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Old 06-01-2007, 02:58 PM   #1
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Default PCS or O2 Sensor?

It'* probably isn't a bad idea to replace my O2 sensors anyway at this mileage, but I'm not sure they are the problem....

With a load (slight incline and accelerations), she is starting to shudder. It'* happens worse when I'm turning to the left and hit the gas (like entering an on-ramp with a slight incline). It could be symptomatic of a misfire, but I've recently replaced plugs and wires and checked the coils. There is no SES, but I haven't been able to get it scanned for possible stored codes yet. I also think that my gas mileage is down slightly (about 28 mpg freeway from 30-31 before) which points me in the direction of O2 sensors or an ignition problem.

List of recent repairs/things I've checked:
New PCV, Fuel Filter, Air Filter, Trans Filter and Fluid.
New Belden Premium wires and Autolite 605s gapped at 0.06
Cleaned TB, IAC, MAF.
Coolant normal, oil normal, trans fluid at top of checked part of dipstick.
Vacuum lines look good.

I'm worried that it may be the PCS, but the slight loss in mileage makes me think that there are darker forces at work. Any insight would be welcome. Is it time to find a tranny shop and go for a ride to diagnosis this, or is there something obvious I'm missing?

If there aren't any codes stored when I take it by AutoZone. I think I need to re-clean the grounds, check a plug and the coils again (just in case), and then I think I'm at the point where I need to find out if it IS the PCS or the o2 sensors. Does this sound right?

Sorry for the nasty-long post, but once I leave work I'm not going to have access to the internet until Monday and I want to get all the info that I can before trying to tackle this thing.
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Old 06-01-2007, 05:30 PM   #2
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Problems with the pressure control solenoid usually exhibit itself as harsh shifting. It would be a long shot that it is the problem. Those who have had a sticky solenoid have found some relief by using some SeaFoam TransTune.

Some things to check - make certain that the bolt and thread for the ground strap from the battery to the floor is good and clean. Clean up any corrosion there, on all the battery cables, the positive connection to the under-hood, and under-seat fuse boxes, and that the 3 screws that hold each of the fuses boxes down are good and snug.

Check also to be sure that the plug wires are not laying against anything, in particular the O2 sensor. Yes, at your mileage, it would be time to consider a new O2 sensor.

What does the tranny fluid look like? Is it nice bright red, or starting to turn orange or brown? If it hasn't been done, it would be a good time to drop the pan and replace the fluid and filter, too.

That should give you a few things to check over the weekend.

As an extra step - read up on the fuse and relay in this thread that would cause a no start and stalling condition. May not be the problem, but is still a good thing to look over.
http://www.bonnevilleclub.com/forum/...ic.php?t=55582
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Old 06-01-2007, 06:29 PM   #3
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Thanks for the reply. Good to know that I may not have a PCS problem after all... as maddening as electrical problems can be, I'm not as afraid of grabbing electrical connections as I am of my transmission.

I'll check the all the grounds, cables and screws... although I have a question about the under-seat fuse box. I have what look like 3 square nuts or inserts in the fuse box where it looks like the screws should be. (I wish I had a picture). I don't have any normal (hex, star, slotted) screws like I have in the under-hood fuse box. Am I missing three screws back there? If not, how on earth do you tighten those? (The square heads are actually recessed below the plastic) Thanks...

Tranny fluid looks good. I just dropped the pan a few weeks ago and it was nice and red and didn't smell burnt.

The plug wires don't appear to be touching anything (I spent more than my fair share of time making sure they didn't). The wire to the number 6 cylinder is about half an inch from the O2 sensor... is that too close? I'll probably plan on replacing the O2 sensors in the next week or so (is there one that is more likely to go bad?)

I'll check out the thread on the fuses and relays... what a monster! That should keep me occupied for the rest of the afternoon.
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Old 06-01-2007, 10:08 PM   #4
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You know...I have yet to pull the cover off the rear fuse box but it looks as if that won't have the 3 screws - just held in by 4 clips.

Just replace the sensor in the rear exhaust manifold. The other checks the condition of the cat., and won't affect the fuel mixture or gas mileage. The wire a half inch away should be ok.
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Old 06-15-2007, 10:10 PM   #5
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Default Fuel Injectors!?

Sorry for taking so long to provide an update, I feel like I'm digging up an ancient thread... I've been traveling for work a little and things have been king of crazy. I really appreciate all the help that I've gotten on this forum and wanted to let you know what'* up.

During some of that aforementioned traveling, I spent quite a bit of time thinking about what else might be causing the problems outlined in the original post... I realized that the fuel injectors probably hadn't been cleaned since the car was new (I bought it at 38000 miles) and were probably due for a good thorough cleaning. It'* worked magic. I'm getting the zip off the line that I've come to expect with the 3800 (It'* my third car with this engine) and I feel like I can pass people on a two lane highway again without worrying about their speeding up.

Anyway, thought I'd better let you guys know what was going on. (As though you were staying up at night worrying about it. ) Thanks again for all the help that gets provided here!

Cheers!
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Old 06-15-2007, 10:20 PM   #6
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It'* always nice to hear back, even if it has been a while. Thanks for letting us know.
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