Random Stumble at all RPM's and all Temps
04-30-2009, 10:40 PM
#1
Random Stumble at all RPM's and all Temps
I have a 93 LT1, I have done some random bolt on mods, (you can see in my profile), lately it has been randomly and without warning stumbling as if it has no gas or no spark but is very brief, like a fish nabbing at a fishing line, and it can happen for about 20 seconds or just once and then stop for the rest of a hour long trip. I have a 1 year old opti spark with 1 year old cables (about 20,000 miles on them both) I just replaced the spark plugs and the fuel pump (the fuel pump replacement makes the car more responsive now) I have specifically driven the car with a Genisys Scanner for about 1.5 hrs, and NOTHING I couldn't get it to do any bucking, then another time during a different drive, it will start doing it. I thought at first it might be knocking because I had a code 43 after I did a clutch install, but after I fixed a wire, the code is gone but the random bucking/stumbling is not. I notice that it happens more often around the 1200 to 2000 RPM range but it has done it during WOT too. Can anyone help with this? Thanks.
05-01-2009, 07:29 PM
#2
Drifting
Member Since: Sep 2003
Location: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
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If yours had a MAF (mass air flow sensor) I would say it needs to be cleaned.
However, believe your year only had a MAP (manifold atmospheric pressure sensor).
So, consider checking its connector for corrosion.
ALso, have you ever cleaned the throttle-body? If not, consider trying that (use cleaner specifically for it -- e.g. CRC throttle-body cleaner). It can be done without removal.
One last thought -- the PCV valve, ever replaced it? If not, if it were occasionally sticking, could have a negative effect.
However, believe your year only had a MAP (manifold atmospheric pressure sensor).
So, consider checking its connector for corrosion.
ALso, have you ever cleaned the throttle-body? If not, consider trying that (use cleaner specifically for it -- e.g. CRC throttle-body cleaner). It can be done without removal.
One last thought -- the PCV valve, ever replaced it? If not, if it were occasionally sticking, could have a negative effect.
05-01-2009, 08:08 PM
#3
Team Owner
Member Since: Mar 2001
Location: Cincinnati, Oh USA
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At night , defeat the underhood lights and idling, look for sparks along the plug wires. Install lost or broken wire looms and dress the plug wires to not touch metal.
05-02-2009, 09:05 AM
#4
I have replaced the map sensor, iac sensor, took entire throttle body apart and cleaned it, drove it for 3 hours and it did the stumbling again but only twice and at about 1200 to 2000 rpm is where it originated and if I tried to add throttle, it would stumble harder, this all happened under load btw. I will check wires, anyone have any more ideas? Thanks