Durandal Posted May 5, 2010 Share Posted May 5, 2010 So i start up my car the other day. It had only been sitting for about 2 hrs since last run. When started it starts revving all the way up to around 2.5K and then instantly drops to 1K and does it again. After 3 cycles of this it stays at around 1.1K. I had my AC off and I cleaned the IAC recently so I don't think its that. Anyone experience this before or have any ideas? Quote Link to comment Share on other sites More sharing options...
Alex Posted May 5, 2010 Share Posted May 5, 2010 Disconnected MAF? Quote Link to comment Share on other sites More sharing options...
Durandal Posted May 5, 2010 Author Share Posted May 5, 2010 Oops. Forgot to mention that it's a JDM so it has a MAP sensor. It is acting like a disconnected MAP sensor but I checked all the connections and they were good. Quote Link to comment Share on other sites More sharing options...
Durandal Posted May 22, 2010 Author Share Posted May 22, 2010 It started acting up again today while I was driving. I had to turn around and go back home. It would hunt through most of the gears but not really when the second turbo kicked in on the highway. I noticed that the first turbo would boost late almost at the 3K mark instead of 2.5K. It's not throwing any codes and I'm thinking it sounds like a boost leak. ON another note what is the knob by the radiator that has "H" on the top with a little sight glass. I could see bubbling in the sight glass while it was idling. Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted May 22, 2010 Share Posted May 22, 2010 The H with the sight glass is the A/C charge point and the bubbling is the fluid. Quote Link to comment Share on other sites More sharing options...
jevansio Posted May 22, 2010 Share Posted May 22, 2010 Although not to your extent I had wierd idle hunting problems with a boost leak post throttle, maybe woth a check? Quote Link to comment Share on other sites More sharing options...
Durandal Posted May 22, 2010 Author Share Posted May 22, 2010 I fitted an electronic boost gauge last summer and the hose it came with was very thin and i've noticed that it is splitting where I tee'd it into the MAP and also gauges pressure sensor. I don't have any hose to replace it with right now. I just went out to start it up after it cooled down for an hour. First 2 attempts at starting it would sputter and die at around 200 rpm. The 3rd time it started up and idles at around 1K nicely. After letting it idle for about 1 minute I shut it off. Quote Link to comment Share on other sites More sharing options...
Durandal Posted May 22, 2010 Author Share Posted May 22, 2010 Although not to your extent I had wierd idle hunting problems with a boost leak post throttle, maybe woth a check? Well the problem was persistent even when under throttle. Would feel like down shifting and laggy throttle response. Quote Link to comment Share on other sites More sharing options...
TLicense Posted May 22, 2010 Share Posted May 22, 2010 Sounds like some kind of boost leak. If the hose for your boost gauge is cracked then that would be a prime suspect, but saying that I doubt you'd have as big a problem as you seem to be having if it was just that... the hose diameter isn't particularly big. However, if you've also been playing with the IAC valve, then perhaps there's something in there. Check to make sure the connector is fully on. Also did you make sure you got the one way valve on the right way? Quote Link to comment Share on other sites More sharing options...
Durandal Posted May 22, 2010 Author Share Posted May 22, 2010 Yah I'm sure the IACV is on right. I was going to check it but wouldn't it only affect the problem under idle and not under throttle? Quote Link to comment Share on other sites More sharing options...
TLicense Posted May 22, 2010 Share Posted May 22, 2010 If the valve is on the wrong way, then it'll struggle to idle and then when you're under boost you'll basically have a boost leak going out of the IACV. I would systematically check everything you've touched as it was working beforehand and isn't working now. Chances are it's something put together not quite right. Definitely replace that boost gauge hose too though. Quote Link to comment Share on other sites More sharing options...
Durandal Posted May 23, 2010 Author Share Posted May 23, 2010 The thing is I haven't touched anything in over a year and it just started acting this way recently. I did replace the hose and took it for a rip and seemed perfect at idle and throttle. Quote Link to comment Share on other sites More sharing options...
Durandal Posted May 28, 2010 Author Share Posted May 28, 2010 (edited) I thought I fixed it with replacing the hoses at the MAP sensor, boost gauge and resetting the ECU. It was working fine for about 2 days however today about 5 minutes into a drive it started again. I have a Greddy EMU but right now I only have the speed cut module active, although it could be a loose wire in the harness around there. Regardless, I'm thinking of checking my spark plugs, IACV and some more vacuum lines this weekend. --QUOTE-- "Most of the time this is caused by an airpocket in the cooling system, there is air in the cooling system that has to come out, this may take a while, removing the top radiator hose and slowly pouring coolant in it will help. I hope that the thermostat was replaced. The reason this happens is that the water temp sensor for the computer is exposed to hot air instead of water and then some coolant will come in contact with it and this constant variation will cause the cycling effect, you need to get all the air out of the cooling system and it will idle normally." (Probably something I should check as well) Edited May 28, 2010 by Durandal (see edit history) Quote Link to comment Share on other sites More sharing options...
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