't alien technology we are dealing with here - I *can* fix this, given assistance from those more experienced than I. And I'm very grateful to you all :)

 

-Ian

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When you've been probing the O2 sensor you have left it plugged in? (Silly question but just checking)

I cannot remember if you purchsed one of those loom thingies or use a pin pierced into the cable (like I do) when probing?

 

I'd replace the O2 sensor, or I can fax/email you correct repair manual way to test if it's broken.

Unfortunately I think it assumes it's going to sort of run and allow you to count how many hi/low transitions it makes and thus check it's in closed loop.

 

How much is an O2 sensor anyway??? They are easily damaged by incorrect voltage.

 

Pete

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Guest Martin F
Originally posted by TRL Performance

How much is an O2 sensor anyway??? They are easily damaged by incorrect voltage.

 

Pete

 

Speak to CW, he can do good prices on these. ;)

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Originally posted by TRL Performance

When you've been probing the O2 sensor you have left it plugged in? (Silly question but just checking)

I cannot remember if you purchsed one of those loom thingies or use a pin pierced into the cable (like I do) when probing?

 

I'd replace the O2 sensor, or I can fax/email you correct repair manual way to test if it's broken.

Unfortunately I think it assumes it's going to sort of run and allow you to count how many hi/low transitions it makes and thus check it's in closed loop.

 

How much is an O2 sensor anyway??? They are easily damaged by incorrect voltage.

 

Pete

 

I've been using the diagnostic port's output! No loom shenanigans at all. I'm getting a replacement from CW, £69 inc flange and postage. Then I'll see what voltages it gives under the same circumstances. And hopefujlly fitting it will cause the car to run properly, but I'm far too much of a cynic to believe that

:(

 

What's the best way to attach the new one to the old one's cabling? There isn't (shock) a multiplug connector, it's a case of clip the wires and reconnect somehow! I know, I'll use ScotchLoks :p

 

-Ian

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More info - Brian Duff's OX1 diagnostic pin is now reading f-all again. Bizarre.

 

Also, I went to take out the new fuel pump to replace the J-spec one (as I know it works) and a good quantity of fuel blurted out when I took off the banjo bolt. So I guess it's getting pressurised a bit!

 

http://www.ian.chisholm.clara.net/gfx/images/brokencar.gif

 

-Ian

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I got the car to run! I swapped back the J-spec pump, and she fires up (black exhaust city) and runs, and revs. Looks like the UK spec pump causes trouble or is shafted.

 

And my o2 sensor reads corectly - DOH!

 

Investigations continue...

 

-Ian

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Originally posted by Ian C

I got the car to run! I swapped back the J-spec pump, and she fires up (black exhaust city) and runs, and revs. Looks like the UK spec pump causes trouble or is shafted.

 

And my o2 sensor reads corectly - DOH!

 

Investigations continue...

 

-Ian

 

Ian, has the 12v fuel pump mod been done too your car?

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