Hey, my dad has a 92 Z-28 and has been having problems with his car stalling out. Even though its not my car I get stuck with fixing the problem haha. The car has an automatic transmission with an L98. The car runs fine with no other problems. It just stalls out sometimes when you put it in gear, reverse or drive. It doesn't stall out every single time, just enough to become an annoyance. Like when you are trying to park it at a car show and it stalls out multiple times So any ideas on what to troubleshoot? My car is carbed so I don't know everything about TPI motors.

 

Does it do this after it has been going fast enought to have shifted out of first gear? If so it could be a problem tourque converter clutch solenoid not allowing it to downshift into first gear. Like try to start a standard in 2nd or third.

 

are there any codes??? mine did that and it was the oxygen sensor.

 

How is the voltage on the alternator?

 

I've had a number of different things give me that same problem. It could be the IAC or a bad injector. Does it feel down on power? Any other symptoms?

 

It could be a bad O2 sensor, a bad injector, a bad or dirty IAC motor, a bad spark plug or wire, or anything else.

 

Hey guys, thanks for the replies. Just got back from vacation. There are no trouble codes. The O2 sensor was replaced with a new AC Delco one a couple months ago. The alternator voltage seems fine. It reads at about 13-14 volts.

The plugs were replaced about 3 months ago with AC Delcos and new Taylor wires were put on at the same time. I took the spark plugs out and they looked good. Wires looked good also. The power feels good, wish I had a 350 . There are no other symptoms. Is there anyway I can check the IAC out to see if its bad? Also can you adjust the idle rpm speed for when the car is in drive?

 

Put your hand on the IAC motor while a friend turns the key on for 5-10 seconds, then turns it off. You should feel the IAC motor moving.

The best way to adjust the idle is with a custom chip. The band-aid way is to open the throttle blades with the adjustment screw until its at the idle you want.

 

You were right about the IAC. We tried what you suggested and felt no movement. So we took the throttle body off and removed the IAC and it was filthy. It was all gunked up, along with the IAC passages in the throttle body. We cleaned the throttle body and disasembled the IAC for cleaning. Cleaned everything up pretty good and did the test over and felt movement, so hopefully that solves the problem.

 

Bringing this back unfortunately Cleaning the IAC helped but the problem came back and has been occurring for the past couple of months. To refresh, the car stalls out when shifting from Park to drive or reverse. Also stalls when in Neutral going to drive or reverse. It will also stall sometimes when sitting at a stop. It does not stall out when going from drive to reverse or reverse to drive. It only seems to stall out once the engine is up to operating temperature.

You don't need to keep your foot on the gas to keep it from stalling when shifting to reverse. You just have to barely tap the gas as soon as you shift it into reverse/drive and the car will idle fine after that. Its just for that one brief second that the car wants to stall.


Yesterday the fuel injectors were replaced because we tested them and one was bad. Was hoping that was the problem but after letting the engine warm up and trying to back out it stalled again. Today a new IAC motor was installed and the throttle body was cleaned but it still stalls out.

 

This morning the TPS sensor was checked. Initial reading was at .59. WOT reading was 4.25. Reading went up steadily while going to WOT so the TPS sensor seems fine.

Warmed the car up and removed the ignition control module to have it tested at Autozone. They tested it 4 times and it passed each time. A new cap and rotor was installed.

That seemed to help a little bit. If I lift my foot off the brake quick enough when shifting I can get the engine to keep running. But if I leave my foot on the brake it still stalls out. Going to buy a fuel pressure gauge later this afternoon so I can check that out. Any other ideas here?

 

Found my fuel pressure gauge so I didn't have to buy one. At a cold start I got 42 psi with the ignition on, 35 while it was running, and 37 when it was in gear. With the engine at operating temperature it was 44 psi with the ignition on, 35 while it was running, and 42 when shifting to reverse (it stalled out again). This was performed with the vacuum hose to the fpr still on.

Running out of ideas here. Pulled all the plugs also today and they were pretty clean. Will test the spark plug wires tomorrow and take the coil to an auto part store to have that checked out.

*update*

Removed the ignition coil and had it tested. Was told that the primary's were in range, and the secondaries were barely in range, but still considered ok going by the books.

 

I have a 99 dodge dokota pickup that was doing the same thing. It never left a code to check. I went to the dealer and the service rep gave me a list of stuff totaling over 2000 dols. everything was changed and it still stalled out. It would run fine sometimes and then sometimes when i was sitting at a light it would start idleing up and down and then stall out. Come to find out the computer was bad. Not saying this is your problem but it sounds like youve tried everything else. I think it can be tested. Not sure. Good luck. I hope you get it fixed.

 

Just for giggles try disconnecting the brake light switch and then the reverse switch also
, and see if it still does it. I think you mentioned something about holding the brakes when this happens . Mine will die from time to time with the custom chip,but has never died with the stock chip go figure, so I live with it because it starts right back up again.