Hey guys,
I had an idle problem on the Swaggin' last spring and cleaned out the IAC valve and changed the map sensor and it helped quite a bit, but now since it has gotten colder, the idles seems unusually high now. Let me explain the symptoms: When you start the car and it's cold outside (below 35 degrees F), it idles high (around 1800 rpms) for about 30 seconds, drops down to about 1500 rpms for another 10 seconds, and bottoms out to around 1100 rpms about a minute after starting. Now this seems a "little" high to me, but I'd probably live with it, but here's the kicker: I stick the car into "Drive" (the car is an automatic), the idle goes up to about 1300 rpms! That is putting strain on the drivetrain, and is certainly going to take it's toll on the brakes eventually, and quite frankly, I don't like driving it that way. I put new IAC valve in, but that didn't change a thing.
I wonder it I should consider a new TPS, EGR valve, Air temp sensor, Thermal Air Temperature Control Valve, O2 Sensor.......? I hate swapping out expensive parts with no guarantee of successful results.
It doesn't appear to have a vacuum leak, and I'm not as versed in 80s emissions systems as I'd like to be, so any helpful input would be greatly appreciated !
~ Mike ~
Do the rpms go down after the engine warms up?
Ok with out getting TOO detailed on what to try.I can tell you how to check your TPS I have a post somewhere here with that!!! But let me keep this simple.Try just unhooking the vacumm line on the egr valve.IF your problem goes away guess what you need to either 1 remove the egr,and clean the carbon out,OR 2 if after cleaning still crappy replace the egr.The egr has a rubber diaphram inside that seals vacumm and if it is leaking or cracked just done,it will make the car idle all over,run #$@& or not run correct period.Clean the egr with carb cleaner and see if it clears up or runs better.I am thinking way too many things right now,but I will find my post and try and share that on the sensor check stuff.Btw you will need a multimeter to check the tps.
It sounds to me like you have a small vacuum leak somewhere. Check all of your vacuum connections for a cracked line.
http://www.j-body.org/forums/read.php?f=28&i=11739&t=11739 Ok took me 30min to find.Go down to dec 15,2010 this is a step by step to check the tps.Plus the LINK for wells is spot on,and do check out the diagnostics stuff, it has been awhile since I last visited this site to familar myself with this site.I have to correct MY post a touch.In the wording when moving the throttle UP and DOWN( I said the voltage should go and down) screw up.In short meter hooked up voltage with set at 20k ohms and then move the throttle UP or down (back and forth) the #s should go up or down smoothly not all irratic like say 12,35,17,51 example.It should be gradual.Unless your egr is sticking and or loosing vacumm(you can test this without car running) with a vacumm gauge!IF it holds pressure good.If it leaks down bad.I just know I probably am leaving something off but,trying to get all this in place quick.Try my suggestion unhook vac line to egr,then clean if still bad,and then vac test it last.Unless your tps is all over the place with a multimeter test.
@ Spike - The idle remains high after the car is warmed up. I don't have a temp guage, so I can't tell how warm the car gets, but it does blow really hot air from the heater !
I talked to a mechanic buddy of mine and he said to change out the PVC valve because if the spring is binding in the PCV valve, it could cause a vacuum leak, and he also suggested changing the thermostat out because if the stat is not allowing the car to get to full operating temp, the emission system will be stuck in a continuous closed loop.
I don't have a multi-meter, but may be able to gain access to one Ron, but I think I may change out the EGR valve just for the heck of it considering the age of the car.
~ Mike ~
You can also check the TPS with a scan tool. The voltage reading works the same as reading ohms.
Well if you go ahead and do a thermostat replace the temperature sending unit as well.This greatly affects how the car adjust the idle,emissions based on what it is reading.Granted your car minus the gauge you will have 2 sending units.One is for the actual temp for the ecm to read and the other is for the dummy light on the dash.Just keep in mind they may list your senders all together so note if it is a single or double wire slide on or plug in for both.They do the oil pressure switch the same way.Just my share after learning the differences on both and mine have been replaced oil and coolant.I have no gauges either.
Well, I checked everything I could for this idle problem (cleaned the EGR valve, checked the TPS, looked for vacuum leaks), and have come up with nothing.
So I'm opening up my wallet, blowing the dust out of it and am biting the bullet.
I purchased a new EGR valve, Throttle Position Sensor, BOTH temperature sensors, thermostat and PCV valve!
The only emmisions components I haven't checked or replaced after this will be the thermal air temperature sensor, vacuum canister, and the ECM !
I even went out and purchased a new exhaust header/manifold to replace the slightly cracked original one.
I'm not big on replacing parts haphazardly, but I've run out of ideas and am sick and tired of the elevated idle in my Swaggin.
I'll try to get it all installed over the weekend and report the results after that.
Wish me luck, guys !!!
~ Mike ~
Thermal air temperature sensor????
Could that thing be the reason mine acts like a spoiled brat when it's cold? Mine idles really rough and doesn't feel like moving when I press the gas when the temperature is really low.
The thernal temp is under the air cleaner or actually inside and clips down with vacumm lines that hood to it from the under side.It operates off temps inside the air cleaner and if I get my techy book will share the real definition as I know it is probably listed somewhere in it.I'd dig my old part out but,with two containers sitting on the box it is in a pain to move it all to show a pic.
This should be the thermal air sensor.It would be under electrical or sensors on advance or auto zone.Hope this helps and yet to find the true definition taking pics the last few minutes of car parts go figure right.
Ok mike go ahead do your work..But after wayne schiff asked?s I starting digging and thinking.Have you bothered to check thermac control.It is the round vacumm operated circle on top of the air cleaner tubing and on the inside is spring loaded to work based on cold/hot temps.If that flap is stuck,or sticking OR the vacumm piece is not holding vacumm this can cause some issues.Like uh crappy idle,poor mpg,hesistation.I would take your tube off the metal part of the air clnr and check and clean that spring and make sure is swivels with ease.Next put a vacumm gauge to the vac line input on top side see if it holds pressure.Granted this may not be the problem and leaky exhaust or something I am over thinking.I have cleaned mine and yeah checkd for holding pressure.This opens and closes based on outside temps and as car warms adjust to optimize your air/fuel for best results.Just check it while replacing all those parts.This never crossed my mine till today and did this on my intake engine resto job back yrs ago.
I'll check out the flapper thinga-ma-jig too, Ron.
AND, that "thermal air temperature" sensor is
one really expensive item !!!
It costs $67.00 on rockauto !
What is so special about that part for it to cost so much ?
I'm only going to replace that part if all else fails, because of the cost and a mechanic friend of mine claims it's unlikely for it to be the cause of my problem.
I had something come up, so maybe I'll dig into it next weekend.
~ Mike ~
Back in the 90's my blue Cav (1984 2.0 Manual trans) had a similar problem when I pushed in the clutch at stop lights (Summer so it was warm). It would surge up and drop down, turned out to be the O2 sensor. Don't know, just throwing it out there.
hey mike this is tom we had to replace and or adjust the iac valve on walts 84 cav 2.0 replaced 2times and had to adjust 2times replaced it because it failed twice and had to adjust it when was stored for winter twice we will see what it does this spring i think it might have been because battery went dead couple of times not sure if this helps but check that iac again ihave had iac problems with my 1990 chevy van and on that it was replaced a couple of times in 8 years i had it
Well Tom, from what my service manual says, the IAC valve on my car isn't adjustable. All you have to do is make sure the pintle is set at a certain distance from the threaded part of the valve (which is was correctly set at), and then drive the vehicle at 45MPH for a few miles steadily after the car reaches operating temperature (which I did). It was a brand new Delphi unit, so I can only hope that it is operating correctly because at $70.00, it's a little pricey to change it out with another new one on a hunch.
Thanks for the info, tho !
~ Mike ~
I am going junking and if I come across another 2.0 I will grab the iac and buy dirt cheap and sell for what I pay for it.Plus shpg maybe usps to keep cost lower.Used or not it may help isolate if it is that or maybe a leaky tbi gasket or intake gasket.I have redone all my vac lines so,mine are fine.Unless something like fpr is sucking air,or losing some pressure idk being well tired again after 532 miles today.When I am focused I will read my factory service manual and see what it suggest and share what I can aside from the above and your shop peep.
Ron Love wrote:I am going junking and if I come across another 2.0 I will grab the iac and buy dirt cheap and sell for what I pay for it.Plus shpg maybe usps to keep cost lower.Used or not it may help isolate if it is that or maybe a leaky tbi gasket or intake gasket.I have redone all my vac lines so,mine are fine.Unless something like fpr is sucking air,or losing some pressure idk being well tired again after 532 miles today.When I am focused I will read my factory service manual and see what it suggest and share what I can aside from the above and your shop peep.
Ron if you ship it USPS be sure to do it at a UPS store that way you can get a tracking/confirmation number to be able to track it. I recently had a package "lost" by my mailman but luckily family video went thru UPS to ship it USPS so I was able to get a tracking number to give the local post office supervisor. Unfortunately the package is still "lost"but they know who lost it and are putting him thru the wringer hopefully.
Holy Crap!!! You paid $70 bucks for your IAC? I got mine at Auto Zone for only $45, and was upset that we had to swap it out. I'm on the third one now, The IAC that Ron posted above is adjustable. When Tom and I did mine, he took my Cavalier out and drove it at 45mph but it would not idle down, so he pulled it, measured it and we adjusted it until the idle was at 800 rpm when the car's in park. When I put it in gear, it runs a little bit lower and she just purrs like a kitten. Just play around with your IAC a bit, use a tape measure and go from there.
Good Luck!
Well, I replaced the EGR valve, BOTH temperature sensors, the Throttle Position Sensor, the thermostat, AND the Oxygen sensor.
I also cleaned and checked the thermal air temperature sensor and it appears to be working.
I then disconnected the battery in order to clear any trouble codes and to reset the IAC valve and TPS sensor as my mechanic friend and my shop manual suggested.
I fired the Swaggin' up and drove it around and the work I did appears to have worked!
I will hold off on calling the job a complete success until I drive her around for a few days to verify that everything remains the way it is right now, but for now, the idle is smooth and appears to be at the right RPMs!
~ Mike ~
Oh, and thanks Ron for getting a test IAC valve - I will get in touch with you if this turns bad on me.
~ Mike ~
No problem I actually got it out of my tbi I have from my 2.0 ohv engine I have in the garage.Hope your simple swaps makes it happy and keeps it that way.I have replaced all my sensors back on various resto work and the only one left is my tps.I had good fun figuring out how the auto stores list the dummy sensor (light on for say oil,and coolant) no gauges on mine.But once I learned plus the difference is on like the oil 2 senders.One terminal plug for dummy light,two terminal plug for actual oil pressure.Same applies for coolant on recall.
Which way does the iac need to be adjusted to lower the idle, inward or outward?
~~1986 Chevy Cavalier CS~~
~~2.0 TBI~~
Ok mike here is a uh free IAC and if this looks like yours I will sell this to you for just shpg cost fedex grd.I cleaned it up and seems ok and did come out of a 2.0 cavalier.Let me know and It will need a new gasket oring use the old one you have to slide on it.Ok