newer head gaskets.... still smokes? o2 sensor installed..... still smokes? help!!!!!!!

Asked by Feb 19, 2014 at 09:44 PM about the 1988 Chevrolet C/K 1500

Question type: Maintenance & Repair

I got a question?? I have a 88 chevy Cheyenne k1500,350 engine and 4 spd manual. i got this truck with no exhaust only headers.. well we rigged up the exhaust to get me by until i can afford new exhaust. well we noticed white/grey smoke coming from the exhaust.the heat is hot,the oil isn't milky,and its not burning antifreeze and the guy i got it from said the head gasket were supposedly new.well i seen that the o2 sensor wasn't hooked up.i had a mechanic look at it and said that its dumping way too much fuel.well i had a new exhaust system install for the header collector back and a  bung welded and a o2 sensor installed although the o2 sensor wouldn't reach so i spliced into the truck wire,added some 14 gauge wire and tapped it up,then connected the o2 sensor.well after that i started the truck and it didn't want to catch and fire until i held the pedal to the floor and it fired up. still smoke??? i need help!!!! the guy said that the computer system may be messed up but idk help please

5 Answers

9,725

As long as your sure that the smoke is not anti-freeze we can attempt the flooding issue. On your EFI system (GM OBD1) the O2 sensor is not used untill the ECM see's a certain engine temp via the ECT (Engine Coolant Temp). This is called open loop, it switches to closed loop when warm and uses the O2 reading to adjust your air/fuel ratio. When in open loop the ECM uses the input from the other sensors and compares those values to multiple tables to select the correct fueling rate for that engine load. Since you have to hold the truck to the floor to start I would say your over fueling. You need to start checking sensors and the fuel system. 1.) The IAC (Idle Air Control) valve on the throttle body may not be opening. 2.) The MAP (Manifold Air Pressure) sensor may be broken or a vacuum leak is preventing it from reading correctly. 3.) The fuel pressure regulator in the throttle body may be holding to much pressure an causing the injectors to over spray. 4.) Injectors may be damaged. There is more but that is where I would start.

1 out of 1 people think this is helpful.

ok well i took it to a mechanic that i know, he pulled the breather off and the fuel pressure regulator was broke, the drivers side injector he said had brass in it like it has been braised and the ring was smashed.on top of that there was some gunk on the top of the tbi system.the gunk looked like silver model car paint. but he still tearing it down so this was just the first thing we found. thanks yetilikesbeer!!!

12,545

Looks like a good testimonial for going to an experienced mechanic with the proper training and tools vs. a back yard mechanic / friend of a friend that can do it for cheap. More money up front to get it done correct, is the cheapest way throughout.

1 out of 1 people think this is helpful.
9,725

Wow I haven't seen the regulator break yet on a tbi. Clean her up and fix the parts it should be good. Did it damage the injectors. And yes. Without being able to talk to the computer it is a shot in the dark most of the time. GM OBD 1 is not supported by most of the handheld scanners for reading live data. But you can get a cable and software for 70 bucks and read your live data with a laptop!! Then these issues can be sorted out easily. Once you have the cable you can talk to almost all GM OBD1 datastreams. Good investment. Got mine off ebay from Fiero tuners.

5,065

I'd do a leak-down compression test...good numbers would chalk it up to worn piston rings~

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