Bigdawgzofny

Have a 98 xlt with a 4.6 romeo. Had to change engines since it had a spun bearing and didnt want to rebuild it so got my hand on one from a crown vic with 70k miles on it...looks clean....oil was clean ...plugs was clean.

Did the swap and truck starts up but it idles bit rough sitting at 675-750 rpm.Giving it gas will get a ping,tap in throttle body,intake area.Only code im generating is po174.....through multi hours of idle.


Cleaned and took readings on the MaF and it reads good.
New PVC and tubing and elbows.
No changes with carb spray test pretty much around the whole top end.
No noticeable leaks at exhaust manifolds.
New motorcraft plugs with grease.
Main harness plugs ins cleans with electronic cleaner and greased.
Both O2 sensors reading good with scanner and voltages changes fine with carb spray introduced....passenger side o2 is also new while drive side is not.
EGR regulator solenoid tested out fine.
New fuel filter.

Fuel pressure readings from valve on fuel rail reads
KOEO 38
KOER 30
With regulator unpluged goes to 40 psi

Im about to take the intake completely off and reseat it or change gaskets but would rather not if there are other things i might be overlooking.Been stumped over this for past 2 weeks and dont want to bring it down to a mechanic shop if i dont have to...but im running out of ideas heh.

Any help would be a godsend right now heh!

Bigdawgzofny

Anyone know if Faulty DPFE would throw a po174 code?
I havent checked that yet but thought it would give a different code with something wrong with egr system.

13Harleyfan

Did you get to hear it run before you bought it?

Bigdawgzofny

No the engine was in the crown vic in the salvage yard.Used the block and heads and switched everything over from the f150 engine.

Bigdawgzofny

Update:

Down to last things to check:

Start taking off fuel injector clips and get to #5 and 6 cylinder and no change when remove em.
R3move spark boot and getting plenty of spark.
Hook noid light up and they are blinking like its a disco on both.
Run stethscope to both injectors...they clicking just fine so they are activating.

Only things left is loss of compression which is prob a stuck valve or maybe head gasket or clogged injectors. Since not losing oil or coolant kinda leaning towrds clogged injector ....time to go out and buy a compression tester i guess heh.

Bigdawgzofny

Well checked the compression and anything ;looks ok at around 120.
switched some injectors around and still same issue with it running lean on second bank.Pulled the injectors and no change in rpm on cylinders 5 and 6. Pull injectors on all other cylinders and there is a drop in rpm.

Not sure where else i should focus on.

KL Mallender

What year Crown Vic is the engine from? hopefully it is a 2000 and older.
Next possibility is if you are using 1995 and older intake manifold gaskets with the 1998 truck manifold.
Good luck,

Kevin.

Bigdawgzofny

98 crown vic

Using the intake gaskets from the f150 engine since i had to use the intake and throttle body from the original engine.

KL Mallender

About the only other possibility I can think of is that maybe a rocker arm has popped off, if it was an exhaust rocker it's possible the tinking sound at the throttle body is actually a backfire up through the long runner intake?
Sounds like you've checked things over pretty good, so I'm grasping here.


Kevin.

Bigdawgzofny

Ok here is a update:
installed new intake manifold gasket and not seeing much of a change still rough.

Here is live data from scanner if any can point to somthing amiss from thewse4 numbers.

this data is from truck running idle for about 30 mins and observing each data point for roughly 30 seconds.

Calc Load% 20.9-23.1
ect 190 degrees
stft b1 -3.9-2.3
Ltft b1 4.6
stft b2 -1.5-7.8
Ltft b2 20.3-22.6
eng rpm 677-729
spark advance 11-20
IAT 75 degrees
MAF (lb/min) .685-.816
TPS(%) 18.4

o2s b1 s1(v) .090-.790
stft b1 s1(%) -3.1-2.3
o2s b1 s2(v) .730-.790
stft b1 s2 (%) na

o2s b2 s1(v) 0-.750
stft b2 s1(%) -3.9-4.6
o2s b2 s2(v) .025-.785
stft b2 s2(%) NA

Update: went outside and checked the ltft and its increased now the range is 28.1-29.6