Author Topic: U12 low range stuttering problem  (Read 9120 times)

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Offline Burga

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Re: U12 low range stuttering problem
« Reply #30 on: Oct 6, 2011, 08:02PM »

So everything is running well. Except...  ::)

I'm at my wits end and have no idea what to do. My car runs fine now, the pipes all stay nice and cold, the fans dont come on at start up, I replaced the temp-gauge sensor with a brand new one (since it was only $10), and my temp gauge now likes to climb. Quick. The car does heat up, yes, but not to boiling point. It's like the gauge needs to be calibrated? I have no idea what to do! Everything's running. Pump is pumping, thermostat was mounted correctly and sealed, no leaks.

ATM the car is only running tap water, just because it was going to be flushed and ran, until I noticed that issue. Seriously, wtf. Also, my belt noise is back, but I think it's due to pulley tensioning...

Anyone got a good rule of thumb for checking pulley tension? And WTF is going on with this heating crap! *le sigh*... The radiator cap is cool, the water in the radiator is warm, so it *is* flowing into there, the thermostat (new one) isn't seized. The top radiator hose is very warm, bottom very cool. It seems like liquid is flowing as it should. The temperatures in there are MUCH cooler than what they were - it's working *properly*. It's just that temp gauge. And I don't like driving with a disconnected temp gauge... >:(

Edit: There's only one connection to the sensor. What does it use as a negative terminal? If this was a poor negative, could the temp gauge have a capacitive effect? 'coz it increases linearly. Seems fairly irrelevant to the temperature of the car..

I bought a new thermostat from nissan, put it in with TOP, up, and temp started to almost hit the top of the gauge when the car was idle, say, at the lights. If I put my foot down a bit to get the water pump really going, the temp would drop, so I thought I had a dodgy water pump. Replaced the water pump (which is a pain in the ass), and while I was there I stick my finger into the thermostat hole just to see if it was blocked. The stupid nissan thermostat has a wide body on it which was restricting about 2/3rds of the flow. I turned it sideways and now I have no problems at all. You may want to check which way around you have installed your thermostat.


Still having issues with the stuttering under ~3K and surge after 3K, and fuel usage. :(

I managed to pick up a fuel pressure regulator and swapped it over, with no change. Altho the previous dick head who messed around with the car hooked up the vacuum hoses wrong. I will be looking at ignition next, and possibly SCV/vacuum. I did a quick and dodgy test to see if it was a vac leak from anywhere obvious, using carby cleaner but couldnt find anything. Pinching the hose from the rocker cover doesnt work cuz the hose is too thick and I dont want to damage it by clamping :P. I might just disconnect it and block the hole.

I was checking something out the other night and noticed that a lot of liquid, fuel?, was dripping out of the tail pipe, and being spat out when the pistons pumped. I think the car is just running super rich. I get a sort of hissing/tinkling/rattling noise too when I gun the gas, and also when the car is engine braking.

I havent checked for any ecu codes yet tho. :(

Offline Cheezel

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Re: U12 low range stuttering problem
« Reply #31 on: Oct 6, 2011, 08:51PM »
I bought a new thermostat from nissan, put it in with TOP, up, and temp started to almost hit the top of the gauge when the car was idle, say, at the lights. If I put my foot down a bit to get the water pump really going, the temp would drop, so I thought I had a dodgy water pump. Replaced the water pump (which is a pain in the ass), and while I was there I stick my finger into the thermostat hole just to see if it was blocked. The stupid nissan thermostat has a wide body on it which was restricting about 2/3rds of the flow. I turned it sideways and now I have no problems at all. You may want to check which way around you have installed your thermostat.


Still having issues with the stuttering under ~3K and surge after 3K, and fuel usage. :(

I managed to pick up a fuel pressure regulator and swapped it over, with no change. Altho the previous dick head who messed around with the car hooked up the vacuum hoses wrong. I will be looking at ignition next, and possibly SCV/vacuum. I did a quick and dodgy test to see if it was a vac leak from anywhere obvious, using carby cleaner but couldnt find anything. Pinching the hose from the rocker cover doesnt work cuz the hose is too thick and I dont want to damage it by clamping :P. I might just disconnect it and block the hole.

I was checking something out the other night and noticed that a lot of liquid, fuel?, was dripping out of the tail pipe, and being spat out when the pistons pumped. I think the car is just running super rich. I get a sort of hissing/tinkling/rattling noise too when I gun the gas, and also when the car is engine braking.

I havent checked for any ecu codes yet tho. :(
Nah, thermostat was installed correctly. I don't know what you mean when you say "sideways", the thermostat is essentially a flat disc with bits sticking out. It's either one way or the other. The thermostat WILL restrict flow, though. That's it's point, almost. It keeps the coolant circulating the engine at an optimal temperature. It closes and opens slowly and slightly to adjust the amount of water flowing through from the radiator (aka cold water).

I removed the surge after 3k, haven't fixed the surging when i first start the car though. Until it warms up it is not happy to cruise along in first. It's on the long list of "to do"s. Mine is fuel pump related (the thing was on it's last legs). Sorry man.

I read about someone else having all the vaccy hoses munted up. Mine has the SCVs controlled, which probably explains the freaky business in the low end while cold (while SCVs are supposed to be actiive), but it doesnt explain why it's only just started.

Liquid falls out when cold? or warm as well? It's not unusual for water/condensation to drip out of the exhaust pipe. Smell it. If it reeks of fuel, even if it is liquid water coming out. As for it being "spat out when the pistons pump", you realise that at idle the pistons pump at 850 rotations per minute, right? So your exhaust would be leaking something akin to a tap. You mean when you hear that "blub blub blub" noise? That's not the pistons you're hearing, otherwise your engine wouldn't be able to produce power. It needs to move faster than that.

So you've either got a tick at high revs - change engine oil, apparently these cars need thick oil (source: everyone on this website.) - 20W-50 is factory rated.
Or you're pinging, which would explain all your eradic surging. Your fuel pump might be on the way out, since at high revs you're running thing. Depends on which it is - a tick or a ping. Go youtube pinging, it's pretty damn obvious the difference between them when you've heard them... btw it doesn't have to be as loud as the horrific videos on youtube. :P

If it's when the car is braking, i.e no load... does it do it when you take the foot off the gas completely? I'd dare say you just need to run thicker oil. Sounds like you're describing a tick. Reason you can't hear it day-to-day is it's quiet, then it gets louder when you gun it.

My 2c

Offline Burga

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Re: U12 low range stuttering problem
« Reply #32 on: Oct 7, 2011, 12:24AM »
Sorry I might not have been so clear in what I meant. Will try to elaborate.

Nah, thermostat was installed correctly. I don't know what you mean when you say "sideways", the thermostat is essentially a flat disc with bits sticking out. It's either one way or the other. The thermostat WILL restrict flow, though. That's it's point, almost. It keeps the coolant circulating the engine at an optimal temperature. It closes and opens slowly and slightly to adjust the amount of water flowing through from the radiator (aka cold water).

Re thermostat.. (trying to explain without a drawn diagram) the bottom part with the spring that sticks into the cooling channel behind the thermostat, which allows coolant to flow (even when the thermo is closed), has two support "legs" on the sides. When the thermo was installed the correct way around, with TOP in the up position, the legs kinda block off the flow.. even with the thermo open, not enough coolant could flow past them. They are quite wide.. almost wide enough to block it off completely. Now I'm not sure if I was given the wrong part, but turning it 90 degrees sideways moves those legs out of the way. Hope this makes sense.

http://www.alibaba.com/product-gs/435814093/Fit_for_Car_Thermostat_NISSAN_21200/showimage.html

I removed the surge after 3k, haven't fixed the surging when i first start the car though. Until it warms up it is not happy to cruise along in first. It's on the long list of "to do"s. Mine is fuel pump related (the thing was on it's last legs). Sorry man.

I read about someone else having all the vaccy hoses munted up. Mine has the SCVs controlled, which probably explains the freaky business in the low end while cold (while SCVs are supposed to be actiive), but it doesnt explain why it's only just started.

Mine seems less sluggish when cold, and first gear doesn't seem to be a problem.

Liquid falls out when cold? or warm as well? It's not unusual for water/condensation to drip out of the exhaust pipe. Smell it. If it reeks of fuel, even if it is liquid water coming out. As for it being "spat out when the pistons pump", you realise that at idle the pistons pump at 850 rotations per minute, right? So your exhaust would be leaking something akin to a tap. You mean when you hear that "blub blub blub" noise? That's not the pistons you're hearing, otherwise your engine wouldn't be able to produce power. It needs to move faster than that.

It was spitting out - just a few drops here and there. Car was at idle, parked on a downward slope, and I could see some clear liquid just inside the tip as well, and spitting out every second or so. I tried to smell a bit to see if it was fuel but couldn't really tell. I only spent about two minutes looking at it as I had just had to jump start it and wasn't in the mood to diagnose it at the time - stupid brake light was on all night and flattened the battery :(. I think I need to adjust the brake light switch there... ugh.

So you've either got a tick at high revs - change engine oil, apparently these cars need thick oil (source: everyone on this website.) - 20W-50 is factory rated.
Or you're pinging, which would explain all your eradic surging. Your fuel pump might be on the way out, since at high revs you're running thing. Depends on which it is - a tick or a ping. Go youtube pinging, it's pretty damn obvious the difference between them when you've heard them... btw it doesn't have to be as loud as the horrific videos on youtube. :P

If it's when the car is braking, i.e no load... does it do it when you take the foot off the gas completely? I'd dare say you just need to run thicker oil. Sounds like you're describing a tick. Reason you can't hear it day-to-day is it's quiet, then it gets louder when you gun it.

I'm currently running penrite 20-50 (extra 10, so 60), which seems to be doing pretty well. I previously had some lighter oil in, and the penrite seems to be much better, especially at start up. It's definitely not pinging, rod knock, lifter tapping, or anything like that - altho I do need to tune up my solid lifters this week, which are making a racket.

It's more like a high pitched hissing or whistling noise.. like air escaping somewhere. I need to go through the SCV and carbon canister connections to make sure that they are ok. I've been wondering if the SCV actuator is the thing which is leaking air or something like that. The noise seems to be coming from that side of the engine. I haven't been able to hear it until the engine is under load, driving around. It also does the whistling when I get up some speed, and take my foot off the accelerator and let the engine brake and slow it down. ie. when the throttle is closed, the vacuum builds up and slows the engine down.

I've been thinking I might need a new fuel pump too, as I'm almost out of options as far as fuel economy goes.

Sorry to hijack your thread - just trying to see if anyone might have a tip or a clue :D

Offline Cheezel

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Re: U12 low range stuttering problem
« Reply #33 on: Oct 7, 2011, 10:51AM »
Nah its all troubleshooting, hijack away. ;D. I get what you mean re:thermostat now. My problem is just the temp gauge sender, not heating anymore. Yay for one problem fixed.

Re:whistling, i get that too, but only under 2800rpm - scv lines must be leaking. I was supposed to say "my scvs are disconnected." in the last post. But that failed miserably :P. So anyhow, i must be leaking from one of the vaccum line seals.. Not an issue since i dont have the SCVs in the first place, just annoying. 20 second fix if i can be bothered to find it.

I've seen spitting exhausts before. Not that I'd know what it means other than that there's a little bit of force pushing it, or that it's very small droplets. :P Understandably not in the mood to diagnose though. I'd be pretty frustrated too.

FSM is your friend for the whistling, though. :D
« Last Edit: Oct 7, 2011, 12:38PM by Cheezel »