I am ready to start doing some different things to the Q, and after leather im going to have about 500 for other things..... And I want to get it back into really good performance......
My plans are to replace the o2 sensors and the knock sensors, which should be good for a while........ I have recently doused the MAFS in brake parts cleaner......
So what other sensors/components affect the Qs performance......? Is there any way to bypass them and have it running at full power all the time??? (ie no retardation)
Sensors/devices that affect performance.....
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
The 90-95Q use very few sensors [the minimal number] to achieve engine control.The only one the 94 adds is a sensor to measure the EGR temperature to avoid adding EGR when the engine is cold and to better regulate the amount for drivability.
The O2 don't affect wide open power other than setting a trim between banks and a minimal amount of enrichening [which the ecu learned from the previous cruise memory cycle.
WOT parameters are burned into the memory [from lab/dyno testing], except the MAF which can trim the equation by 20%.
For example 4,000 rpm WOT: 20 degrees advance and 11.0 millisecs fuel if the coolant temperature is not above 194.99F and the MAF say 150 grams per second of air is flowing in yelding about 210 HP/307 lb/ft of torque.
If you drive up a mountain to a flat valley at 3,000 feet: the air temp will fall 9F and the air density will decrease by 10% so the net change is 9% roughly. The MAF will now decrease its voltage and signal the ecu that only 137 grams per second are flowing in so the ecu decreases the injector open time by 9% roughly to maintain the programmed in air fuel ratio.
The O2 cannot read the AF ratio they only report when it is richer than 14.7 or leaner than 14.7 so they are useless to ecu in WOT.
They did however tell the ecu that just before WOT the driverside bank needed more fuel by 3% [ 2.5 vs 2.575 millisecs] so that both banks were equal in AF ratio at cruise.......the ecu rembers this for a short time [like 15 seconds] and adds 3% to the bigger WOT number for that bank . [burned memory says both at 11.0 millisecs, altitude correction from MAF say decrease this by 9% to 10.0 millisecs and ecu longterm fuel trims say make drivers side richer by 3% so 10.0 on passenger side and 10.2-10.3 on driverside.
Richer is always safer in an engine as the power doen't fall off very much when the mixture is too rich.
If you created full power all the time you would be getting 5 miles per gallon........as it takes 23.2 gallons per hour of fuel to make 278 HP.............[278/2 = 139/6 = 23.2] roughly.
All chip or reprogrammer do is lean the WOT tables and increase the WOT advance to remove most of the built in safety factors installed by the factory for engine wear and tear and dirt buildup and the octane safety limits which allow the engines to run on regular gasoline in emergencies.Some may change the tip in throttle advance curve rate [when ever you WOT the ecu takes advance out immediately to avoid knock and slowly [1.0-2.0 seconds or so adds it back in ]........if you add it back faster the engine will feel strong on the early part of acceleration at the risk of more knocking.
Same with coolant temp sensor reading, the factory has determined that above 194.9F the advance should be reduced by 1.0 degrees per every 5F hotter coolant because the fuel octane requirements go up as the head temperature goes up.
This was all tested back in 1988 on a lab grade gasoline which may have no bearing on the fuel we use today.
The knock sensors are the final arbitrator of what is safe.......all the equations create an advance number that worked in the lab 15 years ago [each year the factory made tiny changes to ecu program to fix things they found.....why ecu year has a different ecu model number].
The knock sensors are like the emergency valve on a water heater to kept it from exploding if something goes wrong. Suppose the coolant temp sensor changes and reads 10F lower than actual or the MAF reads leaner [less air than is actual because it is dirty] or injectors are dirty and not flowing the amount they did brand new.........the ecu doesn't know and has few ways to make sure.......especially after it forgets what the O2 said say in multiple WOT application or just high speed driving above 80 mph!
The O2 don't affect wide open power other than setting a trim between banks and a minimal amount of enrichening [which the ecu learned from the previous cruise memory cycle.
WOT parameters are burned into the memory [from lab/dyno testing], except the MAF which can trim the equation by 20%.
For example 4,000 rpm WOT: 20 degrees advance and 11.0 millisecs fuel if the coolant temperature is not above 194.99F and the MAF say 150 grams per second of air is flowing in yelding about 210 HP/307 lb/ft of torque.
If you drive up a mountain to a flat valley at 3,000 feet: the air temp will fall 9F and the air density will decrease by 10% so the net change is 9% roughly. The MAF will now decrease its voltage and signal the ecu that only 137 grams per second are flowing in so the ecu decreases the injector open time by 9% roughly to maintain the programmed in air fuel ratio.
The O2 cannot read the AF ratio they only report when it is richer than 14.7 or leaner than 14.7 so they are useless to ecu in WOT.
They did however tell the ecu that just before WOT the driverside bank needed more fuel by 3% [ 2.5 vs 2.575 millisecs] so that both banks were equal in AF ratio at cruise.......the ecu rembers this for a short time [like 15 seconds] and adds 3% to the bigger WOT number for that bank . [burned memory says both at 11.0 millisecs, altitude correction from MAF say decrease this by 9% to 10.0 millisecs and ecu longterm fuel trims say make drivers side richer by 3% so 10.0 on passenger side and 10.2-10.3 on driverside.
Richer is always safer in an engine as the power doen't fall off very much when the mixture is too rich.
If you created full power all the time you would be getting 5 miles per gallon........as it takes 23.2 gallons per hour of fuel to make 278 HP.............[278/2 = 139/6 = 23.2] roughly.
All chip or reprogrammer do is lean the WOT tables and increase the WOT advance to remove most of the built in safety factors installed by the factory for engine wear and tear and dirt buildup and the octane safety limits which allow the engines to run on regular gasoline in emergencies.Some may change the tip in throttle advance curve rate [when ever you WOT the ecu takes advance out immediately to avoid knock and slowly [1.0-2.0 seconds or so adds it back in ]........if you add it back faster the engine will feel strong on the early part of acceleration at the risk of more knocking.
Same with coolant temp sensor reading, the factory has determined that above 194.9F the advance should be reduced by 1.0 degrees per every 5F hotter coolant because the fuel octane requirements go up as the head temperature goes up.
This was all tested back in 1988 on a lab grade gasoline which may have no bearing on the fuel we use today.
The knock sensors are the final arbitrator of what is safe.......all the equations create an advance number that worked in the lab 15 years ago [each year the factory made tiny changes to ecu program to fix things they found.....why ecu year has a different ecu model number].
The knock sensors are like the emergency valve on a water heater to kept it from exploding if something goes wrong. Suppose the coolant temp sensor changes and reads 10F lower than actual or the MAF reads leaner [less air than is actual because it is dirty] or injectors are dirty and not flowing the amount they did brand new.........the ecu doesn't know and has few ways to make sure.......especially after it forgets what the O2 said say in multiple WOT application or just high speed driving above 80 mph!
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Q45tech
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- 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
1996 OBD2 is smarter and has 10 times the computer power and uses the O2 sensors for misfire detection at idle and cruise......still can't think fast enough at WOT and high rpms so each sensor is checked better. Not just that they are working [not shorted or open] but using other sensors in comparison that they are working closely and generating numbers that make sense! Still the coolant temp can't be verified as 100% correct so the ecu checks if AC is on and what the sunload says and what the external temp sensor says and the coolant temp history has been in the last few minutes before placing its faith in the number.
Still the knock sensors are the final arbitrator as OBD2 has the capacity to actually add advance to the factory calibration if better than reference fuel in used or somehow the engine improves [with age] [friction goes down].......the air gets cooler [why there is an extra fuel and inlet air temp sensor] or it starts to rain [humidity].
Still the knock sensors are the final arbitrator as OBD2 has the capacity to actually add advance to the factory calibration if better than reference fuel in used or somehow the engine improves [with age] [friction goes down].......the air gets cooler [why there is an extra fuel and inlet air temp sensor] or it starts to rain [humidity].
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
They crack [the plastic case surrounding the piezo components] from excessive temperature and change resistance and sensitivity and resonant frequency.
"i dyno'd 172 hp with bad knock sensors'Guess my 20-30 HP comments should be expanded to 20-45.But 45 HP down would only reduce quarter mile by 0.5 seconds yet the effect is much more..........sluggish and slow unless you are at WOT........sometimes the Q will buck and snort in light 60 mph acceleration!
"i dyno'd 172 hp with bad knock sensors'Guess my 20-30 HP comments should be expanded to 20-45.But 45 HP down would only reduce quarter mile by 0.5 seconds yet the effect is much more..........sluggish and slow unless you are at WOT........sometimes the Q will buck and snort in light 60 mph acceleration!
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
The coolant temp sensor [the 2 terminal one that feeds the ecu] is the 2nd most critical signal to ecu! Fail safe occurs when it is open or shorted. It is a negative coefficient thermister [as the temp goes up the resistance goes down [5,000 ohms cold 220 ohms hot].
The ecu only goes into closed loop control [when O2 are actually read] above 160F and the ideal temperature is 176F. The thermostat begins to open at 170F and is fully open by 194F......somewhere between 176F and 182F is the mean
The under plenum temperature where the knock sensor attach to the middle of each head is 30-40-50F warmer than the coolant temperature reads. So the KS are exposed to 225F-275F...........the KS are speced for 400F. After an engine is turned off the head temperature probably rises another 50F.....325F.
The hot/cold cycling or overheats eventually crack the plastic.
The ecu only goes into closed loop control [when O2 are actually read] above 160F and the ideal temperature is 176F. The thermostat begins to open at 170F and is fully open by 194F......somewhere between 176F and 182F is the mean
The under plenum temperature where the knock sensor attach to the middle of each head is 30-40-50F warmer than the coolant temperature reads. So the KS are exposed to 225F-275F...........the KS are speced for 400F. After an engine is turned off the head temperature probably rises another 50F.....325F.
The hot/cold cycling or overheats eventually crack the plastic.
__________________Brian1995 Q45 & Q45tSo maybe I can get educated a little on performance problems. Is this right? Low power for non-mechanical reasons can be caused by: - bad head outlet temp sensor or bad cooling system- bad MAF- plugged or bad injecotors ( possibly also fuel filter / pressure regulator / pulsation dampener )- bad ignition (plugs, coils etc.)- shorted or open knock sensors- bad timing Mechanical reason except for compression related: - dirty intake system (from MAF to Valves)- weak fuel pump- plugged cats / pre-cats- massive vacum leak- bad mecahical timing (rare but possible if guides were ever done)
anything else to add? How to rank these by likelyhood and how to really test for them is a little beyond me.
anything else to add? How to rank these by likelyhood and how to really test for them is a little beyond me.
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Same things on all modern engines, they all work the same way.The only thing about Q is VVT and that almost never causes a problem.........seen 1 in 1,000 defective at extreme mileage!Every engine has the same sensors [some cheaper or turbos don't have a MAF but they have a MAP sensor].
The 90-95 Q has few sensors than most no inlet air temp sensor or gasoline temperature sensor [the crank angle sensor is actually an exhaust cam angle sensor].
Lots of parameters are measured [or calculated] on FAITH that the owner keeps the car in tip top condition. This HORRIBLE mistake was corrected with OBD2 because owners didn't maintain and they pay now with each illumination of the MIL light......gas cap, bad gas, dirty air filter, least bit of dirt and a light comes on and you fail emission test!
Why make it harder than it is! The 32 valves and precision build allow the engine to act bigger than it is something like a 305-330 cubic inch US type...........yet get the better mileage of a 274 size......unlesss you get on it!
One of my knock sensors finally failed at 11 years and 221,000 miles but even though the car spent all its like in GA and FLA.[warm] I have never had an over heat .........once I did leave the radiater cap off for 2 days in winter........what a mess orange everywhere.
You would be surprised at how many Q come in overheated in Summer they refused our advice previously and wanted some cheap fix without replacing the radiater and doing everything correctly. Most get to pay big or sell us the car for $750.
We are refusing to buy Q cars now as we have 6 parts cars on the lot.
Five-Ten years from now members will remember fondly the good old days when cars/engines were so simple as the 90-95Q.
And diagnostics only cost $90 an hour instead of requiring a MSEE at $200 an hour.
The 90-95 Q has few sensors than most no inlet air temp sensor or gasoline temperature sensor [the crank angle sensor is actually an exhaust cam angle sensor].
Lots of parameters are measured [or calculated] on FAITH that the owner keeps the car in tip top condition. This HORRIBLE mistake was corrected with OBD2 because owners didn't maintain and they pay now with each illumination of the MIL light......gas cap, bad gas, dirty air filter, least bit of dirt and a light comes on and you fail emission test!
Why make it harder than it is! The 32 valves and precision build allow the engine to act bigger than it is something like a 305-330 cubic inch US type...........yet get the better mileage of a 274 size......unlesss you get on it!
One of my knock sensors finally failed at 11 years and 221,000 miles but even though the car spent all its like in GA and FLA.[warm] I have never had an over heat .........once I did leave the radiater cap off for 2 days in winter........what a mess orange everywhere.
You would be surprised at how many Q come in overheated in Summer they refused our advice previously and wanted some cheap fix without replacing the radiater and doing everything correctly. Most get to pay big or sell us the car for $750.
We are refusing to buy Q cars now as we have 6 parts cars on the lot.
Five-Ten years from now members will remember fondly the good old days when cars/engines were so simple as the 90-95Q.
And diagnostics only cost $90 an hour instead of requiring a MSEE at $200 an hour.
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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
The whole master plan by government and industry is to make the cars too difficult to repair after 7 years and get all the old ones off the road faster like in Japan so new cars sales can increase to keep the economy afloat!Have you heard about OBD3 where the road side monitors mail you a ticket every time you pass and fail some parameter.....each car will be transpondered to see how many times you sped also.
Those Democrats are just waiting to get their hands on the technology.
Those Democrats are just waiting to get their hands on the technology.
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Q451990
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Big difference... I had a bad harness, and the most noticeable symptom was a slight bucking under a load (say 40-45MPH up hill in 4th) that would show up right before the transmission would downshift. Keep in mind that the ECU is retarding the timing advance when it's not getting a signal from the knock sensors, so the power difference is like having the timing off a few degrees BTDC. This is the ECU's way of protecting the engine while it can't "hear" what's going on - it just assumes the worst and compensates as much as possible.
Heath
Heath
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elwesso
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Ive been reading up on the plenum removal, and I dont know if will/wont be able to accomplish it....... It seems to be very tedious, and I have taken a gander around the plenum area to see what I am in for, and besides removing the IAC and fuel pressure regulator, it doesnt look too bad........ Every hose I have messed with on this engine seems to be in perfect condition..... And should one break, I will have some hoses handy....... Including the radiator hoses-- no signs of interior rotting or anything.......
Question is....... Ive done plugs, Tstat, and other various things...... Is the plenum in my ballpark, because I want to get these knock sensors replaced.........
Question is....... Ive done plugs, Tstat, and other various things...... Is the plenum in my ballpark, because I want to get these knock sensors replaced.........
somewhere back a few months ago I posted a blow-by-blow of pulling the plenum with times for each step. No photos though.
Plenum remove doesn't require any super-human manuvers or tools, but it is a little tedious because you'll be bent over the car at an almost 90 degree angle for 6 hours.
Of course there is one cevat; if you drop a bolt down one of the runners, you will remember that sound for years, mainly due to all the extra work needed to get it out.
Plenum remove doesn't require any super-human manuvers or tools, but it is a little tedious because you'll be bent over the car at an almost 90 degree angle for 6 hours.
Of course there is one cevat; if you drop a bolt down one of the runners, you will remember that sound for years, mainly due to all the extra work needed to get it out.