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bykerdude59
Dodge Dakota
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5/19/2005
12:20:53
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 Subject: 5.2 runs awesome when it's cold but...
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I live in southern CA and I have 5.2 5 speed. I had another dakota a few months ago but it got totalled. Anyhow this one seems to be really peppy when I first start it up in the morning (when the temp is at the first line. I have changed the thermostat to a 180 degree. Basically just trying to find out why it runs so much better / quicker when the temp is that low. Is it just because cooler engines run better (I already now that) but if the temp hits 180 which is not high it really doesn't have any balls at all. Could it be something with the air/fuel mixture when the motor is colder? Thanks for any input you guys can give.
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gen1dak
Dodge Dakota
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5/19/2005
15:04:24
| RE: 5.2 runs awesome when it's cold but...
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There are some things that come into play once operating temps are reached. Initially, the computer does not take info from the O2 sensor (open loop). Also, if so equipped, the EGR is not functional. Once normal temps are reached, the computer takes info from the O2 sensor (closed loop) and activates the EGR (again, if so equipped). If the O2 sensor has more than 50,000 miles on it, performance will begin to degrade...beyond 70,000 miles, it should be replaced. If it's ok, look at the EGR. At least, that's the way I'd start.
To address the other part of the question, yes, engines run better when the air/fuel mixture is cooler...down to a certain point, plus, to aid in a quicker warmup, computer-controlled engines have a richer mixture at startup and during warmup (thus more power). Since computer-controlled engines are normally operating at the stoichiometric ideal A/F mixture of 14.7:1, they maintain the best possible emissions, but not the best power. Best power tends to be between 12.5-13:1. So, even in a perfectly operating system, a computer-controlled engine will intially have a richer mixture, so it'll feel spunkier. In your case, it sounds like once once the computer kicks over to closed loop operation, it's getting faulty info, or the EGR is malfunctioning.
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ScojoDak
Dodge Dakota
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5/19/2005
15:06:31
| RE: 5.2 runs awesome when it's cold but...
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Just to add what gen1dak said, that's why we have cold air intakes to help get the air/fuel charge cooler for better performance.
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bykerdude59
Dodge Dakota
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5/19/2005
15:16:26
| RE: 5.2 runs awesome when it's cold but...
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Thanks for the great info. Just need to do a search on what the heck an EGR is and where it is located. The truck has 125,000 and the o2 sensors probably haven't been replaced. So which ones should I replace...pep boys wanted like $125 for just one of them. I believe I saw two on my truck.. I have 1 cat. and a super 40 muffler. As far as the EGR is it something that can be easily replaced? Thanks again
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bykerdude59
Dodge Dakota
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5/19/2005
15:35:26
| RE: 5.2 runs awesome when it's cold but...
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Ok I just read lots of past threads. My 99 doesn't have an EGR. So basically I should just replace the O2 sensor(s) Now which one, or do I have to replace both to all? Does $125 sound about right for one sensor?(not including labor) Any places you may recomend to get them? Thanks
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gen1dak
Dodge Dakota
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5/20/2005
00:41:49
| RE: 5.2 runs awesome when it's cold but...
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$125? Ouch! That seems high. More like $60-80 bucks.
Replace both, and reset the computer so it will see the new sensors. Wasn't sure what year yours was, so no EGR. Dude, isn't your gas mileage awful now? Not sure what you have in your area. Auto Zone, O'Reilley's, NAPA.
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bykerdude59
Dodge Dakota
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5/20/2005
11:11:09
| RE: 5.2 runs awesome when it's cold but...
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Well I thought my mileage sucked but by reading other threads my 15mpg on the highway isn't bad at all. In the city absolutely sucks though because the truck is lacking the power to get up and go, so I tend to put the "pedal to the metal". Thanks for the info. I will head over to pep boys within the next 1.5 weeks. Pep boys is obviously over charging...or quoted the wrong price. Thank you
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bykerdude59
Dodge Dakota
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6/15/2005
11:06:18
| RE: 5.2 runs awesome when it's cold but...
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Ok I replaced the upstream o2 sensor. Still no improvement. Do I need to reset the PCM? Any other ideas out there?
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gen1dak
Dodge Dakota
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6/15/2005
11:29:54
| RE: 5.2 runs awesome when it's cold but...
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You should replace all O2 sensors and reset the PCM.
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bykerdude59
Dodge Dakota
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6/15/2005
11:30:34
| RE: 5.2 runs awesome when it's cold but...
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Also my truck runs terrible when I get into some higher altitude. Each weekend I go up to Calimesa, CA which I read it is 3500 feet. My truck always runs poorly when approaching the higher altitude. Could this have something to do with it?
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bykerdude59
Dodge Dakota
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6/15/2005
11:45:53
| RE: 5.2 runs awesome when it's cold but...
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Well I didn't feel the need to change out both o2 sensors because my gas milage isn't terrible (considering the milage most people I hear are getting) and I have not had any check engine lights. I already feel that the $70 for the upstream sensor was a waste of money as it made no improvement. So to pay another $70 sounds like a waste of money to me. I have ready different people theories on the o2 sensors. Some say replace both, some say just the upstream one.
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Converter
Dodge Dakota
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6/15/2005
14:25:20
| RE: 5.2 runs awesome when it's cold but...
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Check the cats it or they could be bad....goodluck
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bykerdude59
Dodge Dakota
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6/15/2005
14:39:02
| RE: 5.2 runs awesome when it's cold but...
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My cat was replaced 3 months ago.
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bykerdude59
Dodge Dakota
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6/15/2005
15:12:03
| RE: 5.2 runs awesome when it's cold but...
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What happened to speed tweaks? Does anyone still offer the IAT relocation kit? I am not sure I want to cut into the factory wiring and use those cheap connectors. Unfortunately I don't know how to solder. Anyhow perhaps the IAT situation could be my problem. Read lots of past threads on it. Basically when the motor gets warmed up, a loss of power occurs. It may be caused by the IAT getting a false reading from the warmed up throttle body. Well I am just throwing out some ideas for myself...if anyone could let me know if I am a$$ backwards or not that would be great.
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gen1dak
Dodge Dakota
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6/15/2005
15:43:53
| RE: 5.2 runs awesome when it's cold but...
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If you're only going to follow the advice that suits you, right or wrong, why bother? Good luck with that.
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bykerdude59
Dodge Dakota
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6/16/2005
12:16:45
| RE: 5.2 runs awesome when it's cold but...
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Ok, I moved the IAT and that seemed to have either fixed or masked my problem. Later yesterday after doing that I figured what the hell and changed out the other o2 sensor...which again did absolutely nothing for my gas milage. Only now I have a puddle of radiator fluid on the ground...I suspect the heater core since it is leaking underneath the truck by the passenger side firewall. Also the smell of radiator fluid is coming from the vents.
This god damn truck every time I get something fixed on it something else gets f'd up on it. First my rear wheel sensor went out. Fixed it, the a day later my 2nd gear synchro went out. That's a $900 fix plus a new clutch which should be replaced. Now I have a god know's how expsensive a bill to fix the heater core issue. Oh and I got new shocks for my truck..the ES9000 . I can't even get to the passenger / rear top bolt to get the old one out. Seems there is a heat sheild from the muffler that is right in the way of a getting a socket in there. One thing after another it seems.
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Woodrow
Dodge Dakota
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6/16/2005
21:25:41
|  RE: 5.2 runs awesome when it's cold but...
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Well,from what I understand about a heater core replacement is not cheap,you will have to dig deep for this one,unless you are able to do it yourself, which it doesn't sound like you are able to..Sorry for the bad news......Goodluck...
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jayb
Dodge Dakota
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6/17/2005
00:11:43
| RE: 5.2 runs awesome when it's cold but...
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"a computer-controlled engine will intially have a richer mixture, so it'll feel spunkier. In your case, it sounds like once once the computer kicks over to closed loop operation, it's getting faulty info, or the EGR is malfunctioning."
if that be the case, wont it throw codes out?
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gen1dak
Dodge Dakota
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6/17/2005
15:50:40
| RE: 5.2 runs awesome when it's cold but...
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EGR was ruled out as it was determined (after the fact) he has a '99. If a sensor had failed, it should throw codes, but this isn't always definitive either. Nothing's 100%.
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