low power at 80 deg

chris2712au · Post by **chris2712au** » Sat Jan 21, 2012 8:25 pm

I am interested if the ECU does something to the tune on over 80 deg water temp.. as when the days are really warm the car suffers big time.. not talking the odd kw.. but bogs hard.. then the next morning pulls really well.. cant seem to track it down.. was thinking MAF.. but why the hot and cold thing.. second by intercooler being oiled up cause it isnt running a seperator on the intake.. any thoughts.. I can run a few log files.. but all seems to be ok.. the only funny thing is it struggles / very lazy to come on boost.. engine temp in 70's ok.. hits 80.. not ok.. Its an s15 by the way.. but have also seen it in some s13's as well..

chris2712au · Post by **chris2712au** » Sat Jan 21, 2012 11:01 pm

maybe the temperature compensation in my maf is not working well.. is there a way to test it.. voltages look ok but is there a cold hot test..

Matt · Post by **Matt** » Tue Jan 24, 2012 5:04 pm

What are the AFRs like when it bogs down? Do you have the aircond at the time when its hot and does this coincide with the bogging?

chris2712au · Post by **chris2712au** » Tue Jan 24, 2012 5:35 pm

I will check them out again.. the wideband is disconnected at the moment.. but I believe that power steering and aircon do it.. does that mean anything ? I have checked the function of the FCID valve and it works ok.. kicks the idle up anyway.. it also happens without but is more noticeable when the power steer / aircon is on..

Matt · Post by **Matt** » Sat Jan 28, 2012 12:03 pm

I've noticed these on both of my cars with aircond on and going to look into it. Aircond seems to require more injection time (it is increased but when looking at wideband the mixture is leaner). So there may be a separate K type adjustment for air cond I am thinking but need to dig all the code to find it

chris2712au · Post by **chris2712au** » Sat Jan 28, 2012 1:59 pm

I am going to get another bung welded in the exhaust for the wideband.. as I had it in the factory location and I dont think it liked it.. going to put it pre cat on front pipe after the flex ? or should i do it on the turn under the car ? was wondering if I just had a manifold leak as the engine shows a slight miss on idle..

when I get my wideband on I get back with some AFR's.. but if you find something in the meantime please let me know.

Matt · Post by **Matt** » Sun Jan 29, 2012 6:19 pm

Position before the cat as far from the turbo on an angle above horizon

Check AFRs at idle to see what they are like to see if that is causing the problem. Mine only happen once A/C on and sitting idle goes from 14.7:1 to about 17.1:1

chris2712au · Post by **chris2712au** » Sun Jan 29, 2012 8:23 pm

maybe the aircon is taking it out of closed loop ? on the s15 the idle up for power steer and aircon is in parallel with the idle air control valve.. the both get air from a pre throttle body source off the cooler pipe so it is all metered air.. I will go past the exhaust shop tomorow to see if they can put the bung in..

chris2712au · Post by **chris2712au** » Tue Jan 31, 2012 5:35 pm

it is killing me, I called an exhaust shop local to me and will they did was whinge about how hard it was to do and that they would need the car for a few hours.. damn it is only a bung.. looks like I will have to do it on the pebbles in my front yard.. go to work and tig it myself..

Matt · Post by **Matt** » Fri Feb 03, 2012 10:26 am

Should take about 30 minutes and cost about $40-$50.

Try another shop if possible. It is a bit of a pain to find the right spot since you have to drill into the pipe whilst its fitted but not impossible

Matt · Post by **Matt** » Fri Feb 03, 2012 10:26 am

Should take about 30 minutes and cost about $40-$50.

Try another shop if possible. It is a bit of a pain to find the right spot since you have to drill into the pipe whilst its fitted but not impossible

chris2712au · Post by **chris2712au** » Sat Feb 18, 2012 3:07 pm

well I got the wideband fitted today.. took the front pipe off and took it to the exhaust shop.. I marked it up, they drilled and welded the bung in..

running the A/F looks good.. giving it a hit.. it is coming onto boost around 12.5 the hitting boost and going to 12.0 - 11.8.. maybe it is the wastegate / turbo just isnt up to it any more..

chris2712au · Post by **chris2712au** » Mon Mar 05, 2012 5:40 pm

it is fuelling up hard... same cells in fuel map... engine at temp ~80 deg cold day.. 11.5afr... hot day 10.8 afr.. I am leaning towards stuffed AFM.. what do you think ?

Matt · Post by **Matt** » Tue Mar 06, 2012 10:22 am

If the AFM is dirty then they normally read lean (because the hot wire doesnt cool down as much as it should so the load signal it passes isnt as high... therefore the ECU doesnt inject as much). If theres another issue with the AFM (internal electronics) then possible

Got AFM voltages from any older logs at all to compare notes with?

chris2712au · Post by **chris2712au** » Tue Mar 06, 2012 5:06 pm

yeah it definitely isnt dirty its been cleaned enough times.. from what i have read about MAF mass air flow meters that there are2 elements inside.. one measuring airflow and the other measuring temperature of the airflow sensor.. so it can compensate the mass of air.. then regarding on temperature adjust the voltage I would think that less mass of air means less mass of fuel.. I am feeling that when it is hot it is not backing off on the fuel.. so injecting the same amount of fuel.. well in theory.. and my cold air intake isnt that great so intake temps vary a bit...

as far as logs.. dont think I have one from before..

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