89 2.3 swap bad idle

[1989rangerob]

so I went ahead and swapped a new motor into my truck. Seems like a good motor. Unfortunately, I'm having the same problems I did with the old motor. I cleared the computer and tested it. it comes in with, can't read low rpm, can't read high rpm, TPS sensor, rich 02, MAP sensor, and I think that's it. I don't know if these things will fix the problem if I replace them. I may need to clean the injectors. I may need a new crank position sensor. What do y'all suggest?

 

[Mikel89us]

Start testing sensors. It may be wiring, so you would test everything before you throw any parts at it. Also, the computer is less likely than anything else, but it could be bad.

 

[Mark_88]

The fluctuating or non readable RPMs is a symptom of the bigger problem and that may be TPS or MAP. If you have a junkyard nearby that has any older trucks or Tempo/Topaz vehicles you can probably grab the MAP from them. They are the same for both as far as I know and the MAP can cause wonky idle...like really wonky idle!

You can try cleaning the contacts on the connector and make sure the vac line is in really good shape and see if that does anything...and spray down the throttle linkage and clean the TPS similarly...before actually swapping the parts...

It's good to have spares of any of these parts because they can be quite expensive and can cause you all kinds of problems...I used to carry spare MAP sensors around with me after my first experience with them failing...never had to replace it after the first one though...

 

[fastpakr]

What are the actual codes you're getting (in order)?

Start with Key On, Engine Off tests. Once those are resolved we can move on to the engine running tests.

 

[tomw]

I would be checking ground and power cables. All that stuff going away at the same time to me indicates a 'common problem' causing them all to appear flaky to the computer.
There is a ground cable from the back of the cylinder head (I think) that is often overlooked after doing the hoisting. It goes from the head to the firewall and is the ground for the cab, I believe.
If you lose cab ground, all the electrical gizzards can appear goofy. You can provide 'backwards' ground via powered components, the brake pedal, and so on, but it is not good enough to give reliable signals to the computer.
To check quickly, but not for amperage carrying, you can put one connector of a VOM on the + terminal, and the other on the -, read voltage. Then put the - on a clean, grounded bolt on the cab, and compare. The voltage from + to - battery should be close to voltage from + to - on the cab if there is a good ground. If they differ, you have a bad connection somewhere. You can bypass the ground by providing a temporary ground using a jumper cable from - to the cab bolts and see if the KOEO tests report back better.
tom

 

[1989rangerob]

I would be checking ground and power cables. All that stuff going away at the same time to me indicates a 'common problem' causing them all to appear flaky to the computer.
There is a ground cable from the back of the cylinder head (I think) that is often overlooked after doing the hoisting. It goes from the head to the firewall and is the ground for the cab, I believe.
If you lose cab ground, all the electrical gizzards can appear goofy. You can provide 'backwards' ground via powered components, the brake pedal, and so on, but it is not good enough to give reliable signals to the computer.
To check quickly, but not for amperage carrying, you can put one connector of a VOM on the + terminal, and the other on the -, read voltage. Then put the - on a clean, grounded bolt on the cab, and compare. The voltage from + to - battery should be close to voltage from + to - on the cab if there is a good ground. If they differ, you have a bad connection somewhere. You can bypass the ground by providing a temporary ground using a jumper cable from - to the cab bolts and see if the KOEO tests report back better.

tom

I made sure to reinstall that cable. I remember cranking it down.

 

[1989rangerob]

What are the actual codes you're getting (in order)?

Start with Key On, Engine Off tests. Once those are resolved we can move on to the engine running tests.

KOEO 22,23

Running: 12, 21, 23, 42, 13, 52

 

[Mark_88]

I was going to cut and paste these, but just for your reference they can be found here...

http://www.therangerstation.com/tech_library/2digitcodes.shtml

Looks like idle control and temp sensor are out of whack for sure...

 

[1989rangerob]

I was going to cut and paste these, but just for your reference they can be found here...

http://www.therangerstation.com/tech_library/2digitcodes.shtml

Looks like idle control and temp sensor are out of whack for sure...

They're in my chilton's manual. There's a whole section explaining how to pull codes. What it doesn't really provide, is a solution. I don't want to spend a bunch more money on this pig if I don't have to. I guess I'll test the sensors next. The coolant temp sensor and sending unit are new. They may have misread because the engine wasn't totally warmed up yet

 

[1989rangerob]

Tps is good. The motor dies when I disconnect the map sensor. I can keep it running by depressing the accelerator but the miss is still there. I disconnected the main vacume line. The rpms went up and the miss was still there. I popped of the plug connectors on the exhaust side and they all had spark. I tested the coil on the intake side with a volt meter and it was good. I took the DIS off and tested it at auto zone and it was good. I tested the crank position sensor with a bolt meter by hand turning the motor and reading the change and it passed. I'm kind of stumped

 

[tomw]

Crossed plug wiring problem considered? Such would lead to definite miss at idle, perhaps hidden miss at higher rpms.
tom

added:
You can test the temp sensor with a VOM, and the resistance should change with temperature change. The computer doesn't know beans about the temp sensor as far as 'is it good..?' It just takes the resistance given... unless it has infinite or zero resistance. Those would be, to my knowledge, the cases where it gripes about the temp sensor as it is obviously not in range of possible temperatures...
The TPS I have has to be 'zeroed' or adjusted if replaced. If you put a meter on the TPS it should show a sweep of resistance as it is moved through its travel. If it has dropout (goes to zero or infinite) then it is likely bad. If it cannot go to the low end, perhaps by adjustment, then it may be bad. Some needed the oval shaped holes opened just a smidge to get the proper 'closed' throttle reading, IIRC.
Given the codes, I would be checking for presence of the 5v reference voltage at the TPS and check the resistance of the temp sensor. I don't think the temp sensor has the 5v but I might be mistaken.
tom

 

[1989rangerob]

Crossed plug wiring problem considered? Such would lead to definite miss at idle, perhaps hidden miss at higher rpms.
tom

added:
You can test the temp sensor with a VOM, and the resistance should change with temperature change. The computer doesn't know beans about the temp sensor as far as 'is it good..?' It just takes the resistance given... unless it has infinite or zero resistance. Those would be, to my knowledge, the cases where it gripes about the temp sensor as it is obviously not in range of possible temperatures...
The TPS I have has to be 'zeroed' or adjusted if replaced. If you put a meter on the TPS it should show a sweep of resistance as it is moved through its travel. If it has dropout (goes to zero or infinite) then it is likely bad. If it cannot go to the low end, perhaps by adjustment, then it may be bad. Some needed the oval shaped holes opened just a smidge to get the proper 'closed' throttle reading, IIRC.
Given the codes, I would be checking for presence of the 5v reference voltage at the TPS and check the resistance of the temp sensor. I don't think the temp sensor has the 5v but I might be mistaken.
tom[/QUOTE

The tps is good. I already did the vom test on it. The crank sensor is good and giving a reading through the dis back to the computer. The coolant temp sensor and sending unit are new and reading correctly in the dash. The insulation on the wires is good. The wires are connected to the right plugs. There are numbers on the coil packs and the wire lengths are kind of obvious. The ect code was in reference to the engine coolant temperature according to the chilton's manual. I know there is also a temp sensor in the front side of the intake manifold. That isn't the ect sensor though, or maybe it is? Anyways, I just re shoed the rear brakes and they're working just fine now. The e brake still doesn't work though. Thanks for the input.

 

[1989rangerob]

I replaced the computer for the the whole truck. It fixed the miss and the idle. Go friggen figure

 

[scotts90ranger]

Probably a bad internal ground, as the ground for all of the sensors you had codes for are most likely common (or the power, same deal), it is 25 years old

 

[1989rangerob]

Well Scott, now it's losing power in 4th and fifth. I replaced the fuel sending unit thinking that it was the problem. Still doing it