Same old problem: hesitation and sensitivity to more than 30% throttle...

[s13_240_rb20]

Well, it has been a few weeks since I have posted anything but I have come up empty handed again. I have put in a new walbro pump into a new fuel cell (to eliminate all that trash from my gas tank).

Now:

I have solid fuel pressure that builds up with vacuum.

I can drive the car so long as I don't apply more than 20% of the gas pedal.

If I apply more than that, the engine will lose power and start gasping and choking out.

OK...I have also noticed some things that might be abnormal so please comment on the following ideas:

My air intake echoes the sound of what is normally BOV sounds at the MAFS, even when my BOV is being silent (while revving of course)

Revving in neutral at the throttle body, I see that my BOV is not releasing the air...I am guessing that it is pushing back out my MAFS.

My vacuum lines to the back and side of the BOV are both Y-d together and a single line goes to the "thingy" mounted onto the air intake arm.

If I remove the vacuum line from the back of the BOV and cap it with my finger, AND THEN REV,....I can hear and feel air releasing from the front of my BOV....

Soooooooo....

Is any of this normal....? the choking persists despite anything I try if I apply more too much throttle at once. However, I have my doubts about the BOV not responding unless I remove a hose and the fact that I hear pressure releasing back out of the MAFS??????

I don't think I have the right software to read Datascan datalogs, but the next time I drive it I will hook up the laptop and start logging my data incase someone else knows how to analyze the data...

--TJ

[rb25drag]

The air noise coming from your MAF is normal I believe. mine does the same thing. Is you more than 20% throttle at all times? Revving and Driving? That sounds like a Bad MAF or its hooked up wrong.

[s13_240_rb20]

The air noise coming from your MAF is normal I believe. mine does the same thing. Is you more than 20% throttle at all times? Revving and Driving? That sounds like a Bad MAF or its hooked up wrong.

major hesitation if revved heavily in neutral, but the worst hesitation and gasping shows up when 30%+ gas pedal is applied while driving...

Is a z32 mafs gonna be a bad result for a stockish rb20det? I still have this z32 mafs collecting dust somewhere in a box. I can try it out again, but I took it off over a year ago (when I first started troubleshooting) because Carl H said it was overkill. but again, my question is "will a z32 on a stockish rb20det run ok or is it an automatic NO-NO??"

--TJ

[240z4u]

Z32 maf is not acceptable without some way of controlling it.

What are you maf voltages doing, A/F ratio? Your not really providing enough factual data to figure out what the problem is.

Do you have a wideband? If not, you definitely need one!

Good luck - Evan

[s13_240_rb20]

Z32 maf is not acceptable without some way of controlling it.

how can I control it?

Do you have a wideband? If not, you definitely need one!

I know, but I have a wedding coming up in 2 month and I can't afford the 250-300 bucks right now..

[240z4u]

You need at least an apexi SAFC to control the z32 maf. Even at that, I would leave it as is until you get it running right.

Figure the wideband is about the same money as an SAFC, your money will be better spent there. I understand on the being strapped for cash, but buying things like a wideband is more like buying tools then performance parts. It will allow you to diagnose your problems.

Evan

[Darius]

Is what you're describing the BOV leaking? Is there black smoke coming out of the tailpipe? It's hard to tell from what you are explaining.

[Carl H]

your bov is hooked up wrong, bottom nipple is for boost signal and the top for vaccum, this ensures the bov stays closed even under 'high' boost situations. for most ppl only the top is nessicary.it sounds like you have an ignitor issue, have you tried swapping it out for another?is the ignitor damaged in any way?

[s13_240_rb20]

your bov is hooked up wrong, bottom nipple is for boost signal and the top for vaccum, this ensures the bov stays closed even under 'high' boost situations. for most ppl only the top is nessicary.it sounds like you have an ignitor issue, have you tried swapping it out for another?is the ignitor damaged in any way?

here's a pic of my BOV lines when I received the clip. They are still run the same way. it's a HKS bov (stock??) you can see the two lines are y-ed together and I traced it on to the air intake...



how should my BOV vacuum lines be routed (to where)? I need to know where the one on the back goes to, and I'm guessing seperately, where should the one on the side go??

ya, my ignitor (the square box on the back of the coilpack cover) has a crack in it. I can still drive the car around, so is it possible that my ignitor is just weakened it's output??

--TJ

[s13_240_rb20]

Is what you're describing the BOV leaking? Is there black smoke coming out of the tailpipe? It's hard to tell from what you are explaining.

I don't think it's leaking....if anything, it's not working like it used to. it doesn't make a sound (except that I can hear it echoing out the MAFS) or release air while revving unless I remove the hose on the back..

No black smoke from the tail pipe...

what is the easiest ignitor to source (price wise) that is a good match for a stockish rb20det?? Just like my z32 mafs, I don't want to get a part that is "overkill" and needs "limiting"...

--TJ

[ka24eracer]

If your sure about the bad igniter , get one from a Z32 and follow the conversion write-up in the sticky .

Worked fine for me !

[s13_240_rb20]

Well, i just unplugged my o2 sensor again, but this time it revved alot easier (with very little hesitation, unlike the many times before). So I left it unplugged and took it for a test drive. Now the hesitation was only on the low end of the gears and very little at that.

So I pulled over and adjusted my CAS (the last thing I tinkered with) and moved it from full-clockwise to midway and it ran almost perfectly. I will try to get out there tomorrow morning and set my timing (assuming I can figure out how by the FSM)...and yes!! I know that I should know how to do that by now...

anyways, I will have to recheck my wiring on the o2 sensor harness before I cough up some money for a new o2 sensor. don't wanna replace a good o2 sensor because of bad wiring..

It doesn't feel like it's making 100% of it's original power, but I can live with 85% until I reset the timing and fix the o2 problem...hopefully that is all that is holding it back now..

--TJ

[Carl H]

you should have stated you have a cracked ignitior, im willing to bet thats your problem.most of the time when ppl have symptoms like you described it can be traced to a damaged ignitor.

[s13_240_rb20]

you should have stated you have a cracked ignitior, im willing to bet thats your problem.most of the time when ppl have symptoms like you described it can be traced to a damaged ignitor.

do you mean that a damaged ignitor can cause hesitation and choking that are "fixable" by unplugging the o2 sensor? I know I probably need to replace my ignitor too, but without my o2 sensor plugged up it is running soooo much better that I can get back to some of the other general maintenance before I spend some more big bucks...

It really needs an alignment and I have a front brake that "clunks" and shifts the steering wheel when I touch the brake pedal. I took the wheel off expecting the brake to be loosely mounted but the only play I found is the rotor wiggling at the lower mount...so I gotta get that fixed too..

anyways, I'll be piddling with the general maintenance while it's drivable and making my plans on the more expensive maintenance...

--TJ

[Carl H]

i find it odd that you seem to have some correlation between unplugging the o2 and it running better.the only thing i can come up with is that with it unplugged it runs richer and since it already has a weak spark it help to keep it going where a lean mixture is harder to perpetuate.

[s13_240_rb20]

i find it odd that you seem to have some correlation between unplugging the o2 and it running better.the only thing i can come up with is that with it unplugged it runs richer and since it already has a weak spark it help to keep it going where a lean mixture is harder to perpetuate.

what if it is bad wiring to the o2? That is what I am going to check first before I buy a wideband. could bad wiring (a short somewhere) cause a hectic response that makes it run too lean or rich and end up with hesitation and choking out??

gotta go to work now...I'll get back to responses in the morning i hope...

--TJ

[240z4u]

Make sure you have power at your O2 sensor heater wires (outside 2 wires). I had no power on the outside pins and it caused some funny issues.

[Carl H]

but the problem here is why is the o2 having ANY impact on it running, ive ran a 20 without an o2 sensor for a month or so and had no issues.