| From | Message |
ES
Dodge Dakota
JOIN HERE
8/18/2006
02:20:33
|
 Subject: Flat spots in rpm ranges
IP: Logged
Message:
Im having strange flat spots in certain rpm ranges.
Setting my vehicle in cruise control in these flat spots kills my mileage. Its a difference of being at 13 mpg and 16 mpg.
If im in park an slowly bring the rpms up at around 1,250rpms they will then drop to 1,000 then i have to press the gas a bit more to get them to slowly climb after the initial drop and once the rpms climb to around 1,500 they take off and rise quickly up until the next flat spot at around 2,000 then at 2,250 they rocket up until rev limiter. You can even feel this same pattern when accelerating. It feels really boggy and unresponsive around the flat spots when driving around town or just goosing it on the highway.
Ive replaced all the parts on the tb for either being bad or lazy. Ive also replaced the 02 sensor ahead of the cat. Im not sure what else to look at.
Your thoughts? Thanks in advance.
3.9 4X4 quad cab 4.10 gears, custom intake, port matched manifold, 1.7 RR, exhaust,msd ignition.
|
Mike Stager
Dodge Dakota
JOIN HERE
8/18/2006
23:46:08
| RE: Flat spots in rpm ranges
IP: Logged
Message:
Do you have a vaccuum gauge handy? disconnect the vaccuum line going to the firewall and connect it to the engine side of the vaccuum line and see what is going on with vaccuum. Measure idle readings, and snap the throttle and watch how the gauge reads. If it is slow to respond, you may have a cat plugging up on you. If it flutters, you probably have an intake gasket leak.
If I've learned anything over the years, the Vaccuum gauge is the most important diagnostic tool you can have for any engine. If you have a haynes manual, there is a section in there specifically for checking your engine with a vac gauge. Can't stress it enough. It will tell you many things about your engine and is worth the $30-40 you pay for it.
|
ES
Dodge Dakota
JOIN HERE
8/20/2006
23:29:19
| RE: Flat spots in rpm ranges
IP: Logged
Message:
The vaccuum reacted the way it was suppossed to it was smooth at idle and fast to react when bliping the throttle. Funny thing is i checked vaccuum a few days before i made this post.
I do have a new problem now...Only lucky thing about it is its happening before a trip i was planning on instead of during. LOL
What happened is i was driving in town and accelerated to speed after someone in front of me took a slow turn. A little after the acceleration while holding speed the engine started to cut out, i gassed it let off the gas, it just kept cutting out constantly with no rythm to it. It cleared up quickly so i thought eh must have been water. It started cutting out again so i figured ill get some water treatment at a near by store, though this time when the missing cleared up it turned into pinging from hell. It sounded like a million hammers on metal every time i would barely touch the gas.
I havent had a chance to give it a look over yet but im hoping i find that it is a bad cap and rotor but considering that the cap and rotor is 3,000 miles old it may not be the problem.
|
?
Dodge Dakota
JOIN HERE
8/21/2006
13:06:36
| RE: Flat spots in rpm ranges
IP: Logged
Message:
Possible coil -shorting out the high voltage
|
ES
Dodge Dakota
JOIN HERE
8/21/2006
15:07:42
| RE: Flat spots in rpm ranges
IP: Logged
Message:
Found the new problem damn rabits chewed up the o2 sensor wires. First it was the squirrels now the rabbits...
Whats annoying is that every problem ive had with this truck wont trip a code. I fiddled with the chewed up 02 wires and now my truck wont start. Talk about a sensitive machine yet the pcm seems to remain oblivious to problems.
?:Possible coil -shorting out the high voltage
Do you mean for the flat spots or the pinging and cutting out i had?
|
bludak
Dodge Dakota
JOIN HERE
8/21/2006
19:20:13
| RE: Flat spots in rpm ranges
IP: Logged
Message:
Just throwin' this out there, but how about the MSD? Do you think it is O.K.? This sounds like an ignition problem. First slow to advance, then too much advance to make it ping. Do you still have your stock ignition system? Would it be hard to change it back, or get another MSD box.
|
J and J Auto
GenII
8/21/2006
21:19:07
| RE: Flat spots in rpm ranges
IP: Logged
Message:
Well I had a porkypine knock my PVI injection
system off heard a noise when backing up seen
something driping and quills in my tire
so don't let the mice bother you LOL
if it still does it check your fuel presure
Larry
J&J Auto
|
ES
Dodge Dakota
JOIN HERE
8/21/2006
21:24:08
| RE: Flat spots in rpm ranges
IP: Logged
Message:
After sorting the chewed up 02 it still wouldnt start. So i started to look for something loose or disconnected and found a loose ground at the pcm. Tightened that up and it fired right up, idle smoothed out, missing completly gone, and no more pinging in all rpm ranges.
Now it runs like it used to but still has the same dead spots in the rpms. Im starting to wonder if its crappy tuning in the pcm.
Ill look at the fuel pressure but im curious do i get better results driving it around with the testor connected or can it be accuratly checked in park?
|
bullet
Dodge Dakota
JOIN HERE
8/23/2006
21:02:44
| RE: Flat spots in rpm ranges
IP: Logged
Message:
I had that problem on a 2001 once and it was the Thottle position sensor. The check engine light never came on but the sensor was bad. It cost about $35 to replace.
|
| | P 1 |
|
Post a reply to this message:
Username Registration: Optional
All visitors are allowed to post messages
|
