I just installed a Jasper 5.4 in my 2000 f150 and all is good except for a intermintant misfire. No codes are coming up at all and on a cyl contribution test its cyls 5,6,7,& 8. All spark plugs are new motorcraft and all coils have been replaced with new motorcraft. when mis fire is happening all you have to for is toutch the throttle and all cyls pick up and run fine. This engine runs great except for this darn intermintant misfire. does anyone have any ideas??? Help

 

I doubt its a base engine problem so check all your vac lines and wire connections. Was the engine you replaced a 5.4 or a 4.6? It can take a while to retrain the ECM as well. Was the engine a shortblock or long block and were timing chains already installed from the manufacturer?

 

All vac lines and wiring conections have been checked and re checked. Its a 5.4L engine. The egr valve and dpfe sensor have been replaced. all compressions have been checked not running 170 - 175 psi and with engine running 85-90 PSI. It was a complete engine with heads and all timing chains installed. I was almost thinking the cam shaft on the left side could be installed one tooth off. its been driven about 25 miles since the install so i dobnt think the computer relearn is a issue. Im stumped. It will idle perfect and then all of the sudden it go into the misfire mode and appears only to be only cyl 5,6,7, & 8. on a cyl contribution usung a snap on verus.

 

Check all the ground and bond connections. I know everybody checks their electrical connections (the ones with power), but often overlook the grounds on motor swaps.

Just my $0.02 Good luck

 

I have checked all conections and now ive removed and cleaned all ground and power conections at the battery and engine block and even the bonds between the engine block and body none found loose. or bad. Ran engine and it still intermintantly missfires on Cyls 5,6,7,&8. Im checking for vacuum leaks now and so far all hoses and conections are good. Im thinking possable a cracked intake??? But why does only 1 cyl bank missfires and it is intermintant??? or maybe the cam timing for bank 2 could be off???

 

Might be time to call the place you got the engine from....there is a warranty??? yes

 

If your compression readings are the same for both banks then I doubt one bank would be out of time. If it was it should read lower compression on each cyl of that bank vs the opposite bank.

 

I believe(not sure its been a while)the 5.4 2000 MY was non power improved but the 2001 up was power improved. With that said are you sure you have the correct intake gaskets for your cyl head to intake manifold application? Also are you sure that the cyl heads on this Jasper engine are non PI so they match with your non PI intake?

 

99+ 5.4L will be PI. But, is it possible he got a non PI jasper engine and put his PI intake manifold on, who knows.

I would wonder, did you use the proper torque procedures for installing the intake manifold? There is a sequence that is very important to follow, if not, it will leak. And which gaskets did you use? Did you use your old injectors and cop's?

I would still go over everything one more time... connectors, ground straps etc..

 

Did you connect the harness to the CHT sensor which is located on the driverside cyl head? That should trigger a code but who knows and may not cause your problem...just a thought. Have you checked for any pinched wires like between the intake manifold and cyl heads, cam covers, etc.. I guess though that it only happens at idle and only on bank #2. Are you sure its all four cyl's on bank two or does it just seem like it? I would try switching the COP's from bank two over to bank one and see if the problem follows the COP's. A low level miss like you are having may not throw a code and can be caused by one or more bad COP's.

 

Still missfiring. the CHT sensor is hooked up. I was thinking I could have a injector stuck open and ive removed all injectors and swaped right bank to left bank and the same Cyls are still missfiring. It appeard the ECM is de fueling the left bank. The left side O/2 sensor is reading 1500+ Mv where the side that is not misfiring reads some where around 750Mv Im baffeled??

 

also I was able to obtain a smoke machine to test the intake and Evap system and there were no vacuum leaks to be found.

 

Under 300Mv is lean and over 600Mv is rich so your leftside is not "defueling" it is rich from the raw fuel due to the missfire. Not sure if that is what you mean or not. Can you have your ECM tested? What was the reason for original engine failure?

 

ok so it seams the left side is rich because of the 1500 Mv and it shows negitive numbers if you look at the fuel trim. I thought there might be a Cat Conv in the head pipe and i remove it to check it out and found no restrictions. so you think it could be the PCM??

 

Compression readings were the same across both left and right bank so it wouldn't appear to be a timing issue. You have done a good job of checking just about everything out it seems. Sometimes you have to get back to basics. Your sparkplugs could be seriously fouled at this point and not functioning right on the left bank, may want to remove them and check. .
Usually a misfire of all four cyls on one bank is a wire harness issue or the timing chain for that head is off a tooth or two. I know you have new COP's installed but I would not trust them completely.. easy to checkout by swapping them to the other bank. What type of failure did you have with the previous engine?