Ecu
Ecu
I've read here & elsewhere that the 90-91 Q seem to have more power than 92-93. What is responsible for this ? Isn't the drive train (nearly) identical ? I'm thinking the difference must be in the ECU. I'd like to try an early ECU in my 92 to see if there is a difference. I've stayed away from the JWT ECU because I prefer to maintain the greater safety margin, and I rarely run the thing up over 4K rpm anyway. Anyone try this on a 92-93 ?
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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
The later year ecu had various tweeks in part throttle cruise/decel/accel to improve the seemless perception of performance and improve emissions.......they ran out of things to do thus the 94 redesign of the cylinder input ports and runners.
I doubt that you could--- feel---- anymore/ anyless power from a 93 ecu vs a 90 ecu-- the car might behave better in warm ups cold running, overheats.
The major problems [90-93] were associated with high rpm then sudden closing of throttle when a slug of richness caused emission problems.
WOT [above 3,000 rpm] look up tables seemed to not change from 90-93 as the corect numbers were the correct numbers.
What we used to say was that the JWT ecu seemed to gain more power [as a percentage] when used on a 90-93 than a 94-95 primarily due to the emission redesign!
Some of the 90 seemed to be tweeked [ecu WOT program] more than 91 or 92 or 93. My guess is the Knock sensors were tuned to be less sensitive [amount of retard] then they found out how really bad US gas had become and changed things in 91-92.
After all the only thing the ecu does is amount of fuel vs air flow and spark advance and injector start/stop time offsets [even though the amount [open time] is the same you have a choice of how soon you start the injection process as a % of valve opening.
Most engines use small injectors whereas the Q uses really big ones and never allows them to be open more than 55% of the available time so positioning the fuel shot in the wide 248 degree open time is a major tweek.....air air fuel air or air fuel air air.
You'll have to do some dyno test to know for sure. Remember 10 HP will not be measurable with a stopwatch due to human variation and might represent 0.10 seconds in a quarter.
Transmission shift time can easily vary 0.5 seconds twice so up to 1.0 second difference depending on transmission condition!
There were some changes in the structure of injectors primarily to improve clogging and last longer on oxygenated fuels.
The many of the 90 Q seem to have matched ports to gaskets [maybe a little more hand fine tuning during assembly] or they just tried a little harder on the first ones since it was a new engine.
I doubt that you could--- feel---- anymore/ anyless power from a 93 ecu vs a 90 ecu-- the car might behave better in warm ups cold running, overheats.
The major problems [90-93] were associated with high rpm then sudden closing of throttle when a slug of richness caused emission problems.
WOT [above 3,000 rpm] look up tables seemed to not change from 90-93 as the corect numbers were the correct numbers.
What we used to say was that the JWT ecu seemed to gain more power [as a percentage] when used on a 90-93 than a 94-95 primarily due to the emission redesign!
Some of the 90 seemed to be tweeked [ecu WOT program] more than 91 or 92 or 93. My guess is the Knock sensors were tuned to be less sensitive [amount of retard] then they found out how really bad US gas had become and changed things in 91-92.
After all the only thing the ecu does is amount of fuel vs air flow and spark advance and injector start/stop time offsets [even though the amount [open time] is the same you have a choice of how soon you start the injection process as a % of valve opening.
Most engines use small injectors whereas the Q uses really big ones and never allows them to be open more than 55% of the available time so positioning the fuel shot in the wide 248 degree open time is a major tweek.....air air fuel air or air fuel air air.
You'll have to do some dyno test to know for sure. Remember 10 HP will not be measurable with a stopwatch due to human variation and might represent 0.10 seconds in a quarter.
Transmission shift time can easily vary 0.5 seconds twice so up to 1.0 second difference depending on transmission condition!
There were some changes in the structure of injectors primarily to improve clogging and last longer on oxygenated fuels.
The many of the 90 Q seem to have matched ports to gaskets [maybe a little more hand fine tuning during assembly] or they just tried a little harder on the first ones since it was a new engine.