ASOG Forums

okay, this is kind of a weird problem that i've had for a while, and i'm not really sure of the cause, although it's been suggested it might be my fuel pressure regulator.  it's a long story...  but first, the problem:

when i'm driving at high speeds (65+ mph, although it's done it at lower speeds) and/or high RPMs (3K+), my engine seems to lose power for a split second.  it can happen one time, or happen a bunch of times, and it's completely spontaneous.  there aren't many symptoms to be honest.  most of the time the biggest symptom is i can feel the car jerk, and i can feel it in my gas pedal.  sometimes i can visibly see the RPMs drop in the RPM gauge.  my cruise control will kick off, and if my check engine light happens to be on at the time, it will flash.  other than that, i don't think there are any symptoms.  it doesn't make any weird sounds, and everything else seems to work fine.

edit:  i have no idea how i forgot to include this the first time, but last nite my car wouldn't start.  this is a new development because i've had this "cutting out" problem for a long time, but this is the first time i've ever had problems starting my car.  i sprayed some intake cleaner in the intake, and after a rough start i got it going, but when i went to start it again today it wouldn't start.  i haven't done anything to it since.

i decided to take a video of my gauge the other day while i was driving, just so you can kinda see what's going on:

http://video.averett.edu/~bryanm/rpm_drop.mov
http://video.averett.edu/~bryanm/rpm_drop.avi
(they're the same video)

this is quite frustrating, however, because for one i can't use cruise control, and when i'm going on long trips on the interstate i'm never sure if i'm gonna make it or not.  i wonder if my car is going to cut out completely.

here's where the long story begins.  a while ago i drove to California, and since then my engine started cutting out pretty bad.  not like it's doing now, though; it would cut out any time at any speed, sometimes completely dying.  the only code i got was for the camshaft position sensor (i don't remember the exact code), which i promptly replaced.  didn't affect the problem.  i even posted my problem on the original ASOG forums.  eventually i found out i had a short in one of the wires in the harness near the camshaft position sensor, but using a multimeter i never found which wire was shorted out, so i twist-tied everything together so it couldn't move and the problem seemed to go away.

i've had a million other problems since then (had to replace EGR valve/solenoid, catalytic converter), but now i don't know what the deal is.  i've always thought the problem was related to the short, but someone said the other day it might be my fuel pressure regulator.  could this be the case?  during the last few weeks, i've gotten these CEL codes:

P0420 (Code 64) - Catalytic converter efficiency failure
P0340 (Code 54) - no cam signal at PCM
P1391 (Code 11) - intermittent loss of CMP or CKP

anyway, other than throwing my hands in the air and feeling like these cars weren't put together very well (granted, the first owner of my car didn't take very good care of it, and it has over 200K miles on it now), i don't know what to do.  i'm willing to change the fuel pressure regulator, and although that seems like a viable solution, money is tight and it doesn't seem like these CEL codes have anything to do with the fuel system, unless they are the results of the engine cutting out from a faulty fuel pressure regulator, which may not give any code by itself.

forgive the long-windedness.  any and all suggestions are appreciated.  i'd like to keep this thing on the road as long as possible.  thanks!

96 might have been the one with the bad ECU.  Check with Nykon.  if you're having all kinds of sensor codes, it's possible it's one of them, but not likely.  Check you hood, is your battery hitting the hood?  That could explain the loss of power.  Does your radio go out when the engine dies?

the first time my car was having problems, before i determined it was a short, we replaced the ECU.  granted i replaced it with a used one from a salvage yard that may have also been a 96, but at this point i don't think it's that.

as far as i know the battery's not touching the hood, and i think the underside of my hood is at least partially insulated anyway.

nothing else cuts out when the engine cuts out, not the radio, not anything.  my lights don't even so much as flicker.  if it was a battery problem it would probably cut out all of the time i would think, and not just at higher speeds/RPMs.

the fact that it won't start is leading me to think it might be the fuel pressure regulator, but that doesn't explain to me the CEL codes i'm getting, unless the lack of fuel to the engine causes it to cut out, creating some problem with the camshaft position sensor, or perhaps i still have the problem with the short in addition to some kind of fuel problem.  again, however, if the short was a problem i don't know why it only acts up at higher speeds, unless somehow the engine is hotter and is affecting the conductivity of the wires, or something along those lines.

i think the catalytic converter code may be unrelated, because i've had to replace the cat before when it stopped up, although i had EGR valve problems at the time.  i suspect the fact that the engine is so old and is burning oil (not too severely) may be causing the cat converter codes...

Well the FPR is an easy piece to replace, but I don't know how much they are.

I am going to say it actually sounds like your timing belt is missing some teeth.  It sounds kinda like the reaction that my Venge had when my idlers grenaded and it skipped.  If it is slipping because it is missing teeth that could cause the intermittent problems and then if you stopped the engine in just the right spot it will be out of time and the computer won't let it start so you won't bend a valve.  I would pull the timing cover off and check it out.

when was the last time you had it changed??

That is the only thing I could think of that would cause it to have a loss of power at 3k RPM (that is pretty much the start of the powerband I think), intermittant misfires, a code for no cam signal and lack of starting now. 

The ECM problems don't match these symptoms.  I will get a copy of the TSB on the ECM if you would like it though.

very interesting you mention that, because the timing belt was changed fairly recently, by myself and my dad.  i actually noticed it seemed to idle a little rougher after that and my dad said we should check the timing, but it's such a hassle to change those things without a garage i let it slide.  i didn't think it could be the timing because a long time ago i had a car and the timing belt was off just one notch and the whole thing shook terribly.  i'm not experiencing anything like that, and my Venge seems to not have lost any power either (considering it has so many miles), which was something else i experienced with the other car.  i just assumed that it was idling rough because the engine has so many miles and is burning oil, causing misfires and all kinds of emissions problems.  but maybe a timing problem would affect the Avenger differently.  the other car was a 93 Dodge Shadow with a completely different motor, not DOHC (or even SOHC for that matter).

my dad certainly knows more than i do about this stuff, perhaps i should've listened to him...

well i feel stupid because it almost certainly feels like a timing belt issue is the problem.  my only concern is that from what i remember these episodes where my engine has been cutting out have lasted longer than my idling problems since the timing belt.

one other thing, i do remember the first time my car acted up really bad (with the engine cutting out) was when i used some kind of hi-octane fuel injection cleaner.  "the outlaw" or something like that.  would that point to a fuel system problem as well, or are all of these problems unrelated?

i also feel like it might be a fuel system problem keeping the vehicle from starting and not the computer, because the engine will turn over.  if there's a certain "spot" at which the engine won't start, wouldn't turning it over remedy that?  in addition, that doesn't explain why it started yesterday after i used the injection cleaner...

now that i've thought myself in circles i'm not sure about the timing problem.  wouldn't it manifest itself in a lack of power or a rough ride?  true, my car idles rough (after it warms up), but it does have 202K miles on it.  it probably wouldn't be a bad idea just to check the timing anyway.  thanks for all of the ideas.  i'm always open to more...

It could be off by half a tooth.  Mine was when my components went away and when we put it back together we were off by half a tooth and it loped and sounded like I had an RV cam in it or something.  My powerband was all sortsa screwed up and it drove kinda funny.  You might just be off by a tooth too.  I would double check the timing on it first of all.  I am sticking to that answer.  Fuel problems usually feel different... kinda hard to explain that.

okay, thanks a lot for the advice.  i'll go ahead and check the timing.  i'm planning on going to a junk yard next week so i think i'll grab a fuel pressure regulator while i'm there just in case.  i doubt they would charge more than a few dollars for it; brand new at Advance i think it's $60.  i think i might grab the connector and as much of the wiring for the camshaft position sensor while i'm there as well, because i've been getting these camshaft position sensor codes for years, way before we changed the timing belt this last time.  i'll post whatever i find out.  thanks again.

update:

well it's definitely not a fuel problem, because it wouldn't start at all today, even after i used intake cleaner.  so i started checking all of the ignition-pertinent stuff: plugs, spark plug wires, etc.  since i'm getting camshaft position sensor codes i fiddled with those wires too.  tried to start it, and it started right up.  while it was running, i poked around at the CmPS connector, and the engine started cutting out on me. 

i replaced the CmPS years ago, but the funny thing was all of the parts stores (Advance, Autozone, NAPA, ...) had a CmPS with a different connector, so you had to buy an additional connector as well, cut off the factory connector, and splice the new one in.  i didn't want to go cutting wires if i didn't have to, i just went to the dealer and ordered the OEM CmPS.  that was where i messed up.  apparently the parts stores sell the CmPS with a different connector for a reason; there's some kind of defect in the original design of the CmPS connector that keeps it from maintaining a good connection all of the time, and it needs to be replaced altogether.

so anyway, i'm gonna replace the CmPS and the connector on the car and see if this finally fixes my problems.  i'm pretty sure that that's at least what's keeping it from starting, which is the major problem at the moment.  i'm gonna do that before i check the timing and see if it fixes my other problems as well.

What's a CmPS and where is it located?

Camshaft position sensor.  Its on the drivers side of the head on the front corner of your valve cover.

Thanks!

My venge is dying at low speeds and blips at high speeds. No CEL codes. I'm changing out the ASD relay to see if that fixes it.

i don't know why but i had trouble logging into the site, so i just created a new login.

...anyway, i just thought i'd post an update.  i changed the camshaft position sensor, and that fixed the problem that was causing it not to start.  i figured out that it wasn't the CmPS itself though, it was the connector.  somebody must have figured out that these things were designed poorly, cause when i got the new one it came with a new connector with a completely different design, so i had to replace the old connector.  once i did that, the car started just fine.

i was still having the problem where the engine was cutting out at high speeds, however.  so we looked at the timing, and sure enough, one of the cams was off by a notch.  we fixed that, and that seemed to do the trick.  ...although my water pump broke immediately after that, making me wish i had done it when i had the timing belt off in the first place.  with over 200K miles it was due to be replaced anyway, but i just didn't think about it at the time.

thanks again for everyone's help, esp Nykon who hit the nail on the head with the timing belt thing.

Glad to hear it all worked out, even if it took some more work than you originally planned.

woooo!!! glad to hear your car is running good again, i had a problem little bit more frustrating where my car would completely die in the middle of driving and would not start up for several minutes/hours.

had my crank sensor replaced... but then it didnt do the trick.... but several days later car started to run fine (3 knocks on wood), since then no problems

maybe it was the CPS  ???

(i am so glad my ECU order didnt go through, other wise would've waster 300$)