'DE bogging has returned, Arghh! / Reasons for running lean?

[slipnfall]

I'm at work so I'll have to follow up later. However the mixture is indeed lean. The ratio is parts air/part fuel. So 10:1 is 10 parts air, 1 part fuel. 10:1 is pig rich. I peak lean around 13.5:1 at roughly 3500rpm.

And no, no parts yet. My order w/Midway was put in 12days ago, but I guess they can't help it if something is backordered. Especially with the obscure parts I always order. I wish they would ship incomplete...

[Magnes]

OK, I get it. Yeah, you should get closer to 12:1 at full throttle.

Interestingly, the EGR should also close at WOT. Maybe next time you are data logging your car, floor it for a second to see if the EGR is being closed. I still find it suspect.

[slipnfall]

Well chemical stoich is 14.7:1, but certainly not practical. I guess you could call 12-12.5:1 'ideal for n/a'.

[slipnfall]

Ok I *finally* got my cap and rotor in today. The rotor has a small chip out of it, but I installed it anyways to see if it made a difference(a replacement is being sent).

SO, I start out on my lunch break, and it starts bucking again!! It was pretty bad, I'd say as bad as it gets. Just as I was about to curse my creator, I noticed my e-brake wasn't fully disengaged. It was up like one notch. I released it and shortly after, it settled down. So I'm thinking maybe my rear brake calipers aren't fully releasing. That would make sense because I usually part with the e-brake on, and the car bucks with the engine hot or cold. Once it get's moving, the pads work themselves away from the rotor enough.

The rear calipers were rebuilt about 15k miles ago, by a stranger with new outer-most seals. I find it very hard to adjust my e-brake properly because the axles interfere with the turning of the wheels(hard to distinguish between brakes dragging and resistance from the axles). That being said when I adjusted it I made sure to leave it a bit lose. Driving a long distance w/out the brake isn't very effective because the tires seems to heat up the wheels/rotors.

So either the calipers themselves, or the brake cable is getting hung up(I see some corrosion on the cable distribution block in the rear). Also a buddy of mine suggested that it may be the soft-lines have collapsed slightly internally, and are acting as check-valves(happened on his '79 chevy truck).

Thoughts??? Totally left-field, I know, but it's usually the simple things that bite the hardest!

Jamie

[slipnfall]

Ok well scratch that idea.... it was acting really bad on the way home. As soon as I pop the clutch pedal in and coast, it's fine. So the brakes can't be causing it. Back into 3rd gear and it's back. It's happening more frequently at higher speeds too: like 40-60MPH.

So a new OEM cap/rotor made it WORSE! I mean, it was going good there for a while... as soon as I install those two, BAM, it's back. Perhaps because I disturbed the spark plug wires? I'll have to re-ohm them tonight...

If I install a walbro 255 pump, is the stock FPR capable of regulating down the increased input pressure? I'm also considering having a spare set of 270's flow-checked and install them.

I just want to throw something! This is frustrating me to no end. The weather is getting significantly colder out FWIW.

Thx for following along.

::edit:: I forgot to add: when I got onto the highway, around 55mph, the car would ONLY act up when cruising. If I accellerated or decellerated, it was smooth as butter! Very consistent, I did this about 4-5 times. ::edit::
Modified by slipnfall at 5:49 PM 12/1/2005

[slipnfall]

Here's some pic's of the cap/rotor I pulled. It has only been in since the rebuild(15kmi rough estimate). The dark stuff is carbon I assume, and those small slivers are plastic-like. I have no idea where they came from, but it's not the 1st time I'v removed them from inside this cap. Is the white arc-marking normal on the cap points, and rotor contacts?

PS-sorry I don't know how to attach more than one pic

[slipnfall]

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[slipnfall]

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[sohcsleeper]

heh did you try to replace the fuel filter get a 300zx one i had a few problems with another car of mine sounds just like what your having and it turned out to be the fuel filter like i changed plugs wires carb everything i could think of then i was like **** i might as well try a fuel filter and boom problem fixed if it is being blocked off it will cause the car to buck when its trying to get gas also might be why u were running lean just a thought

[sohcsleeper]

cheap fix too if it is heh

[slipnfall]

Well I can certainly give it a shot, it's a cheap part. It just seems too consistent to be a clog, that's all.

[Magnes]

How many months will that take?

[slipnfall]

Hey man I can't help when part suppliers are back-stocked...

Trust me I'm trying to get this fixed as quick as possible without pissing away money on un-neccessary parts. Also each time you replace something you just introduce another variable which makes diagnosis harder.

[slipnfall]

I'm reluctant to post this, because I may just jinx myself...but I think I fixed my problem. I received my replacement rotor today, and went about replacing it. When looking at the new cap(like 2days old), I noticed that the contact-markings on the electrodes were *all* the way towards the top of the posts, near the plastic. Obviously my rotor wasn't on all the way. I'm always really carefull with these things because they break so friggin' easy when trying to tap it on. Well my previous rotor was actually cracked, and it must have slipped 'up' recently to cause all these headaches.

The fact that the symptoms got worse after I put the last cap rotor on brought me to this conclusion. I'v only driven it a few miles since, but it hasn't returned *at all*. I even unhooked my EGR this morning to re-confirm that wasn't causing it.

Bring on the remarks, I had 'em coming

'slip

[NISTECH]

Dude your cap looks like ****.That thing is seriously F'ed up. You can clearly see where the rotor ate into the plastic. Thats what that plastic string is wrapped around the electrode. The white arch markes are extreamly extensive. Its no wonder your car was bucking. We could of put this to rest very early on had you posted those photos in the begining of the thread. That was your problem. The reason it did that was because you didnt have the rotor fully seated on the dist shaft. Make sure the new one goes all the way down.

[slipnfall]

hehe, yeah as I said ^^^, it's the easiest things that bite you the hardest.

So it's not normal for there to be arc-markings on plastic surrouding the cap posts? I mean my new one has them also already, with about 1/2 of the intensity of those above. And yeah I realized what those slivers were after I pulled the cap again(and realized what my problem was).

Well that's certainly a mistake I'll never make again. All has been well since then; in fact I dyno'ed again this weekend with the BRM exhaust installed. Roughly +7.5whp, +9wtq

[slipnfall]

Well I hate to do this... but it's back...

ONLY if the engine isn't warmed up, so I've noticed... simple fix, I know, warm it up. Well it shouldn't be doing that, so obviously something else is wrong. I'm going to re-check my rotor, but I suspect it is fine... unless it slipped again.

grr..

[Magnes]

I hate having to repeat myself, so I won't. Maybe you could read the replies in this thread?

[slipnfall]

Excuse me? I don't remember asking for attitude, so back off. I did (and do) read everyone's responses... you suspect that my EGR is remaining [semi] open, a page back, right? Well I don't like repeating myself either: I said I unplugged the BPT control line to the EGR and it did not help. Thanks for the suggestion, believe my I appreciate any help, but leave smart-*** comments to yourself.

[Magnes]

Excuse me? I don't remember asking for attitude, so back off.

You post 2MB of diagnostic datastream, 7 associated jpegs, a link to a dyno pull thread, and it takes you one month to figure out that your distributor cap is on wrong? That was the very first thing NISTECH said to check! That's asking for it, buddy.

Or, you ask about the normal range for O2 sensor output 2 days after I replied to that question on the other thread in the engineering section, so I had to repeat myself. That's asking for it.

Bring on the remarks, I had 'em coming

If that's not asking for it, what the hell is?

It's not as if I never screw up, but I'll take my lumps when they're due.

Now, getting back to business...

There are 3 clues to suggest that the EGR is remaining open:1- Your reported symptoms (cold-start bogging).2- Dyno pull chart (poor full-throttle enrichment).3- The data stream (the ECU is shown to be sending the wrong signal to the EGR control solenoid. This is not a matter of opinion).

There is 1 reason to suspect that it is not the EGR:1- You say that pulling the vacuum signal to the EGR has no effect.

Of course you can see why I might doubt your word. Speaking of which, where exactly is your post where you claim you pulled the EGR vacuum signal?

[slipnfall]

<sigh>... ok, look, this isn't going to turn into a pissing match, but I will post in my defense...

it takes you one month to figure out that your distributor cap is on wrong? That was the very first thing NISTECH said to check!

I checked the cap man, it was one of the first things I reported back on. Not made in Italy, no carbon tracking. I even got a second visual opinion from my co-worker. I *knew* it was suspect, because of the excessive dust inside, and white arc-markings. Beyond that, there was nothing I could do to further 'check' it besides replacing it. Yes it's my fault for not realizing the rotor was not on all the way *then*, but the excessive arcing didn't make it apparent(untill a fresh cap/rotor were on) that it was not on all the way. Yes it, took me roughly a month for my cap/rotor to get in: ordered on the 10th or so and some other backordered items held the entire order up.

Obviously there were some discrepencies over the O2 sensor voltage. I was told the dataloggin values were in mV. This was from the guy who wrote the software. You and NISTECH(later) told me 100 on the graph=1V on the sensor. I wouldn't have asked twice had I remembered your post in the other thread.

1- Your reported symptoms (cold-start bogging).

Re-read my posts, I corrected myself and said it was cold-CAR start, not cold-engine. Before the new cap/rotor I could remote start for 15-20mins and it would still do it. I have not disabled the EGR since the new cap/rotor, and this my next thing to do. It didn't help before, I don't think it's going to help now.

3- The data stream (the ECU is shown to be sending the wrong signal to the EGR control solenoid. This is not a matter of opinion).

Again, I responded directly to you in this thread about this. The 'numbers' on the graphs are NOT related to the output signal voltage!!

The CONSULT data I receive from my software reports EGR as ON or OFF. To translate that to a graph, I represent ON with 30, and ONwith a significantly lower value. This just makes viewing when it switches on the graph easier.

where exactly is your post where you claim you pulled the EGR vacuum signal?

Four or so posts up.

So anyways, I agree and think the EGR is still somewhat suspect. As you and Chris said in the first page, lack of EGR won't cause bucking, but excess will. Replacing the cap/rotor seemed to cure the warm-engine(and highway speed) symptoms, but not cold-engine/low speed. It's obvious the new/proper install of the cap and rotor illeviated some symptoms, but didn't cure the problem. Tomorrow morning I'm going to start-out with the engine cold, if it starts acting up, I'm going to stop, pull the EGR control line and see if that fixes it. It didn't before, so again I don't think it will this time.

Listen, no hard feelings on my end, I just couldn't help but feel attacked...

It's late, I'm out for the night.

[Magnes]

Fine, we've both said our piece, I'm willing to move on. I want to get to the bottom of this because your problem might relate to one I'm experiencing, and besides, I don't think you're a bad guy in the end.

One of the things I need to stress is that regardless of the outcome of the test I suggested, your datalog indicates to me that your EGR is not being cut when it should (when the engine is cold).

First we need to establish the same interpretation of the datalog...

Let me know if this makes sense to you or not.

[s13sr20chris]

electrical part of egr is only a small portion. the best way to check for egr funk is to pull the valve and block the holes off. i have done it with a rag in a pinch. that way you eliminate the control side(elec and mechanical) and the valve itself(they do stick open sometimes).