dhughes214

So I've been troubleshooting my car not really idling/taking off properly, seems to be running a little rich maybe. I've owned the car about a month now and it's done it since I bought it. So today I'm looking around under the hood, cleaning some stuff, wiping stuff down, and right by the firewall, I notice 2 small plugs just hanging there. They plug into a small cylinder type thing with 2 big plugs on the opposite side of it, and the small vacuum line that comes out of the back left hand side (from the front) of the motor runs into, and then out of that cylinder. I plugged the small plugs in, and nothing changed. I'm guessing this means I have a sensor out somewhere. Can someone tell me exactly what this thing is and if there is a sensor that is hooked up to it. I'm still working on the pic, but if you follow the small vacuum line from the back left to the firewall you'll see what i'm talking about. The small plugs are identical, and the two prongs are identical, not sure if they have to be top plug to top prong etc or can go either way.

Hectic

iTrader: (20)

There's about 50-60 different connectors you could be talking about.

:

dhughes214

Ok, got my answer, looks like it's the Power Valve Solenoid. Why would someone unplug the two small plugs from it? Could this be the cause of my hesitation/bog at take off?

dhughes214

Ok s It idles rough at anything below 1000 rpms. If I am sitting at a stop light, and it happens to be idling at 600-700 inince I found out it's the power valve I saved you guys the trouble of answering me and just searched the forums. I'm gonna start a new thread and give more details on my problem.

BenStoked

iTrader: (7)

nah, go ahead and leave it here.
unfortunately, sounds like a dying injector.

dhughes214

Calling All Experts...

Backstory:

My wifes 99 grand am blew up. Motor is toast. F*** Pontiac. Anyways... We were broke, so I bought an 89 Maxima for 900. That's about all we had, could have taken out a loan but didn't want too. So I have to say, I love this car. The body style was way ahead of it's time for an 89. The interior is spotless, and the outside looks good too. I bought it do drive for about a year until my 01 tundra is paid off, then we were gonna take out a loan to get my wife something nice. Now I'm thinking about keeping it forever. But....

Sometimes it has this horrible stumble when taking off. I know when it's gonna come because when I stop, it will idle about 550-650 when it normally idles around 900. The weird thing is, when it idles like this, even in neutral it has a stumble when revving it up. it takes about 3-4 seconds to get to 2800 rpms and then boom it takes off. That's what it does when taking off from a stop as well, it will stumbles and jerks, just like when someone who doesn't know how to drive a stick takes off (I DO by the way). As soon as it hits 2800 rpms, it takes off.

It does have a mild-moderate exhaust leak. Haven't pin pointed it yet, but sounds like rear manifold studs.

I don't think it's my injectors, because it just passed smog with flying colors, and my buddy that has the exact same car as me but with an auto said his mechanic told him if it was my injectors it would have not passed or barely passed. (I know nothing about injectors so tell me if that's incorrect)

Also, it won't idle by itself in the morning when it's cold. I have to rest my foot on the pedal giving it a little gas to keep it running till it warms up. BUT, it seems to run the best AS it's warming up, right before it reaches normal operating temp., it runs great.

Also, there is a slight smell of gas from the engine compartment, like it's running rich.

So I guess my partially educated guesses are oxygen sensor, or maybe coolant temp sensor because I heard that could make it run rich. I think if the exhaust leak was bad enough to create this kind of stumble, it would affect performance later in the rpm range. This car flies. I hit 90 in 4th the other day and it could have kept going. The guy who I bought it from said he maxed out the speedo (only 125) and I definitely believe him.

Sorry for such a long post, but wanted to give all the info I had. I don't have a ton of money, but will bust my *** checking whatever you guys want me to check if it's at all possible for me to do. Don't have an ohm meter or really any electrical testers for that matter, but my buddy works at the JY here and he will let me take whatever I want to see if that's the problem, as long as I bring back what isn't the problem and pay for what is!

Thanks in advance.

Oh, also, the Power Valve Actuator (I think it's the actuator, it has the vacuum line running in, and one running out, with a couple plugs on it, it's mounted to the firewall) was disconnected when I bought the car. I just plugged it back in today and I noticed no difference.

LvR

The power-valve solenoid "switches" the manifold vacuum to the actual power-valve diaphragm under the right conditions - chances are on these old motors that your diaphragm is also cracked and leaking manifold vacuum to atmosphere (just like mine was) and as a result your power-valve is doing nothing as a result (not that you will anyway notice anything at idle whether the power-valve is open or closed).

Before you start chasing more expensive idling funnies, remove the whole power-valve actuator from the inlet and suck on the little vacuum tube there while pushing and pulling on the actuator arm sticking out of the diaphragm assembly - chances are that you can suck air right through the cracked diaphragm in which case you have found a vacuum leak you can address with confidence (just like I did)

FWIW - I have removed my power-valve actuator altogether and fixed the actual valve in a closed position and plugged its vacuum line to the manifold
(my motor has 310K km on it and I am still on an original auto box - trying to get the most out of it and thus not hammering it unnecessarily)

LvR

Not an expert but have some releveant experience I think ..............

As I posted in your other threadOn the stumbling at or near idle thing:

I would check/clean/replace the TPS associated stuff first - I have gone through the same pain recently (including the motor dying on me soon after starting from cold and then refusing to start again till its a bit warmer - this did not happen when the motor was hot), and eventually by pure chance discovered that wiggling the TPS connectors sorted the problem.

maximo018

iTrader: (6)

I say check distributor, fuel filter, and plugs. Sounds like a air/ fuel ratio. As for injectors they may be the culprit. Best thing to do is leave them in the fuel rail fully connected and lift out of manifold. Have someone turn the key to acc to prime system while you see which ones sprays.

maximagician

it this unplugged thing on the firewall?
maybe its the heater hose valve?

Matt93SE

iTrader: (44)

Please don't create multiple threads for the same issue(s). that's bad form and makes you not just a n00b, but a t00l too.
Thanks, and have a nice day.

dhughes214

Thanks for all the input guys. I'm goin down to the jy today, and just because it won't cost me anything I'm gonna grab an oxygen sensor and coolant temp sensor and switch those out, then I'll try the power valve actuator trick, but I don't think it's a vacuum leak because I sprayed carb cleaner all around the motor while it was running and heard no change. I'm still hoping it's something that simple. Maybe I'll pull out all the injector plugs and clean them real good too. If it is the injectors I'll probably end up begging my buddy with the same car to help me do it, I really like this car, even if I had to replace all six injectors and spend close to a grand, I'd have a car that looks and runs amazing for under 2000.

maximagician

huh,who,wah .......cant be me.

maximagician

ohhhhh.... this guy right?

dhughes214

Ok replaced the oxygen sensor, did nothing. Replaced tps, did nothing. I DID notice however that the connector that the tps plugs into was VERY corroded. Basically the prongs were green. I tried to clean them up but couldn't really get anything in there. I think I'm gonna try my wifes nail file! lol. Do you think that is a possible cause? I'm gonna take the time to clean it either way but just wondering if the tps can really cause this type of problem.

LvR

As per my previous post ................ yes - I found it to be the cause

dhughes214

lol. Sorry LvR, I did read that post, I guess I was just seeing if anybody else would chime in and see if they too had problems with their TPS. Not that I'm not trusting your judgement! Just curious to see how common it was. Any suggestions for getting that corrosion out of there?

LvR

In my case the plugs/sockets were beyond sensible salvage so I cleaned the connections and cut back/soldered the wires directly onto the connections on the TPS - problem solved. Sealed it with silicon and will probably never have this particular problem again.

tresboi

iTrader: (9)

Electrical contact cleaner works wonders. It's in a spray can & available at most auto parts stores. I'd suggest you take an hour or so & hose down every connection in your engine bay with the stuff. You may be surprised by the difference. Also, adding a thin layer of dielectric grease will help protect the connections from future corrosion issues.

dhughes214

Thanks guys. I'll probably try cleaning them first, and if it doesn't work I'll solder it on and see if that helps. Also, aside from putting on a new one, is there a way to test the MAF? I was trying to describe to my friend how my car was running. And I told him "you remember that time you put that little "chip" you got off ebay in the MAF of your ford ranger..." and that made me think maybe it's my MAF. I'm still not thinking it's injectors (not only because that would suck) but because if it were injectors, and one (or more) were bad enough to make the car this bad at low rpms, would I still be able to max out my speedo on the freeway (125mph)? Seems like I would lose performance all the way through the range.

LvR

IMO since you "just passed smog" and presumably have a model with an O2, its not the MAF.

May sound harsh but actively fix the already known issues - in this case at least the plugs/sockets/connections on the TPS and proceed from there. No use guessing and talking it all fixed - start somewhere and actually "do" something.

maximagician

has the tps been loosened and moved out of adjustment accidently?

dhughes214

LVR, as I said before, i just replaced the o2 sensor, and the tps. And as I also said before I AM going to clean my tps plug (along with every other plug I can find), but unfortunately this time of year (and every other time of year it seems) time is hard to come by. So I asked about the maf that way if I found time to clean my plugs I could do the MAF at the same time. As for the TPS adjustment: how do I "adjust" it. It seemed when I pulled it and replaced it that it could only slide on one way.

LvR

FSM (see stickies) section EC give all the details on both the TPS and MAF testing.

TPS has slotted mounting screw flanges - if you removed it you will have to make sure about alignment before tightening those screws down. Yes - the actual throttle shaft can only be located in a particular way inside the TPS - the shaft-end shape dictates that, but the actual TPS body can be rotated relative to the throttle body in order to affect adjustment

.................. IMO inevitable when no progress from the OP is reported/evident while known "issues" has been identified, yet "possibly" relevant items gets thrown into the currently unknown status of the original problem (that may very well be cured by fixing the known "issues")


If you want real attitude .................. the time spent discussing the thing to death could already have been used to at least sort the TPS connectors so as to remove a known variable from the equation

DanNY

iTrader: (14)

why not pull the plugs after you crank (w/o coil connected) and then pull the plugs to see which ones are dry?

why make more work for yourself?

dhughes214

Danny that's a good idea. I'll log that away for when I actually get some time to work on this thing. I hardly even have time to post except for when I'm at work! Thank god Maxima.org has an android version. Looks like I'll be reading through more stickies at work tomorrow!

maximagician

anyone else think using mode 4 "switches on\off mode"
is one way to adjust the tps since in mode 4
when you press the gas slightly say,with your hand the lights on the ecu
light up as well as the check engine light on the dash
so if they are lit up before pressing the gas OR not until the pedal has moved
more than slightly than its out of adjustment?

oh and those two tiny bolt type screws will break if more than finger tight

LvR

One can make that deduction, but mechanically the TPS is unfortunately able to be adjusted to actually go way too far in the "closed" direction too - iow the ECU will only start to moan after the throttle has travelled quite a way and not "soon as its off the stop" - as a result I would think its not the definitive method to check alignment (if you have an auto your TCU may also be managing the shift/load points wrong as a result)

maximagician

no, my cars fine. this is not my thread, i was just contributing

ive never touched the tps in my 91 se although many years ago i swapped one on my 92
and used mode 4 to make sure it would blink only after slightly pressing on the gas pedal and not before
or not more than slightly after, if that makes sense.

nowadays i would know how to install and adjust tps with an electrical multi meter instead of using ecu mode 4 "switches on\off mode"
but honestly im still an electrical novice other than doing my own alarms and stereos and testing sensors

Chris Gregg

iTrader: (59)

Through all this, did you ever verify that all the vacuum leaks were resolved? Sounds like other issues too, but those leaks can cause lots of starting, idle, acceleration, and power issues. Just want to make sure you've not overlooked this. Those hoses crack easy and sometimes you have to inspect closely to determine they are damaged/ leaking.