'99 3.9L hesitation & sputter?
#21
For all of you following this harrowing tale, I'm going to start with a few basic part changes. Coil and Crank Position Sensor. We'll see if that makes a difference. After that, I'll probably park it for the winter and start up again in the spring. With 142K on it, I'll probably pull the intake and change that manifold seal next spring, just to make sure it's not the problem. While I'm in there, I'll verify the timing chain is correct and within limits.
#22
#23
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...
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...
#24
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.
#25
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.
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.
#26
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.
#27
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
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
#28
#29
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.....
#30
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.....
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.....