Stall issue...............HELP!!
Thread Starter
Instructor
Joined: Jun 2007
Posts: 146
Likes: 1
From: Williamsville NY
Stall issue...............HELP!!
Hello,I have an 89 with standard 350 - no engine upgrades. Occasionally when I approach a stop the engine hesitates and seems like it will stall. The other day I was at a stop and the engine stalled/quit suddenly.......no warning It started right back up though.
Heres what i've done:
New MAF, new injectors, new high/low relays, air filter, plugs and wires. It idles at 6K . I have noticed a big drop in gas mileage........not that I believe it's related to my problem. Any one out there have any recommendations or troubleshooting tips?? This is an intermittent problem so it's been difficult to nail down the cause. Thanks for your help.
Instructor
Joined: May 2012
Posts: 194
Likes: 1
From: Lawndale CA
Hello,I have an 89 with standard 350 - no engine upgrades. Occasionally when I approach a stop the engine hesitates and seems like it will stall. The other day I was at a stop and the engine stalled/quit suddenly.......no warning It started right back up though.
Heres what i've done:
New MAF, new injectors, new high/low relays, air filter, plugs and wires. It idles at 6K . I have noticed a big drop in gas mileage........not that I believe it's related to my problem. Any one out there have any recommendations or troubleshooting tips?? This is an intermittent problem so it's been difficult to nail down the cause. Thanks for your help.
Racer
Joined: Jun 2006
Posts: 361
Likes: 6
If you idle fine at 600rpm then your TPS, timing and IAC should be adjusted properly, should be. I've seen some compensate for a bad, dirty or mis adjusted IAC by turning the idle screw, thus throwing off the TPS, and when the IAC does work properly, the throttle blades are then open too far.
It sounds to me that your IAC may be sticking or the passage is partially clogged. Clean the IAC and the air passage with throttle body cleaner and see if that cures the problem. If that doesn't work, start with checking your timing and minimum idle and work your way up to the TPS.
If you don't have an FSM you should invest in one.
It sounds to me that your IAC may be sticking or the passage is partially clogged. Clean the IAC and the air passage with throttle body cleaner and see if that cures the problem. If that doesn't work, start with checking your timing and minimum idle and work your way up to the TPS.
If you don't have an FSM you should invest in one.
Last edited by Corvette40; Jun 22, 2012 at 08:32 PM. Reason: Mis spelled word
Racer
Joined: Jun 2006
Posts: 361
Likes: 6
Funny you should mention that. Just today I was working with Dyno Don from Thirgen trying to troubleshoot an intermitant stall on a custom El Camino with an L98. As we ran the motor the tach would intermitantly twitch, which would indicate an ignition problem. We both agreed it felt like a module issue but neither one of us have seen a module intermitantly fail, usually they work or they don't.
We pulled the genuine million dollar GM module and replaced it with Borg unit and the problem was solved. Learn something new every day.
Drifting
Joined: May 2005
Posts: 1,336
Likes: 12
From: Chicago Executive Airport, formerly known as Palwaukee
No-IL Events Coordinator
St. Jude Donor '12-'13-'14-'15-'16-'17
With over forty (40) years experience in the mechanical auto & truck repair industry, I have seen my share of ICMs fail.
And, like you found, some fail on an intermittent basis.
Heat is what does them in. When they cool down, they can work and throw you off your game.
Glad you found the answer!
And, like you found, some fail on an intermittent basis.
Heat is what does them in. When they cool down, they can work and throw you off your game.
Glad you found the answer!
Intermediate
Joined: Jun 2010
Posts: 45
Likes: 0
From: Cincinnati Ohio
I had a similar problem on my '87. I'd pull up to a stoplight and it would occasionally stall. Sometimes it would restart right away and other times I had to wait 15+ minutes.
I had fuel pressure and spark so thought it might be an airflow problem. It ended up that the problem was caused by a dirty throttle body and sticking IAC valve. I took off the TB and cleaned the whole assembly (including the IAC valve) with some throttle body cleaner. That did the trick.
This may not be your problem, but it might be worth checking.
I had fuel pressure and spark so thought it might be an airflow problem. It ended up that the problem was caused by a dirty throttle body and sticking IAC valve. I took off the TB and cleaned the whole assembly (including the IAC valve) with some throttle body cleaner. That did the trick.
This may not be your problem, but it might be worth checking.
Pro
Joined: Mar 1999
Posts: 678
Likes: 0
From: Oslo, Norway
With all the new things you have put in a couple of things has to be done.
Did you install injectors with the same flowing characteristics think it is 22lbs/hr?
If not then you have to adjust the fuel pressure (adj. fuel pressure regualor).
Clean the throttlebody and IAC valve or change it.
Then after years of use the adjusting screw for idle air at the throttlebody adjusting the opening of the butterflies may be worn and the Minimum Idle Air adjustment has to be done.
Did you install injectors with the same flowing characteristics think it is 22lbs/hr?
If not then you have to adjust the fuel pressure (adj. fuel pressure regualor).
Clean the throttlebody and IAC valve or change it.
Then after years of use the adjusting screw for idle air at the throttlebody adjusting the opening of the butterflies may be worn and the Minimum Idle Air adjustment has to be done.
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Race Director
Joined: Apr 2003
Posts: 17,698
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From: moraga ca
With all the new things you have put in a couple of things has to be done.
Did you install injectors with the same flowing characteristics think it is 22lbs/hr?
If not then you have to adjust the fuel pressure (adj. fuel pressure regualor).
Clean the throttlebody and IAC valve or change it.
Then after years of use the adjusting screw for idle air at the throttlebody adjusting the opening of the butterflies may be worn and the Minimum Idle Air adjustment has to be done.
Did you install injectors with the same flowing characteristics think it is 22lbs/hr?
If not then you have to adjust the fuel pressure (adj. fuel pressure regualor).
Clean the throttlebody and IAC valve or change it.
Then after years of use the adjusting screw for idle air at the throttlebody adjusting the opening of the butterflies may be worn and the Minimum Idle Air adjustment has to be done.
My thoughts exactly.