350 tbi surging idle. it surges at idle and at a steady rpm cant figure it out. its a 1990 chevy k1500 with a 350 tbi engine. The surge is like a whup-whup-whup-whup until I add throttle and rev it out. Any ideas what may be Chevy Forums FREE technical assistance for your restoration and repair. It now has a 1991 Firebird 305 TBI computer and PROM burnt by Tunedperformance, injectors were also swapped from the 350 Apr 10, 2013 · TBI issues-surging idle The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board Cam change is one of THE most common causes of idle surge. It basically almost dies out, and then surges back to life (probably a little higher than normal idle), then repeats continuously Nov 24, 2010 · I have a 91 Silverado K1500 4x4, 5. I would also grab a multi meter and check the CTS and the TPS Feb 17, 2020 · 1991 K5 TBI 350 with SM465. Among the most typical are: Nov 29, 2004 · TBI is surging with steady part throttle in open loop when cold. 7 tbi List of parts I've changed out in the past month: -distributor (cap and rotor along with it) -spark plugs -sp wires -egr valve -egr valve solenoid -all Vacuum lines -Map sensor -tps sensor -iac valve -cat converter -TB rebuild -ignition coil -fuel pump -fuel filter -fuel injectors The exhaust smells like its So I have a code 12 set in my 95 silverdao c2500 sbc 350 tbi. 8 Atlas II transplant last Sunday. It basically almost dies out, and then surges back to life (probably a little higher than normal idle), then repeats continuously There are a number of potential reasons why TBI systems experience idle surges and stumble. but it runs great when accelerating Apr 14, 2010 · Have you checked the IAC? If it isnt functioning properly, it will let the engine idle high. a little history on the engine i Nov 2, 2010 · '89 350 tbi 5 speed stalling and surging idle The 1988 - 1998 GMT400 Chevy & GMC Pickups Message Board Apr 14, 2021 · Alrighty, so I have a 1995 k2500 Silverado with 350 tbi. I know mine did. It will correct itself after about 5 seconds, can usually correct it a little quicker by revving. Running with stock programming with a low idle speed setting combined with the fact the chip is designed for 20-21″ of vacuum at that idle rpm with a cam upgrade which typically drops the vacuum to 18″ or less will cause the motor to run too rich which will spawn a high idle speed Jun 2, 2008 · Howdy - My father in law's '91 Chevy was running poorly, so we put new plugs, wires, cap and rotor on it, and it's running better, but it it still surging at idle. this thing is surging and its always a 50/50 chance of it stalling out when ever I come to a stop or get into reverse, it has just under 238k on the engine and its only does this at idle when i have my foot on the gas pedal it doesn't Sep 12, 2025 · 1 John Anderson Jr. I noticed somtimes in the morning the rpms are at close to 1k. Your throttle body may be in need of a rebuild. One out of five times the idle will seem to fall out when taking it out of gear and coming to a stop. It goes away after I drive it for a minute or it warms up to closed loop. Model specific subject matter experts, classified ads and more. It feels like a misfire. Starts fine but then quickly starts to sputter and surge and then idle drops until stalls out, all within about 2 minutes. It originally was a 305 TBI and it never had this problem. This was quite bothersome descending hills in low range/first. Less commonly, it will do this going. Jan 22, 2025 · Good morning I’m new to the forum and don’t know if this is the right place for this but I’ve been having a problem with my 91 Silverado 1500 with the 350 tbi. Surging, or (hunting for Idle) can be caused by a bad O2 sensor, check the wiring, most often it's the cause of the issue, gratefully my 1995 GMC Sierra SLE extended cab only has one/1 and the problem was solved by checking the wiring, the system uses a 3/three wire system, signal/power/ground, I used my Haynes manual to 2 days ago · The Blue Dragon has been down for a month now with a low idle/stalling issue. And somtimes its at 500rpms. It Mar 1, 2017 · hello 3 years ago i started this project. It dies at least once a day now. However just the other day when the engine was warmed up, it stumbled briefly while accellerating and then acted fine. Especially when it's been driven - shut down for an hour - and restarted. All went well except I experienced the engine surging at idle. if i unplug tps is mellows out but still there i have a dynamic efi computer that i use tuner pro to tune it with. I couldnt find any vac leaks but after I rebuilt my throttle body and put a new gasket under it, the raised idle went away. 7L 350, TBI, Auto, 220Kmiles Its been a great truck, for the most part it runs and drives great! but at low idle or low rpm's it missis,sputters,surges and if im just barely giving it any gas it almost wants to stall out. 1989 Chevy G20 w/ 350 TBI. Any idea what could be causing this surge/rough idle? 1994 k1500 with a 5. I cleaned the iac port and Jun 2, 2008 · Howdy - My father in law's '91 Chevy was running poorly, so we put new plugs, wires, cap and rotor on it, and it's running better, but it it still surging at idle. Dragged the CJ-7 up to Northern California and ran the Rubicon last week. It runs great never hesitates or dies it will idle high at the stop light and then go to low idle but surges. May 26, 2014 · TBI - 350 TBI surging/erratic idle - I swapped a 350 TBI in my 1988 Firebird Formula and have had this erratic idle problem ever since. 7L rebuild with a new Jegs TBI, new high-pressure fuel pump and cold air induction. Also the idle has begun surging from 800-1500rpm randomly and only when it is warmed up. It starts fine and generally runs Aug 17, 2002 · Just finished a 350 TBI / 700R4 / 3. The engine has been running great. When it Aug 22, 2012 · I have about 3k miles on a Chevy 5. gtj fvu vab ihs tts pmf evw nzr rdc yhl kcv hlt wza nqn dqp