A series of unfortunate events

[flandersander]

I'm having lots of problems with my truck. I'll tell you the while story, then ask for your advice. Its a 1992 chevy silverado. It has many mods done by the previous owner. He set it up to tow a big trailer. It has dual batteries, which are supposed to be isolated from eachother. He put a piggy back style "computer" that is wired to the ecu. He put a chip in it aswell. It has vortec heads, an rv cam "homemade" headers, truely dual exhaust and a wierd floor shifter. He also put an different torque convertor in it that can be put in tow mode with a switch. It also has a 3 inch body lift, and air bag ss on the rear axle that has an on board air compressor built in. he also wired in two amps and amplified aftermarket speakers. 250 000 km. Okay, thats pretty much everything, now i'll tell you whats happening. Or was rather. It would sound like a tapping or a hard squirting noise coming from the engine under hard acceleration. So, I figured I would do a tune up. On my way to the parts store, the drivers side exhaust pipe started pouring out blue black smoke. It quit in a few seconds. I went on to the store and bought spark plugs and 8 mm wires, just to start. I pulled one plug, and found it didn't match the ones I bought, I assumed because of the vortec heads the previous owner put on. So I took them back and got the correct ones. After i reinstalled the one used plug, it spit and sputtered and backfired like crazy. I then changed 7 of them but couldn't get a socket on the passenger side farthest to the rear- plug, because of the homemade headers. I changed the wires one by one, but I may have mixed the two front wires on the drivers side. I fired it up, and it spit and sputtered and backfired like crazy like it did before. What the heck could be wrong? I had a friend check it out and said the problem wasnt spark, it was that the tbi is giving more fuel to the drivers side of the motor. Could that cause these problems? I parked it in this way, and now it won't even turn over... It just clicks. What do you think I should try? Thanks for any help.

keagan

 

[sepe91]

Did you put the wires on correctly double check that first, if its a fuel issue check to make sure your injectors are spraying right. Mabey check your fuel filter too it would be an easy cheap first start

 

[flandersander]

Well, I tried switching the front two back and forth, and it didn't seem to make a difference... And I did notice a slight difference in the amount of fuel being injected between the passenger and drivers side injectors. But what are the chances that happened while I was pulling the plug. Maybe I wasnt clear enough. I pulled out a plug, then put it back and it started spitting and backfiring.

 

[ChrisAU]

But you replaced that plug afterwards right and the problem persists?

 

[flandersander]

Yes, I then replaced 7 of 8 (couldn't get to the passenger rear one) and the problem persists.

 

[Tempted]

One plug won't cause that. First thing to address is the secondary computer. Figure out what it is and ditch it. You can't get more fuel to one side of a TBI motor. It is an open plenum. Unless there is a blockage the motor will pull fuel evenly. However the "true dual" will cause a problem. These engines are designed to scavenge exhaust gas. Get a mid pipe on it. You lose power and the motor will not run correctly with the two banks separated. The computer can not be corrected to make it work either, it is in the cam. Really only forced injection motors can run without a mid pipe. And as you mentioned, make absolutely certain you got the wires on correctly. After that is addressed if the problem persists, check the fuel pressure. TBI systems are low pressure. Generally 8-12psi. Make sure the pressure remains at idle. Usually black smoke means fuel isn't a problem. Check that all the wires to the distributor are hooked up. You may go ahead and change the coil. If you have fuel, fire and timing then the last thing is compression. You really don't want that to be he issue.

 

[dirtridinz71]

Try unplugging the CTS (coolant temp sensor) and see if that clears it up. I've seen this problem before and that was the issue. The CTS is on top of the intake manifold by the upper rad hose.

 

[Tempted]

Any luck?

 

[flandersander]

Well I went out to the shop today, and it still won't turn over... I'm guessing I need a starter. I'll have to get that figured out first before I can even start with the misfiring issues.

 

[FastOrange]

One plug won't cause that. First thing to address is the secondary computer. Figure out what it is and ditch it. You can't get more fuel to one side of a TBI motor. It is an open plenum. Unless there is a blockage the motor will pull fuel evenly. However the "true dual" will cause a problem. These engines are designed to scavenge exhaust gas. Get a mid pipe on it. You lose power and the motor will not run correctly with the two banks separated. The computer can not be corrected to make it work either, it is in the cam. Really only forced injection motors can run without a mid pipe. And as you mentioned, make absolutely certain you got the wires on correctly. After that is addressed if the problem persists, check the fuel pressure. TBI systems are low pressure. Generally 8-12psi. Make sure the pressure remains at idle. Usually black smoke means fuel isn't a problem. Check that all the wires to the distributor are hooked up. You may go ahead and change the coil. If you have fuel, fire and timing then the last thing is compression. You really don't want that to be he issue.

-TBI is NOT open plenum, its a dual plane intake
-True duals dont cause a problem at all, dont know where you got that idea, but they dont, yes they arent the best idea for exhaust, but it isnt gonna cause issues.
-from what i been told, Black Smoke usually means over-fueling