idle problems- yes, ive searched....

[turboweege]

i have a 90 240 and when i first start it it idles high to warm up as usual, but after it idles for about 2 minutes it starts to surge. ive had idle surge on a couple of my cars before but this is weird because it doesnt "bounce". what i mean by that is the idle will drop about 400 rpms, sit for 4 seconds then raise back up and sit for a few seconds and repeat. ive replaced my o2 sensor and regrounded the iaa. any other suggestions? time to replace the iaa or aac??thanksluigi

[bruinbear714]

I would first pull out the idle air valve and clean it up... it might be clogged, and then make sure the MAF is working properly.

[turboweege]

how do i know if the maf is working right? cant i take it to autozone or something to check it?

[ricebike]

check ecu trouble codes 1st.... if it flashes a 12, then theres something wrong w/ it.

I think autozone can check only if it's bad via ohm meter only. hey, goto autozone.com or to the store & ask online/in person & lemme know.

I've got the FSM but I'm too lazy to start typing it out. plus my newer pc w/ the scanner is out of comission. ask for page EF & EC-88, 89 if you know that this is bad.

also know that this isn't working if the car runs in Fail safe mode... engine won't rev above 2400 RPMs

[180fan]

That problem could also be a bad ground. After I switched out the grounding cables with new ones (my cables were black ugh), and added additional grounds to my intake manifold, and thicker ones to my alt, and basically beefed up the grounds on my car, it was more stable. That's another option or idea to try.

[yellow_jacket]

To check the MAF you can just check the output voltage. It should start somewhere around .5 volts at idle and increase with rpms. I can't remember which wire it is though.

[turboweege]

autozone said they can use a volt tester and a vaccum pump thing. i guess ill clean the iaa and get the maf tested.

[Bobby_Wu]

That problem could also be a bad ground. After I switched out the grounding cables with new ones (my cables were black ugh), and added additional grounds to my intake manifold, and thicker ones to my alt, and basically beefed up the grounds on my car, it was more stable. That's another option or idea to try.

i'm having the same problem and will be cleaning out the IAA this weekend... i would like to rewire the grounding to my engine as well...180fan where did you add the ground to the intake manifold????

[turboweege]

now my car seems to have more of the typical idles surge i have experienced before. ie. climbing up to 100 then quickly dropping off to 500 and them climbing right back up. im gonna do the same this weekend and let you know if it worked.thanksluigi

[ricebike]

ok, syptom & condition 13 unstable idling-after warmuppossible causesmix ratio: check blow-by hose fo leaks, check intake system for air leaks (i had 1 big tear @ the intake boot rite b4 the throttle body-duct taped it shut), check canister purgle line for leaks, fuel pressure regulator solenoid

spark: check ignition timing, spark plug wires, plugs,

fuel: line /filter clogged, air leaks to carbon canister, fuel pressure regulator solenoid.

idle switch: gotta use mode 4 @ the ecu to do this

check egr control valve & the solenoid V while idling if the valve stays up.

measure compression pressure to see if it's the cyl head/gasket.

wish i had a replacement hard drive for my newer pc so i can scan u the pages

[sapix @ RHIT]

If your intake is really really dirty (like oily) then it's your PCV valve, it's a nice easy one to fix after you find it.

[turboweege]

If your intake is really really dirty (like oily) then it's your PCV valve, it's a nice easy one to fix after you find it.

i actually just replaced the intake with a new metal one and rerouted the pcv to a breather filter in hopes it would help. nothing though. the pcv seemed to be workin fine but ill just do it for the 2 dollars they are lol. thanksluigi

[turboweege]

ok, syptom & condition 13 unstable idling-after warmuppossible causesmix ratio: check blow-by hose fo leaks, check intake system for air leaks (i had 1 big tear @ the intake boot rite b4 the throttle body-duct taped it shut), check canister purgle line for leaks, fuel pressure regulator solenoid

spark: check ignition timing, spark plug wires, plugs,

fuel: line /filter clogged, air leaks to carbon canister, fuel pressure regulator solenoid.

idle switch: gotta use mode 4 @ the ecu to do this

check egr control valve & the solenoid V while idling if the valve stays up.

measure compression pressure to see if it's the cyl head/gasket.

wish i had a replacement hard drive for my newer pc so i can scan u the pages

like i last said the intake all replaced, ive replaced the plugs with bosch +4, the wires and coil and battery were new when i bought it like 2 months ago, when i did my leaky injectors i checked all the lines i could see with the fuel rail off.i think this weekend im gonna put on a new fuel filter, new pcv. clean the maf and the iaa and aiv or whatever they are called. im gonna do some more grounding and i might check the egr at the same time too.and whats "mode 4 @ the ecu"?thanksluigi

[ricebike]

http://www.240sx.org/faq/index.html

The electronic control unit have five mode:

Mode I- Exhaust gas sensor monitor (Normal mode)Mode II- Mixture ratio feedback control monitorMode III- Self-diagnosticMode IV- Switch on/off diagnostic systemMode V- Real-time diagnostics system.

[shawns1234]

I had this problem on my nissan truck and it was the MAF

[turboweege]

well, i removed and cleaned the iav and it has reduced it a ton every so often it revs a little but smothes out. its good enough for me....thanx guys