Sr20det slugish and overboosting/running lean

[Loomis112]

Let me just start out with the important stuff. Sr20det(550cc denso, apexi neo safc, z32 maf, walboro fuel pump, gt2871, etc

I have had this problem for about a month now out of nowhere my car started to cut out after 5k. So I started trouble shooting did the timing, changed plugs (bkr6e gapped at.30), seafoamed the car, etc.

I had a local shop do a smoke test and they found a major boost leak so I ended up replacing the intercooler (it was time), to my dissapointment it didn't work.

Then I went as far as to replace the turbo I thought it was bad until I pulled it off and felt no shaft play whatsoever so I slapped a new wastegate on there. Didnt fix it...

Next I finally replaced my wideband with the innovate mtxl and found that I was running pretty lean through the rev range. So I took the afr a few pegs down on my apexi neo.

Still having the problem I redid the timing again and found it was a little off so I put it back (second mark from the right correct?) And it helped a little but then after about 5.5k rpms it starts overboosting and leaning its as high as 15:1 even with the neo adding +50 fuel its crazy

Im not sure what else to do even today I was doing a pull and it just feels slugish and unwilling to move till about 5.5k when it starts overboosting and leaning out.

It feels like theres no boost and then at 5.5k it feels like its boosting up and ready to blow when it hits that overboosting point.

[Loomis112]

Anyone have any similar problems?

[cotbu]

Fix this yet? Where are you located?
If everything is set to stock, tps, timing etc. Try ngk bkr7e plugs gapped to .028
If still leaning out, lower boost and raise fuel pressure at the rail to 50psi without vacuum. Test it out. Sound like a tuning issue though, and those are just bandaids.

From a Highly Tuned Note 4.5!!!

[Loomis112]

Yeah kinda have an update, cleaned maf, tightened intercooler couplers, bkr7es gapped at .28, installed a boost gauge (previous one broke), and I noticed on a pull that for some reason it sticks at about 5psi then at that spike i was talking about at 5k it goes to 10psi then 15psi. Could a blowoff valve opening prematurley cause this? I noticed that the turbo seems to sound much louder after 5 psi and you can hear to bov hiss at anything 5+ and it is a cxracing bov so im not sure

[Loomis112]

Never mind it can be the BOV because the BOV is connected to the manifold so the pressure keeps it closed during boost.

It's on an apexi neo, and the timing is good just checked it. Not sure what else it could be honestly.

My AEM Truboost just blew recently hence the new boost gauge and where the solenoid was I took it out and connected the lines together should I just leave the solenoid in until I get a MBC?

It's a mess right now

[cotbu]

Assuming safc is setup properly.
Boost leak test, the system. And if need be remove the bov or cap it off. Recirculating the bov, maybe an option if it's leaking. But yes a bov can stick, and let boost out then suddenly shut and boost will skyrocket. Cleaning maybe an option as well.

Show us a diagram of your vacuum/boost line routing.

Until you can get boost under control, I would leave it out and run the boost source signal to the waste gate directly.

Your setup is quite common, so it should be easy to figure out.

From a Highly Tuned Note 4.5!!!

[Loomis112]

Heres a video to help show it https://m.youtube.com/watch?v=ecl1RULCqIc


And I have a vacuum lime going from the intake manifold to a T peice, from there one line goes to the boost gauge. The other line to another T peice from there it goes to the waste gate then the bov.

So I guess its just running off wastegate pressure.

[Loomis112]

Ill upload a photo of the diagram shortly

[Loomis112]

http://s1277.photobucket.com/user/Cody_Loomis/media/vacuum_zps0bfbj7eu.png.html?o=0

There's my diagram

[Loomis112]

By the way thank you for your help and suggestions. I'm kind of lost and any help is much appreciated

[cotbu]

No problem. Here's were they start coming out off the woodwork, lol.

S13 sr20det correct?
T, the fpr and the boost gauge together.
Run the bov by itself, and run the waste gate off the bottom nipple.

This is something you can do with the current T's and lines you have. If there is a change, better or worse. Reply.

From a Highly Tuned Note 4.5!!!

[Loomis112]

Alright so before work I decided to put a vacuum cap on the bov and eliminate a T peice. One thing I did notice was that on my after market fpr (circuit sports universal) the vacuum line on top isnt connected to anything but instead is capped off...

With the bov capped I do notice a significant difference its better. But maybe the bov isnt the only thing to.do with it. I'm gonna try what you said when I'm home and see what happenes just thought id share.

It seems to boost up quicker, still stalls on 5 psi but goes up quicker

[Loomis112]

Also I noticed on my fake greddy intake manifold that there is only one nipple to supply manifold pressure/vacuum. Theres one on the throttle body but it doesnt supply anything

[cotbu]

The one on the bottom of the throttle body is either capped off or used for a boost source, do not use it for vacuum/boost source. Connect the bottom nipple to the waste gate.

From a Highly Tuned Note 4.5!!!

[Loomis112]

Yea its capped off im on a test drive right now its still doing the same thing boost spike and leans out over 5k and feels slugish till then.

Could it be a maf thing possibly?

Alao is the an aftermarket fpr supposed to be capped off or what?

Ugh this is frustrating

[cbeuglas]

Every fpr should have a vacume connected on a boosted car. It is suppost to boost fuel pressure as boost levels go up.

[Loomis112]

Guess I'll hook that back up tomorrow and see what goes on

[cotbu]

Yes the fpr should be connect to a boost/vacuum source. That is any port after the throttle body.
it could be the mafs, if could also be the afc.

From a Highly Tuned Note 4.5!!!

[Loomis112]

Alright ill connect it.

Idk if you can answer this but I know on the afc it displays the voltage of the maf any idea what uts supposed to be?? Ive tried searching this but cant come up.with any solid answer

[cotbu]

I don't remember the correct voltage for the z32 mafs on a 300zx, it should be above, .700v for an sr20, and depending on airflow via idle, approximately 1.150v to 1.250v iirc.

You can pull codes to see if it's faulty. The safc adds resistance on the signal line, so voltage display on the afc, may not be the best way to verify a correctly functioning mafs.

From a Highly Tuned Note 4.5!!!

[Loomis112]

Just plugged the fpr back in. It richened the mixture quite a bit which is a relief.


On another note does anyone have a good way to test a z32 maf??