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4.6 stroker problems.

userbmx1315

userbmx1315

NAXJA Forum User
Location
Dallas, NC
stroker has been running good for the past week. now today on my way home it jumped on my started to run like crap and sounded like it had miss fires. got a P1391 code intermittent loss of CMP or CKP.

my freeze frame shows
fuel system 1 CL
fuel ststem 2 CL-Fault
calc load (%) 23.92
ECT (*F) 206
STFT B1 (%) -1.56
LTFT B1 (%) 8.59
MAP (INHG) 2304
VEH SPEED 45 MPH




not exactly sure what this is saying.
my jeep runs and idles just when i give it gas/ rpms itll back fire or stutter


my other code is
P0463
fuel level sensor A Circuit high input

usually get that one. my gas hand wonders sometimes


any clues?


i tried checking my cps and if i'm right its good.
 
userbmx1315 said:
my jeep runs and idles just when i give it gas/ rpms itll back fire or stutter
Click to expand...
that sounds like a fuel pump to me. check the fuel pressure at the fuel rail.
 
I don't know about the codes, but a good idle and a stumble/problem anywhere else sure sounds like a TPS to me. Try and unconnect the TPS and see if it is any different.
 
it wil get up to 1000-1200 rpms and start to stumble and kick and backfire.
ive already changed the crank and cam sensors and the TPS also. no luck yet.
checked the compression in each piston and they are good.
 
If the rpms get that high, I might suspect distributor indexing.
 
Remove the #1 Spark Plug
Remove the Dist.Cap
Remove the distributor.
Bring the #1 piston up to Top Dead Center on the Compression Stroke. Stuff your finger in the spark plug hole while someone bumps the starter. When yo feel air blowing by your finger STOP.
Use a 19mm socket and turn the harmonic balancer bolt clockwise (only) while keeping an eye on the timing marks on the timing chain cover.
Once the #1 piston is at TDC, re-install the distributor so that the rotor is pointing at the 5 O'clock position when the distributor is fully seated.

A word of caution.
Make sure that you rotate the oilpump shaft with a long screwdiver so that it lines up properly with the distributor. Failure to do so will prevent the distributor from fully seating.

Reinstall the cap
Reinstall the sparkplug
Double check the plugwires to make sure you have the correct sequence.
Fire it up.
 
if the ignition timing isnt a problem. id want to check some on the timing chain and make sure it's ok. also might wont hurt to remove the valve cover and check the rocker arms to make sure they're still on and tight (because of the recent 4.6 build)

also you are sure that all cylinders are firing?
 
I had a 1391 on my 4.6 from a not quite indexed cmp/distro. I never detected the misfire but the pcm did. Now to replace the fuel pump that quit on me last week(luckily was 2 miles from home)--good excuse for the walbro 255lph upgrade.
 
it back fires like crazy. after 1100 rpms. cant seems top get it right. it just done it going down the road.
 
i have already rechecked the ind. on the dist its fine. changed the head to make sure the valves were ok. changed the injectors and fuel rail, changed the cam and crankshaft sensors, even the TPS sensor.
i even took off the exhaust to make sure it wasnt clogged

could it be the the computer? it idles fine then runs like total crap after 1100 rpms. it just happened driving down the road
 
Last edited:
time to put the fuel pressure gauge on the rail and watch while you push the throttle.
 
will this one work?
clear.gif
 
i was told to check the timing chain. but could it really be the timing chain? it cranks like normal and sounds fine up to 1100rpms. i'm going to check the fuel pressure as soon as i get some time off from school and work.
 
userbmx1315 said:
will this work on my 98?
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92699
Click to expand...
You should be able to use that. The fact that it ran well and suddenly started running bad rules out the distributor being indexed wrong and should rule out the timing chain unless you didn't install one of the guides or something. The chain would have to be pretty damn loose to slip. I would check the valve train to see if anything bent or something. It sounds like maybe a fuel pump issue so check the fuel pressure and see what you have. Since you are not getting a CEL it's gonna be hard to troubleshoot.
 
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