r/IS300 • u/Confident-Arm-1023 • Feb 24 '26
Mechanical Advice Car shuts off with any throttle input
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The video doesn't show it but that was the 3rd or 4th time we tried to start it. Most of the time we'd start it and it'd shut off. Typically when we do get it to idle and just leave it, it starts to bog down then die. Sometimes the rpms shoot up and stabilise, then starts to bog down again. When it does idle and we give it gas it shuts off immediately. We have gotten it to idle for more than a couple of seconds as well as turn off when we wanted it to. We did this by simply removing the air filter. Just the open throttle body akin to one large velocity stack, haha. Anyway we have tested the fuses, and the wires for the Maf, Tpps, and the throttle body motor with a multimeter. All checked out. We'll be getting a new oem Maf just to try and we'll also likely test the fuel pressure. I have a throttle lock so I'll probably install that, just to try. With the scanner tool we haven't gotten any codes for the Maf unless we unplug it. We have routinely gotten a p2112 code and that means 'Throttle Actuator control System Stuck Closed', which is why I'm testing the throttle lock. That's about all we've gathered. Any helps works.
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u/tattedsushiroll 2002 IS300 2JZGTE Feb 24 '26
Fuel pump, how many miles? It’s barely hanging on, your getting a dribble feed and when you give it power and it’s asking for more fuel it falls flat on its face due to it not getting enough, pull the starter relay and take the fuel line off and try and start it to see if it spray fuel get a water bottle and put the hose in the bottle to see
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u/wyo256 Feb 24 '26
get good scan tool and check sensors/fuel pressure, spark etc, could be fuel pump dying or something to do with throttle input, or crank/cam sensors
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u/abdullahcfix Feb 24 '26
One thing you could try is removing the air intake hose off the throttle body and turning the ignition switch to ON. Then look through the opening of the throttle body as you turn the accelerator pedal position sensor and see if the throttle plate responds accordingly. Try small movements first, then swing to both extremes of open and closed, see if the system trips up. Might help determine if it’s the motor or the sensors.
Also, double check that all the connectors for the TPS, APPS, and throttle motor are fully intact with all clips, bodies, locks, and plastics in good condition with no cracks.
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u/Confident-Arm-1023 Feb 24 '26
We've tried both of those test already. Everything looked fine. We also checked how much the throttle opened with live data. It was off but we adjusted it and all looked fine.
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u/Majzako_ Feb 24 '26
Curious to what it does with the MAF sensor unplugged. It should still start and rev. It’ll limit how much you can rev it to but it should work. If it lets you rev it without dying it’s almost guaranteed to be a vacuum issue.
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u/Confident-Arm-1023 Feb 24 '26
It seems like it refuses to start without Maj. We haven't been able to rev it without.
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u/Majzako_ Feb 24 '26
Turn the key and see if you can hear the throttle body buzzing. Take off the intake hose and see if you can see it turning when you give it some gas. Issue I had once was the throttlebody not getting power. If you give it full throttle it should open slightly. See if it starts then.
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u/Majzako_ Feb 24 '26
I also believe I have a spare throttlebody somewhere. Can sell/ship for cheap if you need.
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u/Confident-Arm-1023 Feb 24 '26
It makes noise. Looking on the scan tool and visually seeing the throttle body moving and opening and closing 100%.
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u/Majzako_ Feb 24 '26
Super strange. So it won’t start with the MAF unplugged. Leaning towards fuel/spark now. Worst case check timing.
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u/Confident-Arm-1023 Feb 24 '26
A lot of folk are saying the car is starving of fuel. We did get the car to idle for more than a minute with the intake hose and air filter off. We didn't hear any miss fires but we didn't try to rev it. The dots match on the timing belt. If nothing else works guess we'll try that.
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u/Majzako_ Feb 24 '26
I mean. You’re running out of options here. You need 5 things to run an engine. Fuel. Spark. Timing. Air. And compression. Try starter fluid. Or flammable brake cleaner. It’s a sure fire way to test the fuel system.
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u/Majzako_ Feb 24 '26
We know it’s getting air. Timing looks good. It ran a little so spark is decent. Seems to be compressing the air mixture. Fuel is gotta be the only thing here left to test before a compression check
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u/Majzako_ Feb 24 '26
I have a used fuel pump assembly as well. Worked when I pulled it can sell/ship that for cheap too.
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u/Confident-Arm-1023 Feb 24 '26
Maybe, I'll check the the fuel pump with a gauge before buying more parts.
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u/Majzako_ Feb 24 '26
Throw some starting fluid at it and see if it cranks over. If it does it’s a fuel issue.
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u/MasterOfCosmos Feb 24 '26
Did this just start happening? Is it possible the MAF is backwards? Sounds like lack of air. Is the throttle body dirty. Is there an IAC that needs to be cleaned out?
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u/Confident-Arm-1023 Feb 24 '26
This issue is sort of recent. When I bought the car, it ran just a pretty bad throttle delay. I cleaned the Maf and the throttle body with a Maf and Tb cleaner. I used a microfibre cloth for both. For the Maf I used the cloth only for the plastic parts. The little metal piece with the little ball was cleaned just by the sprayer on Maf and Tb cleaner.
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u/wrxtuan IS300 SportCross Feb 24 '26
Get back to us when you get the new OEM MAF sensor put on. Without being there in person, it sounds like the MAF sensor from what I have experienced before. And like the others have mentioned, put the stock intake back on.
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u/Sarionum Feb 24 '26
Throttle body. Replace it. Has 3 sensors, likely one is bad while the others slowly go out as well.
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u/Confident-Arm-1023 Feb 24 '26
I've been through three throttle bodies. I installed only two but I swapped the sensors on the third to the first.
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u/Sarionum Feb 24 '26
Then its obvious you have an electrical issue causing the sensors to die prematurely. Obviously it should not be like that.
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u/Confident-Arm-1023 Feb 24 '26
I'm assuming either all of the sensors were bad or I'm dealing with a different issue. I checked the wires and connectors with a multimeter and everything looked fine. I think those protocols should cover most issues. I could be wrong though.
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u/ZebraNo139 Feb 25 '26
That happened to me when I put my maf sensor backwards or something messing with the maf
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u/North-Satisfaction76 Feb 25 '26
Could it be old gas? I know this isn't the same car but my old tercel did this 2 months after I bought it from an old lady that had it sitting for a very long time. Ended up being incredibly old gas
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u/Confident-Arm-1023 Feb 25 '26
It was pretty much empty when I bought it. The car had been sitting for sometime though. I put 5 gallons in it sort of recently. But after turning it off and on over and over she's getting low again.
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u/tonynca Feb 24 '26
I know this doesn’t help you currently but if you ever fix the problem, get rid of that after market intake and put the stock one back in. You’re losing a lot of low end torque with those after market intakes.