Low idle and running rough

[AGlobalThreat]

Lately my car has had a bumpy idle and a slight miss, just recently it got worse and the engine seems to be missing and struggling to keep running. Any ideas? I just replaced the ecu not too long ago, the idle has been like this ever since. When I'm giving it gas it runs fine. The volts drop down to 13 when the idle is low and then back to normal once the car is given some gas. What should I check/replace?

 

[Quin]

Swap the ecu out for the old one

 

[AGlobalThreat]

I don't have the old one it was basically traded for the one I have now. The ECU was replaced because the car would randomly become undriveable. I would have to let it sit overnight and then drive it home. That problem has been gone ever since I replaced the ECU. The problem now is just the idle, the car drives fine and boosts fine (Aside from boost cut! )

 

[Quin]

Have you changed anything other than the ECU?

 

[AGlobalThreat]

I put my odyssey battery back in. Both batteries read the same voltage though when I use my multimeter. I guess I could try using the old one again. I also recently discovered that the head to chasis ground wasn't grounded, so I fixed that.

I was thinking of changing sparkplugs and already checked coilpacks but everything looks good. Some of the vac lines look like they could be replaced, I'll probably buy a big roll and replace all of them.

Also, the stock bov, do I need to cap it off? I have an ebay greddy bov on a 2.5" adapter all hooked up in the IC piping. I've heard that the stock bov leaks at anything over stock boost so should I cap it off or just leave it?

Does a 1jz Fcd get rid of boost cut and speed cut also?

 

[annoyingrob]

Does it idle higher when warm then when cold? If so, it may be that your ISCV is not opening.


No a 1JZ FCD will not get rid of speed cut.

 

[Supratrbox2]

I had sort of the same problem and put in another ecu and seems to be no more. Deff check the ecu, damn things are a pain in the ass.:icon_evil

 

[AGlobalThreat]

How do I get rid of speed cut, fuel cut, AND most importantly boost cut? My old ecu didn't have any of the cuts does that mean it was an aftermarket ecu w/ tuned maps? Or how do you get rid of these damn things

 

[annoyingrob]

fuel cut, and boost cut are the same thing. a FCD will take care of that.

A speed cut defender will take care of speed cut, or you can just cut the pink wire going to the ECU.

If your old ECU didn't have any cuts, then it was most likely a tuned ECU.

 

[AGlobalThreat]

K well I just got back from driving the car and I didn't have that horrible idle like before, so far so good. I still have what appears to be a slight miss at idle though. When I first start the car the idle is perfect with no miss, then as it warms up I can hear the idle drop down and it sounds like the engine is missing.