# 1997 4 cylinder stalling and black smoke



## jacksong314 (May 2, 2009)

I have a 1997 truck with a 4 cylinder engine. The truck will run fine at times. Other times the thing stalls at random on me and black smoke comes out of the tail pipe. I have cleaned and reseated the connection to the MAF. I also bought some MAF cleaner and sprayed it down into the port that has the two wires for the MAF on the throttle body. The problem is not generating any CELs.

From searching the forum, I see that the problem seems common and could be:

MAF
Oxygen sensor
Coolant temperature sensor
Throttle body position sensor
Fuel pressure issue
IAC

Could the MAF be bad and not generate a CEL? I don't want to spend that much money for a new one and it not be the problem. By partially blocking the port that has the two wires for the MAF wires the engine bogs down.

Thanks,

Greg


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## zanegrey (Dec 5, 2005)

why not read the codes and then you will know for sure...

however it sounds as if the injectors are spraying the whole time...


and read the codes...


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## jacksong314 (May 2, 2009)

I took the truck to a family friend's shop and he used his scan tool. He has a very nice one that cost $3k. No codes showed up. I stated in my original post that there is no CEL.


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## jacksong314 (May 2, 2009)

Can the MAF sensor be bad and it not generate a CEL or code? If the MAF sensor is bad, why would it be affected by me blocking the hole or blowing air into it while the truck is running?

He stated that the scan tool was showing that the injectors were staying open at times.


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## CMax03 (Jan 17, 2009)

use a noid tester to see if that's so! If the ecu is firing the injectors to a constant open condition I'm looking at you strangely. If the injector/s are stuck in the open condition sound like you got some water in your fuel or recently used some fuel injectors cleaner and didn't burn off that whole tank in one trip!


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## zanegrey (Dec 5, 2005)

stop driving it till you get this fixed or you will be buying a new engine..

check the main relay on inside fender well ..it is a green one that sends power to the fuel pump.maybe replace it with a known good one.

check pressure regulator ..and check the fuel return for blockage..

but if injectors are wide open it is most likely the ecm.. the ground wire to the injectors is/are grounding out...


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## dentedsub (Oct 23, 2007)

i had that problem in a tbi suburban once. all i did to fix it was run chevron gas. it basically has fuel injector cleaner in it.


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## steve smith (Apr 8, 2009)

Run some BG 44K through your throttle body using an atomizer and put some in through the tank too. If you have any deposits of anykind left in the system this will clean it out and help it to run smooth. If its your computer, go check on ebay for a new one. They have tons of stuff for a HB truck.


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## Wardster (Apr 13, 2009)

jacksong314 said:


> I have a 1997 truck with a 4 cylinder engine. The truck will run fine at times. Other times the thing stalls at random on me and black smoke comes out of the tail pipe. I have cleaned and reseated the connection to the MAF. I also bought some MAF cleaner and sprayed it down into the port that has the two wires for the MAF on the throttle body. The problem is not generating any CELs.
> 
> From searching the forum, I see that the problem seems common and could be:
> 
> ...


I had the exact same symptoms and ended up replacing the MAF and air temperature sensor. I also replaced the plugs (fouled) and oil/filter (gas in it). No problems since and it runs like a top again.

-Wardster


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