1992 - Stall After Surge / Slow Cycling

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jack.rupert
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1992 - Stall After Surge / Slow Cycling

Postby jack.rupert » Fri Mar 01, 2019 8:56 pm

I have a 1992 Beretta with around 70,000 miles which I bought new. My mechanic is having some difficulty with and issue that popped up in the last month - mostly because it never seems to happen for him. Periodically, when no gas is being applied it will stall. Usually, this is preceded be the engine surging and slowing, maybe on a 2-3 second on/off cycle. Most of the time it will start right back up, although sometimes is wants to complain. Stop and go traffic, especially high-traffic side streets is the worst. It does not seem to be dependent on the engine being warm or cold. It can happen within a mile or two of starting up or 10-15 minutes down the road. Most of the time, once it restarts after a stall, it's good for the rest of the drive, but periodically it will get finicky and keep doing it for the next 4-5 stops and then finally work. If gas is applied and going fast, its' good - generally, the problem is at 30 mph or below. Maybe also a rougher than normal idle (in drive, not neutral) and a bad gas smell.

We have already replace the ignition control module (it actually did fail), along with the crank shaft sensor, ignition coil and lockout torque converter solenoid.

What's next other than new car shopping?

Thanks!



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Rettax3
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Re: 1992 - Stall After Surge / Slow Cycling

Postby Rettax3 » Sat Mar 02, 2019 2:23 pm

2.2 or 3.1? No MIL (Check Engine Light)?
Starting at the basics, when was the last time the spark-plugs were changed? Especially since the ignition module went bad, the plugs could be causing some issues not perceptible at higher RPMs -unlikely, but a good tune-up is the best place to start since it should be done periodically anyway, I call it 'clearing the dust off, to see what is underneath'. Dito for your ignition wires.

This does not sound like a fuel supply problem, but with smelling fuel, I would check for leaks. The main thing to look for is the FPR (Fuel Pressure Regulator). Sometimes, the diaphragm inside splits, and allows fuel to be sucked into in intake through the vacuum-line. This causes two problems; Loss of fuel pressure at the injectors and raw unmetered fuel entering the intake. A very small crack in the FPR's diaphragm could cause this minor issue and be intermittent too.

A worn, dirty, or sticky fuel injector could do this too, allowing too much fuel in, or poorly atomized fuel that doesn't burn as well. Run a can of BG 44k through the system -expensive fuel treatment, but if you want a cleaner that works, cheap doesn't do it in my experience.

A bad O2 sensor could be sending poor mixture data to the computer, causing a surge in fuel flow, gas smell and stall from over-rich. As your engine sits idling, even if warm, it can lose enough heat to switch in and out of closed-loop mode (where the computer reads data from the sensor, instead of supplying fuel strictly based on initial programming). A borderline sensor can cause the exact problems you have -even though not necessarily the most likely of your problems, I get the feeling this is the culprit. A $25 part -eliminate this possibility and move on.

Getting a new ICM (Ignition Module) doesn't mean that fixed the problem -hang around long enough and eventually you will get a defective ICM out of the box. Unlikely the issue, but if it misses a few ignition cycles here or there, it will be felt more at idle, and could cause a stall. Same goes for one of your coils.

How about your IAC? This is the Idle Control Valve -the part that regulates the idle speed and the most likely cause of your problem. If it gums up or wears out, it may not respond properly or fast enough.

A vacuum leak is your next place to look. Check all vacuum lines, have your mechanic 'smoke test' it if necessary -this is where they pump a mineral-oil smoke into the intake, and look for it coming out from places it shouldn't. A smart mechanic will also cycle emissions devices, like the EVAP solenoid, to make sure a leak in a controlled vacuum circuit isn't causing the intermittent problem. Your engine is MAP or 'Speed Density' operated, meaning that it doesn't use a Mass Airflow Sensor, so unmetered air is most likely to cause the engine to idle-up rather than stall, but if the IAC tries to compensate and lower the RPM and the leak stops at the same time, surge-and-stall, especially with a worn or dirty IAC.

Lastly, these computers are nearly bullet-proof, and it used to be that every time someone couldn't figure out a problem, they screamed bad ECM. It (almost) never was. But, they are getting old now, so the failure-rate has gone from one in a million to one in 100,000, and one in 10,000.
Eventually it will be one in ten. This could be the problem you have now, though I doubt it.

Good luck, welcome to the site.


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jack.rupert
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Re: 1992 - Stall After Surge / Slow Cycling

Postby jack.rupert » Sat Mar 02, 2019 10:05 pm

Thanks for the suggestions! I really appreciate it. It's a 3.1 and no Check Engine Light comes on (at least until after it dies when the whole dashboard lights up). The spark plugs and wires were done in October, 2017, so I don't think that's the issue. Now I've got a few things to check into. Thanks again.



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Re: 1992 - Stall After Surge / Slow Cycling

Postby whiteretta » Wed Mar 13, 2019 9:44 pm

Any updates on the issue?

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jack.rupert
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Re: 1992 - Stall After Surge / Slow Cycling

Postby jack.rupert » Wed Mar 13, 2019 10:17 pm

That's a good question. I was going to give it week before writing an update and that would have been today (since I got it back from the mechanic). I gave him the list, and he checked and cleaned everything, but didn't see anything bad. One thing he mentioned was he wasn't there for the last repair (the torque converter). The guy who did it, didn't disconnect the battery, so he thought that the ECM might be working off of bad data. After doing that, he thought it ran better. So, I've been driving it for a week and hadn't noticed anything, although, I still think it run rough at stop lights. Then today going to work, something felt slightly squirrelly approaching the last stop light and as I pulled into the parking space at next to zero speed, it felt like somebody touched the accelerator. (Since I was getting ready to brake, it wasn't me). Not fast, that the car was going to run away (or hit the wall), but just enough. However, because of my location, there wasn't much i could do for testing. It went home ok at the end of the day. We'll see what happens tomorrow.



jack.rupert
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Re: 1992 - Stall After Surge / Slow Cycling

Postby jack.rupert » Fri Mar 15, 2019 8:26 am

Sorry for the late response. Still need to get my 5 posts so the don't need approval.

Back to square one. After about 5 miles of normal operation it started running real rough at stop signs, to the extent I felt the need to pop it into neutral in order to keep it running. Then, it decided to stall before I even got to the light – still going about 20 mph or so and was able to coast to the parking lane. It had some trouble restarting. I was getting ready to call a tow when it caught. After that the first light needed neutral to keep going and after that it worked fine again.

Does this give anybody any more ideas? Thanks.



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Re: 1992 - Stall After Surge / Slow Cycling

Postby heavywoody » Tue Mar 19, 2019 3:25 pm

Try unplugging the TCC on the transmission. Should be a plug on the front of the trans, near where the ground wires go from the harness to one of the bolts connecting the trans to the engine block.


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