Let me know if your timing chain looks kinda like mine...

 

Wow, that's a little loose. I was told it had a new chain put in about 10,000 miles ago, so I have to assume it's not going to be loose. I just want to make sure it was installed correctly.

 

Well after spending the winter looking at the truck tucked away in the garage I'm getting ready to start figuring the problems out. I spent some time learning about Fuel trim and the effect it has on diagnosing problems. When I start the truck, the Short Term FT hovers around -3.5% to about +4.0% and then suddenly it will start missing and run horribly (No CEL) and the FT jumps from -33% to +18% and the truck can't even accelerate.
After shutting it down and restarting, it starts to run OK again and FT is back where it was before(.-3.5% to about +4.0%) This tells me that I may have an injector problem. With 145K miles on those injectors, they may be ready to be replaced.
I see Bosch injectors with a 4 hole spray pattern, which is supposed to be an upgrade from the single hole Siemens injector in the truck, but I don't know if it's worth the investment.

So, I'll pull and clean the injectors first and see where that leaves me...

 

I had the same issue, replaced my crankshaft sensor and to be safe my O2 sensor then I turned my key from off to on then back to off 5 times which tells the computer you installed new parts. That will cause it to forget the driving record thus far and will relearn. That fixed my issue immediately after doing the key turn and starting her up. She growled like a bear again.

 

Thanks for the input Steve. I did purchase a CPS last fall, and will install that when this latest band of crappy weather passes... It's got new Denso O2 sensors installed as of last fall which really made no difference in the way it ran. When I bought the truck a year ago in Georgia, it had a code for the post - cat sensor, so I dealt with that until I got it back home in Wisconsin, and it really ran fine the whole way home. After getting it back home is when the hesitation problem and horrible exhaust smell started. I putzed around with it for the summer and never really made any headway, so I eventually put it away and disconnected the battery for the winter. Now that it's getting nicer out, I need to figure out what's wrong with this thing.
So, yeah, CPS and I bought a new coil just to see if that does anything as well. After those 2 items, I'll start looking at injectors.

 

Just to record an update for posterity sake, I replaced the coil and it actually seems to have helped slightly. The exhaust isn't as rich smelling as it was prior to this. However it will run just fine and then will randomly start to hesitate and misfire, and while watching the Short Term Fuel Trim, it goes from -3.0% and jumps all the way to -33.0%, which tells me I may have an faulty injector issue. I've been busy with a million other things, and it's not an absolute priority that I get this truck running, so I've been working on it in my spare time. I ordered an injector tester and once that shows up, I'll test each injector. With 145K on the truck it may be worth it to just replace all the injectors, but I'll go through and test them all first.

 

Another update for those who are reading this..
I tested the injectors Saturday morning and here are the results...

When cold, I get a constant 12.1 OHMS resistance on each one.
I tested the injector pressure drop with an injector tester and everyone was the same. Started at 46.5 PSI and would drop to 31 PSI consistently.
After warm up, the resistance was 12.9 OHMS consistently across all 6 of them.

I'm off work the next few days, so my plan is to change the CPS and pull the injectors and clean them. The truck has developed a horrible rattle in the exhaust which could be the catalytic converter breaking apart, but it was supposedly replaced less than 20,000 miles ago... I'll have to get under the truck and take a good look after work today. This new problem seems to have come up out of nowhere

 

If you get consistent pressure drop across all your injectors, I don't think cleaning them is going to help you.

Clogged cat will give you some interesting issues though.

 

I guess I'm thinking the same thing. The injectors are all consistant and seem to be working properly.
The converter needs to be replaced. I was tapping on it and it rattles like crazy. So, I'm pulling it off today and I ordered a new replacement.

The saga continues.....

 

Well, I got the exhaust system off this morning. The converter catylist material came out like dust when I stood the pipe up on end! Since everything is off, I'm going to install duals on the truck. This afternoon I swapped out the crank position sensor. The one I ordered through Amazon last fall was not correct. The connector was slightly different, so I ran over to O'reilly and picked up the correct one. Got it installed and started the truck. Right now it's crazy loud, with no exhaust, but I wanted to verify the CPS would in fact work.

So, once I get the Catalytic Converter and exhaust installed, we'll see how it drives...

The only thing I'm not sure about is how a clogged catalytic converter an cause fuel trims to go crazy.


More to come.....