The 1947 - Present Chevrolet & GMC Truck Message Board Network

Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1988 - 1998 Chevy & GMC Pickups Message Board


Thread Tools Display Modes
Prev Previous Post   Next Post Next
Old 10-31-2016, 08:29 PM   #1
Registered User
Join Date: Nov 2015
Location: advance
Posts: 8
Low Idle, Rough Acceleration, Shakes a bit

93 Silverado, 350 TBI

After replacing the intake manifold gaskets, I've been experiencing a low idle in park, even lower (200 rpms) in drive. Acceleration is poor but eventually when it gets up to cruising speed 40mph+, it doesn't run as bad.

Also, approx 5 mos ago, replaced ign model, plugs, wires, cap, rotor.

I've done the following:
Checked for vacuum leaks everywhere; cigar method, starter fluid, etc.
- REPLACED PCV to Carb vac line
- tested EGR vacuum - OK
- tested EGR Solenoid - OK
- tested TPS OK, voltage up/down as throttle is moved (ign on, not engine) - OK
- tested MAP Sensor voltage drops as vacuum (vac pump) is applied (goes from approx 4.7 to 1.9 Volts)

Have set timing to 0* several times with brown/tan wire disconnected. Timing then adjusts itself to about 1/2" off the timing tab.

The last test I did was to completely cover the throttle body with plastic to try and smother it from the top, almost stalled but did not.

I still wonder if I did a good job with the gasket sealer when I replaced the intake manifold gasket.

There's a lot to digest, sorry for the long post but wanted to give as much info as possible.

duffs396 is offline   Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT -4. The time now is 12:46 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Copyright 1997-2013