I don't care. I've seen Bosch O2 sensors fail in a year and I've gotten parts bad out of the box. You could also be dumping fuel through a dirty injector and that could have taken out a new sensor. Unless you have the means to check the O2 sensor pattern and test it properly, don't assume it's good. Assumption is the mother of all f-ups.

 

Very true, fuel or oil coming through your exhaust is death to both the O2 sensors and the converter. I would check the engine for blow-by as well as giving the injectors a good cleaning.

 

Alfons,
SInce it may apply to my issues; How do you check for blow by? How do you clean injectors?
I'm shocked at the prices for these things rebuilt they're north of $80. I don't think you can get new ones.

 

Rebuilt what for $80? Injectors? I'm looking at 120pph injectors (yours are probably under 30pph) for my turbo mini-van so I can run E85 and new they are under $70 a piece. I wouldn't buy reman injectors (I've had too many problems with remans) and where ever you're looking it's the wrong place price wise.

Instead of throwing parts at your truck that you don't even know if they're bad, how about paying someone to diagnose it properly and spend your money where it needs to be spent? If I had a customer that wanted me to diag their vehicle so they could fix it, I'd have no problem with that. As long as I got paid for the diagnosis, have at it.

 

I agree with AZ 360 Dakota about getting a professional diagnosis - most people don't have the capability or experience to do a complete "physical" on an engine, so paying someone to do that can be a good investment - it doesn't take more than the cost of a couple of sensors to pay for the diagnosis.

For injectors, I've had luck cleaning most, but then I don't tend to let a lot of years lapse without giving them some maintenance. I usually use Sea Foam as a gas additive and also every so often I run some through the throttle body. On a couple of occasions I've pulled injectors out to give them a soak in cleaner and then used a 9volt battery to open them to run the cleaner through (this doesn't give you the same type of cleaning as a professional ulta-sonic cleaning with throughput testing etc). You need to get new O-rings for the injectors if you remove them, and also get a spray can of silicone lube to use when putting the rings on and the injectors into the engine and fuel rail. If you can't get silicone lube, I would use mild liquid dish soap - just a thin film is all you need.

I think you probably have somewhere around 90 pound injectors (Chrysler was fond of that size for a lot of their vehicles - my jeeps all had that size) and I found that the Mustang injectors worked much better (better spray) for about the same amount of money. Also, if I had an injector that needed changing, I wouldn't buy just one - if one's bad, the others aren't far behind. I found that it's a lot cheaper per injector when you get a whole set and well worth it. It's not that difficult to change them and by the time you add up the garage price of injectors as well as their labor, you'd be saving big time doing it yourself. If you've never worked on a fuel injection system before, do a bit of research before you start - there are lots of instructions, pictures, and videos available to walk you through it.

When I used the term "blow by", I might have led you into a misunderstanding & if so, I apologize. I tend to use it (without thinking) to cover a bunch of oil/pressure related problems. Blow by specifically means the condition of the rings and the ability of combustion related elements to "blow by" the rings and end up in your oil pan causing all sorts of bad problems. This "ring condition" will also allow oil to get back up into the cylinders where it gets partially burned during combustion and the unburned stuff goes out your exhaust - I tend to lump this into the overall blow by condition. I also started to include other oil problems under the same umbrella - these include oil leaking through your valve guides into the cylinder, oil that ends up in your crankcase vent system that gets routed back into the intake and gets burned, etc. Based on this, you can see that I can't give you one thing to check for to see if you've got unburned oil coming through your exhaust, but an overall physical examination of the engine should be able to tell you that - things like compression testing, cylinder leak-down testing, and examining various things like "how much oil on your air filter", all tend to give you that answer. Once you know the answer(s), you'll be able to see if it's worth trying to repair the engine or not. My opinion is that if the engine isn't "tight", it's not worth the parts and labor required to fix it. I would rather get a better engine from a junk yard than go through a rebuild process - at least you get a warranty with a junk yard engine & it's not that hard to do a quick "tightness" check before you drop it in.

 

Leak down testers are available for not too much money at Harbor Freight.

In the olden days, we did a few tests and observations to get an idea about the condition of an engine (especially if we were buying a higher mileage engine.)

1/ Do a compression check. Compare it to the specs in Haynes or the FSM, but pretty much anything over 140 psi is good. Look for major differences between cylinders, too. >5 or 10 psi is not good. When you pull the plugs to do the compression test, observe the condition of them--black and oily is not good.

2/ Check the manifold vacuum >13 or 14 psi is good at idle.

3/Check the oil condition (smell it!) Does it smell burned or nasty? Usually worn out engines use oil, and combustion byproducts get into the oil.

4/Physically check the exhaust at startup and running down the road. Blue/white smoke is bad & has a rather distinct, sour odor. And check the tailpipe, black oily deposits are bad.

5/Pull a valve cover off, sludgy--waxy deposits are bad.

6/Do a general inspection of the engine--coolant & oil leaks are bad indications.


Wrecking yard engines can be a good alternative. You want one that's had a compression check done before it was pulled from the vehicle. And you want to ask if replacing seals and gaskets voids the warranty (usually 30 day) because it is a good idea to replace the rear and front main seals and pan gasket, valve cover gaskets, and intake (plenum) gaskets while the engine is out of the car. Merely listening to the engine run before you buy it is not enough.

 

Don't use silicone where it can get sucked into the combustion chamber and burned, it can screw up your O2 sensor. Use WD-40 or a light coating of engine oil or some other petroleum based product.


There is no way a 5.2 is running 90pph injectors. I'm running 96pph injectors and 25 psi of boost in my mini-van. The fuel requirement per cylinder in my 4 cylinder van is going to be more than a 5.2 since I'm making more horsepower with 4 cylinders than a stock 5.2 is making with 8. You also don't want to switch to Mustang injectors unless they are the same size you're replacing unless you change the cal in the PCM. I ran into this problem with my 98 5.9 into my 94 5.2 swap. I ran the 98 injectors thinking they were bigger on the 5.9 but they were smaller than the 94 5.2 injectors. The stock injector size for a 94 5.2/5.9 is somewhere between 25pph-35pph. I found a chart online that gave the sizes per year but I can't find it now. I'll look for it later and post it, it's a handy chart.

 

I was wrong, stock 5.2/5.9 injectors are even smaller than I thought. Depending on the year/part number they are 23-24pph. The 4.0 Jeeps are even smaller at 21pph. This is the chart I used to determine that the '98 5.2/5.9 injectors were smaller than the '94 5.2/5.9 injectors and that's why my truck was running bad when I first did my 5.9 swap. You have to match the injector to the PCM unless you can change the calibration.

http://www.justfuelinjectors.com/ser...flowchart/Page

 

I was also wrong on the injector volume, I'm not sure where I had my head stuck yesterday, but it certainly affected my memory - the standard 4 liter injector is a 19 pound, not 90. Sorry about that.