Ok, I've had a strange idle problem for a while now. Only when I come to a stop or I'm in park, my oil pressure drops when my rpm's drop to around 500 rpms. The idle will jump around there a little bit and the car will shutoff. Now, I took the IAC out and took off the TB and cleaned them VERY well and it still did it. So, yesterday, I went to the drag races and while I was wainting at tech, at idle, it surrged again and I gave it a little gas and it FINALLY showed an error code after these months of never showing one. It was a code 44. Now what do I do??? Help!

 

Ice,

Start diagnosing for the lean condition.

BTW - how old is the oxygen sensor?

 

Ok, what diagnoses should I do. And I really dont know about the age of the 02 sensor. I had my engine replaced about 3,000 miles ago. Of course it wasn't a "quality" shop as I would say. And I really dont know if they put a new one in. If not, then its about 140,000 miles on it, unless the guy before me swapped em. How much are they?

 

I had this problem and it turned out to be the timing was way off. Have you done anything with your distributer lately?

 

I havnt done a thing to anything. That's why I dont understand what's going on.

 

Dont know if it'll help much, but I raced it yesterday at Bristol, TN and it only trapped a 17.0 @ 8? mph. Which I really dont think my car would be that slow. (look at my sig) So, my tuning could be off, but then again, it wouldnt run well if it was just running lean either? Dont know if that helped, but it could.

 

sounds like the beginnings of a dying fuel pump to me.

 

either that or like said before the o2 sensor

 

I have the repait manual for '82-'92 Firebirds. I can check it out and tell you what it is (unless you already know). Don't fell too bad, I'm bringing up a code 43.

 

Thanks, but I know what the code is. Its an 02 sensor running lean. I just am trying to figure out why. Plus, there is a code listing in the tech section of thirdgen so, if your ever looking for one and dont feel like pulling out the manual.

 

Your time is pretty normal for a mostly stock 305, especially in hot and humid conditions. None of your mods are going to change that significantly.

If you don't know how old the oxygen sensor is, you can replace it for about $25. Clear the codes, then drive it some more. If the problem persists, Mrr23 might be right about the fuel pressure, but you need a reliable sensor first. As long as you're shopping for parts, a fuel filter change might be a good idea, too.

 

Actaully the fuel filter was the first thing I changed when the problem started. I guess I'll go for the o2 sensor first. Then if that doesnt work, I sould try a new fuel pump?

 

I was getting the same problem. Turned out to be my fuel pump. Get a good quality fuel pressure guage that will allow you to tap into the schrader valve on the fuel rail and make sure you disconnect the vacume line.

If your line is long enough you can tape it to the windshield and drive the car around, when the code or symptoms present themslves again verify your fuel pressure. If its dropping or low while your car is sputtering, that would indicate a faulty pump.

It also would not hurt to change the O2 sensor anyway. I got mine for around $30.00 from NAPA.

Dont let the problem nickel and dime you, diagnose the symptoms first. If it is your fuel pump, I would suggest going with AC Delco. They are more expensive, but will last longer. I originally went with a CarQuest brand and had to do the whole job over again less than a year later......or you could go with a quality aftermarket pump (Holley, ect.)

Oh yes....allow me to introduce my self. This is my first post after many years of lurking.

Jeff Foster liven in Honolulu. Active duty Navy. CPO (E7). I have a 1992 Z28, Purple Haze Metallic w/ Paxton SN93 (hunk of junk) and the usual bolt ons.

I go by Fratsit on the board and over at camaroz28.com.

 

i was having a similar problem with an intermittent code 44 and replaceing the stock o2 with a new one seemed to solve the problem. IMHO those times are pretty bad, even for a 305, you should at least be able to run high 15's with the tpi, even the crappy stock lo3 could get into the 16's. Id say it lookes like that engine is really starving for fuel. Checking the fuel pressure at WOT would probably be a good idea.

 

Thanks guys, and welcome to the boards fratsit. I'm about to go get an oxygen sesor now and replace it. See if it helps. I'm thinking that it is running lean, b/c 17's??? I know it is better htan that. So, I'll see what it does tonight and if it doesnt work out, I'll check the fuel pressure and see whats going on. How would I check the fuel pump to make sure it's working properly? Checking the pressure? Thanks for the help again

 

if the poor performance at WOT was fuel related, then the o2 wouldnt have much to do with that since the ecm ignores the o2 at WOT. Replace the o2, but check the FP as well. Mount the gauge where you can see it from inside the car and step on it and watch the fuel pressure. It should remain steady throughout the rpm band.

 

I agree with dimented24x7........

Your fuel pressure should be steady all through the RPM range. If not that would indicate a weak pump.

As for checking the fuel pump, you could disconnect the weather pack connector above the fuel tank and check it on the power side with a voltmeter to ensure you are getting the full 12 volts. There is really no way to check the pump itself, that I am aware of, since it is in the tank.

When my pump was going out, I could here it overspeeding inside the tank. They are pretty loud when running properly, but I could here mine getting louder. It sounded as if it was cavitating.

Hope this helps and good luck.

Frat
Honolulu

 

If you think you may have a vacuum leak, check the hose routing on the underhood VECI label:



The front hose on the right side of the plenum is for the FPR, and the rear hose is for the HVAC controls, cruise control, etc.

 

Ok, its the one that goes to the HVAC. Can someone post a pic of the where exactly ythe hvac is, the hose has come off the port on the plenum. Thanks

 

The vacuum line is a rubber hose, about 7/32" I.D. It is routed from the left side of the engine compartment, under the plenum, and to the rear fitting on the right side of the plenum. There is a "T" fitting in the line near/behind the brake booster, with a small hard plastic line feeding the HVAC controls, and a rubber line continuing to the cruise control unit. There should also be vacuum check valves in the line near the "T" fitting.