Fireresq473

Hey folks,

I've got one for you. I have a 1993 Silverado Ext. cab 4x4. I've had the old white ghost since 1996. Great truck. I had the motor rebuilt at 140,000 and it now has 156,000. The problem is that is idles low (400-500 rpm). When I put it in gear, it idles around 200 rpm. And it's a rough idle!!!! It also will almost "choke out" when the accellerator is feathered to around 1000 rpms. I have had the O2 sensor, IAC valve, fuel filter, and a complete tune up done...........to no avail!!!!!! Any suggestions. One was that I needed a new computer. Been down that road twice and almost $1400 later still not right. I just hate to get rid of a good truck just because it won't run right.

Thanks,

Dave.

shawnvw

Check for little to no vacuum at your PCV valve or other hoses coming off the throttle body. Could have a plugged throttle body

Fireresq473

I'll check it tomorrow (Monday) and get back to you. Thanks for the heads up. I'm really at a lose on this one.

Dave.

morris757

i am having the same problem with my 97 silverado 2500... i changed the plugs, wires, cap, and rotor with no change, i took it in for a diagnostic and they told me it was my fuel pump so $700 later still ran like crap, filled it up with premium and the truck an perfect... then driving it later that day it started running like crap i dont know if it has anything to do with it running crappy below a quarter tank, but im out of ideas at this point... and money

98white5.0

I don't know much about EGR valves but you might check that also.

Jusbo48

Idle air control valve is goin bad probably, sometimes taking it off and cleaning the end with carb cleaner does the trick.

lukemoore646

or thaking the whole tbi off and giving it a carb cleaner shower works pretty good too

suzuki-guy

He already replaced IAC valv(idle air control valve) First before buying parts do the free stuff(if you have tolls it's free if not still cheap) First Clean the throttle body(take it off the truck to assure a good job) Second Check your fuel pressure Could be fuel pump going or bad pressure regulator. Second Take a vacuum tester and apply vacuum to the EGR valve directly. If there is no change with vacuum applied replace EGR valve. Second Apply vacuum to EGR valve solenoid same thing no change replace. Third Spray Cab. Cleaner around intake manifold base and vacuum lines if engine idles up or chokes replace Intake gaskets or vacuum lines. Hope this helps do these checks and report back.

silverado_svc_body

my 1990 chev 2500 has the same problem although instead of running really low idle it was puking fuel down the throat and choking ittself after half throttle, I went through all sorts of stuff on the truck, rebuilt the tbi, checked all the valves, controls, sensors and transfunctioners, swapped the computer with an identical truck, fuel pressure was strong and steady, no DTCs, changed the regulator, got mad, ripped the tbi and manifold off, stuffed a 4 barrel on it, drove it to the store bought a 6 pack with the rest of my money and planted myself in front of the tv for the rest of the day.

Jusbo48

Just curious, what kind of manifold and carb did you use and how
does it work with
the electronics.