OK, here's the thing: my car idles fine when it is cold, but, once it warms up it starts idling funny and eventually dies (seems to be common around here). When driving, it will surge and sputter around normal cruising RPM range, also when I am getting ready to stop and push in the clutch the RPMs stay at about 2000 until I actuall stop and sit for a few seconds. At first, I was getting code 32, and found my MAP sensor was bad. I replaced that and cleared the ECM, but it seems to be worse now. It still does the same thing, but I do not get a trouble code out of the ECM now. So, next I went through nearly every inch of vacuum hose and replaced most of it (you know, it was only like four bucks). Car also has recent plugs, wires, coil, and EGR solenoid, but it was doing this before I changed all of these things. That's just a little history to let you know about what is NOT the problem. Here is my question: while searching for vacuum leaks, I was hearing a whistling sound coming from my TBI unit. Is this normal (I know it needs to draw in air to mix with the fuel), or could I possibly need to tear this thing apart and start replacing gaskets?

 

Does it sound kind of like a teapot? Mine makes that sound. I can hear it from inside the car.

 

Sounds like a faulty O2 sensor....

 

I don't know how I forgot to add new O2 sensor in my post, since I had just changed that thing maybe a half hour before I posted I think I may have found my problem though. I went out there before I went to work, and carefully sprayed carb cleaner around the gaskets while it was running, and found that if I spray the area around the fuel pressure regulator, the RPM drops for a second. I stopped and got a new gasket kit for it, so I am going to try tearing it down and re-sealing it.

 

A faulty gasket at the TBI will cause a high idle. Its equivelent to having the throttle open. The sputter/surge could be a faulty or dirty IAC. They go south after awhile when the stepper motor gets plugged up with 20 years worth of gunk and varnish.

 

I don't think it's that, to be honest. I don't see how spraying carb cleaner on the regulator itself would cause engine RPM to drop. Is the regulator leaking any? Did you check for actual fuel pressure? If not, I would check your fuel's pressure, then check for a faulty ignition module....

 

I own a 91 bird, tbi (305 v8). I am having a similar (if not the same) issue. When the car is cold, it's fine. When it warms up, it idles sporadically; inbetween about 100 and 2500 rpms. First it falls, then it goes up, falls, goes up, continuing this surging cycle untill it dies. Most of the sensors are new along with the cat., the engine was swapped for a rebuilt (same model/size) about 40,000 miles ago. The car has 203000 miles. I only does this once in a while. I took it to the dealer and they said nothing was wrong with it. I'm looking into fuel injectors. Maybe we can get through this thing together. My co-workers and I are aircraft mechanics so we should be able to figure this out. I'll let you know everything I try and what it does. No codes mean no problems right?! NOT!!!

 

I wasn't thinking the regulator itself, I was kind of spraying the gaskets to check for bad ones, and I think I was right. Just to be clear, the little red straw was on the sprayer so I was not just spraying carb cleaner all over the place. I just came in from working on it, and here is where I am at: The TBI unit is three pieces with gaskets inbetween them. The bottom gasket is the one I was suspect about (I believe the piece it is under is called the fuel metering something or other, it is the piece with the bowls), and when I pulled that off, I found that gasket in four pieces. Now, I am by no means a mechanic, but I'm thinking that whistling sound may be a vacuum leak caused by that bad gasket. I may be wrong, but either way, I know that gasket being all busted up isn't any good for it. I'll keep you guys updated on my progress with that to let you know how that panned out, but for now, I messed it up even worse. I went ahead and bought a whole gasket kit for a complete rebuild, figuring I might as well go ahead and replace all of them including the base while I was in there, and what the hell, it was only 6 dollars, so I tore it all down, and when I went to put it back together, I apparently put a little too muscle to one of the fuel inlet fittings and cracked the "fuel metering something or other" from above , so I have to see if I can come across one. But I got a bad feeling I am going to end up having to go to the junkyard and buy a whole new TBI unit, because I am sure I won't find that one little piece anywhere, and I am hoping to have this thing fixed this weekend, because insurance on my truck expires and transfers to the Camaro April first.

 

Here are the areas in question, two show where I am suspecting a vacuum leak, and one of the area that I cracked. These are not my actual part, just pics I snagged off ebay real quick. The gasket between this assembly and the base piece was the broken one.

 

The piece you are looking at is the injector pod. The "gasket" that goes between this pod and the TB unit does nothing more than keep unfiltered air from making it into the air cleaner assymbly.

Like Dimented said, a vacume leak will do nothing more than give you a high idle. With our MAP sensor based system the air is "metered" after it gets into the manifold. It doesn't care how it got into the manifold, the MAP sensor will see the change in vaccume and compensate for it. The IAC valve (on the side of the TB) is nothing more than a computer controled air leak. If you leak air in somwhere else it can't do it's job.

The gasket you want to replace doesn't really matter. Your problem lies elsewhere.

 

I bought the rebuild kit for mine; rebuilt the tbi, hope it runs tomorrow...

 

OK, so far I have gotten nowhere. So, I did a Google search and found a TBI troubleshooting guide. It was a deal like check MAP sensor, is it good (yes/no), if good go to step 2, is coolant temp sensor good (yes/no), if good go to step 3, so on and so forth. Then I got to the last step:

.....6. Is the charging system operating properly and is the voltage measured at the battery and the injector 13 volts or higher with the engine running?
Yes – Go to step 7.
No – Repair charging system. Note the discussion about older style AC Delco single wire alternators. If still running rich after reparing go to step 7.
7. If you have gone through all of the above procedures and the engine is still running rich you will need to call tech support. In many cases the.......

This is a NO for me. I have known for a while that my charging system will be in need of some attention sooner than later, but never checked into what was bad, the battery or the alternator. If I leave it sitting for more than 10-15 minutes with the key on, but not running I won't be starting it back up without another car and jumper cables. When the car is running, the volt gauge hovers at around 12V, and I had always thought that it should be reading at about 13 with the engine running. Could this really be my problem? I've never seen a bad alternator or battery cause a car to run poorly, but just simply, either it will start or it won't. I am just wondering how credible this article I found is before I go digging into my charging system. I mean, I know I need to look into that anyway, but right now, the idle/surging issue is first priority. Thanks

 

13v at the injector? What wires are you supposed to probe to check that?

 

Yes, very likely.

 

If you are getting a whistle find a mechanics stethiscope,pull off the probe so it's just an empty hose so you can better hear where the leak is coming from and with the engine running place the hose at any place where it might cause a leak.I have a leak coming from my throttle shaft in between the bores of the throttle body.If I Barely lift the throttle it's whistling dixie.So what I'm saying is that you could just have a bad throttle shaft and it worn out.

 

ok it sounds like your battery needs to be replaced. Big deal. I rebuilt my TBI, after I finally got the car to run it didn't do it very well; it ran so rich I almost went blind under the hood from the fuel vapors. Since I wasn't going anywhere soon (no car to drive) I pulled the TBI apart and switched the injectors left for right. Long story short; the injectors ARE LEFT/RIGHT SPECIFIC. I hope this helps and that I didn't make a fool of myself.