noctalunais

So! I have a 180sx currently running a s13 red top sr20det engine imported from Japan, and it's been giving me some strange issues for a while now.

For some reason it seems to be over fueling and hesitating/ lagging at high revs when it's warm. To the point where it feels like it's barely making boost but it goes fine when cold. Which really confuses me! It seems to run better and faster when it's cold.

I've checked and cleaned the afm, added a splitfire coil pack, checked for boost leaks, just about everything I can think of. I'd love to run the ecu codes but unfortunately the plastic screw thing you need to turn has been threaded really badly so I can't do it at all.

I'm trying to get to the knock sensor at the moment but the bastard is just in the most innacessable place; even then I'm not sure if it's connected in the first place.

It starts fine every time, idles perfectly, doesn't blow any smoke and aside from this issue runs like a dream.

I would really appreciate any help to finally get this issue sorted!


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xpinoyxmk

Sounds very very similar to my issues, still haven't figured it out either.

Does your hesitation in higher rev's start around 4500-5k rpms? Found I had 3 cracks on the cylinder of #4 coil pack. Still haven't tested to see if it fixed my problem and my timing was a little too retarded according to my tuner, so make sure yours is correct.

Also, does your engine misfire at idle and if you rev to say 1500 rpms?

I'm still making building good boost, but for you check exhaust leaks.

Have you checked spark plug gap?

Been searching everywhere for a solution. Came up with TPS, CTS, knock sensor, bad mafs, coil packs, plugs, boost leaks and timing. Any of those variables could be causing these problems.

noctalunais

Hey there! Yea that's about where my hesitation starts, it literally feels like it's bogging.
I'll endeavor to get my timing checked out, I wanted to take it to a dyno to get everything looked at but the only decent one is about 2 hours away.

There's no misfire on idle and at 100 revs it still holds perfectly.
I've also checked for exhaust leaks, but what method would you suggest to re check?

And yea I've checked all the plugs and gaps, a couple of times even and they don't seem to be impacting.

And yea I get what you mean, every other day I come across some different idea on the Internet for a cause.
Keep at it man!!

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xpinoyxmk

Well my breaking up in the higher rpm's are gone. Guessing it was either the cracked coil or timing to retarded.

Noticing though that when i punch it WOT, I get a quick hesitation before it boosts up. Your car do that?

As far as checking for exhaust leaks, only way I've found that works best, is to start the car and feel for any air escaping from around the exhaust components, just be careful you don't burn yourself. Probably best to do it on a cold start.

noctalunais

Yea I definitely get the hesitation before boost, it seems to accelerate best with a slight peddle depression. Punching it just makes it lag back.

I'll have another check for exhaust leaks tomorrow.

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xpinoyxmk

We must have the same issue, all our issues match. Think I'm going to check TPS, pull the valve cover and check to make sure all my rockers are still in place, and check for exhaust leaks once again.

I'll update if I find anything.

noctalunais

I'm thinking so too, what sort of fuel system are you running?
And do you get a massive black stain where your exhaust comes out?
I'm tending towards thinking it might be an over fueling issue.

I've got a Tomei fpr set to factory pressure but I'm thinking the rising rate might be causing my problem. I've got a friend who also has an sr, so I'm going to try his factory fpr and see if it makes a difference.

I'll keep you updated!



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xpinoyxmk

93/98 mix

My tune is from Enthalpy and he sets up the tune rich, so can't really judge without a wideband.

I'm running walbro 255 -> z32 fuel filter -> hks 740cc thru stock fpr. I don't think my issue is fuel related.

Was told by my tuner to keep the stock fpr till 500ish which I won't be going anywhere near any time soon.

Didn't have time to look under the valvecover yet.

Juantwo3

coolant temp sensor?

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DriftDXB

I have the same issue, car bogs at 4-5k RPM and then continues on like nothing happened - do let me know if you find a solution.

ultimateirving

Replace your Cts if they have never been replaced. It's cheap and easy to access. Also verify tps is set properly. ~.45v closed and under 5v wide open.

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noctalunais

I've had good luck with replacing my fuel pressure regulator!
It's pretty much eliminated the over fueling and has as far as I can tell removed the flat spots/ hesitation/ whatever it is.
That being said I'm still apprehensive since I've had the problem so long!


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