2003 Dodge Dakota O2 Sensor Readings

SPIDERMONKEY1187

MEMBER
2003 DODGE DAKOTA

Engine Performance problem
2003 Dodge Dakota 6 cyl Two Wheel Drive Automatic 83k miles

My vehicle is very slow to accellerate. I have an OBD2 diagnostic software suit from OBDCOM. There is no MIL set. There is a puffing/hissing sound coming from my engine bay: I have not replaced anything yet it is still stock. I have captured data from both O2 sensors, and Engine RPM and generated a graph. At around 2500 RPM which is very hard to maintain manually my Primary O2 sensor's readings are very erratic. Shouldn't it stabilize at a constant environment. I also noticed the secondary sensor going above 1v is this an issue?
I believe the problem is due to an exhaust manifold leak letting ambiant air into the system. I would like to be a little more positive about this before I spend money on those. Also a secondary question. If I replace the exhaust manifold will there be much benifet if I replace them with headers? Thank you for your time!

5 Replies

2CARPRO JACK

MECHANIC
11,533 POSTS

You may have a partially plugged exhaust, this will cause slow acceleration and can create exhaust leaks due to too much backpressure. Try loosening the flanges at themanifolds and see if it has better acceleration, if so the cat/cts may need replacing. Headers are more of a choice for the vhicle owner, personally I dont think the maintenance is worth the 3 HP you may get out of it. They loosen up and leak, plus they need to be emissions compliant.

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Friday, August 14th, 2009 AT 7:54 AM

SPIDERMONKEY1187

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It passed CA smog test last year and this problem has been going on for a while. Should I get the CAT tested?

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Friday, August 14th, 2009 AT 11:13 AM

2CARPRO JACK

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Might not be a bad idea to have the backpressure checked. Have you checked fuel pressure as well? The rear sensor going out of range a little could be caused by the cat efficeincy getting worse

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Friday, August 14th, 2009 AT 11:36 AM

SPIDERMONKEY1187

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Thanks for your help with my question. As I removed the exhaust manifolds I noticed one of the bolts on the drivers side was already broken off. When I took off the drivers side manifold I noticed what looked like a spot where gas had been escaping. Attatched is a photo of each for comparison. I think that was the problem though. Now I have 3 bolts stuck in my engine that I have to get out. Can you provide some advice as I imagine this is going to be a difficult adventure. I have a tap and die set but I don't have alot of experience in this area. Any advice is appreciated. Also is there any inspection criteria for the exhaust manifolds? Things I should look for/do to them while they are off? Thanks guys I reall appreciate your help!!!!!!!!

Mike

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Thursday, August 20th, 2009 AT 7:45 PM

2CARPRO JACK

MECHANIC
11,533 POSTS

If they had broken bolts, you may want to have them surfaced slightly to assure a good seal. As far as broken bolts, that can get tricky and costly if you make a mistake.I use LH drill bits, they spin backwards so that they are trying to unscrew the bolt while you are drilling, sometimes they just back right out. Otherwise you need to use easy-outs once the hole is drilled (down the center of the bolt)