Idle hanging up, Need Help

[ipozestu]

First of all I did preform a search. I didn't find anything I could use.
Recently I completed the install of 24lb/hr injectors, 75mm MAF (calibrated), K&N FIPK. everything went pretty smooth with disassembly, and assembly. All gaskets were replaced, vacuum lines checked and rechecked. All good right, wrong. IAC is buzzing like crazy so I replaced it. Buzz is gone. All good right, wrong. Now the idle hangs up about 1800-1500 rpm, and will kick down after some time. Once it kicks down it idles beautifully. I have tried resetting the computer, checked the idle with the IAC disconnected:500RPM. Checked for vacuum leak with injector cleaner. None to be found. I don't know what else to do. I could really use some help here.
Thanks
Jeff

 

[Alec]

Do you have an aftermarket throttle body? If not, you probably need one

How long does it take for the idle to kick down after you start up? It is normal for a motor with a bunch of bolt-ons to idle a bit high until it warms up, though it sounds like yours is too high.

Do you have a chip? (it would be helpful to list all your power mods)

 

[ipozestu]

yea Alec I have all the bells and whistles.
Cat-back
JBA headers
66-mm BBK
High Flow intake
K&N FIPK
75mm Pro-m calibrated for 24lb/hr injectors
24lb/hr injectors
Jet chip(soon to purchase Apten)

The warm up time is sufficient, I would expect that to take some time. Say I'm driving down the road, I come into a stop sign, and the idle remains at a higher RPM and doesn't kick down. If I sit there for quite some time the idle will drop to normal spec. i am wondering if the TPS is not showing the PCM that it is at closed throttle. I haven't checked the output voltage mentioned in james t's recent posts. What do you think of this. I installed a T for a water temp sender. The stock sender in now installed in the T along with the new Auto meter sender. The T is of course external from the block. When I fist installed it the temp hardly registered. I was thinking that the brass disipates to much heat and didn't allow it to get hot. So I insulated it with some fiber wrap. I am getting a reading now but still is showing cooler than mid point where it usually is.

 

[ipozestu]

?

 

[ipozestu]

Any thoughts?

 

[Alec]

Take the JET chip out and reset the computer and see what happens. If that doesn't work, check your TPS voltage and modify it according to James T's TPS mod thread.

 

[james t]

im with alec on this one. take the chip out, and reset. then check to see what the TPS is doing.

 

[ipozestu]

Went out to lunch CEL is on. I am certain that it is IAC problem/failure. It's brand new. Time to order another one I guess.

 

[Alec]

IAT or IAC?

 

[ipozestu]

IAC Alec. I fixed it

 

[ipozestu]

So the last few days have been interesting. Installes new IAC, removed JET chip, checked TPS voltage, idle still won't kick down like it should. This is the kicker, you would think that by installing 24lb injectors I would be running rich.... Nope. At WOT the A/F gauge is off the charts, Keep getting CEL for Bank 1 and 2 to lean. At first this didn't make much sense to me. I have a hypothisis. I am figuring that at WOT when the injectors go into open loop all six of the 24lb injectors opening up must really drain that pressure in the fuel rail. The lost power and indication does come back after some time. It doesn't seem to happen when you are already at cruising speeds and you press the pedal to the floor. i figure this to be because the injectors are already at a fairly lengthy duty cycle so the pressure and volume is already there. What is it that I need to fix this. A new adjustable FPR or fuel pump. Hell I don't even know if I am on the right track here let me know what you think. Oh yea, any new ideas on the Idle. I'm stuck on this one.

 

[Alec]

You probably need both a new FPR and pump. I'd try the FPR first.

 

[Apten]

the calibrated maf may be off. can you send me a flow sheet? If so, I'll check it for you. I've seen this twice now where the pro-m MAF's calibrated for #24 injectors are WAY lean on the low side of the slope and needed chip correction.

Brian

 

[Alec]

Hopefully I won't have that problem when I install that MAS

 

[Apten]

here's the difference between the stock air meter and the typical pro-m one for stock injectors. The calibrated meters for larger injectors are a little further off, plus they cause the engine to miscalculate VE which changes the fuel and spark loading.

Note that near the high end of the transfer function it's either around 10% rich, or 7% lean if you get all the way up. 7% lean means if you are commanding a 12.4:1 air/fuel, you will actually see somthing around 13.3:1

it's not a big deal except on a supercharged applicaiton or nitrous, but you can see how fixing the EEC Transfer function to match the flow values will get you better overall performance and drivability.

If the meter differences get near 25% either way, that's when you have real problems.

Brian

 

[ipozestu]

Brian should I fax the cal sheet to you so you can look it over? PM me with your fax # or I'll give you a call in a couple of days.
Thanks Jeff

 

[psychotic]

Just so you know, my idle is around 1500 then drops to a lil below 1000. I never considered this a problem. I have K&N intake, exhaust, throttle body, apten chip. It doesn't bother me, but I'll watch to see if you find a solution.

 

[psychotic]

oh, and like you I installed a new IAC valve, to get rid of the howling.

 

[Rick]

Sure seems to me like their is an intermittant vacuum leak.High idle that suddenly kicks down, and lean running cylinders lead me to believe this. I'm not very familiar with the engine controls, but if there is a solenoid that routes vacuum or something that kicks in and out that may be the source. Possibly from the vapor recovery system??