My '89 VIN E 305 TBI 5-speed Firebird starts perfectly, but begins to misfire or starve (can't tell for sure) after about 2 seconds. Can keep it running by working the pedal or throttle body, but it dies and sometimes backfires when under load, like putting it in gear. Have put new fuel filter in line, new knock sensor and knock module. The engine and TBI were rebuilt 450 miles ago. No problems until last week during heavy rainstorm and right after I refueled, problem started about 1/2 mile from gas station (right as I got home, luckily). Thought that I noticed pre-ignition over the rainstorm noise while driving home. Thought that maybe moisture or condensation got in tank-added STP Moisture Remover and a bottle of octane booster. Called gas station-no one else reported any problems (busy local Citgo). While investigating problem I checked the wiring harness where it passes through the body inside the right fender and received a mild jolt. Thinking I fried something, I let it dry out a couple of days, sprayed the grommet area exposed wires with with ignition dryer, took the ECM and prom out and installed it in another identical Firebird without any problem. No error codes appear anywhere. Checking all sensor values with my ScanTool everything appears normal (although the Scan Tool does not have the capability to check everything that's listed in the GM book). I have a GM manual and have performed the following checks per the book: started it with timing connector disconnected (no difference), checked coil resistance (external coil), disconnected fuel line at TBI and pump rate was (1) pint in less than 15 seconds, so the pump flowrate is good. Have not yet checked fuel pressure because I have no gauge yet. Visually checked injector spray patterns-both looked OK to my untrained eye. Blocked vacuum lines one at a time (heater, vapor can, power brakes). Has new EGR valve and distributor, wires, cap, rotor, thermac valve (air cleaner flap control), all 450 miles ago. Ran car at night-could see no eerie blue glows, sparks, auras, or anything else that looked like stray electricity. Could this problem be the fuel pressure regulator in the TBI, or the Spark Control in the Distributor? Any ideas on what else I should try? Please offer any advice or tips you may have!!

 

Well dont know if this will help you but mine did a similiar thing about a week ago and i replaced the IAC and it runs better than b4.Hey,Its worth a shot!

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1985 Firechicken
2.8 v6
Mods:
TB Coolant Bypass
My own kik @$$ dual intake
Freshly Painted(bright metallic blue)
Mods to come:
Either an 80 series flows or super turbo dynomax.Cant decide!
An engine is like a person,to scream it has to exhale hard -Flowmaster

 

You could have bad plug wires, or they connect poorly and let moisture in, Use some silicone lubricant where they connect to the distributor cap, test it, and if that doesn't work go for the spark plug area. ALWAYS TRY THE OBVIOUS FIRST.
A common sense, approach is far less taxing than chasing some ghost. it will save you some stress to just sit back relax, and think slowly about the obvious possiblities. Try reading a Dummies book on Car Repair. It may have some symptoms with a common solution, ask a parts person at the parts store, some of their people's information is priceless...Just don't stress too hard and find out it was something stupid like a paper-clip stuck somewhere..I have done this many times and it is much better to take a step back and ask around. You are doing right by asking us on the messageboard, just continue the questioning.

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--Steve S-- 84 Trans Am 305 (cough)LG4(cough), 5 speed, Flowmaster 80 series, otherwise an emissions restricted slow 150 hp(chilton rating) 240 torquer that needs RELEASE!!!!

P.S. Daily Driver

[This message has been edited by 84TransAm (edited January 15, 2001).]

 

[This message has been edited by 84TransAm (edited January 15, 2001).]

 

My TPI 350 did the smae thing. I checked EVERYTHING. Some here said check the IAC and I did and it was caked with carbon. I did a simple spring function check and it was junked. $35 and the car ran like new. Fires right up within 1/2 of turning the key. It should be on the throatle body on your car, they are basically the same part with same function. Take it out and look at it. If the plunger sticks out more than 1-1/8 inch, carefully try to push it back in. It may take a little turning clockwise. Once you get the plunger down inside of the body, take an old tooth brush and clean it up. DO NOT USE SOLVENTS. Reinstall and reconnect the wires. Try to start your car, if it does it again, it's scrap. I got my new part from discount auto, $35.

Good Luck, I hope I helped you out.

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1987 GTA 350,rebuilt in 1998. new heads, headers w/y-pipe, 45,000coil, accel plug wires and cap&rotor, k&n, b&m shift kit and trans cooler, modified mass airflow sensor, manual fans switch. No time slip.

1993 Bonneville SSE ALL STOCK. 95,xxx miles and stil counting...

 

Well if your idle id bad and the car can barely run I would say it is your distributor or something in the distributor like the module or something. My brother had the same problam as you yesterday on his formula and his whole distributor was bad.

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88 IROC-Z 305 TPI 5 speed
Performance Resource Chip, Flowmaster American Thunder cat back exhaust, B&M Ripper shifter, MSD coil, TB bypass, TPIS MAT relocation kit , TPIS 170* t-stat, Richmond 3.73 gears, March Power & Amp pullies, Home made Ram Air, Steve Spohn SFC's, TPIS AFPR, Ported plenum by Daniel Burk, Gutted cat
Best et: 14.338
Best mph: 96.97
Best 60': 2.106
http://hometown.aol.com/famioso15/johnnyiroc.html

 

Some things to check first before you go spending money on parts like I did, lol. Make sure you IAC is working properly and is nice and clean. I would also check all the wires and connectors to all the different sensors; TPS, CTS, etc. My car had similar trouble and it turned out to be the Coolant Temperature Sensor. Both the connector and sensor itself were corroded and rusted. Just go with all the obvious and simple things first. Good luck with the problem.

 

does it only do it when it rains? If it does, take your distributor cap off and check for burn marks on the inside of the cap. If there are burn marks present, just replace the cap and see if that fixes it..