I have a s14 nissan with a stock auto 1jz vvti engine in. For months now I can't find the problem. The car when it reaches running temp and you start making boost suddenly feels like a switch is flipped, turbo screams to make boost but nothing, no power amd misfires, can only accelerate without boost. I unplugged and replaced the coolant sensor, the car performs as it should with the coolant sensor unolugged. But I am afraid to go WOT. Please help?
1jz vvti misfires and looses power, but runs better with coolant sensor unplugged
- Thread starter Deew
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- coolant sensor misfire
Also. I am new. Name is Dewald. From South Africa. Hope to meet some people with knowledge on this thread. Thanks
s13silvia
doughnut muncher
Test your coolant sensor connector for live and earth. Try unplugging your O2/TPS/ MAF after and see if they have the same result as unplugging your coolant sensor; also test these with a voltmeter. If so it's putting your ecu into limp mode and you shouldn't be abusing the car on this mode, but it is worth testing a little boost to see if the car drives correctly, or the same (as this is where you're getting the issue).
If it drives well on boost in limp mode (shouldn't really let you rev high) this would indicate your ECU is stopping the car running correctly due to an error with the feedback signal from somewhere - you'll need to troubleshoot for this. I'd be thinking high potential for MAF or O2 sensor here, not your coolant sensor or TPS.
If the car acts the same (splutters and missfires on boost) it often suggests either a faulty coilpack(s) or a boost leak.
When you say it feels like a switch is flipped; many cars run in open-loop (no or limited sensor feedback) during the warm-up phase; then once at operating temperature it goes closed-loop; so all your sensor feedback signals are registered by the ECU which in turn helps it deliver appropriate timing, fuel and air. So again; this would point to a sensor failure - each of which can be tested relatively easily with a voltmeter (plenty instructional videos on youtube)
If it drives well on boost in limp mode (shouldn't really let you rev high) this would indicate your ECU is stopping the car running correctly due to an error with the feedback signal from somewhere - you'll need to troubleshoot for this. I'd be thinking high potential for MAF or O2 sensor here, not your coolant sensor or TPS.
If the car acts the same (splutters and missfires on boost) it often suggests either a faulty coilpack(s) or a boost leak.
When you say it feels like a switch is flipped; many cars run in open-loop (no or limited sensor feedback) during the warm-up phase; then once at operating temperature it goes closed-loop; so all your sensor feedback signals are registered by the ECU which in turn helps it deliver appropriate timing, fuel and air. So again; this would point to a sensor failure - each of which can be tested relatively easily with a voltmeter (plenty instructional videos on youtube)
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Thanks so much. Just came back from testing.
Car can't start if I unplug tps, maf. When I plug the coolant sensor in and drive until it is warmed up and keep the boost below 0psi nothing changes, just as soon as it goes in to positive the switch is flipped and misfire at higher revs, no power occurs, heavy on fuel as well.
The car when the coolant sensor is unplugged performs as it should up until 0.5bar tested, did not push futher because of fear of killing it. Does any of this make sense?
Also. The 1jz vvti engines only use a maf right? No map sensor on them like the non vvti?
I will still have to try with o2 unplugged
Zammish24
Member
vvti engines run off MAF sensor.
If the car runs better with the coolant sensor unplugged, it will be running richer as a fail safe.
What ECU have you got? how did you wire up the ecu to think it's in gear?
I had the exact same issue turned out to be the neutral start switch wire needed grounding
Hi. Thanks so much.
Well it still has the auto transmission, with the trans and engine both still running off the standard toyota ecu. It's interesting because I have a weird issue where if i go above 120 km/ph it feels as if it gears back out of overdrive. And I still have not fixed the performance issue. What whould be a sign that my neutral start wire is not grounded.? Thanks again.
Zammish24
Member
Ah then I'm unsure, if its already got the auto box then ignore my previous comment, Figured this was a auto - manual swap.
do a code check that should point u in the right direction
Chizzel
New Member
DID YOU EVER FIGURE THIS ISSUE OUT? I’m having similar issues, I have a manual gear box however, but acts the same as yours