Damn, still running lean - drag. Hang in there, there's plenty left to check(!)
A few questions-
* When you tested the Engine Cooling temp sensor, did you test it when the motor was hot? What was the value? (Reason for asking: you said the engine temp gauge "barely gets an 1/8th of the way up" I'm concerned the ecu may not consider the motor to have reached operating temp, in which case it would be running in open loop and not using the O2 sensor to calibrate mixture. There is a test to see if the ecu is running in open loop - it requires a voltmeter to check, let's hold off on that for the time being, but please check the resistance of the ECT when engine is hot if you haven't already.
* Did you set the timing after installing the new sensor & plugs? Did you jump the terminals in the check connector while doing that, and what was the timing when you first looked at it?
* Did the IDL & E2 terminals of the TPS have continuity when the throttle was closed (idle position?) What were the throttle closed and throttle open values of VTA & E2?
* Does your motor have sounds in the front of the motor when just started that sound like shaking marbles in a tin can?
* Does your motor ever ping?
Okay, a few things to check:
TROUBLE CODES:
I know this is a bugaboo, but we're working in the dark and at this point it could save a lot of blind guessing if we knew what the computer thinks. Even if it has no codes, that in itself is useful to know.
The procedure is very simple, but sometimes the flashes are a little hard to count, is all. First, make sure your check engine light works: it should come on when you turn on the ignition but before you start the motor. If that light doesn't work, you would have to check the bulb if you wanted to retrieve the codes, unless there's a scanner/code reader that a shop could use, but I don't know if there's a place to hook one up.
Assuming the check engine light works, all you have to do to get the codes flashing is:
- Turn the ignition on but don't start the engine. Turn off fan or any other accessories.
- Jump terminals TE1 and E1 in the check connector with a paperclip.
- Back in the cab, leave foot off the gas pedal as it will only work with TPS signaling the idle position, but put the transmission in neutral.
- Count the little flashes of the check engine light.
If there are no codes, the check engine light will just continuously flash twice a second. If there are codes, they are all two digits. It will flash however many times for the first digit, then there will be a 1.5 second pause, then it will flash for the second digit. So code 12 would be: a flash, followed by a 1.5 sec. pause, followed by two flashes. It's that simple.
There could be 2 or more codes, however. There's a 2.5 second pause between each code. After all the codes have been "flashed", there is a 4.5 second pause. Then it gives all the codes over again. It will continue looping through all the codes as long as the ignition is on and TE1 and E1 are jumped. For this reason, wait for the 4.5 second pause before starting your counting so you're sure you're starting on the first code.
If you have trouble counting all the flashes, and some people do, ask a friend or family member. They don't have to know anything about cars, it just seems to come naturally for some people.
EGR:
One possible cause of a motor running hot is a failed EGR. That's the exhaust gas recirculation valve that is a metal disk at the back of the valve cover on the intake side. It has one vacuum tube attached to the top, and out of the side of it comes a (rusty) steel pipe that is bolted to the back side of the plenum. If you look below it, there's another rusty pipe that leads back to the exhaust manifold.
The engine adds exhaust gas into the intake for several reasons. One is to cool the cylinders. Seems strange, but it does it by diluting the mixture some, which lowers the combustion temperature. That's for keeping NOx emissions down, but it also helps the motor avoid pinging. So if the EGR never opens, the cyls could get hot. The EGR actually improves the efficiency/gas mileage of the motor a little bit.
On the other hand, if the EGR is always open, that could cause surging, and possibly a lean condition, but it would also cause the motor to stumble and hesitate, probably pretty badly.
To check it, an easy way is to let the motor reach operating temp, then hold the rpms up into the middle rpm range, around 2000-3000, and (carefully!) see if the EGR pipe bolted to the back of the plenum is hot. Next test, pull the vacuum tube from the top of the EGR valve (see the fsm for diagrams to identify it - ENGINE/Emission Control System--Layout--Fed and Can) and test with your finger to see if the tube has vacuum. That tube SHOULD have vacuum on a hot motor when revs are 2-3k, and it should NOT have vacuum at idle.
VACUUM LEAKS:
Various ways of checking:
- Propane torch: open it without lighting it, and wave it around all the vacuum hoses, as well as all the joints around the intake, and listen for an increase in idle speed.
- Starting fluid: same as the propane torch
- Brake cleaner - I've heard this will actually cause a decrease in idle speed, but I've never tried it.
There's another test that would be great, namely a fuel pressure test, since low fuel pressure could cause a lean condition. But you need a fuel pressure gauge with the right fitting to check it, so unless you have one, you'll need to get a shop or a techie friend to do that for you. You could put that one off until we work the above issues.
I know it must be frustrating to still be having trouble after so much work, but hang in there! We will eventually find the trouble(s), and by the end of all this checking, you're going to know a hell of a lot more about your motor than you did, and that may come in useful in the future.
Note to other forum members, especially 22RE owners: please feel free to chime in here with ideas, or if I've gotten something wrong, or if I'm missing something, lol !
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