Question: 1986 c4 350 tpi non runner

[MIKE CULLEN]

Which scanner 1986 c4

i BOUGHT THE VEHICLE A NON RUNNER,I HAVE REPAIRED THE DISTRUBITOR,THE PICK UP COIL WAS SHOT ,I REPLACED THE IDLE CONTROL STEPPER MOTOR AND THE EGR VALVE ,HOWEVER I AM NOT GETTING IT TO IDLE CORRECTLY AND I GET A BACKFIRE ,INDICATING A LEAN MIXTURE ? HOWEVER THE MAIN REASON FOR THE POST IS TO ASK ,IS IT WORTHWHILE BUYING A AUTO X RAY 6000 SCANNER FOR THIS OBD1 MOTOR ,OR AM I BETTER OFF USING PAPER CLIP METHOD ? THANKS GUYS

 

[boomdriver]

Flash codes only display memory. That does not allow real time data to be displayed. Buy a scan tool when you want to do precision tuning with real data. You take that info and give it to a "tuner" that can make a custom chip for your car based on your upgrades and needs. A scan tool helps diagnose conditions BUT you have to know what you;re looking at...otherwise its just a bunch ( big bunch) of numbers in columns that don;t mean anything.
Use the flash codes and a FSM for now.

Backfiring thru the TB is more indicative of a bad intake valve or slipped timing if its consistant.
If the BF is horrible and the engine will not take throttle thats the MAF system...relays OR the MAF itself.

Read the flash codes. There is no point in speculating until the memory has been seen.

Lean mix? thats not likely in EFI unless someones jacked around with the PROM and tried to burn their own chip...highly unlikely.

One possibility is the EGR is connected directly to a vac source and not thru the EGR solenoid. IF the egr were open all the time it could cause the backfiring...

Make sure ALL vac fittings/hoses are connected and routed exactly as they were from the factory. The different hoses do different things with different levels of vac.

Look for airleaks in and around the TB. Bottom plate if the coolant was bypassed and TB/plenum gasket. Runner gaskets also.

These are not anything like carbed engines. Its a computer and things have to be set up correctly or the ECM cannot do its job.
A non-runner is usually the end result of bubba tech applied to a modern electronic control system,. Its amazing at how fast the old school mentality can down an EFI car......

Just go thru things and get them as they should be...it'll run.

basic diagnostic tools...
fuel pressure tester gauge
spark tester
vac tester/pump
timing lite
paper clip/ jumper wire
FSM ( not a chitlins or haynes) a real $100 manual

Good Luck !