97 expo dont run right

[Racenut]

You need to check spark! If the plug is wet with clean gas, then you know that the injectors are working.

Get something like this:

http://www.sears.com/shc/s/p_10153_...21x00003a&ci_src=14110944&ci_sku=00914130000P

Pull a coil out and hook the tool up to it, then plug a regular sparkplug into the end of it and set it on the valve cover for a ground ( or a test lead with aligator clips one to the bottom of the plug and another to a good ground ) DO NOT PULL THE PLUG FROM THE CYLINDAR WHILE DOING THIS then start the truck and see if the tester light pulses. If the tester does light up and pulse, then you know you have spark on that cylindar and if not then you do not have spark. Repeat on all of the passanger side cylindars.

BTW bad o2's will not cut out one bank. The only thing the o2's will do is tell the computer to give more gas or less gas ( injector pulse ) depending on the air/fuel ratio.

 

[strokin393]

You need to check spark! If the plug is wet with clean gas, then you know that the injectors are working.

Get something like this:

http://www.sears.com/shc/s/p_10153_...21x00003a&ci_src=14110944&ci_sku=00914130000P

Pull a coil out and hook the tool up to it, then plug a regular sparkplug into the end of it and set it on the valve cover for a ground ( or a test lead with aligator clips one to the bottom of the plug and another to a good ground ) DO NOT PULL THE PLUG FROM THE CYLINDAR WHILE DOING THIS then start the truck and see if the tester light pulses. If the tester does light up and pulse, then you know you have spark on that cylindar and if not then you do not have spark. Repeat on all of the passanger side cylindars.

BTW bad o2's will not cut out one bank. The only thing the o2's will do is tell the computer to give more gas or less gas ( injector pulse ) depending on the air/fuel ratio.

Could I unhook the harness from one of the coilpack and hook a test light up to the ends of each harness to see if its getting power to it? I did take a coil from driver side that works and put it on pass side and it seemed not to work on the pass side, so that's why I'm thinking its not coilpacks and maybe 02 sensor or the harness not getting power or maybe bad ground if that's possible for it to be getting power to driver side and not passenger side.
The guy that hooked the code scanner up said something about an open loop. I don't know what that means.
Thanks for the info

 

[Racenut]

Yeah you should be able to check voltage at the coil conection wich will tell if the coils are getting power. It could be a bad spot in the harness / pinched or broken wires, or a bad ground.

As for "Open Loop" usually that means, is that the truck has not gotten up to operating temp so the computer is still running off of factory defaults that are stored in the computer and not running off the sensors.

Once the computer goes into "Closed Loop" then it is reading all of the sensors such as o2, air temp, mass air, etc. At this point the computer will use the data from these sensors to change the fuel and timing curves.

It is normal for all vehicles when they are first started to run in "open loop" until the computer senses that the motor is up to operating temp. A bad sensor will also keep the computer in "open loop" but you would have a check engine light if this where to occur.

 

[strokin393]

Yeah you should be able to check voltage at the coil conection wich will tell if the coils are getting power. It could be a bad spot in the harness / pinched or broken wires, or a bad ground.

As for "Open Loop" usually that means, is that the truck has not gotten up to operating temp so the computer is still running off of factory defaults that are stored in the computer and not running off the sensors.

Once the computer goes into "Closed Loop" then it is reading all of the sensors such as o2, air temp, mass air, etc. At this point the computer will use the data from these sensors to change the fuel and timing curves.

It is normal for all vehicles when they are first started to run in "open loop" until the computer senses that the motor is up to operating temp. A bad sensor will also keep the computer in "open loop" but you would have a check engine light if this where to occur.

What do you mean by I have to check engine light to tell? You saying let it run for long time and hook the code scanner up to see again after the temp of motor gets up? I don't think my check engine light works so I guess I'll just have to have the guy come over and hook the scanner up every so often.

 

[strokin393]

Ok, I pulled the oil cap off and saw steam and condensation on it. I might have a blown headgasket. How hard is it to replace that on pass side?

 

[Racenut]

What do you mean by I have to check engine light to tell? You saying let it run for long time and hook the code scanner up to see again after the temp of motor gets up? I don't think my check engine light works so I guess I'll just have to have the guy come over and hook the scanner up every so often.

If you have a sensor that is not working properly when the computer tries to go into "Closed Loop" it will turn on the check engine light and set a code.

It should not take a "long time" to get the motor up to operating temp, but it would probably take a good 15 - 20 min.

 

[Racenut]

Ok, I pulled the oil cap off and saw steam and condensation on it. I might have a blown headgasket. How hard is it to replace that on pass side?

Get a compression test done. You would need to do both "Dry" and "Wet". For the "Dry" test all you do is hook up the gauge and perfome the test on each cylinder and write down all the numbers.

Then go thru and perform the test again, but squirt a little bit of oil down the spark plug hole before hooking up the gauge. Perform the test again and write down all of the numbers.

Once you have finished compare the numbers if you see a large difference between the "Dry" and "Wet" numbers on a particular cylindar then you have an issue with the rings.


Have you performed a "Cooling System Leak Down Test"?

The Cooling system leak down test will tell you if you do have a blown head gasket between a cylindar and a water passage in the head.

Have you perfomed a "Cylinder Leak Down Test"?

For this test you hook an adapter to an air hose and force compressed air into the cylinder. This will tell you if you have a bad Intake valve ( you will hear air coming thru the intake), or a bad exhaust valve ( you will hear air coming thru the exhaust ), or bad rings ( you will hear and feel the air coming out of the PCV Valve hole in the valve cover).

How many miles are on the truck?

If the milage is high and you have a difference in the compression test numbers it would be easier and more benificial to pull the motor out and put in new bearings and rings at the same time you are doing the Head Gaskets.

 

[strokin393]

I'm draining the oil now and I see no water, just black oil. I just don't know. I had a friend tell me I had bad 02's, had someone say head gasket, and so on. I really don't know and don't have many tools here to do them test. It backfires when I go to start it after having it running before. I think the pass side not burning the gas.

 

[Racenut]

I'm draining the oil now and I see no water, just black oil. I just don't know. I had a friend tell me I had bad 02's, had someone say head gasket, and so on. I really don't know and don't have many tools here to do them test. It backfires when I go to start it after having it running before. I think the pass side not burning the gas.

All of those tools can be rented cheaply at your local parts store. If you have any questions about the condition of the motor those tests will let you know if there is anything MECHANICLY wrong with your truck, or if it is all electrical.

Just trying to guess at what the problem is, is really just a waste of money and time sice you do not really have anything to go on!

If you want to figure out what is wrong with your truck, then you need to do the above tests and rule out mechanical. Sice you are saying that there are no codes in the computer then that tells me it may be a mechanical problem.

BTW regarding the black oil, you can still have a head gasket that is blown between 2 cylinders and with that you will not see any water in the oil. Also if it is not a bad leak in the head gasket sometimes it can "blow" all the water from the cylinder out the exhaust.

 

[strokin393]

All of those tools can be rented cheaply at your local parts store. If you have any questions about the condition of the motor those tests will let you know if there is anything MECHANICLY wrong with your truck, or if it is all electrical.

Just trying to guess at what the problem is, is really just a waste of money and time sice you do not really have anything to go on!

If you want to figure out what is wrong with your truck, then you need to do the above tests and rule out mechanical. Sice you are saying that there are no codes in the computer then that tells me it may be a mechanical problem.

BTW regarding the black oil, you can still have a head gasket that is blown between 2 cylinders and with that you will not see any water in the oil. Also if it is not a bad leak in the head gasket sometimes it can "blow" all the water from the cylinder out the exhaust.

I see oily gas or something in the pass side exhaust. I guess I'll get someone to do a comp test for me one dy then maybe give up and sell the truck. Thanks for your help. I'll post back later