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Discussion Starter #1
hi as per rule this should be the other way round, less fuel with higher inlet temps but my r33 seems to work the other way, at hotter inlet temps it starts running lean and i have to add fuel to keep the afrs constant, and when the iat is cooler i have to take air away any ideas why this is?, im using a g4 xtreme it that matters
 

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Discussion Starter #3
the iat correction tables you can sit at idle at 30 degrees its spot on then 35 its too lean no ect correction is active and the cell stays in the same place, when driving its fine
 

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(original post is a little confusing)If you are leaning out as temp rises it is backwards. Shouldnt be a huge difference, just enough to richen up the mix to stop det. Make sure you are above 1.000 IAT correction for the temp you want your ECU to start adding fuel. Anything less than 1.000 and you will be removing fuel. If your tables look good, swap your IAT and Water temp sensors. They are the same sensor and should both have a yellow plug.
 

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Discussion Starter #5
hi thanks it is a bit confusing isnt it!
im running seperate iat and water temps sensors so thats not really an option, i have to drive the car all week next week so will have a play around and see what happens
 
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You maybe having atomosation issues that changes with heat an injector spray pattern changing or something along those lines.

For safety if your IAT's are getting that hot I would add fuel/remove timing to keep the map and motor safe.
 

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you are running different sensors to the stock ones? If so Ok. If they are the stock ones, they are the same and can be interchanged. I agree with Abbey, make it safe untill you can fix the problem.
 

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dunno if it was a smart move, but I feel my car has run a lot better after moving my IAT from the plenum to just after the intercooler. I had to shift my IAT correction table of course, but since I spend so much time in traffic, heat soak was becoming a problem.
 

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Discussion Starter #9
is that temp too high then? i checked them against using a lazer thermometer and it they are correct usually its around 30 degrees when driving normally
 

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Discussion Starter #10
i think i may have found it when you look at the runtime values in the link you can see that the tps voltage lowers with the heat going up, at 20 degrees the tps reads 0.8% or 0.41v at 35 degrees sitting at idle the tps slowley moves down to read 0.0-0.1% and 0.39v, if you manually hold the throttle at 0.8% the afr looks alot better again, now i just need to work out why its doing it, a bad earth/wiring is my first guess
 

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Discussion Starter #11
well it wasnt that! i am tending to agree with toby and abbey that its a heat soak problem, when i leave the car for half hour or so and come back the idle is terrible almosy cutting out and afrs of 18 to 21, if you sit with the ignition on after a drive, then you can see the inlet temps creeping up, if i adjust the iat to compensate then after the heat soak is gone but the temps are still roughly the same then it runs too rich, i have full hks hardpipes ans braided teflon fuel lines of -6an into a sard rail at both ends then off to a sard type rj fpr then braided again back to the return, im wondering if these lines are causing the heatsoak or its just the heat of the manifold?

im looking at using the link to increase injection time after startup when the iat is over 40 degrees but it doesnt seem easy if even possible to do, plus its also just a "bandaid" fix rather than an actual fix, also if i had electric fans then i could just run them on for a while after the engines shut down but with the viscous that again is not possible
 
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Check that your inlet air temp sensor is an unshielded, fast reaction type. They are far better for turbo engines than the slow, shielded type. I run Marelli ones.
Think he is using a stock Nissan sensor moved, open tip sensors are far better but aren't for roads cars. They arent as robust as as stock car sensor a small back fire and your have a broken sensor with a open tip sensor.

GTR-loz sounds like you need to increase start fuel and the length of time it takes for the fuel to taper off after start up.

I would say it isnt anything to do with the fuel pipe's but hot fuel can cause a problem thou but playing with the start fuel/time will help.
 

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Discussion Starter #14
cheers i am using a delphi sensor (link recommended) in the intercooler pipe before the plenum but its set to no adjustment at these temps anyway i seem to of somehow broken my lc-1 while programing afr curve!!! when ive fixed it i will have a fiddle with the startup fueling but is it normal for it to need increased fuel for around a minute after startup?
at below 60 degrees i have warmup enrichment on anyway but after 60 this is off again this doesnt seem to help the afrs increasing with iat they should be going down (getting richer)
 
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Yes sometime's we find you may need to taper the start fuel off over 90 to 120 seconds.

I have seen the problem your talking about on a few GTR's I just add more start fuel and extend the fuel add time like I have described.
 
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