2003 Camry Hiccups @ 2800 RPM when it is hot outside

toyota
camry

#1

The particulars are 2003 Camry, 4 cyl, manual trans. When it gets to be 90 degrees or hotter outside, the car hiccups when accelerating through 2800 rpm. That is the most common scenario. Pretty much any gear and the problem gets worse the hotter to outside air. It never throws a code or check engine light. It doesn’t stall although it feels like an istantaneous loss of ignition. I can set the cruise control and it will periodically happen when driving through the desert. It repeats as often as it wants to…no overall pattern, uphill or flat, no difference. Dealer says nothing is wrong since it won’t throw a code. No issue in the winter, only hot summer driving. Any ideas?


#2

The problem might be with a crankshaft position sensor being effected heat and vibration.

The crank sensor is one of the primary inputs into the computer. If the signal from this sensor is lost, even for a second, the computer see’s no reason to operate the ignition and fuel systems so the engine stumbles.

Since this problem is predictable, watch the tachometer when this happens. If the tach suddenly drops to zero RPM’s when it occurs, the computer has lost the signal for crankshaft rotation.

Tester


#3

If the tach doesn’t do anything completely wonky at these times, I would have a look at the throttle position sensor. Most are just potentiometers and can develop dead or otherwise compromised spots. The throttle position and rpm range will often go together, and electrical devices on the edge of failure often show it first with some heat on them.


#4

Thanks for the ideas. I can tell you without question that the tach is normal and the car will continue to accelerate past the dead zone @ 2800 RPM when it happens. It is just bizarre how it coincides with the outside air temp increases. It makes me wonder if the sensor that detects the air intake temp could be faulty as a possibility. I have tried mashing the gas to wide open at the instant it happens (thinking this would radically change the throttle position sensor) and I detect no difference in the length of time that it stutters. It is like a momentary kill switch for the fuel injectors, but again, the tach is normal and it won’t throw a code no matter what. Worst case I’ll borrow a computer connected OBDII and try and log data from some of the sensors. I would sure appreciate any other ideas you have. Bill