EFI Question

[whitevanman]

Had the ex Scooters Shitetrak in for it's MOT today...it failed as the emmisions could not be tested as the engine surges between 1500 -2000 rpm, guy at the garage reckons its the throttle position sensor...

 

the question is is this the most likely culprit? is there a way of testing the TPS? any other helpful advice?

[cobblers]

Definitely possible - you can test them with a multimeter. Probably has three pins - usually the outer two will have a fixed resistance between them no matter where the throttle is at, and the resistance between either of the outer pins and the middle one should change smoothly as the throttle is opened.

 

You can also probably check it in situ - Most systems supply a ground to one pin, 5v to another and the final pin should have a voltage that smoothy goes from approx 0.5 to approx 4.5 as the throttle is opened.

[Station]

Or idle control valve! They test it at two separate rpm variables.

[whitevanman]

I don't think it's the ICV as it is only between 1500-2000 rpm that there is a problem, I've checked for vacuum leaks etc to no avail, trying to get a seconhand TPS for a shiterak is not easy........

[Des]

Could be worth a blast of carb cleaner in the throttle body, ICV, and anywhere else that takes your fancy.

[oldford]

Is the fuel filter on the right way round?

[whitevanman]

Is the fuel filter on the right way round?

No idea, but strangely thats what the Daihatsu guy mentioned as well......

[whitevanman]

OK, after spending a part of the evening playing with it ( before I had to collect a GTE)...I have it running perfectly..........How? well I took the TPS off and disconected it does this make any sense at all??

[scooters]

yes - that makes perfect sense. If I recall, when I first got the car it was hunting and I went onto a jap car form to ask about irregular idling and the TPS is always blamed especially in 90's shite - shoguns prone to it as well. It isn't necessary, always fails and is expensive to replace - well done!

 

PS it might also fail on the off side front brake which was binding a bit

[whitevanman]

It only failed on the Horn as it died at the time and the inability to test the emmisions, which with removal of the TPS it passed no bother

[Pete-M]

Check the engine temp. sensor. If it's anything like a Bosch or Lucas system there are quite often two of them, one for the gauge, one for the EFi system. If the EFi system one has gone kaput it'll cause this kind of mayhem, and it'll be crap on fuel.

 

It's not always TP sensors that screw up, it's just that people tend to diagnose the symptom rather than the cure... Has it got OBDII?

[whitevanman]

Check the engine temp. sensor.Has it got OBDII?

No idea if it's OBDII or not, I'll check the secondary Temp sensor now that you mention it

[oldford]

No OBD, there will be a little plug in th loom close to the passenger side underbonnet bulk head. Code reading is acheived by shorting two pins on the plug, turning on the ignition and noting the blink code from the engine management light. If the light isn't on, then there will be no stored codes.

 

There are two temperature sensors, one for the gauge and the other for the EFi.