Stroker, & timing, & cams....Oh my!

[Frank Z]

So I’m at approx. 13k on my 4.6L and have had a CEL since day one. The code hasn’t changed since I first started the motor and to be honest…I’m freakin’ sick of seeing that ugly amber glow. So here’s the particulars:
4.6L
Crane Cam # 753905 (advanced 4 Deg.)
New Cat. (OEM Style)
New O2 Sensor after cat
’99 intake
APN Header
New-ish Crank Position Sensor
OBDII Error Code P1391

I’ve talked to the machine shop about it and they seem to think it’s the intake opening a touch early and that inturn allows a small amount of fuel/air vapor into the exhaust which may be causing the O2 sensor to see slightly more hydrocarbons. I haven’t had the emissions tested, it’s not required here anymore.

If the CPS were causing the problem I would’ve been stuck on a trail along time ago.
Since it’s a 97, adjusting the TPS isn’t possible.

Before you suggest it, tape over the CEL isn’t an option.

Any suggestions on how to fix the problem?

 

[MaXJohnson]

Is it possible the routing of the CPS wiring is loose or mis-routed since the stroker was installed? This may result in the wiring rubbing against a sharp edge and wearing through the insulation. Could cause an intermittent short in the signal from the CPS back to the compuda

 

[Frank Z]

No, I made sure the routing of the CPS was well away frop any possible damage before dropping the motor in. I wish it were that easy.

Thanks for the reply!

 

[corbinafly]

So I’m at approx. 13k on my 4.6L and have had a CEL since day one. The code hasn’t changed since I first started the motor and to be honest…I’m freakin’ sick of seeing that ugly amber glow. So here’s the particulars:
4.6L
Crane Cam # 753905 (advanced 4 Deg.)
New Cat. (OEM Style)
New O2 Sensor after cat
’99 intake
APN Header
New-ish Crank Position Sensor
OBDII Error Code P1391

I’ve talked to the machine shop about it and they seem to think it’s the intake opening a touch early and that inturn allows a small amount of fuel/air vapor into the exhaust which may be causing the O2 sensor to see slightly more hydrocarbons. I haven’t had the emissions tested, it’s not required here anymore.

If the CPS were causing the problem I would’ve been stuck on a trail along time ago.
Since it’s a 97, adjusting the TPS isn’t possible.

Before you suggest it, tape over the CEL isn’t an option.

Any suggestions on how to fix the problem?

translation please??? Is it an O2 sensor code?

 

[5-90]

P1391 is a Chrysler-specific code (as I've been able to find) meaning "Intermittent Loss of CMP or CKP Sensor Signal."

With that in mind, I'd start by making sure that the wiring to the crankshaft or camshaft position sensor didn't get buggered up when you put in the stroker (and I'd probably check the wiring to the cam sensor a little more thoroughly than the wiring to the crank sensor. Although, if the signal is regained from either sensor quickly enough, you probably won't notice anything from the seat...)

(When working from a code, I've found it helpful to start by actually looking the code up. While the code isn't always a direct pointer to the problem, it can get you looking in the right direction. I've listed codes from the Jeep FSMs on my site in the Tech Index...)

 

[Frank Z]

Been there, done that.

 

[5-90]

Been there, done that.

And no wiring faults at all? Don't stop at the connector - check for a pinched wire or something like that. I hate to be the one to tell you this, but you're actually going to have to inspect the entire wire for signs of damage (been there, done that...)

 

[Frank Z]

The stroker has been in for almost a year and I've been searching for a CEL cure since it first happened, so yes the wires have been checked numerous times.
FWIW, I'm going to take the heep to a shop that has a diagnostic scanner and see what it tells me.

 

[Dr. Dyno]

Disconnect the battery negative lead for at least 10 minutes to reset the computer, then reconnect it and see if the CEL comes on again. If you're lucky, the CEL might stay off.

 

[j99xj]

This is the kind of stuff that keeps me from wanting to build a stroker.

 

[Davesxj]

I drove about 1000 miles with my CEL on after my stroker swap. The code it gave me was for an O2 sensor..

Problem ended up being the battery temp sensor??!!?... I had just forgot to plug it in.

Just thought I'd say sometimes it isn't what you are expecting so don't rule out the absurd.

 

[5-90]

The stroker has been in for almost a year and I've been searching for a CEL cure since it first happened, so yes the wires have been checked numerous times.
FWIW, I'm going to take the heep to a shop that has a diagnostic scanner and see what it tells me.

Just wanted to make sure - a lot of people check the sensor (or whatever the code is on about) and then stop.

 

[jeepinwi]

This is the kind of stuff that keeps me from wanting to build a stroker.

My stroker has been running for exactly 1 year and has about 18k miles on it. I've had a CEL for the past about 10k miles, but I've ignored it. It has always came up as a "cylinder 6 misfire", but I haven't found the problem yet. The engine still runs the same as the day I installed it, so I haven't been bothered by the CEL.

 

[codyj86]

check pin drag on the connectors too. working in a stealyershit (dealership) you'd be surprised by how many female terminals are 'loose' shall we say....
plugging and unplugging just makes it worse. and like 5-90 said. take the entire wire out of the loom and inspect it. if there is a spot in it that so much as looks strange, splice in a new section.

also, is this code a constant history code? or current? how many times does it fail if it is a history code? when does it fail? engine hot? cold? rain? off camber situations? again, like 5-90 said, could have gotten pinched and broken inside the insulation.

 

[Frank Z]

So here's the latest poop.
The CEL has been on for nearly a year. I replaced the cam position sensor not long after completing the stroker break in, it had seen better days. The new sensor had no effect on the CEL or the error codes.

I checked out the CEL and it measured within spec, it's been a while so I couldn't tell you what the exact measured values were.

Flash forward to this morning. I'm 4 blocks away from home and am heading to my son's high school and then to find a shop with a diagnostic scanner. Red light turns green, I give it a little gas...and the jeep shitz the bed. Tried to restart and the engine turned over, spit some smoke out the tailpipe and nuthin' else. A guy behind me gave me a quick tow home.

I got it into the driveway and it started up just fine but died as soon as attempted to pull into my garage. After much cranking it started again so I held the brake and ran the RPMS up a bit and nursed it into the garage.

I pulled the codes via the odometer and got Code #11...dead crank position sensor.

The new sensor is in and the error codes have been cleared. I've had it out for a few test drives and so far so good. The CEL hasn't come back on...yet. Maybe the bulb finally burnt out?

If anything else changes I'll post up again.

Thanks for the info folks, I do appreciate all of the input.

 

[Wrectec]

Yeah the CKPS can still cause you problems and not be completely bad (no start) as you had before, they can also cause cam sensor problems as well since they share the same feed. As far as your machine shop saying the O2 sensor might be reading too many hydrocarbons...well the O2 sensor as the name suggests only reads oxygen and the computer just "assumes" a vehicle is running rich or lean based on high or low levels of oxygen so you can see why this sensor is mistakenly replaced so often. But any who glad you are back and running again.

 

[Frank Z]

I've never heard of a bad CPS lasting for nearly a year before giving up the ghost. Just my luck I guess.

 

[corbinafly]

I've never heard of a bad CPS lasting for nearly a year before giving up the ghost. Just my luck I guess.

Happened to me.

 

[streetpirate]

Happened to me.

x2

started out it would die when i went over speed bumps. went like that for almost a year, then wouldent start one day. it was the cps.

the speed bump thing sucked when my starter was going out, every time the heep died you had to jump out and smack the starter with a tire iron to get it going again.