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Hesitation while under load

13K views 40 replies 4 participants last post by  asian195 
#1 ·
Just got my son's 93 Sentra running. Got the car for free, it sat for almost 4 years. I had to replace all the injectors and it fired right up. Idles great. Been driving it for about a week now, mostly to and from drivers ed with my son. Anyways, I noticed when under load, like going up a hill, it has a bad stutter/hesitation. I also noticed that the more throttle you give it, the worse it gets. It pulls harder up the hill at 1/4 throttle, compared to half or more.

This weekend I'm going to change plugs, wires, cap and rotor. Also gonna check for a possible vacuum leak, since I did have the upper intake off I might have forgot something.

Any other ideas with looking into? Thanks.



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#2 · (Edited)
Sounds like when the engine is under load it doesn't have enough power. Definitely do a full tuneup, which also includes adjusting the timing. You have to unplug the TPS to adjust the base timing on a ga16de. On my car I also have to unplug the the larger solenoid on the iacv or my idle will sky rocket when I unplug the TPS. Also you need to have your idle adjusted to spec for your timing to be set. You sort of have to go back and forth back and forth between adjusting the idle and timing before you get both to spec.

Make sure to get NGK plugs, if you have some crappy plugs like bosche platinum 4's, or split fires (aka miss fires) then you never know what problems they will create. The most common problem I've seen with the bosche platinum 4's that I've seen, is your car idles like crap and will barely run right.

Get a new fuel filter too, they are dirt cheap.

I also recommend getting ngk wires from rockauto.com for $45. They are $119.99 at Autozone.com lol.

I would do a compression test to see if your motor is on it's last leg or not. Also you better check the fuel pressure before and after the fuel pressure regulator.

Have you checked the car for trouble codes yet? It's so simple you should definitely do it.
 
#3 ·
I haven't checked for any codes. Already replaced fuel filter, checked fuel pressure and compression while I was diagnosing why the car wouldn't start. They pressures were all good. After what I've read on the net, I believe a tune up, timing and idle adjustments, possible iacv cleaning etc, should be good. Writing on it later today. Well keep this updated. Thanks.

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#4 ·
So today, I taught my son how to change the oil and how to check the other fluids. Also showed him how to use his jack and install his spare tire. We also checked the brakes to see if they needed replacing.

But anyway, after that we drove to the auto parts store and picked up plugs, plug wires, cap and rotor. On the way home the car died on us. It's definitely electrical, either the battery is bad and not taking a charge, or more likely the alternator isn't charging. Called a buddy to tow us home. Gonna diagnose the problem tomorrow.

I will admit I bought duralast plug wires, but I will take them back and order ngk ones from rock auto. Thanks for letting me know the price. I will just use the existing wires until those come.

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#5 ·
Update, replaced the spark plugs with NGK, kept the original plug wires, ordering NGK today. Replaced distributor cap, but they gave me the wrong rotor. Will get the right one today when I return the wires and wrong rotor. Also cleaned out the iacv, set idle by ear since I don't have a tach, might be a little high, and set timing to 10°. The timing was at 0°. Quick test drive and it seems to run a lot better, will do some more driving later to be sure.

As for why it died on me yesterday, still a little unsure on. As we were driving it things on the dash started not working, beginning with the radio, then the turn signals were very dim, then the Speedo stop working eventually lost power. Obviously we were running on battery and the battery was running out of juice. This morning I checked battery voltage it was just under 12 volts, so I started the car. Checked the alternator output, 14.4 volts. So obviously they are both working from what I can tell. I cleaned up the terminals and connections at starter, under the battery tray and at the alternator. There wasn't much corrosion so we'll see if that fixes the problem.

If anyone has had this problem before, please speak up and let me know what you did too fix it.

Thanks guys...

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#13 ·
That's crazy, you never had to recharge the battery once? Now that I think about it, neither did I. Well when batteries sit, they do slightly charge themselves back up. Example, I have some completely dead AA's sitting around, but if they sit for a couple days, I can put them in my flashlight and they will be super bright, but within a minute they go back to being 100% dead.
 
#12 ·
The same thing happened to me on my 94 Sentra. I swore the alternator was going out, but every time I tested it, it tested 14.4 volts. I decided to take my multimeter with me where ever I drove and finally the cars dash lights started to dim so I pulled over and tested the alternator and it said about 7 volts also. Alternators often go bad like this, they don't just go 100% dead, but have intermittent problems right before they die.
 
#9 ·
I know that you said, that you cleaned the connections for the battery and such. You may also want to look at the cable real close, I did that and my connections were clean and tight, but I found that the cable itself was bad. Something got in there and corroded the inside of the cable, on top of that the PO apperently was fond of spliceing the cable. I found 7 in the negative battery cable alone! I ended up replacing it with a new one, had no problems since. Hopefully everything you have done cleared up the problem, but if it comes back, look into this.

On your alternator, get one from Nissan, they cost a bit more, but are worth it.

Where are you located? I have a 94 and consult for our cars. We can hook it up and see if you have any "hidden" codes. Also it has a tach and a base idle function on it so we can check that while we are at it.
 
#14 ·
I used to have this very experience with my '04 Xterra until it became really embarrassing. So I took it to my technician and all he did was to just reset timing. I mean he simply just tweaked the ignition slightly and since then it's been running like a turbo engine. I think you could try that too.
 
#15 ·
I ended up putting a few extra grounds on mine since the one behind the battery likes to corrode, I agree that you have a bad alternator. I haven't yet, but still put a ground wire from the back or the alternator case to the engine block and a extra one from the block to the battery. I also have one going from the negative cable to the body. It cured all of my electrical problems. Having a few extra grounds never hurts!
 
#16 ·
Thanks, I will definitely do that. Extra grounds should be good.

I replaced the alternator last night. It is a parts store brand. I didn't have time to go to a Nissan dealer and I need the car running. I'm going to take the car for a really good test drive tonight probably a couple hours just driving around, while my son is in drivers ed.

With the tune up done, timing set, etc, it seems to run better, but I haven't got to "really" drive it yet. Tonight I will know for sure.

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#18 · (Edited)
Adding extra grounds is a great idea considering how bad they are on a b13. I ran a million new ones in my car, and I even used 4 gauge wire. Definitely add one from the battery negative to a driver side strut bolt. Also a great one to do is to add one from the passenger side strut bolt to the intake manifold. You will see two stock grounds side by side on the intake manifold on the passenger side, I used one of those bolts. A guy on this other forum said just doing the intake manifold one stopped his headlights from dimming when he slowed down.

Another little thing you should do is replace the pvc valve. They are dirt cheap and simple to install, and it will prevent the car from stalling when coming to a stop if your old one is messed up, which they usually are with age. When I checked mine recently, it didn't even have the spring in it which it's supposed to have.

So you definitely unplugged the tps when adjusting the timing right?

It's just when you said it was at 0 degrees, I started wondering if you did it right. If you didn't unplug the TPS, then you were getting false readings and therefore did it wrong.
 
#22 ·
i did that when i did the tune up and timing. but from what i know about how this engine works, it definately seems like the IACV is the cause.

i am going to replace the PCV, since it was suggested, just in general.

to be a little more specific, when i say erratic idle. what it does is just go back and forth between about regular idle and a high idle. since i dont have a tach on it, i cant tell you exact rpms. rough guess by feel, 700-1300 rpms span.
 
#23 · (Edited)
I figured you did that, mabye you missed a spot, or you may have used the wrong type of cleaner (it didn't clean everything out properly, even though it may have looked like it.)? That or the whole IACV is bad. You may have to go to a junkyard and pick up one, that or order a new one.

Edit: what type of cleaner did you use for it anyway?
 
#25 ·
I used throttle body cleaner on mine, I have heard of people using electrical parts cleaner also. I think that carb cleaner should work just fine though. How was the gasket between the IAC and the intake? I have heard that if there is a leak in there, it can cause all types of havoc and it may look like you have problems with your IAC even if you don't. Mine was iffy so I used a small bead of make a gasket that is sensor safe to make sure I had no leaks.
 
#27 · (Edited)
With the whole coming to a stop and crazy idle scenario, it sounds like a bad pvc to me. When you take your old one out, check to see if either the spring is missing like mine was, or if it's full of gunk like how I found my brothers pvc valve.

The gasket sealer on the iacv is almost a must. My old gasket turned hard as steel, and so I knew I better use some gasket sealer to prevent an air leak.

One more thing on the list, check the small rubber hose under the egr valve. Mine disintegrated and so did this guys: http://www.nissanforums.com/ga16de-1-6l-engine/170704-diy-egr-valve-removal.html - look under step 3 to see what I mean.
 
#28 ·
#29 ·
Pulled the pcv out and cleaned it. Idle issue still present. Question, which end is the spring supposed to be in? Valve cover side or vacuum hose side? But either way it didn't appear to have it. Which could be why idle issue is still there.

So another question, where did the spring go? How much damage can that spring, bouncing around the inside of your engines cause?

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