Idle Problems And Hesitating - R32 Skyline

[BenA31]

I've been having a few idleing problems with my rb20det on the occation over the last few months.

Somtimes it will run fine and idle is stable with boost gauge reading 18-19 Vac. But then somtimes i start it up or come to the lights and it will start droping in revs and nearly stalling with vacuum goin to about 10-15ish. Also whenever this problem arises and the car is driving it starts to hesitate alot.

I've done a ECU diagnostic check and it came up with fault 13 i think it was which was to do with the coolant temp sensor. I've checked the conection and seems to be alright.

Has anyone else ever had this problem?

I've already checked for Vacuum leaks in hoses and piping but found none.

AFM looks clean too.

i don't know if to replace the coolant sensor sensor(is it same as water sensor) or start checking elsewhere like

O2 sensors , timing, EGR VALVE (if rb20, has one??), Coil Packs etc

any suggestions. sorry for long post.

Edited April 3, 2008 by skypy12

[raist60]

I found with my car when it came over it had set of resistors tucked into the plastic conduit about 10 cms down from the actual sensor. THis had broken and caused the ECU to keep losing signal from the TEMP SENSOR, which caused my idle to be rough because it was dumping extra fuel in there.

Be worth checking the actual signal cable itself before replacing the sensor.

[BenA31]

you mean the plastic wiring conduct of the coolant sesor?

cos my whole loom has been replaced including the the coolant sensor a few months back due to computer change over from stock one. It doesn't have any wiring conduct around it any more and from what i remember there isn't any resistors in the wiring. But i'll check it out.

[West]

Same problem with my car ( R33 ), i posted the other day, i'm going to clean all the electrical contacts ( things like throtle .....eg.. ). Clean the air filter, spark plugs tomorow BUT just found out another thing is it could be my IDLE CONTROLLER, not too sure yet but i'll check the water temp sensor as well but if it's water temp sensor wouldn't the water gauge raise as well???

[BenA31]

..................not too sure yet but i'll check the water temp sensor as well but if it's water temp sensor wouldn't the water gauge raise as well???

no, well not in the case with my car, it has two different sensors basically right next to each other, one for the computer and the other for the temp gauge on the dash.

[West]

no, well not in the case with my car, it has two different sensors basically right next to each other, one for the computer and the other for the temp gauge on the dash.

Cool, i guess my would be the same too, i'll keep you updates while you do the same thing.

[Cubes]

My ecu reported coolant temp sensor also.

I used the RB25DE one from my RB30DET buildup and the error went away. They were different colours though?!?! Seems to be ok. Idles fine.

I still get the flat spot on low throttle when the engine is stone cold. It only lasts for the first kay or two.

If I remember correctly my RB20 coolant temp sensor was yellow where as the rb25de one was red/purple.

[BenA31]

well today the problem got worse. tried to start car up for work....well it cranked over fine then just kept on stalling. And each time i noticed that it would idle alirght for a little then as the vacuum pressure/level just dropped down to zero it dyed. I opened up the bonnet and tryed to keep it running by giving it some gas constantly, and it sounded like it was leaking/hissing from the pipe goin from the plennum to intercooler whenever i gave it some gas. is the hissing normal or obvoiusly a leak causing it to act crap? couldn't feel air coming out. Also was backfiring and popping heaps.

Anyone able to help me out or point me in some sort of direction???

i'm starting to feel as though it may not be the temp sensor but a leak or timing...

[West]

My problem almost solve ( i hope ), after clean all the electrical contacts....everything pretty much clean excepted for the water temp ( next to the radiator shrould ), it was kind of dirty and look like burn to me, the plastic connectors were melt...eg.

I gave it a good clean ( gonna put new connectors on ) then adjust the screw ( for idle i think ???? behind the plenium ) a bit and from then till now problem havn't araise since.

Havn't clean the AAC out yet as the whole UNIT looks like a motor to me so didn't touch that one yet, havn't done a long drive test as yet ( to see if idle still playing up ) but i will in a week time.

As for this week i'll just drive around to trail it out for a bit more.

[BenA31]

yea sounds like i gotta do the same. prob do it at end of week after assignments are finished for uni.

How exactly do i clean out the AAC? and where is it/ look like?

[rbs13]

take the bugger off and spray with carby cleaner.. i drenched it in carby cleaner about 5 times to make it really clean.. came up a treat after a while.. also used an old tooth brush to scrub round.

[Carlito]

Hi guys,

Dunno if this will help or just add to the confusion - my RB20DET has been giving me grief with this over the last 6 months. I don't know what to do anymore - I'm frustrated and miserable

Car started with the occasional erratic idle, just out of the blue. I did some research on SDU, did the AAC cleaning, fiddled with the idle speed screw, did some research in the engine manual (I have a pdf I got from a guy online somewhere) but I couldn't find the cure. Eventually a couple weeks ago I took the car to a guy who's supposed to be one of the top mechanics at the Nissan dealer (they let him borrow the Consult to work with at home!) and he did a diagnostic with it and found nothing. I think he tried setting up the idle and the mixtures with it, but it didn't work. He told me I should change the plugs.

Went and got some Denso plugs (the equivalent ones to the NGK PFR5a-11 that's the original plug) and took out my Denso IQ20 Iridium plugs (they looked almost new, just a shade of yellow/brown on the insulators ) gapped them to 0.8 and put them in. Saved the Iridiums

Started her up and it was running well, just a little high rpm, so I decided to check the throttle position sensor according to the manual. The readings are supposed to be 2k ohms with throttle closed and 10k wide open, but the best I can get is 2k ohms closed, 8k ohms wide open, and that's with the TPS fully twisted to clockwise.

Set it back where it was before, but now it idles at 1200rpm

Disconnect the AAC plug to adjust the idle, and it drops right down to 700rpm. Plug it back in, up the idle goes to 1200 again.

So now in order to get it to idle at 1100rpm the screw in the AAC valve is all the way in. I've cleaned the engine temp sensor terminals, changed vacuum hoses and had a listen round the engine to see if I can hear any air leaks - there are none. The car runs ok mostly, but now it will occasionally and for no apparent reason run REALLY F--KING RICH to the point that it wants to stall - this is in any gear. Oh, and it has a real bad backfire at WOT - probably stuffing up my poor stock turbo, since I found a bit of oil in the J-pipe.

At my WITS END with this. Seriously considering selling the thing - I went and test drove a Dodge Ram pickup last week :Oops:

Any suggestions? I'm wondering if I need a new engine harness - maybe there's a bad terminal or a wire break somewhere.

I should say, the car has some minor mods - Greddy Airinx filter, GTR front mount IC, DSM manual boost controller @ 12psi, 3" exhaust, Greddy 1mm metal head gasket (legacy of a warped head a while back due to overheating), manual gearbox conversion.