94' 3VZE Automatic.

When I start the truck it idles fine (between 800-1000rpms -- when it's warm 800 rpms). When I go into any gear (Reverse, Drive, anything else), the RPM's drop to about 400-500RPMS and car starts to putter and shake a bit.


Stuff I have done:
-EGR Block Off
-TVV/BSVS Blocked Off
-5MM AutoLite Spark Plug Wires
-NGK V-power Spark Plugs (gapped 0.32)
-Seafoam Treatment
-Fuel Injector Cleaner Treatment
-TPS Unplugged (still runs the same)
-Turned up idle from BISS screw (did not help)
-89 Octane

I am thinking o2 sensor or fuel filter is what's left before I start ripping my hair out.

Possible Causes (Pulled from FDM):
1) Engine ground bolt loose. (Nope)
2) open in E1 circuit. (Nope)
3) Open in injector circuit. (Nope)
4) fuel line pressure (injector blockage, ect.). (Nope)
5) open or short in oxygen sensor circuit. (Nope -- replaced)
6) oxygen sensor. (Nope -- replaced)
7) ignition system. (Nope)
8) engine coolant temp. sensor (Nope -- replaced)
9) volume air flow meter (Nope -- replaced)
10) ECM (Doubtful -- ruling out)

 

800-1000rpms when cold? Meaning it varies up and down?

The idle drop when in drive, etc. is normal as the auto places a vacuum load on the engine. The sputtering is not, though....of course.

 

Putter and shake....hmmm....thought about it for a moment. So, is it misfiring a little? How does it drive?

 

Correct, like when it first kicks on it will idle around 1000+ RPMS or so then slowly come down to a steady 800 RPMS (in park).

It drives pretty well actually, only thing sucks is when I get to a light and I am sitting there at idle. Possible vacuum leak somewhere? I do have a CEL it's engine code 25 that's why I mentioned changing the o2 sensor next.

Also, when I blocked off my TVV I capped both ends. So, I have it capped on the charcoal canister and another on the "P" port on the throttle body as well. Should I have run a hose to connect them directly?

 

Okay.....sounds like the cold idle/base idle is correct.

Yeah....having the purge can hooked up is a good idea. I can post a link later that describes why.

Do you know how to test your O2 sensor? Do you have an ohm/volt meter?

 

I know what the TVV system was for so I get the "general" idea. I will hook that back up but I doubt it will solve my issue.

As for the o2 sensor it needs to be replaced I am doing that no matter what just awaiting the funds. I do have an ohm/volt meter but have to figure out how to use it.

 

ok you shold really take out them plugs my girl trust me there junk and will cause more problems then good! get autolight cheapos there the best for these engines check your trany fluid see if its dark or low cause then that could cause the verter to lock up a lil more then it should bringing down the idle as well


wow i just sounded all smart and stuff lol

 

Update:
I now have connected the line from the charcoal canister directly to the "P" Ports on the TB. Didn't fix it like I assumed it wouldn't. I will check my tranny fluid tomorrow since it got dark out my way.

I am still hoping *crosses fingers* that it's the o2 sensor and this will alleviate the issue.

 

Wasn't trying to offend your intelligence, and I wasn't suggesting it would solve the problem. Do whatever you like, though. I was just trying to help.

 

Didn't think you were insulting my intelligence at all I apologize it came off that way. I had a feeling that the line needed to be hooked directly to the TB and you just confirmed it for me. Now down to the real issue

 

Okay...

It could be a vacuum leak. Sounds like a small one, if so. You can go around the different vac lines with a pair of pliers and cut them off one by one to track down the possibility. That could also cause the code.

I'm not sure what Allan is trying to say with his spark plugs statement, as a rule everyone uses either ND or NGK's with better results. ND's can be had cheaply at Auto Zone. As well, check the ignition cables and rotor/cap.

Ugh....I hate the kind of problem you're dealing. It could be a number of things, but start with those. I would think if it were the O2 sensor you'd have driveability issues...loss of power....and that's why I asked. But, test it. Atleast, I would. I'm not a 'throw parts at it' kinda person.....mainly because I don't have that kind of money...lol.

4crawler has a decent write-up on using a meter. Go to his cheaptricks page under TPS adjustment and you'll find it there.

 

I am not quite sure what you mean by "go around the different vac lines with a pair of pliers and cut them off one by one". Do you just mean find all the lines and make sure they are connected, if they are, cross it off the list as an issue? Should be easy to do considering my EGR and TVV are blocked off and that's like half of the emission system! [sarcasm]

I am not the type of person to just throw money at the problem either but I found an OEM-quality o2 sensor (brand new w/ warranty) for $50 so I couldn't pass that up.

 

i think he means pinch the vac lines with pliers!!

 

HA! Ok...so what will be different/what will that do?

 

Yes..that's what I meant...

Theoretically, if there's a leak, "pinching" off vacuum lines could stop a small leak.

When I was troubleshooting the AAV on my 22re, I used a pair of vice grips to pinch off the vac hose going from it to the plenum so I could watch for effects while driving. Well, it didn't change anything...how the vehicle ran when at low rpms....but, it turned out to be a problem with the VAM. I had been troubleshooting this problem for over a year thinking it must've been a vac leak somewhere, or valve adjustment, or the O2 sensor (seemed logical as it was throwing an O2 code), or the fuel pump relay, and on and on. I was beginning to hate my vehicle, damn it!

Anyway, essentially your just looking to see if pinching off lines will change the condition. Only you'll need to do this with small vice grips while throwing it in drive watching for any change then. However, the only real, conclusive method I've ever found for pinpointing hard to find leaks is with a smoke machine. A nearby mechanic/friend has one. Charged me like $10 for the 3min's it took to find it. Those tools are the bomb!!! Maybe you can find a mech who has one and wouldn't rob your ass to check your motor with it. One would hope....I don't like a lot of mechanics I've run across.

All that being said, you seem a smart girl. Get familiar with that meter, eh. It could be something like your VAM. But, since you found such a dandy deal on the sensor, try that first. Easy one, for sure. Just don't throw away the original for the moment...it may be working properly.

Oh, btw...no telling how lean your running. So, if you hadn't thought of it, go easy on the pedal so as not to get things too hot.

 

BTW, just an FYI....capping off the TVV isn't really necessary. I mean, you did it, so it doesn't hurt. But, understand it's a rather self contained valve. It can remain open or shut and not affect anything so long as the peripheral components are not connected to it and/or are blocked off.

Directly connecting the canister to the P port on the TB was a good idea. That's what I would have done. Keeps fuel vapors from possibly building up too much in the fuel tank.

 

Well I was more of forced to blocking it off. One of the plastic ends coming off of it broke (do'h!) so I was going to take it off and do that awesome write up I found on here and replace it with the metal tubing. Well I got it loose and when I went to grab it....it fell....into oblivion I cannot find it for the life of me. It must have fallen underneath the intake plenum to somewhere I can't see/reach without taking off the plenum. That my friend, is a later project.

 

Oh...you mean you blocked off the coolant tap in the sensor cluster? I though you meant you blocked off the vacuum ports. Lol...if that's the case, then definitely necessary.

 

Just an update on mine..so I was searching about the vac lines like crazy and found my TPS was unplugged (durrr) I plugged it back in and started the truck. When the truck is cold it idles fine in any gear, but when the truck warms up it starts to putter at idle no matter what I put it into.

So, still awaiting my o2 sensor hoping that this is the main problem.

 

Cold idle air valve.....sounds like it's sticking open. Or, coolant temp sensor.