RBpete Posted February 6, 2022 Share Posted February 6, 2022 Hey guys Recently had my rb20det Gts4 Rebuilt. The car seems very laggy until about 4.5-5k revs until boost hits all at once, when shifting on the highway from 3rd to 4th or 5th gear it also jerks and shudders until boost hits again it definitely does not seem normal. Sometimes between shifting it will pop out the exhaust. The car has just had timing set up correctly and also a vacuum leak test. also had a compression test done which came out good. next thing to try will be testing the tps If anyone has any ideas on where else to try look at would be appreciated! car just has a fmic and a walbro 255lph fuel pump. still factory ecu Link to comment https://www.sau.com.au/forums/topic/483306-rb20det-laggy-jerky-between-gear-shifts-sometimes-popping-out-exhaust/ Share on other sites More sharing options...
GTSBoy Posted February 6, 2022 Share Posted February 6, 2022 How old is the fuel pump? Have you measured the fuel pressure at the rail while the engine is under load? The TPS will not cause what you describe. It will be fuel or ignition. Link to comment https://www.sau.com.au/forums/topic/483306-rb20det-laggy-jerky-between-gear-shifts-sometimes-popping-out-exhaust/#findComment-7960789 Share on other sites More sharing options...
RBpete Posted February 7, 2022 Author Share Posted February 7, 2022 @GTSBoyFuel pump is new. I haven’t tested the fuel pressure under load but that might be worth trying! fuel pump is still just plugged straight into factory loom without a constant 12v Link to comment https://www.sau.com.au/forums/topic/483306-rb20det-laggy-jerky-between-gear-shifts-sometimes-popping-out-exhaust/#findComment-7960798 Share on other sites More sharing options...
Dose Pipe Sutututu Posted February 7, 2022 Share Posted February 7, 2022 On 07/02/2022 at 1:09 PM, RBpete said: fuel pump is still just plugged straight into factory loom without a constant 12v that's a problem itself, aftermarket pumps consume more current than the OEM wiring can handle - not to mention the OEM drop resistor isn't very helpful in keeping these modern pumps alive. You need to wire it properly OR PWM them. Link to comment https://www.sau.com.au/forums/topic/483306-rb20det-laggy-jerky-between-gear-shifts-sometimes-popping-out-exhaust/#findComment-7960802 Share on other sites More sharing options...
RBpete Posted February 7, 2022 Author Share Posted February 7, 2022 @Dose Pipe SutututuThe reason i thought it may of been tps is because idle bounces up and down sometimes Link to comment https://www.sau.com.au/forums/topic/483306-rb20det-laggy-jerky-between-gear-shifts-sometimes-popping-out-exhaust/#findComment-7960809 Share on other sites More sharing options...
GTSBoy Posted February 7, 2022 Share Posted February 7, 2022 'sgot nothing to do with it on an RB20. Link to comment https://www.sau.com.au/forums/topic/483306-rb20det-laggy-jerky-between-gear-shifts-sometimes-popping-out-exhaust/#findComment-7960814 Share on other sites More sharing options...
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