Quick question

Z-type wrote:

I have to assume my lower intake manifold gasket is bad. Therefore also causing a vacuum leak, causing my oxygen sensor to get insane.

Does it make sense to anyone?

Yes it makes sense, It could be your LIM is leaking both fluid (coolant) and air into the engine.
The coolant is disturbing your O2 sensor and combustion in general also the vacuum leak(s) are affecting your idle.
I f you know it's leaking it isn't going to hurt to replace it and along the way you may find other things that can contribute to this problem, bad SC gasket, other vacuum hoses that aren't that visible now but when you start taking everything off they will be evident. Also, replace your fuel injector o-rings, another possible source of vacuum leak and poor fuel mixture, more noticeable at idle and low RPM's.

I think I'm just going to take a few days off in a week or so to get this done right. Kinda sucks though - I wish I would have done it when I had my supercharger off to change the coupler. I was like, two steps away. Oh well...at least I know how to get to it. I printed out that write-up to get my supercharger off so I'll just pull that printout out from the 'ol file cabinet. I just replaced that supercharger gasket too...

Anyway, I guess I'll have to get a supercharger gasket, LIM gasket, and fuel injector gaskets. I had a suspicion the fuel injectors might be a source of vacuum leak too. Screw it...I'm just going to replace everything. To me, this kind of work is fun anyway. I really enjoyed changing my coupler, so this will just be a slightly more involved extension of the same thing. I wish I didn't have to do it, but I will.

Anyone else think this is a good route to go? It COULD fix the problem I guess....maybe...

The LIM gaskets are certainly a likely contributor to your low coolant situation. But to your fluctuating idle - it could be a vacuum leak, or simply a dirty MAF. Make sure you clean the MAF with MAF cleaner while you have everything apart.

Quote :

Anyway, I guess I'll have to get a supercharger gasket, LIM gasket, and fuel injector gaskets. I had a suspicion the fuel injectors might be a source of vacuum leak too. Screw it...I'm just going to replace everything.

The only thing wrong with doing things this way is that you'll never know what the problem was. Only way to correctly diagnose is to change one thing at a time - bonus is you'll probably fix it before you replace everything, saving you money (especially when you're talking about injectors!). It can take longer to do it this way, but remember how much fun this is!

Yeah I undersdtand you completely AA, but I'm only replacing the LIM gasket, supercharger gasket, and injector o-rings. Even, if for some reason, it doesn't fix my idling and O2 sensor issue, it needs done anyway so I won't REALLY be wasting my time. But at least I'll be able to potentially eliminate it as a source of vacuum leaks! That's another reason I'm doing it.

As for the MAF, it LOOKS clean and I clean it every month or so just to be safe, but that's not to say it isn't bad.[/i]

Well, I'm going to tackle the LIM gaskets and such tomorrow. Wish me luck!

Like I promised, I changed the LIM gaskets and things. Also changed the fuel injector o-rings and supercharger gasket, of course. Everything went decently smooth. I started the car and ran it for two minutes but shut it down because I still have to add more coolant. It ran great and nothing disastrous happened right off the bat, BUT, once I get the coolant in I'll take it on the road and see what happens! I'm hoping this fixes a lot of things. Allow me to follow up with some highlights:

-Everything came apart fine
-Checked all vacuum lines again to make sure they were in good shape, in case i missed anything the last couple times I checked
-Supercharger seems heavier than I remember (lol)
-LIM came off easy like it was supposed to but i bumped something and coolant got all over the drive belts
-Something to note is that the bolts for the LIM were VERY VERY loose. They werent just finger tightened on, but it should NOT have been able to undo them that easily. This is surely why the thing was leaking.
-What I found on and under the gaskets was horrific. Layers of coolant and oil on the gaskets (enough for me to be pissed at whoever was in the engine last) and a loooooooot of cleanup to be done. Took some time but it was done right.
-Everything seemed to go back together fine and like I said, she fired right up and ran like a champ for the few minutes I had it going.

Again, tomorrow I'm going to add the rest of the coolant and make sure everything is working right and not leaking or whatever. Wish me luck again! *crosses fingers*

I'm a little disappointed right now. The engine runs fine, like it did before, no coolant is leaking or anything else for that matter (that I'm aware of) but....

The engine light still kicks on. I'm going to TRY to get it scanned again this week to make sure it's not a new code and it's still my PO171 (O2 lean) code. I've noticed symptoms of when the light most commonly comes on:

-Idle (in any gear)
-Coasting downhill
-Light constant throttle

All of this is at operating temperature. At this point, if you've been following this very confusing post, I've knocked out almost every other option besides a bad oxygen sensor. I've been avoiding changing it because of the other options that could cause that code. I'm about 99.9% sure there's not a vacuum leak. My EGR works properly, my EVAP works properly, my MAF, IAC, and TPS sensors all check out.

At this point, I don't have any way to watch diagnostic information to see if say, the O2 sensor is being 'lazy'. But I would have to assume, after all the researching and work i've done, that my O2 sensor is bad.

If anyone has ANY suggestions or ANY information I would absolutely love to hear it....EVERYTHING helps!

Thanks everyone!

-Andrew Z

Very very VERY exciting update. I found a vacuum leak in the ONLY place I didnt look! The EGR gasket! The gasket is a little crummy and fragile and sure enough, I sprayed cleaner around that gasket because I wanted to try testing it again anyway, and the engine almost stalled out then the idle rose a little higher and settled back down. Bingo. This could be my issue. I ordered a new gasket so I'll put it on tomorrow and see what happens....

In the meantime, can anyone tell me if there's just one gasket or an upper and lower? A mechanic I talked to once said there might be two.

Thanks!

Fixed the vacuum leak at the EGR with the new gasket. I should have taken a picture of the old one. It was fairly gnarly. I'm really hoping this $4 gasket was the fix to my problems. I suppose only time and a few dozen miles will tell the tale!

Im cautiously optimistic .

Might want to also check the EGR tube where it goes into the SC. (and all along the tube) Its common for them to get cracks with age. When i changed my LIM gaskets, I didn't make sure it was close enough before tightening up the flange, and ripped the tube a bit.

Glad things are coming together though!

Thanks for the heads up, Karma. I didn't think of that. I had assumed the tube would be strong enough but I guess anything is possible! Oh and thanks for doing that writeup on the LIM back whenever it was you did that. It got me through changing my coupler (a few months ago) and my LIM the other day. Much appreciated!

And so far so good on the car. I hate to jynx it but I haven't had any problems to and from work today. It's only 7 miles but it's a variety of driving conditions so it was a decent first test. I'll be making a 100 mile round trip tonight so we'll see how it goes then...

Thanks for all the help everyone! I hope the car holds up .

I think I jynxed the car.

Nothing has changed since day one of this problem. I'm at a loss here and dont seem to have any more possibilities but the O2 sensor, but that doesn't explain my RPM fluctuations when coasting, or does it?

I don't know if those two problems are even related...they don't seem to be, and they're BOTH intermittent to the point it's very hard to predict when they'll happen. Sometimes, my engine light will be off all day and I'll have no problems with the RPMs, other days my light wont turn off and the RPMS will still be fine, others the car is real 'fun' to drive because of the RPM issues and the SES light staring me in the face....

I'd hate to replace the O2 sensor but I guess it could very well be a 'lazy' one at this point...hard to say...

Andrew,
You really need to be scanning to see anything definitively.
Yes, It could be a lazy O2 sensor, but might not be based on the intermittent nature of the problem. Lazy O2 would constantly be lazy.
You could have an EGR problem as well. If the EGR valve is lazy, sticking intermittently and generally not operating smoothly throughout it's range, it could also produce what your experiencing.
You need to be able to watch both the "commanded position" and the actual position of the EGR at the same time. If the PCM is commanding a certain amount of EGR valve opening and the valve isn't responding properly you will have an issue and will be obvious with a scanner.
Same for your O2, you can watch the cross-counts and compare the #1 O2 sensor to the #2 O2 sensor and see how they match up.
I'm sure there could be some other things that might be the culprit but I would start there.

Well, I did think it might be the EGR not helping the situation but at the moment, I cant afford a new one, but I'm sure I could swing a working used one, just to see. Also, lucky for me, I only have one O2 sensor so that makes things slightly more managable.

I do have a guy down the road who can scan and watch diagnostic data from the car's computer, but he's always busy so I'm looking into TRYING to afford a scanner of my own that I read about here on this site. Anywho, in the meantime, I did watch the diagnostic data while the car was idling when I last got it scanned. What exactly should the O2 crosscounts look like in terms of the actual numbers I should be seeing? I saw them fluctuating quite rapidly from 0- ~32, and this was when the engine light wasn't on.

I know I need a scanner to be able to do this and I"m doing my best to get a hold of one .

Sorry I'm busy at the moment I'll collect my thoughts and re-write them down later so we can start afresh on this situation.


Thanks again everyone

You might look at the Car Code scanner. Can't tune with it but it works fine as a comprehensive scanner. See

http://www.obd-2.com/daq4.html

and surf around. I use this one.

Albertj

Albert, will that one work for Series I ('95)?

Andrew,
I think your money has been well spent up to this point.
That is, replacing LIM gaskets and such is good preventive maintenance and you said you had some leaks that you've been able to correct in the process.
But I am not suggesting replacing an EGR valve or an O2 sensor just because it could be the problem.
This is the point where I believe your money is better spent on knowing what the problem is.
Be it either buying the scanner necessary for you to troubleshoot the problem or paying someone with the proper skills and tools to troubleshoot the problem for you.
Just my opinion at this point.

AA wrote:

Albert, will that one work for Series I ('95)?

COme to think of it, as a scanner it's for '96 and newer cars. List is here

http://www.obd-2.com/

What to do - go to the obd-2 web page and send an email to Alex Peper - ask what he'd use for scanning a '95.

Albertj

Thanks Rick and all others. I guess the car might hold out until I'm able to afford this scanner for myself:

Link

Karma posted it a while back and I've heard more good about it than bad and it should do all I need it to do to pinpoint the issue at hand. I can't keep paying for other mechanics to scan the car and make suggestions so I'm just going to get this so I can do it myself. I understand the information I'd be looking at, I'd just need to know some parameters and limits or ranges for certain numbers and operations whenever the time comes.

Though, since this issue has been floating around my head for the past couple days like crazy, I've been trying to pay more attention to the idling and SES light and patterns between each other or patterns between other things like my speed, vacuum at the time, gear I'm in, etc. I have a video I'll post later of what the car does so there's a visual. Who knows, maybe someone will recognize the problem from the video! It's possible. Anyway, I'll post that later.

Thanks again everyone!

Will be getting the aforementioned scanner sometime late this week. Hopefully I can get to the bottom of this problem once I get the scanner working and am used to operating it.

Doing some reason, I'm starting to suspect my MAF sensor MIGHT be going funny and could be contributing to all my issues in general. I'm not sure on the specifics of why it would be, but from what I've read I suspect it a possible cause of a problem or two. Again, I hope I find that out when my scanner gets here. The reason I mention it is because my Traction Control light comes on as well. Maybe that might clue someone in to a possible cause of my idle and Lean O sensor code. Any thoughts on that? Thanks in advance!

I'm not 100% sure about the '95s, but your MAF sensor should set an SES, but should not set the trac control. Bad MAF could easily cause the lean code as well, but so could a vacuum leak.

I highly doubt the SES and Trac lights are related. Wheel bearings are well known for setting the TC/ABS light though, the wheel sensors usually go as your early warning sign that the bearing may be on it's way out. Optionally, you can easily have a bad wire going to the wheel speed sensor, or a problem with the ABS head unit.

Good luck!

after doing all that you plan, don't forget to remove and clean with electric parts cleaner ,your air idle control valve. this contributes to allot of drive ability issues. do that and then see how she runs and then do all of the above. remember to use all the appropriate solvents for specific sensors. these cars are sensitive to AICV problems

FWIW my faulty MAF has set my SES and trac control lights.

L67 wrote:

My faulty MAF has set my SES and trac control lights.

how does it set a "Traction Control Off" Light.?
I can understand the SES light, but TCS......