Why did the 1.8 engines have L-jet? |
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Why did the 1.8 engines have L-jet? |
VaccaRabite |
May 31 2024, 08:05 AM
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#1
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En Garde! Group: Admin Posts: 13,571 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
Has there ever been a reason Porsche/VW speced L-jet injection for the 1.8 engines instead of D-jet like the 1.7 and 2.0 engines used?
Usually when manufactures do this there are financial reasons for the change. Either they have the same engine on other vehicles they produce, or its just cheaper to use whatever part is being used. But Porsche didn't use the T4 motor on other cars at the time. And if it was cheaper, they would have done away with Djet on the 1.7 and 2.0. I don't think VW was using l-let at the time for the bus... but maybe? There has to be a reason that Porsche wanted Ljet on the 1.8. Zach |
technicalninja |
Jun 2 2024, 05:13 PM
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#2
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Senior Member Group: Members Posts: 1,948 Joined: 31-January 23 From: Granbury Texas Member No.: 27,135 Region Association: Southwest Region |
Two ways to measure load on an engine.
Manifold vacuum- D-jet, also MAP sensor. Can calculate load Weight of air- maybe more accurate in operation than MAP, L-jet K-jet also MAF sensor. This actually measures the amount of air being consumed. All modern stuff I work on has BOTH now... It's helps to get all of the available data. This is a NICE quick read regarding Bosch Jetronic overall. I have learned the "death date" of L-jet and it happened exactly as I described... I also learned that "Mono-Jetronic" exists. Chevrolet TBI! Ford CFI! Millions of them... Only uses a TPS to determine load but totally dependent on O2 control. Super simple. https://en.wikipedia.org/wiki/Jetronic |
wonkipop |
Jun 2 2024, 05:43 PM
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#3
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Advanced Member Group: Members Posts: 4,658 Joined: 6-May 20 From: north antarctica Member No.: 24,231 Region Association: NineFourteenerVille |
Two ways to measure load on an engine. Manifold vacuum- D-jet, also MAP sensor. Can calculate load Weight of air- maybe more accurate in operation than MAP, L-jet K-jet also MAF sensor. This actually measures the amount of air being consumed. All modern stuff I work on has BOTH now... It's helps to get all of the available data. This is a NICE quick read regarding Bosch Jetronic overall. I have learned the "death date" of L-jet and it happened exactly as I described... I also learned that "Mono-Jetronic" exists. Chevrolet TBI! Ford CFI! Millions of them... Only uses a TPS to determine load but totally dependent on O2 control. Super simple. https://en.wikipedia.org/wiki/Jetronic yes @technicalninja the old 02 sensor. the next big thing. and a massive investment by bosch. bigger in someways than the whole development behind the earlier efi systems of D jet and L jet. bosch controlled the patents on that after they finally succeeded. its made them a fortune. the lack of a suitable 02 sensor stalled the timeline of the Nixon Clean Air Act. they were meant to get to a point in 1975 that they did not achieve until the early 80s. the carmakers and (even bosch) simply could not deliver the technology to make the standards in the time span. The USEPA worked with the carmakers to amend the plan realistically. the 02 sensor was the critical bit needed. the difference between CARB and USEPA was an agreement reached between the USEPA and carmakers as well to assist with the introduction of technology. more of less split the domestic car market in half and meant in any one year USA and foreign car companies only had to address 50% of the volume of sales to the new standards. the remaining 50% would use the californian stuff the year after in the other 49 states. L jet evolves. quickly becomes L jet with added suffixes as the 02 sensor kicks in. not sure when the last airflow meter is done. but i know that 964s had AFMs in the very late 80s. and some domestic sales australian stuff still had them in the 90s on new cars. in the absence of an 02 sensor L jet is assuming load but its got no feedback. it was able to do a better (more accurate) job guessing (or assuming) what that was than D jet could. but it still could not make the standards that were aimed for in 1970 for 1975. no one could. |
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