Idle problems and quite a few questions

[BigmacK192]

Good morning guys.

I've got an 89' GT with some idle issues. Did a KOEO and KOER test and pulled a few codes.

21, 31, 41, 82, 44, 94

The engine is a stock 5.0 block, B303 cam, Excel coil, AFR heads, Comp-cam rockers, TFS Street Heat upper and lower intake, A/C delete, Smog pump is intact and spinning, but everything else is disconnected from it. No cats, EGR is intact, and I bought this car as is. I've done small work, cleaning it up. My first fox body.

I dealt with a rough idle all last year, but didn't have time to get to it and had to store it. Pulled it out of the garage yesterday to get the first drive of the season in, and she idled just like she used to.

Crank it over and it surges to 1500, drops to about 500, and then surges back up. It will do this consistently for at least 2 minutes. Sometimes it levels out, sometimes it doesn't. A little kick to the throttle and it will smooth out and idle at just about 1000 rpm. And then it runs completely fine.

The check engine light comes on every once in a while, so I checked it. Like I stated before, KOEO and KOER resulted in those codes 21, 31, 41, 82, 44, 94. I'm fairly sure that I can ignore 82, 44, and 94, as they are AIR components.

21, not sure about. Temp outside when I ran the test was about 45* F, and I've heard that can cause a false error on this sensor, but I'm not sure. Any way I can test? I don't want to start throwing more parts at the problem.

31, EVP, I've replaced already. The car had a stuck EGR valve on it when I bought it. Idle was horrible at purchase, so I replaced the valve and the vacuum solenoid on the passenger side strut tower, and the idle was okay for a while. Then it slowly degraded. I took it off, cleaned around it, bolted it back on, and still the same error.

41, Lean condition right bank (if that's correct). No smoke that I've seen. I'm not sure even where to start here.

Thanks in advance for the help. I realize this is my third post ever on the forum, but really, it's like my first, haha.

 

[Jkstang78]

Check your idle air control valve. It is right next to the thorttle body.

You can take it off and spray some carb cleaner in it, and see it that fixes the idle problem. They usually get gunked up.

View attachment 226452

 

[SpartaPerformance]

Check your idle air control valve. It is right next to the thorttle body.

You can take it off and spray some carb cleaner in it, and see it that fixes the idle problem. They usually get gunked up.

View attachment 226417

I agree, it actually comes apart and you can clean it out really well that way. As for code 31 I'ld replace the coolant temp sensor, if its out of range and your car is stuck in cold idle it can make it run bad and throw different codes.

 

[liljoe07]

Why replace the coolant temp sensor?

If the engine running codes were ran with a cold engine, then this code will flash. ECT needs to see temps above 160-170* to not throw a code.

Now if the test was done with the engine at operating temp, then the ECT sensor may be suspect. But it could be a wiring issue also. Its not advised to blindly replace a sensor with out testing.

 

[BigmacK192]

Thanks for the suggestions. Took off the IAC to clean it up, slapped it back on, and idle quality is still the same, though it was pretty gunked up. Found out that one of the vacuum lines below the intake, passenger side, was burned through on the header. Cut, capped, and tried again, but the quality was similar. Ran a KOER after it was up to operating temp and the ECT code disappeared, so I think you were correct liljoe.

My other question and the issue that has me worried, is that the car has developed an oil leak that's fluctuated in size over time. It seems that it runs down the oil pan, dripping, and pooling beneath the car on the garage floor. At first, I thought it was the drain plug gasket (polyurethane), so I swapped it at the last oil change. Still dripping. So I tightened all the oil pan bolts back up, thinking they could have vibrated loose. No difference. There was also a slight drip between the engine and trans.

Well today, I looked and it's dripping by BOTH drain plugs, and between the engine and trans, after some spirited driving and a highway romp. I've heard people suggest rear main seal, but I don't believe that'd give me drips at the front of the engine. So, what's my course of action? Swap the oil pan gasket? How would I go about that?

Any suggestions would be great.

 

[HISSIN50]

Make sure the PCV system isn't backed up. Pull the valve and make sure it's free and the spring isn't broken, and clean or replace the mesh screen under the grommet.

Keep lookin for vac leaks. The PCV could have popped partially out (due to excessive presssure). Another thing to check is the EVAP hose where it goes under the front of the plenum. The hose rots and can cause a decent leak.

Good luck.

 

[liljoe07]

What Hissin said.

Also you have a lean code( code 41) on the passenger bank. A quick test to determine if that bank is acutally lean or not, is to swap the O2 sensors around in the exhaust pipe. If code 91 now shows, its a problem with the 02 sensor on the Right side( buts its now in the Driver side)

 

[BigmacK192]

Well I took a look at the PCV system just now. Pulled the valve itself, shook it, and heard that it's still moving inside, so I think that's okay. The valve itself, as well as the grommet, both have a light coat of oil on them. This tells me the screen is probably bad, but it looks jammed down there and I couldn't reach it without probably ripping it out of the intake. I'm expecting to have to replace all the PCV components too, after seeing this.

The car has a cam, aftermarket heads, and a few other goodies that would up the compression. Would crank case pressure really cause this big of a leak though? If this can fix it, I'd be a happy man.

I've checked for vacuum leaks and found nothing yet. I'll be checking the evap hose and swapping those O2 sensors tomorrow morning. Just got her back on her back on the ground and I am tired.

Is there anything else I should consider to be the cause of this?

 

[HISSIN50]

I use a long pair of needle nose pliers to pull the screen. Some use a magnet (I don't have luck with that method - the breather doesnt slide in and out real easy for me) or a drywall screw (to use as a handle). It's tough to see and do this but it's done with the plenum installed.

If you replace the PCV stuff, use a motorcraft PCV valve and grommet (they fit tight together - some aftermarket stuff doesn't).

Crankcase pressure has to go somewhere. If the PCV is clogged, the next least path of resistance is often the front and rear seals.

Joe's advice for the O2 swapping is spot-on as usual.

It doesn't sound like you have a big leak and the leak might not be the cause of the issue (since it only happens while cold and once you hold the throttle down for a couple minutes, it smooths out). I would do the ECT calibration testing that Joe mentioned. Test it at ambient temperature (assuming it's not real cold - those sensors are not real accurate below like 50*F).

 

[BigmacK192]

I use a long pair of needle nose pliers to pull the screen. Some use a magnet (I don't have luck with that method - the breather doesnt slide in and out real easy for me) or a drywall screw (to use as a handle). It's tough to see and do this but it's done with the plenum installed.

Got a pair of needle nose that I'll use. Good advice.

If you replace the PCV stuff, use a motorcraft PCV valve and grommet (they fit tight together - some aftermarket stuff doesn't).

I learned that lesson the hard way, having a Duralast (my ass) part fail within 3 days of application.

Crankcase pressure has to go somewhere. If the PCV is clogged, the next least path of resistance is often the front and rear seals.

Guess it makes sense. Previous owner of the car said that there was always a small leak, and since I ran her hard at higher rpms, guess that causes more pressure within the engine.

It doesn't sound like you have a big leak and the leak might not be the cause of the issue (since it only happens while cold and once you hold the throttle down for a couple minutes, it smooths out). I would do the ECT calibration testing that Joe mentioned. Test it at ambient temperature (assuming it's not real cold - those sensors are not real accurate below like 50*F).

I plan on doing that too. It's sunny and temp is climbing today, should be just fine. I'll hop back on and update, including a few pictures for you to see what's going on. I appreciate the help guys. I've been looking for a good forum, and this one definatley fits the bill.

 

[BigmacK192]

http://img203.imageshack.us/img203/8145/p1010998i.jpg
http://img534.imageshack.us/img534/9986/p1010992s.jpg
These are the oil spills I woke up to this morning. This is larger than it's ever been.

http://img716.imageshack.us/img716/4894/p1010991r.jpg

PCV screen looks pretty clogged up to me, cleaning it now.

http://img710.imageshack.us/img710/8311/p1010994y.jpg
http://img175.imageshack.us/img175/2282/p1010995h.jpg
http://img717.imageshack.us/img717/6851/p1010996.jpg
http://img97.imageshack.us/img97/6523/p1010997d.jpg

More pics of the oil leaks I described, just so you guys have a proper visual. Anybody ever had a leak like this? A friend of mine says his oil pan gets loose and he tightens it a few times a year, but I think this is more significant that that.

 

[BigmacK192]

PCV is out and smothered in oil.
http://img710.imageshack.us/img710/8940/p1010999v.jpg

Any suggestions on cleaning this? If I soaked it in brake cleaner, would that work? Or would carb cleaner be better?

 

[liljoe07]

I soak it in gas. Or purple power. What ever will cut the oil.

 

[BigmacK192]

So I cleaned the PCV valve as best as I thought I could, and while I had the valve off and the screen removed, it seemed like the oil drip stopped. The car was sitting in the garage for 5 hours and not a drop hit the floor. After the cleaning and the O2 sensor swap, I put everything back together and ran it, doing KOEO and KOER tests. The lean condition disappeared, but a few new ones showed up. I did two tests, and got different results each time. All the codes I saw:

13, 57, 64, 67, 82

13 and 82 appeared in the second test only, 54 in the first only, but 67 repeated in both and 64 repeated in both.

What this means, I don't know. Also, the oil leak has started up again. It's marginally smaller, but still worrying me. I'm considering doing a breather on the passenger side valve cover, replacing the PCV screen or even putting a breather on there too. Any suggestions are welcome.

 

[liljoe07]

Clear the codes and start again. List what codes are the KOEO and what ones are the KOER codes.

Those freaking big ass pictures have my slow ass computer in WTF mode. Took me forever to reply. Try and size them down next time.

 

[BigmacK192]

Clear the codes and start again. List what codes are the KOEO and what ones are the KOER codes.

Will do. I'll post results later.

Those freaking big ass pictures have my slow ass computer in WTF mode. Took me forever to reply. Try and size them down next time.

Sorry about that. They're removed for now, I'll resize and repost later.

 

[BigmacK192]

So, here's the results of the morning under the hood.

KOEO: 82......10 second interval....... 11

KOER: 94, 44

Cylinder Balance: 90, which I know is a pass across the board.

Smog system is disabled, so it looks like I'm code free.

I also slapped a breather on the valve cover on the passenger side and it looks like the oil leak has slowed. The PCV screen soaked in brake cleaner for over 2 hours, the residue left over was pure black. I dried it, slapped it back in, but it still didn't look like it was clear enough to have air pass through it. Looking to replace that. But it looks like it's alright.

Idle problem still exists, but it's now one in every 10 starts cold. Not sure what's going on, but I think I can live with that. Little blip on the throttle and she levels out.

 

[liljoe07]

Smog is off the car right?

For whats its worth. You shouldnt run an open breather and a PCV at the same time. It allows for an unmetered air condition. You are not getting any lean codes. But the ECM is probably trying to compensate for that. Should have the Throttle body to filler neck installed to factory spec. Drive it around and let the computers adaptive strategy take control. See if the symptoms get better.

 

[BigmacK192]

Smog is off the car right?

For whats its worth. You shouldnt run an open breather and a PCV at the same time. It allows for an unmetered air condition. You are not getting any lean codes. But the ECM is probably trying to compensate for that. Should have the Throttle body to filler neck installed to factory spec. Drive it around and let the computers adaptive strategy take control. See if the symptoms get better.

Yes, smog is off the car.

And I found a new PCV filter screen and slapped it in. I'll put the filler cap back on (the hose from the throttle body to filler neck is installed), giver her a run, and see how we do. I'll keep you posted.

But is having a breather and the functioning PCV really that bad? The engine is far from stock, and the compression is definatley higher.

 

[Celeb]

Might want to put a nut on that one that's missing on the upper to lower stud.

Also, is that RTV oozing out from between the upper and lower?