My Q has been running extremely rough over the past two months. It would stumble upon acceleration and my fuel mileage was down. I replaced the injectors, plugs, vacuum hoses and fuel filter.
This morning the engine performed great, unlike the previous weeks. The only difference is that it was 30 degrees cooler out than previous weeks. I did notice that on days where the temperature was above 85 degrees things got worse. Now the temperature is 55 degrees and the car has improved 90%.
Is my MAF possibly bad? I’m running a K&N filter. Can the oil from it deposit on the MAF film?
Boudreaux
MAF ??? AMBIENT TEMPERATURE MAKES A DIFFERENCE???
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Q45tech
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- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: MAF ??? AMBIENT TEMPERATURE MAKES A DIFFERENCE??? (BOUDREAUX)
The coolant temp sensor reading triggers an ignition advance reduction of 1 degrees every 5F above 195F......................this with bad KS is wht problems show up worse in summer heat.
AC on [or just hight external air sensor] sends a signal to ecu also reducing ignition advance.
Bad intermitent solder connections in MAF are always temperature sensitive.
30F of heat is only 3% less dense air so 3% [ PLUS whatever ignition retard occurs] of engine power reduction.
Important to graph coolant temp rise vs ambient rise to make sure coolant never exceeds 200F while engine is running.
AC on [or just hight external air sensor] sends a signal to ecu also reducing ignition advance.
Bad intermitent solder connections in MAF are always temperature sensitive.
30F of heat is only 3% less dense air so 3% [ PLUS whatever ignition retard occurs] of engine power reduction.
Important to graph coolant temp rise vs ambient rise to make sure coolant never exceeds 200F while engine is running.
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maxnix
- Posts: 22627
- Joined: Mon Jul 22, 2002 8:11 pm
- Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45
Re: MAF ??? AMBIENT TEMPERATURE MAKES A DIFFERENCE??? (BOUDREAUX)
K&N oiled filters have ledd to many MAF sensor failures. OEM filters are cheap from Joe. Replace annually and be safe and happy and economical.
It's all in the prevous posts.
It's all in the prevous posts.
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: MAF ??? AMBIENT TEMPERATURE MAKES A DIFFERENCE??? (maxnix)
The MAF may not fail from oil just become contaminated and VERY INACCURATE in reporting true air flow.
Oem MAF are accurate within +-5% [most better like +-3%] so with O2 feedback the AF gets spot on, however there is a 20% limit to how much the ecu can correct for errors.....................exceed that and problems begin to show up.
We always find MULTIPLE PROBLEMS.................there are always a series of variations from brand new.................fixing the major culprit gets things back within the 20% but you want the adaptive learn to return to 100% not just 119 or 115 or 81 or even 90......................98-102 is what you desire. No ecu stress from having to cover up problems.
Oem MAF are accurate within +-5% [most better like +-3%] so with O2 feedback the AF gets spot on, however there is a 20% limit to how much the ecu can correct for errors.....................exceed that and problems begin to show up.
We always find MULTIPLE PROBLEMS.................there are always a series of variations from brand new.................fixing the major culprit gets things back within the 20% but you want the adaptive learn to return to 100% not just 119 or 115 or 81 or even 90......................98-102 is what you desire. No ecu stress from having to cover up problems.
