My 85 Firebird has been idleing kind of rough the past few months. The car idles fine when the engine is still cold, however after it has been running awhile it starts to idle rough when I stop at stoplights. I usually only notice it while I have my foot on the break, if I let off the break a little and let the car roll foreward it seems to be ok though.

Also, the car starts up fine when the engine is cold but if I've been driving around awhile, park it, then try to start it a short time later sometimes it takes several tries before the engine will start.

Someone told me that my EGR valve might be sticking causing a vacume that is causing the problems. If anyone has any other ideas of what could be causing the problems I'd like to hear them. I just want a second opinion before I buy anything because I'm kinda on a tight budget right now.

 

What to buy....
VACUUM HOSE AT ABOUT $2!!!
Next remove the EGR and find a media bead blaster.
Clean that item up, NOT DISTURBING THE RUBBER SEAL UNDER THE metal cover.
Remove chunks of caked on carbon.
THEN HAVE FUN
Find every broken cracked hard plastic Vacuum line ya can and repair the air leaks.

5/16" hose does the trick very well!

MPFI Units DEMAND 100% NO VACUUM LEAKS.
Next don't laugh...
I had fixed my EGR set up on the 1985 Firebird
FIXED IT!
Knew I had....went thru the vacuum lines, changed EGR's, FIXED IT FIXED IT!!!!!
Kept getting (often) the SES code for the EGR problems.
Finally my Ignition Control Module died.
I replaced it, BUT I threw a alot of the correct Dielectric Grease under the ICM.
Guess what, my EGR Code has FINALLY stopped flashing.

Related?

I do know that ya need ZERO VACUUM LEAKS FOR A MPFI UNIT TO FUNCTION THE WAY IT WAS ENGINEERED.
Good luck with your mission.
EGR valves RARELY FAIL.
It's what causes the weak EGR signal that is the problem.
AND PART OF THAT EGR PROBLEM IS AN ELECTRICAL SIGNAL, too. Beside weak vacuum signals & carbon build up.

 

My car had the same problem. I've got an 87 Firebird. My mechanic fixed it by unplugging the EGR valves. It was that simple. The only problem is that then your check engine light will always be on because your computer will say that your emissions system isn't working correctly, which is true if the EGRS are unplugged. But this may very well fix the problem. If you can stand the check engine light always being on, then this is an extremely cheap fix. It may be against the law. I'm really not sure about emission laws. But if your car was made in CA which I bet it was, the emissions system is incredibly complex anyway...so yeah I'd try unplugging the EGR valves. Hope this helps!

Firebird68025

 

Yeah any EGR fiddling violates emissions control stuff. If there's another way to do it I'd try it...why be a mass polluter when you can gain back your power and idle qualities without sacrificing other things? Not to mention a constant Check Engine light could mean you are late in knowing about other problems that your computer does because it throws a code but you don't realize it.

 

I replaced about 10 ft of vacuum lines today. The ones that went to the charcoal canister looked pretty bad on the outside so I replaced them. I doubt that the problem is in any of those lines,because it still acted up on my way back to school this evening.

I didn't get a chance yet to take out the EGR to see how much carbon was in there.


firebird68025 what do you mean by unplugging the EGR valves? Did you mean take the whole thing out or unplug a connection to it? I may end up trying that just to test wether or not it is even the EGR. I really don't like the idea of having my check engine light on all of the time.

 

Just disconnect it, don't take it out. Having your check engine light on isn't that big a deal. I just recently had my mechanic replace a whole bunch of crap to be able to plug them back in. My car runs like its new, but it cost just under $500. I would try disconnecting the EGR. Otherwise, I don't know what to do. Sorry...

 

I disconnected the vaccum hose from the top of the EGR and took it for a test drive. I didn't notice any difference. No check engine light came on either. When I got back to my apartment I played around with the vaccum hose disconnected and with it hooked up. I still couldn't notice a difference between it being hooked up or disconnected. Would that rule out the problem being the EGR valve or not?

While I was messing with the vaccume hose I noticed that the eninge was really only idleing rough whenever the alternator kicked on.

 

Do you know what type of EGR system you have? There are 4 types I think. Theres ported, digital, positive backpressure, and negative backpressure. They all work basically the same but there are structural differences between them. Look on the valves and see what letter is stamped below the date or if there isn't a letter. This will tell you what kind you have. Then I may be able to help you more.

 

I would THINK that disconnecting a vacuum hose from ANYWHERE, including the EGR, would have an effect..and the EGR hose is a fairly large one I think. The valve cycles open and closed probably so sometimes it might not leak vacuum..I dunno, I just think it'd be noticeable. What if the valve failed and stuck in open loop operation...wonder if that would throw a check engine light or not..

Now, what do you mean when the alternator kicked on? Do you mean it got rough when you did something to increase alternator power draw..such as, put headlights on, turn stereo on, put vents on, etc? What was the alt gauge reading before and after?

 

The hose on top of the EGR that I was messing with was a fairly small, smaller than the other vaccum hoses that I replaced anyway.

About the alternator kicking on... When I had the hood open and the engine running I noticed that every so often the part of the alternator on the front side of the pulley would start turning. It would turn for a few seconds and quit. Whenever that part starts moving the idle gets rougher. I didn't have the headlights on, but the heater vent was on. I didn't mess with it as I was testing it though. My car doesn't have a guage for the alternator.

I'll check to see if I can find a letter stamped on it tomorrow, assuming the weather is halfway decent.

 

You don't have an alternator gauge..you have an amp gauge. Starts at 0 and goes to like 18 maybe??? Can't remember for sure. Should be somewhere around 13 when the car is running. Oh and shut your vents off and your alternator will stop doing the start/stop click thing. Its supposed to do that.

 

LOL, yeah, it's an air conditioning compressor, not an alternator.

Pulling the vacuum line doesn't really "rule out the problem being the EGR valve or not". Our 82-89 2.8's use a vacuum op'd EGR that can get rusty and stick open. Happened to me. Next time your car runs like crap, pull over somewhere safe, shut the motor off, and feel the underneath of the EGR valve. The diaphragm should be all the way down. Mine was sticking open- EGR would activate (via the vacuum line) as usual (+40 mph, engine warm, low rpms), and wouldn't de-activate. Here's the message: https://www.thirdgen.org/techbb2/sho...threadid=62507

First I went to Pep Boys and got a replacement EGR; yeah, well, it was a ugly bright brass-colored universal EGR with the vac line aimed the wrong way. Took the damn thing back and paid $20 more for an AC one from a dealership; painted a nice gloss black, with the vac line input facing the right way.

 

LMAO Tom..you beat me to it... Amp gauge, alternator gauge...everyone knows what I mean.... Might as well just say the doodad needley thing hooked to the alterna-whatsahickey. And a roughness is normal when the a/c compressor clutch engages. It draws quite a bit of power, especially when it needs to be oiled like mine does. Gives the car a nasty shimmy not to mention a bad engine tone..they sell cans of 134a refrigerant with oil added...just bring the can and the car to a local shop with a guy you know working there, or some place you've had work done at before...if they like you, they'll take the 5 mins and put it in for free...it's not that hard, just a 2 man job.

 

AC Compresor

While I was driving back from working on an economics project about an hour ago I realized that I got the two confused for some reason. Thanks for cathcing that too though.

Whenever the AC clutch does engage it makes the car shake pretty bad. When I'm sitting at a stop light the side windows start shaking as well as just about everything inside of the car.

I'll take a look to see whether the EGR is all the way down the next time it acts up.

 

The only guages that my 85 has are the fuel guage, speedometer, and odometer. Not having the all of the guages is definately my biggest dislike of my 85.

 

It doesn't have a tach?

 

So..to recap...do the problems you describe earlier in the post only occur with the a/c on? If so..don't use it!! At least run a can of 134a with oil through..it'll help it a tad....

 

No the car doesn't even have a tach.

The problem occurs even when the AC is off. It happens everytime that I have been driving for over 15 minutes or so and I am sitting at a stoplight. It doesn't shake the whole time I am stopped. It shakes several seconds, then stops for a few seconds. When the hood is open and the engine is running it only shakes when that clutch engages.

I'll give the can of 134a a try when I get a chance.

 

Check vacuum lines and take out and clean your IAC valve. Just unplug it on the bottom, take the 2 Torx screws out, and slide it out carefully...use carb cleaner to clean it, and spray some on a rag and clean the inside of the IAC passage. Don't be too excessive with the carb cleaner, and get off as much as you can before you put the IAC back in..reconnect it and fire the car up again. It might run funny for a few minutes because of the cleaning and the carb cleaner also. Just make sure the engine pulls in as little of it as possible, as it strips off protective coatings in EFI cars. Hence, why they call it CARB cleaner and not throttle body cleaner.

 

I agree, skip the carb/choke cleaner! Actually, the IAC on his '85 will unscrew like a big spark plug; only the 3.1's got the IAC with the torx screws.

'85, what's so bad about not having a factory tach or oil pressure or water temp? Factory gauges on the f-bodies are known for always being inaccurate. Take it as an opportunity to add "real" gauges. Ever hear of an a-pillar pod? They take two 2" gauges and mount 'em on your windshield. I've added a Sunpro tachometer, and Summit oil/water temp gauges. This summer, they'll all be coming out for Autometer gauges.

Personally, I really like the way added-on gauges look- when they're done Tastefully. I get a kick out of these import-driving morons that decide to put a 5 inch monster tachometer on their dashboard, that's just freakin' ridiculous.

My tach is hung under the dash pad lip, and blocks the driver's side air conditioning vent. Only bummer is if I'm driving with my left hand on the top of the steering wheel, my arm blocks the tach. No biggie.

 

Kinda funny..last can of discount carb cleaner I bought from DAP, specifically for use only on cleaning the IAC valve, I looked at the back under directions and it had directions to use on fuel injected cars. Morons.

 

Jeebus Christ.....if you're gonna correct someone, at least correct them right. It's a VOLT GAUGE. Volts and Amps are not the same thing.

 

Man I hate getting on the alternators topic..I always get the two mixed up. Drives me freakin crazy!! Ok, our power systems are 12v...with the alternator running they tend to operate at around 13-14v, which is what the voltmeter picks up correct?

 

The gauge monitors battery voltage ONLY. The battery is 12.6V fully charged. When running, the alternator is charging the battery which raises battery voltage to 13.8-15.2 volts.

You COULD have an Amp Guage to see how many Amps the alternator is pushing......kinda worthless though.

 

Yeah, problem is, an amp meter needs to be in-line with the circuit it measures. That means to install an amp meter, you need to put it between your positive battery cable clamp and the battery's positive terminal. This isn't too good for cars, because you wind up running a 0 gauge (thick!) wire into the passenger compartment, hooking up to the amp gauge, and then running back to the battery.

Volt meters measure voltage drop "across" circuits- and that makes them good measuring tools for alternators. B/c of ohms law, volts and amps are related; if one drops, so does the other.

Ohms law is V=IR, by the way.

 

can i just remove my egr valve and seal up the untake hole it will leave behind, i was thinking of doing this by cuttinga piece of sheet metal to size and then just geting the gasket for it. I want to remove it so i can put i the an fuel line connection pieces but the egr valve is to close to my fuel inlet. If i take this off will it cause any problems with anything other then a check engine light coming on, and most importanly will it still pass the state inspection, thanks

 

You're not going to meet any state emissions standards with your EGR valves unplugged. Sorry And make sure to watch your gauges close if you do this. Your check engine light will always be on and you may not catch when something goes wrong because the car would throw a code and you wouldn't be able to tell. So just watch your gauges close and listen to your car. You can usually tell when something is wrong that way.

 

Keep in mind that the computer is also designed to function with EGR controls in mind. Disabled/fiddling with the EGR system could, and very probably, result in reduced gas mileage AND engine performance.

 

Tom I don't like not having all the guages on my car because my 84' has the full guages and I kind of miss not being able to monitor them on my 85'. I've been tempted to add a water temp. guage quite often though. I'd like to be able to know if my car is getting hot before the light comes on. When adding a water temp guage, does the sensor for the new guage just plug in where the old one does?

The IAC is the sensor that it on the side of the air filter, right?

 

Nope..IAC is on the passenger side of the throttle body. Upside-down clip, 2 torx screws.

 

I finally got some time to mess with the car today. I took off the EGR valve and sprayed a little WD-40 into the passage on the bottom. I took a bolt and pushed the rod attached to the bottom of the EGR and worked in the WD-40. My car feels like it idles A Lot smoother now. I hardly notice any shaking at stoplights now.

Thanks for all the suggestions.

Thanks for the clarification on the IAC Nixon1.