Doing a bunch of work on 4.0 SOHC, should I replace fuel injectors while I'm at it?

[traildog]

Truck has ~160k miles and I'm going to do some more towing this summer, so I'm doing a pretty thorough service with timing chain tensioners, water pump, thermostat and housing, valve cover and intake manifold gaskets, etc. Should I replace fuel injectors or leave them alone? Engine runs well.

Secondly, if I'm doing them is it best to use Motorcraft injectors? I normally order from RockAuto but they currently don't have the motorcraft injectors.

Thanks in advance

 

[rubydist]

I would leave them alone, but that's just me.

 

[sgtsandman]

The only thing I would do if the engine is running fine otherwise is dump some fuel system cleaner in the tank when you go to fill the tank and run it until the tank is dang near empty. That will clean the injector nozzles of any build up for a more efficient spray. Take your pick on which brand to use. I like Chevron Techron and run it in the tank twice a year.

As far as other things to help the engine run more efficiently, cleaning the throttle plate and throttle body around the plate every so often helps it work more efficiently and will clean up any build up that can cause the plate to stick. The same goes with the mass air flow sensor. Only use cleaner made for that. They are sensitive. If it looks particularly grungy, you can very carefully use cotton swabs but don't damage the wires or you'll be buying a new sensor. Lastly, if the O2 sensors are over 100,000 miles or more than 10 years old, they are tired. The chemicals and coatings wear out and get used up over time. I'm due for a senor change myself due to both mileage and age.

 

[Uncle Gump]

I certainly wouldn't change those factory injectors for anything aftermarket.

 

[JoshT]

If they are working, they are probably better than anything cheap you'd buy to replace them. If they did need to be replaced I'd find a reputable place to buy a set of reman, flow balanced , factory injectors.

If you aren't taking them off for other reasons, don't touch them, just run some system cleaner like sgtsandman said. If you are taking them out I'd probably just install some new o-rings and reinstall and run some fuel system cleaner. Only reason to remove them if they ain't faulty is to pull the lower intake, and I wouldn't do that unless there is a leak that needs to be fixed. Maybe it has to come off for the timing chain tensioners, not familiar with that on a SOHC.

Dad's 2002 with 150k+ miles is still running the original timing chains and tesnioners, I'd hop in and drive it across country tomorrow. As for the VC gaskets, Waterpump, thermostat, etc, if it ain;t broke don't fix it. If the valve covers aren't leaking now, changing the gaskets is more likely to cause one. If the coolant was maintained properly, there isn;t likely to be anything wrong with the weater pump. New thermostats are hit and miss, you could end up replacing a perfectly good one with a new one that fails in less than 1000 miles.

If you must do more on the injectors, I just did a DIY rebuild on the injectors for my V8 swap. Didn't do a before/after and don't have means to flow test, but at over 180k I did want to test them before reinstalling in the engine and one thing lead to another. To test the way I wanted I purchased one of those injector test kits off amazon and a couple of bottles of Gunout carb cleaner (one was plenty). I knew I needed to replace o-rings. Was looking at o-rings and figured what the heck, I'll buy a seal kit (8 injector, 6 injector also available) instead that includes new filter baskets and pintle caps (or spacers?). Pintle cap pops off and filter basket pulls out with a wood screw so easy to change. Then while I had the fliter baskets out, I decided to run them through a few cycles in an ultrasonic cleaner filled with Seafoam. Took them out and let them dry, pressed the new filters in with a small vice (probably could have done it by hand but the vice was there).

Like I said no before and after, but they cleaned up very well and they had a nice spray pattern when I used the tester on them. Did I waste my time, possibly, but now I'm happy with what I'm putting back in.

 

[gw33gp]

I have 294K miles on my original injectors. They still work fine. I do run a cleaner through them once in a while.

 

[traildog]

Thanks guys. I'll go for the injector cleaner and leave them alone if at all possible.

I've got some decent oil leaks in a couple places around the valve cover, and the nub that holds the PCV valve into the back of the driver's side valve cover is stripped (had to glue the PCV in in with RTV to fix the vacuum leak that was there when I bought it), so i'll be replacing that valve cover anyways. I guess I'll see how the intake gasket is looking when I get in there and get it cleaned up. Got a bunch of oily crud around some of the vacuum hoses on the intake, not sure where it's coming from but will be trying to replace as many vacuum lines as I can.

Thanks for the other tips. I just had to clean the throttle body, replace TPS, and clean the MAF to fix a rough idle issue, so those are all good. I'll add O2 sensors to the list to do.

Any merit in replacing the EGR valve preventatively?

 

[sgtsandman]

Thanks guys. I'll go for the injector cleaner and leave them alone if at all possible.

I've got some decent oil leaks in a couple places around the valve cover, and the nub that holds the PCV valve into the back of the driver's side valve cover is stripped (had to glue the PCV in in with RTV to fix the vacuum leak that was there when I bought it), so i'll be replacing that valve cover anyways. I guess I'll see how the intake gasket is looking when I get in there and get it cleaned up. Got a bunch of oily crud around some of the vacuum hoses on the intake, not sure where it's coming from but will be trying to replace as many vacuum lines as I can.

Thanks for the other tips. I just had to clean the throttle body, replace TPS, and clean the MAF to fix a rough idle issue, so those are all good. I'll add O2 sensors to the list to do.

Any merit in replacing the EGR valve preventatively?

Normally no. They can plug up over time. So, pulling it and giving it a good cleaning isn't a horrible idea. The the same with the idle air control valve.

 

[traildog]

Thanks