Hesitation Upto 2200 Rpm

[agentx]

Hi guys, I need a bit of help troubleshooting something. my rb20 r32 hesitates unless i give it alot of throttle till the engine temp gauge hits half way mark. It literally stops hesitating as soon as it hits EXACTLY half way mark. And also the hesitation is always till the 2200 rpm mark, it goes away if i go over 2200 rpm and goes away completely as soon as the car reaches half way on the temp gauge...

After reading around, the likely suspects are temp sensor / fuel pump / CAT sensor / TPS, i just cant figure out which ones fit the criteria described above, anyone have any ideas? What should i replace first?

Cheers

Edited April 4, 2010 by agentx

[jjskyline79]

You can forget cat sensor that just lets you no if your cats on fire.

Fuel pump not likely

temp sensor could be

tps doubt it

but 02 sensor more likely imo my advise change it anyway

[agentx]

thanks for your reply, but how would an o2 sensor be fine after hitting 2200 rpm or half way temp mark (not trying to be smart, just want to know the connection)

Cheers

[jjskyline79]

no worries

from what i no the 02 sensor only works at low revs anyway so after around 2200 its not used

but im no expert

Edited April 4, 2010 by jjskyline79

[jjskyline79]

Also sounds like a cold start valve problem but i dont no if the rb even has such a thing

[zebra]

how long since you changed the plugs?

[paulr33]

um, the ECU when its running on cold maps has basic timing and isn't very aggressive

im not sure if you can define "hesistating" but you arent meant to trash it when its cold

under 80deg water temp the ECU will run under correction and it wont be as good as when its hot (at 80deg)

if how long before it gets to half way on your guage? 2-3 minutes? 30 minutes? an hour?

mine take about 5 minute to get from cold to around 70deg ish and then its fine

when its warming up i drive it normally (anything other than flooring it)

[Don Dada]

All rbs i have driven "hesitates" from dead cold but only takes a couple mins of normal driving to get it going smooth

Does it always used to do it, or is it a new prob?

[soturi]

zzz my daily does this...every morning (sss pulsar) so freaking annoying...i've had a go at plugs, o2 sensor, filter, but apparently its just an sr thing so oh well

All of my mates Rb's are a bit sketchy when 1st started...but yeah after the warmup, tis all good.....and yeah how long does it take for your car to come up to temp?

[agentx]

thanks for all these responses guys! to answer a few questions, the car was performing perfectly till about a few months back (no major work done before this started happening). The hesitation isnt just the car underperforming due to the engine being cold (Ive worked with cars for quite some time now, this is definitely a fault). The problem takes around 10-12 minutes of driving to resolve and the gauge to come half way.

To describe the hesitation a bit further, if you constantly have the accelerator pressed with the same amount of force and the rpm keeps increasing, as soon as it hits 2200 rpm, it feels like the fuel supply has stopped and the exhaust note changes and it feels like someones let the accelerator go all of a sudden, and then if you give it some more gas ... it goes above that 2200 rpm spot and starts to accelerate again.

I mildly suspect my CAT is not in perfect condition (collapsed maybe?) Im getting that checked out in a week or so ... but i dont see how that can affect this at the same RPM and only till the car warms up?

I have changed plugs and bought brand new coil packs as well in the last 2 months. fuel filter has been changed.

fuel pump is another suspect you reckon?

[agentx]

anyone?

[bubba]

Thermostat stuck open? causing it to take a lot longer to reach operating temp.?

I know that my 32 ECU is in cold start until 65deg.. and it sounds like what you are describing is cold start.

[agentx]

Hi mate; i'll get another thermostat and test it out but the problem is the performance while cold, not really how long it takes to get to warm level ... it shouldn't just be cold start ... i know performance is slightly decreased when the engine is cold but this is a definite fault.

cheers

[bubba]

Hi mate; i'll get another thermostat and test it out but the problem is the performance while cold, not really how long it takes to get to warm level ... it shouldn't just be cold start ... i know performance is slightly decreased when the engine is cold but this is a definite fault.

cheers

The performance decrease is due to the maps the ECU is using when below 65deg, it's not due to a cold engine/poor atomisation/etc.

My point about the thermostat is that it normally gets to operating temp. very quickly if driving so you wouldn't notice it for too long at all normally. But, IF your thermostat is sticking open then it's suddenly going to take a lot longer to get to operating temp. and as such you now have a lot more time to experience the cold start running.

Could be other things like dodgy connection on water temp sensor holding it in cold start for longer..

I know that when I built my 30, I snapped the RB20/26 water temp sensor so threw the RB25 one in there.. different resistance.. ECU thought it was in cold start all the time!

[Birth]

Hi bubba, I am having troubles with idle and changed my temp sensor to one from a different NIssan. I know that it is a different colour to the one I had; what colour is the 20/26 one and what colour is the 25 one?

[krzysiu]

My car used to do this. But since the powerfc and splitfires were put in it has never done it again. Revs 100% fine when cold

[bubba]

Hi bubba, I am having troubles with idle and changed my temp sensor to one from a different NIssan. I know that it is a different colour to the one I had; what colour is the 20/26 one and what colour is the 25 one?

20/26 is yellow and 25 is brown

[bubba]

My car used to do this. But since the powerfc and splitfires were put in it has never done it again. Revs 100% fine when cold

Personally I'd rather a more agressive cold start to remind me not to hammer the car when cold, with the 3L it drives perfectly fine under 2000rpm on cold mornings, torque ftw

[lagperformance]

what can i say!!! why are you driving any rb when its cold??? let it warm up to at least the first line if not halfway by the sounds of things a blown headgasket or warped head is the way your going show your animal some respect turn it over a little build up some oil pressure fire it up give it a little flutter between 1 and 2 let it settle to a nice idle 10 mins later drive it.

all rbs run like dogs when they are cold actually most engines are not designed to be thrashed send me pm when you need new engine.

cheers

lagperformance

[Birth]

Bubba, mine is red. I kind of remember that when I got it the guy told me it was off a 300zx though my memory is a little hazy on this.

How do I know if my car is on cold start? Using a Consult cable I can see that the car is running at about 65 degrees when warm which is about the middle of my temp guage. Is there any other way to see of the car is running at cold start.

Thanks Ben.