Hesitation Issues

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Robb
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Hesitation Issues

Post by Robb »

Tried posting this in KA basic, but apparently I'm not authorized?

Anyway...

OBDII KA24DE, n/a
Auto trans

I checked voltages on the white wire of the MAF, 1.7 at idle, 2.6-2.8 at 4000RPM. Obviously doesn't seem right. Cap, Rotor, Plus, Plug wires were all replaced when trying to troubleshoot this. I also cleaned the MAF with no luck.

I had a friend pull another MAF for me. Welp, said MAF did not work. Read 2.6-2.8v, again. So I went out and bought a brand new MAF, 2.6-2.8v at 4000 RPM. Engine grounds show continuity, TPS is checking out.

Yesterday I checked the injectors, replaced the fuel filter, replaced the distributor cap, checked for vacuum/intake leaks, cleaned the IACV, regapped the plugs with note of signs of fouling due to unburnt fuel on all four plugs, also noted that timing was a few degrees off. Retimed the motor and set idle but still having issues only when the motor is warm.

When the motor is cold, things seem to run fine.

When the motor is warm...
Idle = misfire every 30 seconds - 1 minute
Press on the gas slightly = fine
Press on the gas 1/4-WOT = stumbles until 2500 RPM then takes off
Above 2500 RPM = Pulls nice and hard

The thing sounds like a Subaru when on the throttle until it gets going. I like the sound of a flat four, but not in this car, hah. Beginning to suspect a bad coil, but that's in the distributor since it's an s14, right? Ideas/Comments/Opinions? Really need some help here..
Last edited by Robb on Mon Aug 15, 2011 12:02 pm, edited 1 time in total.
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biggie
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Post by biggie »

Tried replacing the ECU Temp Sensor?
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carcrzy920
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Post by carcrzy920 »

if it sounds like a subby then you either have a leaky injectors, torn injector o-ring, fouled plug, or bad wire.
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Post by s14BEAST808 »

had the same issues, and replaced every thing you did. Turned out it was just the damn fuel pump. let me know if that helps. PLEASE let me know if it helps. Also it wouldnt hurt to stab another dizzy in there. When the mafs unplugged and you WOT it, does it stumble all the way to 2<500? Or does it rev fast then bog at 2,500?
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Post by Robb »

I bought a new CTS yesterday, have yet to put it in though.

carcrazy920, Injectors are fine, plugs are fouling across the bank from unburnt fuel running through them. Wires are new.

s!4beast808, I have to check the fuel pressure. Replaced the fuel filter thinking it might be clogged/restrictive, but maybe the strainer on the fuel pump?

When the MAF is unplugged it will rev fast and then bog around 2500 like it's supposed to. It sounds a bit rough when revving fast, but doesn't sound nearly as bad. Different fuel dumping smell though.
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Post by NateDogg »

What is the voltage on the MAF ground?

Maybe add another ground wire if it's above .03V.
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Robb
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Post by Robb »

Put in the new CTS and set timing again. No luck :(

Rev:
http://www.youtube.com/watch?v=E1wkDhEayQ8

Drive:
http://www.youtube.com/watch?v=y3CZraEsXmQ
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Post by supakat »

Long shot but status of air filter?
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Post by Robb »

Brand spankin' new as of yesterday evening.
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carcrzy920
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Post by carcrzy920 »

could be fuel pump, or FPR, injectors are fine but what about the injector o-rings, if there not installed correctly they will tear for sure
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Post by Robb »

The injectors weren't leaky, so does that eliminate the o-rings? Or will a tear manifest itself as a vacuum leak?
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Post by carcrzy920 »

if the orings tear since there sidefeed injectors they will dump fuel into the cylinder. so if there torn from age or improper install then it will just be dumping the fuel in.
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Post by s14BEAST808 »

replace the pumpppp
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yojo006
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Post by yojo006 »

Test the fuel pump, ..test everything, dont keep throwing parts at the car as we all know that costs $money$...i had the exact same problem on my 98 kouki and it to is all stock. My MAF had the same Voltage readings and everything, i even tested my MAF on a friends car and it ran fine....Long story short...it was a an intermittent problem with the MAF after all..i havent had a problem since...oh and Yes, Nissan Altima 9?-98 MAF are the same as the 95-98 MAF's...Good luck. Hope this helps
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Post by Robb »

I was trying to take a look at the EGR and EGR-BPT, but I can't quite remove the EGR valve itself. Might need some swivel sockets or something. Annoying. Any tips on cleaning it once removed?

Also, couldn't be my MAF, like I said, tried three different ones (one being brand new).

Man, it's just becoming a huge headache.
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Post by Robb »

A friend dropped me a fuel rail with FPR I will swap out.

Backtracking to the fuel pump, wouldn't it cause everything to lean out if it was going bad? I've eliminated injectors/o-rings because ALL plugs are fouled, highly doubt all four would fail at once. So I would imagine FPR if anything involved with fuel.

I was also suggested O2 sensor. Recommendation on testing?
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yojo006
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Post by yojo006 »

Robb wrote:A friend dropped me a fuel rail with FPR I will swap out.

Backtracking to the fuel pump, wouldn't it cause everything to lean out if it was going bad? I've eliminated injectors/o-rings because ALL plugs are fouled, highly doubt all four would fail at once. So I would imagine FPR if anything involved with fuel.

I was also suggested O2 sensor. Recommendation on testing?

Why dont you just put an inline fuel gauge in the feed line? 2 birds with one stone..1-Fuel pressure from pump 2- making sure the fpr is working properly.
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Post by Robb »

I don't have a fuel gauge unfortunately, and nobody locally lends them out. Sears has one, but it's $60.

I did end up replacing the FPR today - that wasn't it :(
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Post by supakat »

Go to harbor freight. Yea it is probably not 100% accurate but you could just use it to get an idea.
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Post by Robb »

I'm a bit lost as to why a faulty fuel pump would cause all cylinders to foul the plugs?
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Post by supakat »

You did everything new so it might point to the ecu. A rare occasion but still happens. Or something stuck in return line. Odds unlikely but you can never tell.

Pump will not foul them out, but regulator will if stuck.
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Post by Robb »

That's what I figured, was unsure of why everyone was telling me different. :(

If anyone has an OBDII Auto ECU, please PM me..
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