Hesitation, stumble, detonation, bucking and search not hitting home base

[BCs300z]

Man, I feel really defeated writing this. But everytime that I get a good lead out there is cyberspace, the thread never finishes with the fix. I am not an amatuer mechanic, but am new to sr's. Most of my experience is on TT Z's. So here is goes.

Engine is an SR20DET RedTop in an S13. Everything about this car works perfectly, except......

When I first finished the swap, had problems with low bucking and stalling. Consult said the TPS was bad, so I changed that out. Car stopped doing that and start hesitating around 2K or so, under cruizing throttle.

Then I came to find out (via consult and the internet) that I needed a skinny 02. Fixed that. Now car runs better, but feels like it losses fuel completely when getting into it under boost. Came home, double checked for boost leaks and found one. Fixed it. But problem still there. Came back, installed a good TT Z fuel pump I had laying around, running better, feels stronger, but still the same problems.

Put in new plugs this morning. NGK BKR6EIX-11 gapped to .036. Runs like a freakin champ. I am really happy at this point. THen I get to the highway, where I can WOT and the same cutting out, pinging, crap! I let off the throttle a little (to 35% or so) starts boosting and accelerating fine again. Doing 3rd and 4th gear pulls, at modderate throttle...its great...start letting into the throttle again at 3-5K and the same dead, like the brakes are on, and I can hear the detonation. Came home. Changed out the MAF from an SR to an E KA MAF. still the same problem.

Checked the timing...dead on 16*. Using a piece of spark plug wire...I have never trusted those loops. O2 sensor working fine.

Only code that I am getting through the consult is an A/T fault. Appearently, I have an auto SR ECU. But so far, I don't see that being an issue.

ANOTHER CRAZY FIND: Is that the consult is showing my TPS at .05 V or so lower at the ECU. IE: set via voltmeter at the TPS to .46V I see .42V at the consult. So I set the voltage to the consult reading (thereby getting .54V at the TPS) and the car ran better.

ANOTHER CRAZY THING: At normal operating temp, and the RPMs steady, I see 16* via timing light, but I show 6-7* through the consult. Rev the car...settles to 15* and then settles again to 7*. But again, the mechanical setting is right on.

My next coarse of action is to do the Z32 PTU mod.

And on another note, I wired this car up to be as close to stock as possible, meaning, I left in the wastegate actuator control soleniod. I have also unplugged it, which didn't change anything

Like I said, I see threads describe this same thing and then never go anywhere. Please help a guy out. I am just trying to finish this car to turn around and post it in the classifieds....cause that is what I do.

BCs300zCustom Import Arts, US Div
Modified by BCs300z at 4:29 AM 3/15/2008

[240_SeX]

I have problems almost identical to this, i thought a boost leak was to fault and parked it for the winter. however after reading your post i wonder if there is an intermitten fault in the cas. maybe that would explain the wacky consult readings. maybe try a known good cas and see if it helps?

[BCs300z]

Gonna track down one of the local guys and borrow his to test. Perhaps that will work.

I also just came across something interesting. Found a pinout diagram that showed pin 28 being the Auto trans throttle position signal (kick down).

I also found something stating when changing from the 6 pin tps to the 3 pin tps you used 4 of the 6 wires. white, black, light green and red (spliced together) Yet I cannot find anything to suggest that is to "activate" both tps signals.

Can anyone confirm a difference?
Modified by BCs300z at 6:55 PM 3/14/2008

[blinker_fluid]

I know auto sr had a different tps,6 pins instead of three. If you're harness is 5-speed and the ecu is auto some of the pins may be off. I would first try to borrow a good 62 ecu. Also could be the timing is 180* out.

[BCs300z]

Timing is good for sure. Been over that about 2 dozen times, with the valve cover off and on. Gears, chain, cas, all are spot on.

I will try to track down another ecu. worth a shot.

Been reading now for hours...think my eyes are bleeding!

Found a couple ideas... seems this issue happens to a vast majority. Of those, a good percentage report the fix in the ignition. At this point, I have to concur.

Going to bed now, but will try some stuff in the morning and report back. Going to try building a ground web and swapping in some z32 coilpacks. LOL.

I can't help but think that perhaps I am drowning out the spark with fuel, however the car doesn't smell rich at all. Dunno.

AHHHHHHHHHHH my eyes!!! Good night

[CoupedUp]

I would seriously invest more into the timing issue. If the ECU is see 6-7* when Mechanical is 16*, this would put the timing way off making it cut out and be all crazy.

I would do CAS and ECU swapping/troubleshooting before coil pack wiring/replacement.

Im assuming upgraded fuel pump since youre a TT guy. Get a fuel pressure gauge, make sure your base pressure is right and make sure that the pressure continues to rise with boost.

[BCs300z]

ahhh, Feel better sleeping on it. Gonna try nailing down that timing thing too. One thing that did come back to mind, is that when I first got the engine, I took the cas out to inspect it, and while turning it...it almost felt as though it would occationally "slip". When rotating it at a good pace by hand, it would "feel" like it would becoming momentarily "loose" (like a wheel loosing a little traction) and then be fine again. And not all the injectors would click on the first couple rotations. After rotating a couple times, then all four would fire fine.

But again, this is all feel...it looked to rotate just fine and really gave no true casue for concern. I have seen Z CASs that don't fire off the injectors right away either.

I put in a TT pump. I was getting the same issues with the KA pump too prior. Waited to install the TT pump as last resort...which still made no change in the overall situation, so fuel does not appear to be a factor. Have not yet put a gauge inline, but other testing on the fuel system suggests no issue at all. Again, nothing changed between the KA and TT pump, just "felt" a little stouter in the @$$ dyno.

I am going to check the CAS first then. Sounds more and more like the curprit. I will post up my results post haste. I have a NA Z coming in the shop for a bad fuel injector tomorrow, and an s13 coming in for an A/C line fix. He has an SR! May have to borrow his CAS for asec while he's here. LOL.
Modified by BCs300z at 4:29 AM 3/15/2008

[BCs300z]

UPDATE:

First, only cause it is most fresh in my mind...got an email from a fellow member with the same issue andit turned out to be ECU. Hmmmm...

Back to this morning.

Started the day by changing out the #6 injector on a Z. That was easy and the perfect fix. After that, I decided I would check out a couple things on the s13 again.

I started by checking ground to and from everything. Everything and everywhere, making sureit could get back to the chassis. Sure enough, no matter where I went, I was getting less than an Ohm back to the front corner of the fender. Did ad one more ground to the head.

Then I tried to adjust the TPS again. The car was warm, and I was showing .38 volts on the consult. So I checked the TPS, and it was off, like around .40. I adjusted it again, only this time, I took my center pin voltage reading off the number 20 pin on the ECU. .465 volts now. Consult proves the same. Perfect!

Then I read something about the nuetral switch and remeber that I did not wire that in, because I could never find the g/o wire in all the plugs near the fuse box. I did wire it up in the plugs near the front right, but I could never find the wire after that. SO I wired that up, from the transmission to the wire in the reddish plug near the battery. Cool.

Started it up, and it actually smelt rich. Never smelled this rich before. Went fora drive and she is driving awesome. Perfect and smooth. Lovin it...until...I give her that magic amount of throttle and then....craps out and bucks, detonates, until I back out. I could be at a slight acceleration, and just ease a little more and pop, pop, pop, then ease back out and I'm good again. WTF?

So I cruize back home pissed. Checked everything again via consult. Even so far as to swap out with two other MAFs, just to compare readings. they were all good.... Next...I pulled the plugs to check them and they all look just between lean and fine. The porcelin looks white and new (they are only 2 days and 20 miles old) and the ground is ashy white. they look fine to me, but perhaps a tad on the lean side. Also checked the compression and got between 140 and 150 all the way accross. Happy.

The guy that was coming with the SR20DET S13 isn't today, so no swapping out ECU or CAS today. OK...so still a little peeved, I needed to relax, so.....

So I cut out the nostrils in the pig nose. LOOKS AWESOME!!!!!!!!!!! more air too. love the freebies!

Happy again, I started cleaning up my mess and went out again. This time, I had the consult on the column and could watch the RPM, and TPS. Trying to see that crucial moment when the car started giving out. I could race the throttle from idle to WOT (and get a perfect 4.2V) at a stand still. TPS is working fine. This also proves that the CAS is right on too. I even slowly accelerated up to 6K RPM (at the halt) and it purrrrrred all the way there. I start to drive and the car is fine leaving the neighborhood. Occasional hitting 2V (50%) on the TPS and No issues. Get out on the highway again, start into it. I tried easing in, I tried romping in, I tried everything, but there was no clear cut RPM or throttle position that caused the issue. Nothing has changed. Feeling defeated for the day, and needing to head home to take the kids to a B-day party, I went home.

THEN>>>>Since I know I couldn't come back here without testing something fuel related>>> I thought of the be-all end-all McGyver stuff. I took a good FPR I have from a Z32 and added it to the fuel track. Or in otherwords, I now have two FPRs, so the Z one SHOULD correct anything that the SR one is not. NOPE. Still the same. DAMN!+

The car runs perfect....absolutely awesome and keeps me with a grin on my face...until you get into the throttle.

After all the testing I did today, I am about 99% sureof two things.

- ONE - It's an issue with regards to being under a certain amount of boost. Tomorrow, I am going to hook up a secondary gauge and moniter it externally. Same testing as with the TPS...looking for that level that kills it all. However, I think this will be for nothing, since........

- TWO - MY ECU is trash. It has to be the ECU. Really. I am sure the magic 8 ball would agree. Now to track one down just to test.....

More to follow as I try to swap an ECU next. But please chime in if you have other ideas.

***PS. I know that this is lengthy, but I want to be one of the good threads out there that someone like me reads and says...."UREEKA!!!!!" and doesn't post all over again.

[burntricer]

my timing is also seeming to be bouncing around. i do not know what is causing it, i have tried to change the knock sensor to see if that was a problem. its not, let me know if the CAS changes anything on your car.

[neverlift]

could your knock sensor be going haywire or a lil emo? IF not its an over rich problem. Stock boost? Maybe the stock fpr isn't able to handle the 300zx tt pump(shouldn't be an issue but it has happen )

My problem was probably the tune was too rich or how I had the fueling setup was too soon, but it felt the same as someone slammin the brakes!

[BCs300z]

HAPPY DAYS! I GOT IT...DOG GONNIT!

So today, I started off the morning by trying to get a hold of a couple SR guys I knew in the area, to try and get some testing parts. No luck in any of that. So I didn't bother with the car at all.

Until around 2 or so. I got bored and went down to the shop, and decided to mess with it a little. I thought that I should at least I would get rid of the crazy McGyver FPR setup I had going, and put things back into place. I wiped the bay down a little, and was about to leave it at that. Then I thought, why not just tear the CAS open and check it out.

I had done this before, when I first got the engine. I did so to clean. Well this time, I was curious a little more into the firing marks. In taking apart, I was carefull with everything. I TORN IT DOWN TOTALLY!!!! Took it completely apart....and then noticed something...

I put it all back together again, and noticed that the disc had a white mark. And the CAS housing had a white mark. And when you line the two white marks up, you can see another yellow mark THROUGH the second smallest firing hole. It was like Goonies, when the kid lined up the islands in the coin piece. See the pic. I figured this was a base mark of some sort.



However, looking at the pintle of the cas (with the gear) it didnt line up. THis to me was very odd. Perhaps it was made wrong or something. Stands to reason that if the inside marks line up, so should the outside respectively. AND IT DIDN"T.



So I thought to install it again...but this time off a little. SO that the inside marks would line up inside the CAS once inserted. I put it in, and turned it to half way, and tried to start the car. It started for a sec and choked out. Couldn't get it to start again.

So I lined up the crank marks and pulled the CAS out and tried again....same way. Got it in, yet this time it sat in there easier. Sure enough, the car fired right up and ran great.

Waited for about 7-10 minutes for the car to warm up, shut it off, pulled the TPS, fired it up, set the timing, turned it off, plugged the tps back in, and fired her up again. Was still dead on 16* where I put it, and was running very nice.

OBSERVATION:

- When I first got the engine, the CAS was turned fully counter clockwise (putting the upper bolt to the far right side of the hole)- When I got it all running and set the timing, I was set right in the center of the CAS.- This time, the CAS is nearly all the way clock-wise (to the far left of the hole)....WHICH is where there appears to be a little of that service tape the dealer puts on the CAS when they do a 60K....which a little bit of it is still on one of the bolts. Hmmmmm.

I don't get it. Its crazy, but I was dead on 16* before...at a different spot.

ANYWAY...ON TO THE GOOD STUFF.

IT HAULS @$$. NO ISSUES AT ALL. NOTHING. ALL GONE. BOOSTS HARD. EFFING SWEET!

I can't say for sure if my CAS was made wrong, or I effectively got into the correct tooth I wasn't before. Either way, it was a timing issue. And the funny thing is...I did everything by the book before with the valve cover off and everything. Nothing was off on the chain, and the dots were right on inside the head meshed with the cam. I just had to set my CAS off by one spline in the gear. Crazy.

So now....

The car is finally on the market.....

zerothread/322095



Enjoy!

[burntricer]

bookmarked.

[schanne]

^ samething..

[240_SeX]

after reading your post i wonder if there is an intermitten fault in the cas. maybe that would explain the wacky consult readings. maybe try a known good cas and see if it helps?

Great work.....This make me feel like a psysic

[BCs300z]

Great work.....This make me feel like a psysic

If life ever brings our paths to cross, lunch is on me. LOL

[240_SeX]

If life ever brings our paths to cross, lunch is on me. LOL

Thats funny actually i have pondered moving to TN. But im happy you found it out....I just had a lucky educated guess. Good luck with the sale

[skyyred]

UREEKA!!

[Kalypso]

bookmarked.

[supergl74]

I tried the CAS fix and it didn't work for me.

[mistamacadamian]

i had the same problem as well, nice z though. whats done to it?