Idle problem

[JpZero]

so i have a 97 eclipse rs and i just recently noticed that when my car is at an idle every few seconds it will drop rpms 2 or 3 times in a row and then raise back up to the regular rpm rate. I think it maybe miss fires but it was to my understanding that a thing like that would cause the check engine light to appear and it hasn't. All i have on the car is a AEM short ram air intake. anyone have any ideas what might be wrong? thanks for the help

oh and on another note does anyone know where i can get one of the computer inputs that does the system check when i have the check engine light appear? (i wanna do all the repairs to this car) thanks again

 

[4UH8ERS]

so i have a 97 eclipse rs and i just recently noticed that when my car is at an idle every few seconds it will drop rpms 2 or 3 times in a row and then raise back up to the regular rpm rate. I think it maybe miss fires but it was to my understanding that a thing like that would cause the check engine light to appear and it hasn't. All i have on the car is a AEM short ram air intake. anyone have any ideas what might be wrong? thanks for the help

oh and on another note does anyone know where i can get one of the computer inputs that does the system check when i have the check engine light appear? (i wanna do all the repairs to this car) thanks again

My car has always dropped rpms 2 different times after i stop to idle. If i pull up to a store and put it in neutral it will start to idle at 1100 then after about 3 seconds it will idle at 1000 then about 5 seconds later it will start idling at 900 and just stay there. If your rpms are dorpping and then rising again then you might want to check your vacuum lines and also clean your IAC.

 

[rcjr9186]

how far does it drop down? are we talking about dropping to a grumbeling 200-300 rpms? then shooting back up? or are we talking about it starting at 1500 and dropping down to 800 or 900? if it's the first thing... sounds like timing, if it's the second, that's normal.

 

[TheCykotik1]

###### the idle control valve. my talon idles down to about 1200 for a sec then drops down to 1000 or 900 after a second or two. and u can check that engine light at advance auto parts for free, any shop would charge u like 60$.

 

[JpZero]

it dropes down to 300 - 200 range then shoots back up to 900. Today i went to turn on my heater and the car almost stalled i had to wait till i started moving again before i turned it back on

 

[rcjr9186]

sounds like timing... how many miles on the car and when's the last time the timing belt was changed?

 

[Locke]

oh and on another note does anyone know where i can get one of the computer inputs that does the system check when i have the check engine light appear? (i wanna do all the repairs to this car)

Can purchase at AutoZone or Advance

I think it maybe miss fires but it was to my understanding that a thing like that would cause the check engine light to appear and it hasn't.

A CEL would only occur if the ECU was getting a bad signal. Bad plugs or wires wont cause a CEL.

it dropes down to 300 - 200 range then shoots back up to 900. Today i went to turn on my heater and the car almost stalled i had to wait till i started moving again before i turned it back on

I would begin as stated and check your vacuum lines and clean your IAC. Does the car ever stumble during acceleration? I would check your plugs and wires, and test your coil pack.

As far as it almost stalling when you turned the fan on, check the alternator. It should spit out +14V, and put the battery on a load pile.

sounds like timing... how many miles on the car and when's the last time the timing belt was changed?

While it is always worthwhile to check such things, I doubt it is an issue in this case. Idle problems that happen with bad cam time generally results in a stumbling or very erratic idle. Stumbling every couple revolutions, as opposed to every few seconds, would lead me to think it could be a timing problem.

I have had an unstable idle in the past, it was a sticky IAC, cleaning it stopped the problem. Also, my revs used to drop for a moment (about 300rpm) whenever I turned on my lights or fan. It ended up being a junk battery, I went ahead and put an Optima Red-top in, never had the problem again.

Hope you get it figured out soon.

 

[JpZero]

awesome thanks guys ill check out the vacuum lines and IAC. It dosent stumble during acceleration only when im at a stand still. i never thought of the battery though.... i do have a pretty off brand battery that the original owner had placed in and i added my sub and amps to the car after so it could be my battery draining ill look into that as well.

thanks for all the help everyone

 

[Locke]

To add, if you do replace your battery, and seeing you have amps and subs, I would recommend Optima's Yellowtop batteries. They are dual duty, starter and deep cycle.

Don't forget to let us know the solution, when you get to it.

 

[JpZero]

ok so its been about a week or so since this problem has occured, i changed my battery to an optima yellow top and the problem has seem to decrese as in the rpm drops arnt as bad as before so im going to change my spark plugs / wires to see if it will correct everything but its a start

thanks for all the help you guys

 

[Locke]

Don't use platinum plugs.

Glad to here it's coming along.

 

[JpZero]

yup i changed my spark wires to nology spark wires and now its running fine thanks again everyone

 

[Locke]

NP. Glad to here its running smooth.

 

[GST racer]

i know this thread is done with and all, but what if the problem was intermittent?

for example, i have a 98 gst, 106k miles. about 75 percent of the time the car will idle horribly. It will bounce from 200 rpm all the way to 1200rpm, and even if i try to give it gas and hold it still, it still wont hold steady. but 25 percent of the time, it will idle ok, usually slowly going between 700 and 900 rpms. the needle had never actually stayed still for longer than 5 seconds or so. ive replaced the tps, throttle body and fiav, and the iac with other used parts, and still no difference. ive also switched the maf to an "unhacked" one, with honeycombs and all. any ideas as to what that could be?

i have these parts installed...

evo3 16g
evo3 ex manifod
3" exhaust
255 fuel pump (while the car is running the fuel pump makes an "on and off" whistling
sound...is that normal?)
aeromotive fpr
550cc
afc
ngk bpr7es
ngk wires(3000 miles or so)
greddy fmic

does this sound liek it could be a timing problem, or (hopefully not) a crankshaft position sensor? please help!!! thanks in advance

 

[4UH8ERS]

1. Thats normal for the 255. That sucker gets a little whiney.

2. I'm about 99% sure thats not a crank sensor problem, especially if the car doesnt completely die.

3. I see your wires are pretty new, how bout the plugs? Pull them and check to see if there fouled out, because theres a good chance you might be running rich, which would cause a stutter or a stall regardless of throttle or rpms like you ststed.

4. If you are running rich I would look into the upstream o2 sensor, mine took a crap and had similar symptoms and i never got a CEL.

5. If your timing is off or jumped a tooth ot two it should be very noticable at higher rpms. Most the time you will actually lose alot of power with bad timing.

 

[GST racer]

I actually just went to advanced auto tday, and scanned the codes again. it came up with tps malfunction. im thinking it might not be adjusted properly, if that was true would it throw a code?

i took my old tps out to the car, unplugged the new(well, used) one, and plugged in this old one, and just let it sit on the intake manifold. started the car up and it idled ok, it still hovered between 700 and 900 rpms.

im going to check the spark plugs. they are due to be replaced anyways i suppose.

could this have anything to do with black smoke pouring out of the exhaust at 17+ psi? i was also going to check for boost leaks and compression.

as far as timing, the cams appear to be lined up right, although i dont know about the rest of it. im going to get the timing belt done soon, hopefully in the summer, and replace the water pump and whatever else needs replacing also, so ill hopefully get that timing set right.

one other thing, i can almost always induce a flame-shooting backfire. if i drive in 1st gear, or 2nd or 3rd, and get up to about 5k rpms, and then let off the gas and clutch and let it wind down, it crackles and pops a little and then a loud POP. what could that possibly be?

 

[Locke]

one other thing, i can almost always induce a flame-shooting backfire. if i drive in 1st gear, or 2nd or 3rd, and get up to about 5k rpms, and then let off the gas and clutch and let it wind down, it crackles and pops a little and then a loud POP. what could that possibly be?

Exhaust cam could be advanced to far, and opening during the power stroke.

A crap load of fuel (way too rich), being unburnt during combustion, could ignite in the exhaust manifold.

An overly retarded spark event, would have combustion still occurring during exhaust stroke.

Running without a catalytic converter will makes these backfires seem worse, as the cat usually arrests the flame during a backfire.

Many of the above things can also cause a stumbling idle, but would not usually be described as revving up and down.

 

[VelocitàPaola]

i know this thread is done with and all, but what if the problem was intermittent?

for example, i have a 98 gst, 106k miles. about 75 percent of the time the car will idle horribly. It will bounce from 200 rpm all the way to 1200rpm, and even if i try to give it gas and hold it still, it still wont hold steady. but 25 percent of the time, it will idle ok, usually slowly going between 700 and 900 rpms. the needle had never actually stayed still for longer than 5 seconds or so. ive replaced the tps, throttle body and fiav, and the iac with other used parts, and still no difference. ive also switched the maf to an "unhacked" one, with honeycombs and all. any ideas as to what that could be?

You're better off asking 4G63-related questions in the Newbie Forum for now. This section is for 420A related questions only.

 

[95'clipseRS]

Mine was doing he same thing only different. It would idle fine, then rev itself to about 2500 RPMs. Did a little research, and when I installed my SRAI, i only connected one of the two hoses to the SRAI. So I hope that when I connect the other hose, it will idle fine.

 

[4UH8ERS]

Your definately running way to rich. Your 4g63 buddies could probably help you out a little more in your situation.

 

[GST racer]

yeah, good point about the 4g63 and being in the wrong forum. im sorry about that, and i just recently noticed that this was a NA thread/sub forum. i just assumed everyone had turbo'd dsms...

well thank you all for the info, ill check on some things, and start posting in the right forums . thanks again