Help! I'm going BROKE! 2000 Jimmy Diamond Ed

[ShesKlassy]

It spits and sputters and backfires and the rpms drop until it kills. If you feather the gas you can get it to go for the most part, but the hotter it get through the day the worse it gets. It always starts up just fine even right after it kills you just can't get it to go once it's been driven for a while. I've had the fuel pressure tested and it is good all the way through the rail to the regulator. I have had every sensor replaced. The coil replaced, the plugs and wires replaced. Last year I also had the intake man. gasket replaced and a new set of liffters put in because they were makeing noise. The truck also has a new rad. and water pump that was done before the intake. It does not over- heat but gets VERY hot if that make sense. No leaks of any kind. I have also replaced the fuel filter.

 

[barks507]

Did you try cleaning throttle body and MAF sensor?

 

[ShesKlassy]

I took it to a mechanic who scanned it and then replaced every sensor there is to replace.

Throttle position sensor
Crank Position sensor
Mass air flow sensor
Electronic Ignition Module
O2 sensor
Coil
Plugs
Wires
Distrib. Cap and rotor
Set the timing
Fuel Filter
I have had the fuel pressure tested and it is good from the pump through the rail to the Fuel Pressure Regulator.

With-in the last year the truck has also had a new rad. and water pump. That wasn't the problem so I had the intake Manifold Gasket replaced and at the same time I had a set of new Lifters installed.

I'm almost afraid to take it to another mechanic. I have spent $3200 in repairs in the last year and it still isn't running right.

 

[kvn4]

im taking it to be the egr as i had same issue.

 

[Z15]

Sound like electrical problems to me.

Do you have any cheap ignitions parts on it? There is a lot of imported junk being sold by the discount auto parts stores. If its made in Chine, throw it away.

 

[Molson02536]

It spits and sputters and backfires and the rpms drop until it kills. If you feather the gas you can get it to go for the most part, but the hotter it get through the day the worse it gets. It always starts up just fine even right after it kills you just can't get it to go once it's been driven for a while. I've had the fuel pressure tested and it is good all the way through the rail to the regulator. I have had every sensor replaced. The coil replaced, the plugs and wires replaced. Last year I also had the intake man. gasket replaced and a new set of liffters put in because they were makeing noise. The truck also has a new rad. and water pump that was done before the intake. It does not over- heat but gets VERY hot if that make sense. No leaks of any kind. I have also replaced the fuel filter.

Try this for me, disconnect the MAF sensor wires from the MAF sensor. This will put your PCM to run in a open loop.

When the engine is first started, and rpm is above 400 rpm, the system goes into 'Open Loop' operation. In 'Open Loop', the ECM will ignore the signal from the Oxygen (O2) sensor and calculate the air/fuel ratio based on inputs from the coolant and MAF sensors, but mostly from a pre-programmed table in the PCM.

The system will stay in 'Open Loop' until the following conditions are met:

1. The O2 sensor has varying voltage output, showing that it is hot enough to operate properly. (This depends on temperature)
2. The coolant sensor is above a specified temperature about 40oC/104oF.
3. A specific amount of time has elapsed after starting the engine.

The specific values for the above conditions vary with different engines and are stored in the PCM. When these conditions are met, the system goes into 'Closed Loop' operation. In 'Closed Loop', the ECM will calculate the air/fuel ratio (injector on-time) based on the various sensors but mainly the O2 sensor. This allows the air/fuel ratio to stay very close to 14.7:1.

Post back to me and let me know how your Jimmy ran in a open loop.

Molson02536

 

[ShesKlassy]

Try this for me, disconnect the MAF sensor wires from the MAF sensor. This will put your PCM to run in a open loop.

When the engine is first started, and rpm is above 400 rpm, the system goes into 'Open Loop' operation. In 'Open Loop', the ECM will ignore the signal from the Oxygen (O2) sensor and calculate the air/fuel ratio based on inputs from the coolant and MAF sensors, but mostly from a pre-programmed table in the PCM.

The system will stay in 'Open Loop' until the following conditions are met:

1. The O2 sensor has varying voltage output, showing that it is hot enough to operate properly. (This depends on temperature)
2. The coolant sensor is above a specified temperature about 40oC/104oF.
3. A specific amount of time has elapsed after starting the engine.

The specific values for the above conditions vary with different engines and are stored in the PCM. When these conditions are met, the system goes into 'Closed Loop' operation. In 'Closed Loop', the ECM will calculate the air/fuel ratio (injector on-time) based on the various sensors but mainly the O2 sensor. This allows the air/fuel ratio to stay very close to 14.7:1.

Post back to me and let me know how your Jimmy ran in a open loop.

Molson02536

OK After sitting in the garage all night (in minnesota 35 degrees last night) I unplugged the MAF and when I was pulling it out of the garage sputtered at bit but then I took off and drove it about a mile. The temp was deffinitly above 104F and it ran great while I was dring it. Back in the driveway I stomped om the gas pedel several times and it won't sputter or hesitate at all. It is now sitting in the driveway just the way I turned it off waiting for your reply. Should I hook the MAF back up or leave it unplugged. I should also mention that yesterday I took it to a muffler shop and had them cut the cat. converter off. He checked it all out and looked through it and said that it was not the problem and he welded it back on.

 

[ShesKlassy]

Disconnected the MAF

I disconnected the MAF and drove it a couple miles. When I first tried to take off it sputtered but other then that it ran great. IT was almost fully up to tempture when I pulled it back in the driveway so I know it got up to 104f.Once I was in the driveway I stomped on it a couple times and Could NOT get it to sputter or Stall. I do have to say however I live in Minnesota and the was a very cool night and morning and the problem really gets bad when it is very hot outside and the truck has been run in the heat. I also took the truck to the muffler shop and had the Cat. Converter cut out but the shop owner said that it was very clear and he welded it back on so that eliminates one of the things I thought it could be.