Lean Misfires at 2700-2800 rpm

[badass3000]

just another thing to think about... If you noticed in my video, I am no longer using the stock TB (or all the sensors/valves on it). So if my car still has this prob then I think we can rule out that stuff.

[3000hybrid]

Originally Posted by DoctorDex

Just thought I'd throw in that I partly fixed my hot start problem.

It turns out the brand spanking new ISC installed last fall had seized. I'm assuming it seized because it has been bathed in alchy for quite some time. For the time being I put my old stocker back in. Now the car starts up easily when hot, but it still runs lean for the first minute or so. Cold start ups are fine.

Interestingly enoguh, even though my ISC works, my rpms still drop when I turn on the AC? Whats up with that?

What is your ISC counts for idle.Also what's your TPS volts at at idle now? When I deleted my FIAV I had to bump my idle to about 900RPM. Before that when I would turn on my AC my idle would drop really low. Now it jumps to about 1050RPM for a sec and settles down at 900 again.

[3000hybrid]

Originally Posted by badass3000

just another thing to think about... If you noticed in my video, I am no longer using the stock TB (or all the sensors/valves on it). So if my car still has this prob then I think we can rule out that stuff.

What type of TB are you using. And how do you get a throttle position reading?

[DoctorDex]

Originally Posted by 3000hybrid

What is your ISC counts for idle.Also what's your TPS volts at at idle now? When I deleted my FIAV I had to bump my idle to about 900RPM. Before that when I would turn on my AC my idle would drop really low. Now it jumps to about 1050RPM for a sec and settles down at 900 again.

Since I have solid mounts, idle speeds of <1000 rpm are rather annoying. Therefore, I have my idle bumped up to ~ 1000 rpm (with the AC on) and when the AC is off it sits at ~1150 rpm. My ISC count usually sits at around 0.

I have tried to decrease my idle to stock (700 rpm), but then when I put the AC on my idle drops to 500 rpm.

[ProwlerGT]

Originally Posted by DoctorDex

Since I have solid mounts, idle speeds of <1000 rpm are rather annoying. Therefore, I have my idle bumped up to ~ 1000 rpm (with the AC on) and when the AC is off it sits at ~1150 rpm. My ISC count usually sits at around 0.

I have tried to decrease my idle to stock (700 rpm), but then when I put the AC on my idle drops to 500 rpm.

Drop your idle to 800 to 700. Datalog your ISC when you are turning the steering wheel while in park and also separately when you turn on the AC. You can do both at the same time if you want. If you see no counts that IAC is no good.

You should ohm both your IACs per the spec in the manual. Clean out the "newer removed" one with electronic parts cleaner first and them ohm it. In fact I would clean out the one you have in as well. IE: disassemble and clean and be careful so you can reuse the internal gasket.

If alcohol is getting into the IAC you may wanna reconsider the positioning of whatever you have setup on the intake.

EDIT: Also, at the idle you are running there really is no point for your IAC to even be there unless you are stating your idle is that high possibly due to a vac leak.

[3000hybrid]

Originally Posted by DoctorDex

Since I have solid mounts, idle speeds of <1000 rpm are rather annoying. Therefore, I have my idle bumped up to ~ 1000 rpm (with the AC on) and when the AC is off it sits at ~1150 rpm. My ISC count usually sits at around 0.

I have tried to decrease my idle to stock (700 rpm), but then when I put the AC on my idle drops to 500 rpm.

ProwlerGT is right on the money. It looks like you IAC isn't working at all. I have a spare IAC I can ship you also with the ECU. Hit me on the phone and I can get the items shipped out today for ya.

[green-lantern]

damn, looks like my car is getting this problem I get a lean spike when cruising at about the 2500-3000 rpm range when I roll into the throttle then it sputters some then clears out but it seems I am running leaner all over than before. Using SAFC I have increased the fuel in low throttle about 13% and this helps but it seems like I keep having to increase it more and more.

I started a thread about it in the na to forced induction area because I am a TT convert.

Weird and a little concerning

[badass3000]

Originally Posted by 3000hybrid

What type of TB are you using. And how do you get a throttle position reading?

Nissans Q45, it has its oun TB positioning sensor but thats the only thing on it.

[3000hybrid]

Originally Posted by badass3000

Nissans Q45, it has its oun TB positioning sensor but thats the only thing on it.

Will your stocker still fit on your custom plenum? If you don't have it I can send you one of my spares for troubleshooting. They all have working sensors. I always keep the important stuff after I part cars just for these cases . PM me here on on FL3S.

Mann, I have watched your video a ton of times and it still sounds like something in the rear valve cover like a collapsed lifter. I think you said you've already checked them though right.

[3000hybrid]

Originally Posted by green-lantern

damn, looks like my car is getting this problem I get a lean spike when cruising at about the 2500-3000 rpm range when I roll into the throttle then it sputters some then clears out but it seems I am running leaner all over than before. Using SAFC I have increased the fuel in low throttle about 13% and this helps but it seems like I keep having to increase it more and more.

I started a thread about it in the na to forced induction area because I am a TT convert.

Weird and a little concerning

Have you pressure tested? Sounds like a leak if it is over the entire RPM range.