Engine running bad (too rich)

[jochen]

Merry Christmas everyone,

 

this problem is old actually, but I haven't done anything about it for almost three months now...

 

Problem is that my engine isn't running properly (1993 GP LE 3.1). It is running too rich. I can smell that and see it when I take out a spark plug and look at it. But lets just tell the story from the beginning.

 

I started having problems with the starter, which I am pretty sure is unrelated. The solenoid is dying and hence every time I started the engine it sounded as if the battery was weak. Eventually I wanted to start the engine and couldn't hear anything. Some gentle hitting with an iron rod will get it working again, however.

 

Now before the engine problem came up I noticed something strange with the electrical system. Whenever an electric consumer comes on, lets say I hit the break and the break lights turn on, the voltage seems to drop momentarily. It'll recover right away. The reason I think that is whats happening is that the headlights will briefly dim and when the engine is idling I actually hear it working harder against the alternator everytime I hit the break or the indicator lights are lighting up.

 

So one day in early October (yes) I drove from one end of town to the other via interstate, parked the car and came back 5-10 mins later. Wanted to start the engine, so turn the key, starter working relativly fine but released the key a little bit to early. At least thats what I thought I did. So the engine didn't start/stalled. Normally I'd just have to restart, it would just take a few seconds instead of the usual instant firing up.

 

But this time the engine started and stalled again after a second or two. After two or three times I caught the stall by pushing the accelerator and managed to drive to the store next door where I wanted to go to. While driving (just a two minute ride) I noticed that the engine, when I step of the accel, is reving up and down slightly but I thought that is related to that stall and it'll recover.

 

I parked the car again and when I came back about 30mins later it wouldn't start. Absolutely no chance. Had to get a lift from someone else and after returning the next day the engine would start again. Same thing with the bad idle though. It would nearly stall, then catch it and rev up quite high. When under load, e.g. in D but standing and idling it would be fine. So I drove the few miles back to campus (50mph road) and it was relatively ok. As the engine gets warmer the idling problem was also observed with the transmission in Drive.

 

Later I couldn't start it again and I had to wait for another day. On that occasion I drove it back to my house where it is still standing. But the reving up and down (down to a near stall and then quickly up again) was much more pronounced and happened even under light load. I did stall the engine once and luckily it restarted right away again.

 

After a week or two I briefly started the engine to see if it is still running, which it was. Started right away and the unstable revs where there whever in park or in drive. Didn't drive that time.

 

Now, has anyone got an idea how to diagnose that. Since I also have this problem with the voltage dropping I fear it might be something electrical. Otherwise my guess would be the injection system. I'm not a great mechanic and only have fairly basic tools. Would be grateful for any hints on what I could do myself to find out what is wrong.

 

I hope this was detailed enough a description, but I'm sure you'll have some more specific questions that I didn't think of.

 

Cheers,

 

Jochen

 

[rockfangd]

check engine light? it sounds like the map or maf.. check vacumn lines, pcv valve, to start

[ns87]

Now before the engine problem came up I noticed something strange with the electrical system. Whenever an electric consumer comes on, lets say I hit the break and the break lights turn on, the voltage seems to drop momentarily. It'll recover right away. The reason I think that is whats happening is that the headlights will briefly dim and when the engine is idling I actually hear it working harder against the alternator everytime I hit the break or the indicator lights are lighting up.

 

That to me sounds like the alternator is dying...at least thats what mine did.

 

Your poor idle sounds like fuel system. I never knew what caused my problems bc I've replaced fuel pump and injectorsl

 

I can't do much on cars myself, so take what I say with a grain of salt

[gimper]

Hmm well it's can be a bad connection between the alternator and the battery too -- check your aux pole and also all the wiring to and from the starter/alternator clean all the main power wiring and reattach. I fixed this kind of problem before, loose nuts, oxide etc on main power wires...

 

Cheers Gimper

 

[3WH12-96]

I agreewith Gimper you have an electrical issue ALT BATT at this point prolly dead ALT... causing dead and failed BAT ....failures of this nature cause many many other failures that may seem non related but are... start with the vehicles charging and electrical system first get that corrected and completely operational then see where you stand with the other "ghost" issues..... one thing at a time

 

[ShockTherapy]

the alt and battery for sure, i would also look at your FPR, and your o2 sensor.

[jochen]

Thanks for all the replies. I have more of an idea now what to look at.

 

I tried to start the engine again, the other day. I couldn't convince the starter to do anything. The long standing and cold weather might have killed it for good.

 

I checked the error codes and there was only the continous 12 readout. I also had the battery charged, but I think it didn't take on anything. The Ampmeter showed the same after a night of charging. So my strategy now will be to first put in a new battery. Then see if with full voltage and a few more knocks the starter solenoid will work again, at least temporalily.

 

If I get the engine to restart I'll check if the voltage is still unstable when switching on anything and replace the alternator.

 

Battery and alternator should be easy to replace. But the starter would be tough, I fear. Of course it is a big mess down there because of the slightly leaking oil pump drive shaft and from what I read here in the forums it is not going to be very easy.

 

Will I need to raise the car? I'm on a slight slope, so in that case I'd have to tow the car somewhere else to work on it. Also since my problem should be the solenoid can I replace that alone or is the starter+solenoid one single unit?

 

Cheers,

 

Jochen

 

[Supreme Cutlass]

Have you checked your o2 sensor?

[jochen]

Have you checked your o2 sensor?

 

No, I assumed it couldn't be it because the ECM doesn't use the readings from the sensor until the engine has warmed up. And since the problems persist from the start...

 

Am I wrong in my assumption?

 

[jochen]

I agreewith Gimper you have an electrical issue ALT BATT at this point prolly dead ALT... causing dead and failed BAT ....failures of this nature cause many many other failures that may seem non related but are... start with the vehicles charging and electrical system first get that corrected and completely operational then see where you stand with the other "ghost" issues..... one thing at a time

 

 

I replaced the alternator and the starter. I left the old battery for the time being but charged it. The starter is working fine now and the alternator seems to be OK. From the sound of the electrical door locks and testing the indicator while doing the idle relearn procedure it seems that the problem with the voltage drop when a load comes online is gone now.

 

However the engine is still not running very well. At no point so far have I pushed the gas pedal.

 

After reconnecting the battery I decided to perform the idele relearn as described here in the forum. I started the engine which took a few seconds (it sat there for three months) and it was running pretty rough. I put the transmission into drive and kept it running for ca. 6 minutes. After a while it the revs became a bit unstable, slowing down and speeding up again. But close towards the end of the five minutes it got it more under control and I thought the ECM is getting it better under control.

 

I stopped the engine, tried to restart after 10 secs and it would stall. Two more tries and I got it running again. This time I thought it ran even a touch worse than the first time. After five minutes I stopped the engine again.

 

After a few minutes I wanted to restart but couldn't get it to run. It would fire up and I kept going with the starter, then thought it is getting stronger but it would only do a few more cycles at ultra low speed and then stop. Did that twice and then gave up. I'll try again tomorrow to see if it is starting better when cold.

 

So, where should I go from here? I didn't replace the O2 sensor for once because I thought it shouldn't be the cause of the problem, since it isn't used until it reaches temp, and also the repair manual said it might not be possible to be removed from an entirely cold engine without damage.

 

Any way I can test other sensors and whatever?

 

Thanks,

 

Jochen

 

[Andrew]

i would start looking for vacuum leaks, replace your pcv valve and plugs just for the hell of it.(since they are cheap)

 

then test the fuel pressure at the rail, lets make sure you are getting enough fuel. if that is ok, then id look at the injectors, have them ohm tested.

[slick]

Yep, definately check for vacuum leaks or leaking or bad intake gaskets. You can use throttle body or carb cleaner to spray at these while the engine is running. Any change in the idle when you spray it and you know it's a culprit.

 

Too much fuel could be a few possible things really.

 

BTW, how long has it been since it's had a full tune-up(plugs, plug wires, air filter, fuel filter, pcv valve)? If your plugs are bad, you may be smelling some unburnt fuel as well(gonna kill your catalytic converter here soon).

[Crazy K]

it sounded to me like it could be a bad fuel injector, which could be shorting out...

 

for now... replace the things you should regularly replace, if they have not yet been done.

fuel filter, air filter, plugs(use ac delcos not bosch), and wires if worn

 

 

and check:

 

the egr passage and the Idle Air Control valve's passage for blockages. I often scrub the egr passage with a round battery terminal cleaner brush.

 

pull the vac line off the fuel pressure regulator and make dure there is no gas in the vac line.

and with the engine running (hoping you get that far) unplug the vaccuum line from the fuel presure regulator(and block it with your finger), it should affect the engine idle slightly.

 

 

as for injectors... I like to pull the upper intake off and remove them all, check their ohm reading, and reinstall with fresh O-rings. a step you may have to do if all else fails.

[jochen]

Yep, definately check for vacuum leaks or leaking or bad intake gaskets. You can use throttle body or carb cleaner to spray at these while the engine is running. Any change in the idle when you spray it and you know it's a culprit.

 

Too much fuel could be a few possible things really.

 

BTW, how long has it been since it's had a full tune-up(plugs, plug wires, air filter, fuel filter, pcv valve)? If your plugs are bad, you may be smelling some unburnt fuel as well(gonna kill your catalytic converter here soon).

 

I changed the plugs a bit more than two years ago. The previous ones must have been in the car for years. The gap was big enough to stick a childs head in with lots of electrode material lost but the engine ran just fine. I set the correct gap on the new ones, put them in and didn't experience a notable difference, really. When I first had the engine trouble I took one out and it looked fine. Carbon on it, from running rich, but one gentle wipe with a paper tissue and it was perfectly clean again.

 

I never touched the plug wires and to be honest I really don't want to. Boots are coming off fine when bend and twisted right. I replace the air filter quite regular and it is bright white clean right now. Fuel filter wouldn't surprise me if it was the factory installed one from 1993 and PCV probably the same.

 

Once this ice strom is over and the temp is coming up again I would like to first replace the PCV. I see the hose going from the front cylinder head going to the intake hose. Is there another one on the rear going to the actual valve? The online repair manual I use is a bit confusing regarding my model. I think it says that there are two hoses, one delivering purge air into the crank case and the other one with the valve letting air out. How will I get it off? Just pry it out of the head with a screw driver??

 

Cheers,

 

Jochen