I have a strange one that i had to deal with once. My o2 sensore wire has a ground shield around the wire. This shield is connected to ground near the ecm. My problem was from y mechanic replacing my o2 sensor and splicing the ground wire with the o2 wire. Hence dragging my o2 voltage down to ground making the ecm think its running lean, it then poured more gas in and was actually running ritch. When the engine starts up it waits fro the engine to warm up before pulling data from the o2 sensor which leads me to believe that it might have soemhting to do with your problem. Forgive me if this was already covered there was too many posts to read them all. When i was having this problem the car ran horrably, would stall at lights and would be unable to start again without waiting for all the extra fuel to drain out.

Another thing to check is your egr valve, if its leaking or opening up at the wrong time it can cause all kinds of wierd running problems. Try pushing on the plunger while the engine is acting up to see if it changes ur idle speed, it should pretty much stall the engine if u press the plunger up for too long.

HTH

Hey thanx for the info Nick. Yeah, I already covered the O2 sensor. Put a brand new one in and the wires are fine. You're right about my truck running rich. You're also right about the truck running without the info from the O2 sensor at first. On cold start the truck runs without that info cuz there is nothing for the ECM to retrieve (open loop). After reaching running temp, the ECM retrieves info from the O2 sensor (closed loop)and adjusts the air/fuel ratio accordingly. When we hooked up my truck to the Sniffer, as I've come to know it (Exhaust Gas Analyzer), it said I was running rich. We disconnected the O2 sensor and the levels dropped. So I went ahead and changed it. No change in performance though.

We've done the EGR thing too. Again, it's seeminly fine. But I do appreciate your input. There are a lot of posts on this thread but I am grateful for everyone who takes the time to input their ideas. Between all of us, we will squash the gremlin. Though I get extremely frustrated and say things that almost make my truck blush, I won't give up on her. She's not only my daily driver, she's truly my best friend. Whoops, I think the cat just heard that... <img src="/forums/images/graemlins/ignore.gif" alt="" /> <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

Have a Happy Turkey Day...

dawn...

how 'bout that little grounding strap on the back of the head? and any/all other grounds?
<img src="/forums/images/graemlins/smile.gif" alt="" />

Hey Phil. Thought about that too cuz on rebuild, we forgot one of those and the truck did some pretty messed up stuff with the dash lights. Talk about gremlins.... <img src="/forums/images/graemlins/evil.gif" alt="" /> The normal "beep" you get when you start the truck sounded like a chirpy critter that was having the life choked outa him <img src="/forums/images/graemlins/ignore.gif" alt="" /> <img src="/forums/images/graemlins/rolleyes.gif" alt="" />. But we quickly figured out the problem (Cudos to Sanels once again) and put another one in, problem solved.

But hey, like I keep on saying...I so appreciate the advice and suggestions.

dawn...

I know this might sound very strange, but I have a 2003 Xterra SE SC and it had the exact same problems you are having.... After several weeks in and out of the shop only to be told nothing is wrong because it didn't happen all the time and the shop could never get it to lose power I figured out that there was a problem with my gass cap... new gass cap problem solved... strange I know, but it worked...

Somebody please play Santa and give me the gift of insight that will make this truck happy. I have been 'round it, and through it, yet still the gremlin rules.

Tuesday the truck was, once again, the center of attention in the lab. The instructor took his trusty stethescope to assist in diagnosing what we all thought we heard..."an air whoosh at the intake somewhere." In the end he concluded that it may be the normal sounds you hear entering the throttle body. But in five years I've never noticed this before. I have changed the throttle body assembly but that noise was there with the old one as well.

He then began checking each plug wire in turn. Number one and two were not sparking each time. The first time he took them off there was nothing, the second time, he got zapped, the third time there was nothing again. We agreed that those cylinders may not be firing all the time. I have changed the coil, rotor, and wires. The cap and rotor were new as of June and the cap looked excellent so I didn't bother with that. The only thing left as far as electrical that would make it misfire would be the dizzy. I had heard a clicking noise coming from the dizzy last week so I thought "BINGO", problem solved right? Wrong.

Yesterday I switched out the dizzy with another and still no change. I drove the truck home and at first it seemed fine then it was right back to its old symptoms. Depress the pedal and the truck just won't go. Then suddenly you get a spot where you are able to accelerate but no "umph". I did notice that if I put it in "2" I am able to get a bit more "umph" a bit more quickly and with a lot less "deadness" in the pedal. It still feels as if it's lurching and I can still put it in neutral and rev it as if nothing is wrong. But once in gear it is sputtering. The idle is aweful...jumping all around most of the time.

I put it in reverse to back into my garage which has a slight incline and the truck did not want to go at all. I managed to get it in there but was shocked that I was nearly unable to use reverse.

K', whose gonna be Santa? I know someone's got the advice I need, we just haven't realized it yet.

dawn...

I will apoligize first and then give my advice. I didn't read the whole thread so if this has been suggested forgive me.

What about the ECM? Have you tried a different ECM? Just a thought if you have access to one or someone lives near you with the same truck. Just plug the new one in and see how it acts.

Tomorrow or Saturday I will check the injectors with that fancy injector probe light thingy. I could do the NOID light thing and I will if this fails but I'm pretty sure the ECM is functioning correctly and the NOIDS only tell you if the ECM is sending the signal correctly or some crap like that.

I will also listen with the Steth to see if all injectors sound the same and I will use the spark tester to be sure they are sparking and.......WAHHHHH, what else??? I'm at a loss here but I'll keep plugging away at it. Not only cuz I want to cuz I want my truck back but also cuz I want to say to everyone who has said to park my truck....it's junk...."IN YOUR FACE"....and then have a beer <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" /> or two or three....

Aw c'mon!! You're killing us with suspense! Ok, here's a long shot. When it's warmed up, just as an experiment, take the vac tube off your EGR where it connects at the transducer and hook it direct to a port on the throttle body chamber and see if the power returns. DO NOT drive around like this! You will be pulling loads of hot exhaust gas into the throttle chamber that will cook the day lights out of it and anything attached to it if you run it for more than a minute or two. Just pull out of the garage and back in. If the power has returned the EGR circuit IS the problem. The trouble with the finger push/engine dies method of EGR check is the EGR port can be clear but, that doesn't confirm you're getting vacuum to the EGR. The EGR works in such a narrow range of throttle positions it's tough to check the vacuum too. Presuming you checked out that little thermal valve that feeds vacuum to the transducer (top-shaped brown thing) pull the bottom tube off the transducer with the engine running. You should feel hot exhaust gas coming out of it. If you do not feel hot gas you need to take off that steel tube it attaches to (firewall side of throttle chamber) and clear it and the opening it threads into. Mine was so gunked up with carbon I had to use carb cleaner and a drill bit to clear it. Second thing is check the top of the transducer. If it looks bubbled or scorched that means the membrane burned through and it's not going to work. Replacement is the option. The back pressure transducer only uses the pressure from the exhaust system to actuate and send vacuum to the EGR. If hot gas is getting by, the transducer is defective and the EGR won't work.

Wow, awesome reply RT. I'm gonna do as you say this weekend. Yeah, the suspense is killing me too....in more ways than one. I am able to drive the sucker in cold running conditions only and still feel the "miss" but able to get where I need to go.

And to think, I've been dissing winter!!! <img src="/forums/images/graemlins/rolleyes.gif" alt="" /> Right now, it's my saving grace to get where I need to go in short little trips.

Thanx for the advice and I'll keep ya'all posted. Someday, somewhere, somehow, this information will prove valuable to someone who runs into the same type of trouble. But if it was gonna happen to someone, I shoulda figured it would be me.....yeah-yeah.....a girl who wants to be a mechanic....what a test of my abilities this has been <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" />