OK fellas, I'll try and go over everything here. First off, the 5.8L I just installed is having some rough idle/ miss issues. Almost sounds like it's only firing on 7 cylinders. Upon startup it seems to run fine but when the high idle kicks off it gets rough.

Background:
-I just took out my '95 5.0L due to valvetrain probs and swapped in this low mileage '92 5.8L (had been sitting in a guys garage for a couple years). 5.8 came from a speed density F-250 and my '95 F-150 is MAF. I left ALL the wiring in my '95 engine bay when I pulled the 5.0 and simply plugged it into the 5.8 once it was in (running it with my 5.0 MAF computer). The only thing that did not plug in was the knock sensor towards the firewall on the back of the block as the 5.8L does not have one. Also, the ACT is in the lower manifold (driver's side) on the 5.8 but I'm using the one from the MAF 5.0 that's in the air filter box.

-The 5.8 has all new plugs, wires, distributor (app: '93 F-250 w/ remote ECM). Timing was set to around 8* w/ spout connector unplugged (where it would run the smoothest). I've triple checked firing order & all the vaccum connections (ran new hose where needed) and everything is plumbed where it should be or capped. I took the IAC valve off the 5.0 upper, cleaned and installed it and it seemed to help the idle abit but not a cure-all (IAC from the 5.8 was in bad shape). Swapped EGR valves with the one I had on the 5.0 as well & made a small improvement. Before the IAC/EGR swap the truck would die when put into gear, now it runs ok but still rough. I installed a brand new O2 sensor as well when I re-worked the exhaust. Also smells abit rich.

-The only code I'm popping of note is a 327 KOEO which I think is EGR/EVP circuit? (don't have my code book infront of me at the moment)

Only thing that wasn't messed with really was the ECT on the 5.8 (the one on the heater tube where it attaches to the lower intake). I just plugged the connector in. If this is not working would it throw a code? The rich smell and rough running has me thinking this "could" be a possible source?

I have not done any fuel pressure checks. This engine did sit for a couple years but I did verify 5 of the 8 injectors "ticking" with a stethescope (couldn't get to 2,3,4 as the upper intake is in the way).

Also of note, it seems to run on the warm side. Operating temp on the gauge is between the "M" & "A" of "NORMAL" slightly above mid-range. I intalled a brand new water pump & 195* thermostat on the 5.8 before I dropped it in. Running 50/50 Zerex G05 & distilled water. If I stabbed the new distributor in 1 tooth off I would think it would show with the timing light/ balancer check?...

I know troubleshooting over the web is a bear but any suggestions you guys might have in smoothing this engine out would be greatly appreciated.

Thanks,
Fungus

 

The 5.0 ECU is a good place to start. I know it'll run like that but you'd be better in the long run I think to get teh actual 5.8 MAF ECU.

Also not sure but I would think the open knock sensor might be posing an issue if the ECU is looking for it.

The ACT location shouldn't make too much of a difference i wouldn't think, so long as its functioning properly.

As for running warm. Did you have an issue with that prior? Maybe the radiator could use a flush.

 

Thanks for the response!

 

Check the fuel pressure. I had an issue with my truck where it sat too long and the fuel went bad and clogged up both my fuel pumps and my fuel filter. I had enough fuel pressure to start the vehicle but it would run rough or not at all.

 

Pressure should be around 39 lbs at the rail.

 

The truck itself only sat for a week while I was swapping engines & was/ is my DD so the fuel in the tank/ lines is fine. I AM going to change the filter and run some techron through it though. My concern would be a plugged or gummed up injector as they sat for a couple years on the 5.8 along with the rail/ regulator. At 1500 rpm+ it smoothes out fine but not sure if the higher rpm just makes the "miss" less noticeable or not...

 

The underlined area was my concern.

If you can't get to the 2, 3, & 4 injectors to test them, maybe a good idea to take them out and check or replace them. Sounds like you have checked most other things.

Also, just thought of this, you should be able to check to see if the cam has any runout or issues by connecting your timing light to cylinder #8. You should get the same timing as #1. I haven't done this myself, I just read about it the other day so I am not really sure how much it will tell you but maybe someone here knows about that.

 

I hear ya! I was just hoping to prevent pulling the upper intake... again... LOL! I did keep all 8 injectors from the 5.0 so I've got plenty of spares to clean/ rebuild if needed. I'm hoping, if an injector is stuck, that just driving the rig & running some injector cleaner with the fuel will free it up. The Chevron stuff with Techron comes HIGHLY recommended so I bought a bottle & am just waiting to change the filter today to dump it in and top off the tank. Wouldn't want to "clean" any crap out of the filter that's in it and have it run downstream.

 

I had to test some used injectors I got from a junk yard to make sure they worked. They were easy to test: all I did was take my truck battery charger (which puts out 12v @ 2 amps) and I quickly touched the leads on the injector. You should hear a click or even see gas come out if it's in there. Just be careful to not give them too much electricity at once, they run on a duty cycle so aren't designed to have constant power, you may damage them.

 

Can anyone help me out with the vaccum routing on this solenoid? Canister purge solenoid? Currently I've got the pass side nipple plumbed to the canister itself. The driver's side nipple runs into a splitter with one line going to a barb on the front of the throttle body (pass side) and the other looping around to the backside of the throttle body (driver's side). The last two lines I described were cracking and just fell apart so I replaced them with new line but not sure I got the routing correct! Seems strange they both run to the TB. Is one supposed to go clear around to the intake? I've got several un-used barbs that have been capped off on the intake.

 

So I figured out my problem!...

The TB that came on the 5.8 was sticking abit off idle and really annoying me so I cleaned up the one off the 5.0 real nice. When removing the TB (pictured in last post above) I noticed that it had 3 vaccum ports NOT 2!!! The bottom port on the driver's side I didn't see when hooking everything back up so it was open... VACCUM LEAK! Swapped TBs & the one off the '95 only has the one passenger side port and 0 on the driver's side. I was able to delete some vaccum line off the solenoid and just run a single line to the pass side port on the TB. Runs MUUUUUUCH smoother! Very pleased with this 5.8 now that it's running like it should. Twas a good swap.

 

Glad you got it fixed. I took off the driver's side a long time ago. But I'm actually putting them back on now. Funny that you're now taking them off

 

Well, the TB I just put on that came off my 95 5.0 doesn't even have any vacuum ports on the driver's side so it made it easy!

 

OK guys, I thought I had it licked but apparently not... I'm still getting a rough idle at times & it runs rough all the time from 900-1300 rpm. At 1400 rpm it seems to smooth out real nice and run/ accel as it should. Every once it awhile when at a stop in gear with foot on brake the idle will chug and then pick right back up - does not stall but acts like its going to then catches itself.

I've cleaned the TB, EGR & Idle air bypass & installed all with new gaskets. This engine has a new distributor, cap, rotor, wires (run according to spec w/ stock looms) & plugs that were gapped to spec by me. Timing set to 10* with SPOUT removed. Not throwing any codes with either KOEO or KOER tests! It runs decent but is one of those ANNOYING things that I know is not right & want to get it 100%! Worn vacuum hoses were replaced and I checked for leaks again yesterday using almost a whole can of starting fluid on ALL vacuum connections/ intake mounting area & there are NO vacuum leaks.

It was suggested to me by a guy that helped with the install that it could be a worn TPS. The TPS thats on it is the one from the 5.0 (I did remove it from the TB when I cleaned it and reinstalled it). I also have not done anything with the ECT aside from plug in the connector. Not sure if the ECT is giving erroneous info to the the CPU and maybe its not going into closed loop? The problem seems to get worse when the truck is warmed up. I have extras of both sensors and could easily swap either or both of them out.

Any insight ya'll might have would be great!
Thanks!

 

A mis-adjusted TPS could cause slight idle/off idle issues. I suppose a bad ECT sensor could as well.

If the 5.8 had been sitting for a while, the injectors could be gummed up. The 5.0 injectors are the same size and will swap right in.