R33 Misfire After Water Temp Gauge Install...?

[swanny180]

Hey

Weird problem... My R33 has started misfiring after I installed a water temp gauge in it a couple of hours ago...

And not your typical on load 5000rpm misfire either.

Basically its idling high (around 1400rpm or thereabouts) and when you tap the accelerator, instead of the revs rising they drop first (say down to around 1000rpm) and *then* will rise.

Took it for a quick drive and feels sluggish and misfiring when depressing the accelerator at low rpm (under approx 2500rpm) and at low throttle (under 20% shown on AVCR)

At higher rpm (around 3k and over) and with more throttle, the car drives fine like it should, makes boost, pulls well etc.

Not sure why this is happening? Drove fine before water temp gauge install, not driving fine now...

Any ideas as to what could have done this?

(ps. Getting the water temp signal from the factory wire going to the ECU. Didnt cut the wire, just stripped it back and joined the gauges sensor wire to it)

[skiwhine]

maybe adding the extra wire has induced a voltage change in the temp sensor wire, best thing to do would be dissconnect it and see if its still ur problem, if so jus get another temp sensor n get 1 of thost adaptors u put in ur radiator hose n use that instead..

jus 4 my curiosity why bother connectin a temp sensor up? u have one on the dash....

[75coupe]

um maybe cause the dash temp sensor isn't accurate & doesn't give an actual temp... you should see the difference between the speedo on the dash and what the PFC says...

[swanny180]

maybe adding the extra wire has induced a voltage change in the temp sensor wire, best thing to do would be dissconnect it and see if its still ur problem, if so jus get another temp sensor n get 1 of thost adaptors u put in ur radiator hose n use that instead..

jus 4 my curiosity why bother connectin a temp sensor up? u have one on the dash....

Yeah thats a possibility, might give that a go...

Do already have a separate temp sensor that you put inline on a radiator hose, but decided Id try the simpler way of using the factory signal and seeing if that works...

And yeah I realise you have a stock one, but its really quite useless.

It doesnt show you any actual numbers, and it stays in the one spot regardless of actual temp fluctuations - by the time youve seen a change, youve already done damage to the engine basically

[swanny180]

Anyone else with any thoughts as to what might be causing the problem?

What would typically cause an engine to drop rpm initially when the accelerator is pressed?

[Strik3r]

could be your AFM... it incorrectly tells the computer how much air when u tap the throttle and therefore the computer dumps too much fuel. The fuel cant all be burned so the car misfires and revs drop.

[paulr33]

id say youve cut the wire to the ecu somehow so it doesnt have water temp

[swanny180]

Definitely havent cut the wire to the ECU, the wire for the gauge was spliced to it.

I cut the wire going to the gauge this morning so it is no longer connected and viola, problem solved!!

Bit weird nonetheless?

[mattymagoo22]

Coolant temp sensor works on resistance, the additional wiring most likely gave the ecu an incorrect reading and rubbish in means rubbish out.

[gotRICE?]

could be your AFM... it incorrectly tells the computer how much air when u tap the throttle and therefore the computer dumps too much fuel. The fuel cant all be burned so the car misfires and revs drop.

Do you consider a misfire the burble noise you hear, or the loud pop, more often than not followed by a orange flame out the tailpipe?

Just curious.. mine very rarely burbles under decelleration, but between gear changes when giving it max boost blah blah, it pops.

Also with that little "tap" on decel it will too But thats for Baller flame effect y0. (im a very new skyline owner, so the flame was ammusing for a while untill i read it can be deadly to your exhaust wheel )

[RB30-POWER]

you need to fit a seperate sensor for the water temp guage, you can't just go piggybacking the factory ecu coolant temp sensor.

its an nct thermistor so as soon as you alter its resistance by additional wiring and loads, it will give false readings to the ecu.

fit a seperate sensor and disonnect it asap before it burns out the pullup network in the ecu for good.

[siddr20]

I was just gonna ask.. even if you read it from your ecu, wouldnt the temp guage still sit in the same spot?

Or will it show the true figures on the guage? but i dont see how, since you still taking it from the ecu.

But i woul be wrong.. just curious thats all