I have a 97 3.0 gas that I was going to swap but I have had a change of heart. Now I need to figure out what is wrong with the motor I have in it. When I got the truck, the coolant was dangerously low. I have filled it up and I don't think it is burning coolant, but I have to wait to get a tester to check compression. When it is cold, It runs fine. Its when it is warm where the issue is.

I have been starting it up and driving around town to get the engine to temp, parking it, and then restarting it after about 10 min. It idles fine but as soon as I add any throttle, the rpms drop. I add a little bit more and the rpms jump up and it sounds like it is missing.

I have replaced the Idle air control valve. It also has the start of an EGR delete. When I had my exhaust done, he welded the hole in the head for the egr tube. I put a cap on the intake today to see if that would also help the issue but it did nothing. I was also able to pull 5 of the plugs and one looked a little wet, but I am unsure what I am really looking for when it is missing. I didn't pull the 6th cause Its the passenger rear and didn't want to get completely coated in dirt that day. I should pull it and see. I do not have any o2 sensors in the exhaust yet and am looking to get them soon. I just need for find the correct simulator for downstream as I didn't have him install a 3rd bung. I also didn't have him install the cats as I don't need to worry about emissions here.

Where should I start to get this thing diagnosed? I am getting an obd2 reader this week to check for any codes. With COVID, no one is doing code scanning and I can't even borrow it to do it myself. I have the Factory Service Manual and the Haynes manual. I was thinking about checking for vacuum leaks as there is one part that is just dangling that isn't even connected that I have never seen before. Ive bitten off a bit more than I can chew so any help is appreciated.

 

It's not going to run correctly when warmed up with out any o2 sensors, it's in limp mode.

 

I mean, I had a good thought process. I've always ignored o2 sensor codes so i thought that it wouldn't hurt too much if they weren't installed. I've got some coming tomorrow that I'm going to try and throw in.

 

Yes, +1 on the O2 sensors, they are NEEDED

But so was the EGR system
You will need to keep an EAR OPEN for pinging/knocking when driving, especially under acceleration, BACK OFF the gas pedal when you hear it

Picture of piston after pinging/knocking: https://canadamotoguide.com/images/s...ged_piston.jpg

And it will end up like this: https://i.ytimg.com/vi/T7FMnwBAIJM/maxresdefault.jpg

EGR system was used to cool the engine cylinders when they were under a load to limit the spike in NOx gases, a toxic exhaust emission, that happens when engine cylinders get too hot
EGR system had the side effect of reducing pinging/knocking which allowed engine tuners(Ford) to use a more aggressive spark timing for better power

Since you eliminated the EGR injection you will get pinging/knocking on Regular gas(87 octane), so if it gets bad/constant you will need to run 89 octane or maybe 91 to 93 octane to reduce it
Octane is a Heat Rating, the temp that the fuel will SELF Ignite at, pinging/knocking is self ignition caused by heating the fuel above that temp

 

Yeah, I saw something about that elsewhere. I was planning on running my tank empty and then going up in octane. One issue I'm having right now with getting the o2 sensors installed is that the previous owner broke the post cat plug and the drivers side plug. I don't know what wire goes where and I cannot find an accurate wiring diagram in the haynes or factory manual. Sensors will be installed tomorrow as long as the tropical storm leaves quickly and I can figure out the wiring. Lucky for me, the passenger side o2 sensor was still there when I had the exhaust work done so I can use that for the post cat simulator.

 

That won't work.

The 2 front o2 sensors are needed, they control how much fuel the injectors inject.

The post cat o2 sensor is just to check if the cat is functioning, has nothing to do with the engine running,

 

I have new ones for the front coming. I would rather replace both vs have the old one be bad and keep throwing MIL codes. Just going to use it to keep the post cat codes at bay.

 

So the o2 sensors have been replaced. It did the stall thing right away after I installed the new sensors but I shut it off and restarted it and it was fine. Took it for a drive down the street and back and got a good live data capture. I parked it and shut it down, restarted it and it was doing it again.

 

I think I got that figured out. Might have been the maf sensor. Left it unplugged from when I replaced the idler yesterday. But as I know, it takes a few tries to get it right.