'86 SE V/6 w/4sp. Engines runs rough...will not idle well and seems to be running poorly at all speeds. Acceleration is smoother than deceleration.
I have replaced: spark plugs, wires, cap and rotor, put on new dist, retimed, added new IAC and MAP sensor. Car has new fuel filter and 02 sensor. No smell so I rule out the CAT.
Put car in "Field Service mode, per RALPY'S directions, THIS IS WHAT I HAVE: SES light blicked on rapid mode for a minute or so, then went int slow mode(one flash per sec.) I drove car for about five miles at 1500-2500 RPM and light continued in slow mode. When I got home I turned engine off and took paper clip out. Restarted car and service eng light is out (dark)...indicates lean fuel mixture, I hear,

THIS IS STILL DAVID HERE, I RAN OUT OF ROOM FOR ABOVE POST. I do not know where to go next to solve this problem.
The only code I receive from the diagnostic center is 12. I had problems installing distributor but rechecked PICKUP coil and put in new ignition module, so everything should be OK. OH,AND ALSO, I ALMOST FORGOT TO MENTION, I INSTALLED A NEW PRIMARY COIL. I ALSO CHECKED IT, AND IT IS OPERATIING PROPERLY. FUEL IN CAR IS GOOD...EVEN TRIED AN OCTANE BOOSTER AND THREE BOTTLES OF INJECTOR CLEANER. THERE ARE NO VACUMN LEAKS THAT I CAN HEAR, I DID WASH THE ENGINE, BUT IT RAN FINE AFTER IT DRIED OUT. THIS PROBLEM HAS BEEN WITH ME FOR ABOUT TWO WEEKS NOW. ANY IDEAS ANYBODY?

I'm not all that familiar with the V-6's but you might try looking at the EGR tube. I understand they are notorious for cracking and makes the engine run like crap.

David

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His Fiero: 1984 2M4 Coupe

Her Fiero: 1984 2M4 Convertible

Did you try relearning the idle? Unplug the battery, let sit for 5-10 minutes, plug the battery back in and drive for 10 minutes at varying speeds.

If that fails, have your charging system checked (battery & altenator).

You forgot to change the TPS on the throttle body. Actually, you won't always hear a vacuum leak. The signs of a vacuum leak are high idle(1500 rpms or higher) even when warm, and glowing exhaust manifolds. The rough running could be a bad EGR valve or solenoid. A broken/cracked EGR tube can also cause a high idle. It is not easy to spot the breaks in them. finally, an exhaust manifold leak can cause the engine to run funny also, the O2 sensor will detect the extra O2 and try to add more fuel. This one you should be able to hear. Hope this helps, instead of adding to your confusion.

Avengadore: car runs rough at all speeds, but on highway at speeds over 40mph is smooth enough to run OK on cruise control
BIGGEST problem is with idle...engine will idle between 1000 and 1500 RPM (varying pretty quickly between diffent speeds) occasionally it will almost stop running ...dip to 500RPM and then recover quickly to 1500RPM as ECM kicks in more fuel.
I checked electrical power to TPI (trottle position sensor) and it is OK. However, engine runs the same w/elec to TPI as w/out. IDEAS! Thanks for thoughts........

The TPS is used to tell the ECM how far open the throttle butterfly is. It uses this to calculate how much air is entering the engine. At idle the IAC will control how much air the engine will get. If either of these are running out of range they will set and error code after a couple of minutes. The ECM is trying to hold the idle speed of the motor to 950 rpms +/- 50 rpms once the motor has reached operating temperature and is in closed loop operation. If your O2 sensor is not working in closed loop, the car will run terribly and get horrible gas mileage. When you put the car in diagnostic mode, do not start the engine, just put the key in the position before it will start the engine. You should see a code 12 three times before the actual stored error codes start to flash. Once all the error codes have been displayed it should flash a code 12 again. The high idle would suggest a vacuum leak, and it probably is a cracked EGR tube. The one that connects the EGR to the underside of the upper plenum. This craks are very hard to see or hear without removing the pipe itself and flexing it. You also could have a disconnected or broken vacuum hose under the upper plenum or throttle body. You say you washed your engine. You could have gotten moisture inside one of the sensors and now it's affecting how the engine runs. Try running your engine at night in a dark place, to see if you can spot any arching from the plug wires. I have seen plug wires that were bad from new, and these will also make the car run crappy. Im still willing to bet you have some sort of vacuum leak. If you disconnect the battery for five minutes it will erase the error codes. You then will need to drive the car over 40mph for about 1/2 hour so the ECM can relearn.

[This message has been edited by avengador1 (edited 07-22-2003).]

EGR TUBES,,,? where are they on the engine? Are you talking about the tubes running to the PCV valves.........the one that runs from the bottom of the air cleaner plenum (the big rubber tube that runs from the air cleaner to the TBI?) and to the front valve cover. And then the tube that runs from the rear valve cover PCV to wherever?
Also, are you recommending that I change the trottle position sensor?

I tend to agree with avengador1, EGR tubes seem to be a common problem on the V6 engines.

I am unfamiliar with the V6 engines. I have looked in the Chilton manual and it shows a V6 (does not say which one) on which the EGR is mounted near coil and distributor. The EGR valve sits on what appears to be the exhaust crossover pipe. The tube that feeds exhaust gas into intake comes off the EGR and passes by distributor. EGR tubing will be metal.

[This message has been edited by ralpy (edited 07-23-2003).]

I found them and checked them out per manual. They are OK and doing the job they should be doing.

Not Tubes, but tube or pipe. What did you do to check it? The EGR valve is mounted to the crossover pipe for the exhaust, and has a shinny silver insulating cover on it, this is what makes it hard to tell if it is cracked. You would have to remove the insulating cover to properly check it for cracks or leaks, did you do this?

OK< Avengeador1, I know what you are talking about now. I checked the PCV valve pipes...thought this was what you meant.
I will take EGR valve off again... I had it off once already to clean pintle and put a new gasket on it.
EGR valve, according to the manual, can be checked by holding diaphram up. I did this and engine started to run very rough.... it did not, however, stop running (according to the manual the engine is supposed to stop). Does the fact that it did not stop indicate a leak? Thanks, David

you there, Avengador?