Chronic Stalling Problem 93 Beretta

[Wisconsinite]

Hi, I have a 93 2.2L Beretta that hasn't run well for years. I'm almost ready to give up on it, even though it only has 108k on it. I'm pretty good at repairs, but not diagnosis.

Starting about two years ago, the car would die after decelerating from highway speeds. It seemed like a classic case of stuck TCC solenoid. A Chevy dealership replaced the TCC. A few weeks later it starts dying at stops again. I unplugged the TCC solenoid, no change.

The stalling gradually got worse, dying at idle and slow speeds with poor acceleration. I can keep it going by popping it into neutral at stops, but barely.

I've tried all the easy stuff. I replaced the IAC, air filter, spark plugs, and spark plug wires. Each repair seems to help, but only briefly.

I can still drive the car with the idle adjusted all the way in. Before I go anywhere I rev the engine to about 2500 rpms. After a few seconds the engine tone changes (higher pitch). Once I do that I can drive it, but it bogs down if I try to accelerate too fast.

My next hunch is the ignition coils and control module, but it's a shot in the dark.

Any ideas?

Thanks for your time!

[Wisconsinite]

I also replaced the fuel filter recently, with no improvement.

[Money pit Beretta]

Are you losing any coolant? These engines are known to have head gasket problems.
Is it running rich?
Ok now that I think about it....it sounds like a clogged conveter and may be broken, that is what is clogging it up. You can test to see if it's media is broken. Jack the car up and bang on the converter with your fist. If it rattles then you have your answer.

[Wisconsinite]

Thanks for the suggestion! I will give it a try tomorrow.

[Money pit Beretta]

Your welcome.

[Wisconsinite]

Well, the catalytic converter seems fine. No rattling, not much rust.

Well, I could try to figure out if it's getting good spark, air and fuel. When I try to throttle it up it briefly accelerates, but bogs down as the pedal approaches the floor. I could pull off the air intake for a test. If the main valve opens as throttle is applied..

[Money pit Beretta]

Pull the vacuum line to the fuel pressure regulator and see if there is fuel inside.

[Rettax3]

Check your fuel pressure, it sounds like your pump is getting worn-out. Usually, they either run, or they don't, but I have seen a few instances of symptoms like you are describing, although I don't think I've ever seen one limp around for that long. Still, it is an easy test. '93... You should have the multi-port FI, so I think you are looking for 47 psi +/-.

You mentioned doing basically everything else relating to a tune-up, but have you replaced the oxygen sensor yet? That could be a problem too.

A good way to check the mixture of your engine (rich or lean) is to pull your spark plugs -reading plugs is becoming a lost art unfortunately, but pull all four of them (this will help determine if you have a bad injector or two, and can even help point the way to a leaking head-gasket (as Money Pit mentioned), or a bad ignition coil (as you were thinking). Look for heavily blackened, sooty plugs (rich condition). Check for white crusty residue on the plugs (coolant issue). Most service manuals actually give a nice break-down with pictures of symptoms to be found by reading the plugs. Your engine is particularly easy to pull the plugs on, so I would theck them second if your fuel-pump pressure tests good, but my money (I am actually not a gambler, so my money in this case is $0 ) is on the fuel pump.

Good luck.

[Wisconsinite]

Okay, thanks for the input.

I pulled all the plugs. They look okay to me, but I'll post a picture if I can.

I pulled the vacuum line to the fuel pressure regulator. I couldn't see any gas in the vacuum line, but it did smell like gas. That is what you meant for me to do Money Pit?

There is a cracked vacuum line at the MAP sensor (I think that's what the flat plastic thing is). I have patched it before, but I will see what a new sensor costs, or patch it with heat shrink tubing (which I've heard seals it well).

There are two vacuum lines that look bad (lots of cracks on surface). They are involved with the fuel canister solinoid, whatever that is. I'll replace those.

I don't have a fuel pressure gauge, but I'm going to Oriely's right now to buy one. I'll report back when I have tested the fuel pressure.

[Wisconsinite]

I just got back from the store with parts. The car barely made it over the hills. I had the trouble codes pulled. It found 8. Out of the possible 15. I bought an O2, TPS, and MAP sensors. I also got some vacuum line to replace the cracked sections. Installation time!

Here's the codes.

13 Oxygen sensor voltage stays between 0.35 and 0.55 volts for 40 seconds. Engine was at normal operating temperature and had been running for at least 2 minutes after start with a throttle angle above 5%.
14 Coolant temperature sensor signal indicates a temperature below -30° F or above 275° F for 3 seconds after the engine has been running for 2 minutes.
21 TPS voltage was above 3.9 volts for 5 seconds when the MAP sensor signal showed manifold vacuum to be 15 pounds or more and engine speed was less than 1750 RPM or TPS voltage was below 1.9 volts for 64 seconds.
23 Inlet Air Temperature Sensor signal showed an air temperature below -30° F or above 302° F for more than 2 seconds after the engine has been running for 2 minutes.
24 When engine speed was between 1700 and 3600 RPM and throttle position angle was less than 1%, the MAP signal showed low voltage (high manifold vacuum) for at least 5 seconds.
25 Inlet Air Temperature Sensor signal showed an air temperature over 304° F after the engine has been running for 5 minutes and 20 seconds and the vehicle speed was greater than 15 MPH.
32 EGR open command did not change the fuel mixture when the command was given during off idle operation. EGR opening should cause the mixture to be slightly richer because of the low oxygen content of exhaust gas.
33 MAP sensor signal voltage was higher than 3.7 volts for 5 seconds when throttle opening was under 5%, or MAP sensor signal was lower than 0.3 volts when throttle opening was over 15%.
42 The EST signal did not change when the ECM applied bypass voltage to the ignition module.
44 Oxygen sensor voltage was under 0.27 volts for 25 seconds of closed loop operation.

[Wisconsinite]

I installed the O2, TPS, and MAP sensors. Plus the vacuum lines. It runs better, but still bogs down on the hills. Much better acceleration, and does not die right away when shifting into D or R.

But, after the test drive I put it in Park to listen to the idle. It sounded fine for a bit, then rpms dropped till it almost died, then it revs up and recovers, then slows down even more, then recovers, then slows, etc. Eventually it just shuddered and died.

I'm still going to check the fuel pressure if I have time tonight.

[Wisconsinite]

I'm having trouble checking the fuel pressure. Okay, I'm a cheapskate and I didn't want to drop $40 on the kit at Orielys. I might buy one on the Internet. There are dual purpose ones that do fuel and vacuum. I did pull off the pressure regulator and it seemed there was plenty of pressure left after the car was shut off. (and yes, I had a dry chemical fire extinguisher nearby).

Unless there is another way to determine whether there is adequate fuel pressure?

And before anyone points it out, those sensors may have been unnecessary. The O2 was frosty and probably bad, but the TPS and MAP codes could have occurred when I was fiddling with the engine before I took it into town. I also could have tested them prior to replacement.

[Rettax3]

I'm having trouble checking the fuel pressure. Okay, I'm a cheapskate and I didn't want to drop $40 on the kit at Orielys. I might buy one on the Internet. There are dual purpose ones that do fuel and vacuum. I did pull off the pressure regulator and it seemed there was plenty of pressure left after the car was shut off. (and yes, I had a dry chemical fire extinguisher nearby).

Unless there is another way to determine whether there is adequate fuel pressure?

And before anyone points it out, those sensors may have been unnecessary. The O2 was frosty and probably bad, but the TPS and MAP codes could have occurred when I was fiddling with the engine before I took it into town. I also could have tested them prior to replacement.

I don't tend to throw parts at an engine to diagnose, but frankly I don't think you did anything bad by replacing those parts -if your MAP was cracked and your O2 sensor hasn't been replaced in a while, it is probably due. Even if they don't solve the problem, they will eventually help the car to run better.

Okay, I really recommend testing the fuel pressure, and most stores like O'Reillys and Auto Zone will be able to 'loan' you a pressure test kit (you buy the part at an inflated price, use it, then they refund your money). But, if they won't, or if you can't plunk down $50 for an afternoon, you could try to get the car to the store and have them test it there.

Lastly, you COULD try to rig something up... Since you are smart enough to keep an extinguisher on hand while working on this stuff, you MIGHT be able to get away with something like this, but it can be risky and isn't really worth the time and trouble with the alternatives you have available... But here you go:

Remove the Schrader valve from the fuel pressure test port on your car. Push on a short piece of fuel-hose (rated for 50 PSI, at least) over the threads of the test-port, and clamp it on with a hose-clamp. It is ~3/8". Get a cheap dial-type tire-pressure gauge, remove its' core (Schrader valve), and insert the end of the gauge into the hose, and clamp it down with a hose-clamp too. If you need to, use something to adapt the 3/8" fuel hose down to a 1/4" hose, or what ever you need to get a good tight seal onto the end of the gauge, I'm sure you could find something at a hardware store for a few dollars. Remember thatr you are going to be exposing this jury-rigged POS to 50 psi of fuel pressure, that will happily spray everywhere it can if this all pops apart... So, with an assistant who can shut off the ignition at a moment's notice should this come loose, test the fuel pressure on the tire gauge. Remember to cycle the ignition a few times to charge the system, since you will have lost all pressure in the rail when you removed the Scrader valve. You should have a static pressure reading of ~47 psi. My book says down to 40.5 psi is still serviceable too. You should also check the fuel pressure while the engine is running, provided your setup isn't leaking during the static test. While it is running, remove the vacuum line from the pressure regulator, the pressure should rise slightly.

On my '97 Twin Cam Z-24, GM decided to save .50 cents by NOT providing a fuel test-port, cheap-@$$ M0^#&*-F^@%er$, so I installed one. Using a compression-fitting TEE and a high-pressure Scrader valve assembly, I cut the fuel line and built my own test-port. I've retro-fit two or three Twin Cams this way. Now, the fuel pressure on these cars can be tested using a tire-gauge. That would be an option for you too, and maybe a little safer because it will limit how much fuel can be leaked out during testing, and won't allow a hose to pop loose and spray raw fuel everywhere. But, it will still cost you probably ~$10 -just use the auto-parts store's loan-a-tool program, and be done with it. You will either find your problem, or eliminate the fuel-pump as the issue.
Good luck.

[Wisconsinite]

Funny you should mention that, I can't find the fuel test port. The book says it is mounted on the rail, but it isn't there. I tried to rig up a Schraeder valve onto the line that feeds into to pressure regulator. I couldn't get a reading though.

I'll call around, see if any local stores lens out testers.

[Rettax3]

Funny you should mention that, I can't find the fuel test port. The book says it is mounted on the rail, but it isn't there. I tried to rig up a Schraeder valve onto the line that feeds into to pressure regulator. I couldn't get a reading though.

I'll call around, see if any local stores lens out testers.

The line going into the regulator is the return line, so there shouldn't be any reading there. Looking over the sketch of your system, I don't see a test-port location noted, so it is possible that, like the 2.3 Quads and 2.4 Twin Cams, and of course the 2.0 and 2.2 TBI engines as I can't think of a single GM TBI system equipped with a test-port, your car may not have a test port either. Stupid, cheap GM... I actually had a test TEE-fitting setup to screw into GM fuel-lines that offered a conventional test-port, but it was stolen along with most of my diagnostic tools and my computer last year. Most of the loan-a-tool testers will have some kind of splice-in TEE fitting for engines that lack a test port, but you might have to cut your fuel supply hose to use it, and buy a double-ended brass barb fitting and hose-clamps to fix the cut (use two hose-clamps on each side of the splice -that is how GM does it when they use screw-type clamp-on fittings on these high-pressure fuel systems) .

You can also just try to plug the fuel-pressure gauge into the end of the supply line before it reaches the manifold and injectors, it will show if the pump is healthy enough to give pressure or not, but it won't show proper function of the regulator or if the pump can maintain pressure and flow... If you do this, you should be seeing pressures above 50 psi, as they are un-regulated...

Edit: Just an idea, but you could try to PM Koots, I believe he has a MFI 2.2 also, he may know if/where the test-port is on the car...