Jersey

Hey all. Ok, first an update on my sudden rich idle condition for all that have read/replied in my other post. Ripped it all apart AGAIN last night, AFM, boot, I.C. pipes...etc..and checked all sensor values AGAIN and this is what i found out - nothing is wrong with any of it! So....i checked my meter against my buddies Fluke. Guess what...my POS meter was out of calibration! ah ha! So, i started re-checking all the ohms/voltages on all the sensors AGAIN and the O2 is NOT reading in spec. At idle after warmed up, it shows about 280ohms. Running it @ 2000rpm for at least 4 minutes, it goes up to about .410 and that's about it. Snap the throttle plate closed - it jumps back down to .1 and then levels off around .340. No wonder the little green light on the ECM never flashed after running it @ 2K for over 4 minutes - it never broke the .45 threshold! UG. Anyway, i picked up a new O2 today and will install it tonight. Lesson learned...check your meter every now and then! Ok, so here's why i posted this topic - i'm looking gain some more knowledge on these sensors. Some of you may know me but for others, I'm basically trying to stretch the most out of a stock L28ET and it's components. The crazy reasoning behind this? MONEY Married/2 children, this is a "toy" as wife refers to it and does not exactly enjoy consistently spending lots of cash on, new house = bigger mortgage and taxes suck....blahblah...i'm sure you get the idea. I also think you can get the L28ET to really perform with little tweaks here and there without breaking the bank and i enjoy trying as long as i get the darn time! ha. All in question are referring to a L28ET which some components/values may differ from the N/A ZX's. I'm pretty sure the ECM adjusts the air/fuel mixture relative to the values returned from ALL these sensors basically by adjusting injector pulse width - the duration the injector stays open and sprays. And that's basically my question - do all these sensors, by means of the ECM, effect injector width? Please correct me on anything i post here as i'm always willing to learn and if you have any other information on any of these components and/or if they do more than effect just the injector, please, share at will! 1 - ATS (Air Temp Sensor) - mounted inside AFM - increases or decreases resistance relative to air temp. 2 - AFM (Air Flow Meter) - It has an initial resistance value (i believe for the ET's it's suppose to be 280-400ohm) This initial resistance value also has an effect on the full sweep values of the flapper. 3 - HTS (Head Temp Sensor) - increases or decreases resistance relative to cylinder head temp. 4 - O2 (Oxygen Sensor) - increases or decreases resistance relative to oxygen measured in downpipe. 5 - TPS (Throttle Position Sensor) - Connected to the throttle plate and has idle, off idle and WOT contacts. It sounds (by ear) as if this sensor actually controls injector pulse speed when changing from idle to off idle contact, but not sure. 6 - Another question on the TPS - there is a 3rd WOT contact that is unused on the ET. Why? Is there a way we can use this contact when we are at WOT, stretching every gear down the track, to throw more fuel at the increased boosted air? Sorry for being rhetorical in any of the information i asked because i'm sure it's all somewhere in the archives but, if you have a minute and know some or all of the answers, i'd appreciate it. Thanks.

Great time Scott! Congrats!!!

Got it. Scary grinding away at the T5, huh?

Hey Moby, 525. Yup, i had to do the same thing. Just grinded a small section of the T5 webbing away so the mount would slide far enough forward. God i have so many pictures of my entire swap, just wish i had a place to post them all!!! Let me se if i can find a good shot of it and i'll try to post it. Good job btw!

Thanks guys. Just looking to put 'em on the rear for dragging so it sounds like it'll work. 225/55/15 works on a 6.5" rim without too much bulge? Sounds good. Hope it wont cretae a problem when i air them down to like 20psi or so. Nion, i cant get to any of your pics. Send me a few if you can...i'd like to see it. Thanks again.

Ok, thanks phil. Keep me posted how you make out in the rear. Thanks.

What size tires are mounted on your ZX rims Phil? Thanks for the reply BTW.

I'm looking for a cheap alternative to put the widest 24-25" tall tire on the back of my '73, just to run at the track. I know the 84-85ZX N/A rims have the same bolt pattern (4x4.5), are slightly wider than earlier rims (6.5") and have a 30mm offset which would put the tire under the wheel well a little more, but i'm not sure if it would be too much and rub the stock 240 strut tower? I was thinking maybe a 245/50/15 would work (also a little wide for the 6.5 rim..hmm) I'm just trying to squeeze the maximum size rear wheel on by getting it as close to the strut tower without rubbing it and also still drop inside the stock outer fender lip so it would slip under when lauching hard, creating ass drop. Thanks in advance for any ideas.

And i just read your post again...That's all any of us can do through the computer...troubleshoot by generalization. Understood. I meant for someone with good knowledge from CA to physically put thier hands on his car and help him out. I didn't mean that the people from CA on this board couldn't help him out over the internet...i meant, actually get thier hands dirty under his hood. UG. Can you see i'm real sensitive about this??? I never like to offend ANYONE and i always think before i speak/type/act, and i seem to have offended you. Anyway, sorry. Not meant.

327...i didn't mean it at all in the way it seems you took it. Sorry, i must have worded it incorrectly. What i meant was....i'm sure there's got to be a bunch of guys/gals out there in CA that know a bunch about this swap and have good experience because that's all i hear about over here in NJ..."you should see all the Z's in CA and what they do to them!" It was kind of a sarcastic statement when i said that i was surprised that there wasn't anyone in CA to help him out...because that's kind of the way out here in NJ, very limited. I'm sorry if you took it the wrong way...it was not intended like that. Expression over the internet sometimes gets confused. I really didn't mean to offend you, or anyone from CA for that matter, if i did 327. I really don't know the difference between northern/southern CA and would never generalize anyone, from anywhere. I think us Z owners are our own breed anyway I've got to get out there one year and check out your "Golden State"

525 - send your Z to NJ and i'll have it right in a week! I'm surprised with all the 240ZT's out there in CA that there's not one person around with GOOD knowledge of the swap and could lend you a hand. NJ is a different story. I know of about 2 people total here that have done it. Wish i could stretch a helping hand acroos this damn internet to help. Launching...i do the same as 327 does... and when i see the third yellow just light up, i start releasing the clutch with the R's at around 35-3800. You just have to get the feel for it and it might be tough without good tires. Release the clutch as much as possible just on the edge of spinning...start spinning, in with the clutch a little, grabbing good...release a little more...back and forth to gain maximum traction as possible with your current setup. This will also create as much load on your motor throughout the gear which helps build boost. This may not be the right way, but it works for me. At the track, 1-2 shift and all after, the clutch is just snapped out. On the road, i have to feather just a little bit on the 1-2 shift and then snap it out 2-3 and 3-4. Good sticky tires help a lot. They allow you to release the clutch more without slipping and in turn put more load on the motor creating more boost early. That's what i think anyway For a test the other night, i slapped a pair of 205/70/14's on the rear (about 25" tall compared to my 22 1/2" 215/50/15's) and MAN, what a difference. I love it and would love it even more if i could get better traction. They were skinner BFG's and couldn't hold the pavement AT ALL compared to my Dunlops. I only did a couple of quick launches and they were slower because i had to REALLY slip the clutch but, with the larger diameter tire, i think is really going to help me at the track. We'll see next week if all goes well. So, i feel it really depends on YOUR specific setup on how to launch YOUR Z right. AND BTW - for those of you possibly going to flame me...i do tests on the road like this VERY LATE at night (1-2am) on an open freeway with nobody in site. I wouldn't put my wife and 2 children in danger like that, what gives me the right to put someone else's family in harms way. I understand.

Thanks guys. Z-Gad - are your fenders flared also or do the 235/60's squeeze under the outer lip? Those are pretty tall in a 15"....about 26"? I'm wondering if i can get away with like a 25mm offset 7" rim, and go with like a 275/50/15 or maybe a 265/60/14. That would give me a little more contact with the strip.

Hey all. With my current setup - L28ET, T5, 3.54's and 215/50/15 Dunlops that measure only 22 1/2" tall...it's time to get some taller tires/drag radials for the track. I need something like a 25" and as wide as possible. Does anyone know what offset i can use that will sit the tire in as far as possible without hitting anything under HARD launching and also, just clear the outer fender lip so it will tuck under without hitting? I put a set of 205/70/14's on last night, which measure about 25" that are mounted on stock ZX 14x7 zero offet star rims and i think this is really going to help my 1/4 mile time. 1st gear was actually usable and it built boost unlike the shorter tires which did not creat much of a load. The only thing is that these 205/70's are super skinny and with the zero offset, they just clear the outer fender lip when the rear is dropped due to launch sag. Anyone with suggestions/experience about which offset i can get away with or a 2.90 R200? Thanks in advance.

I'm running American Eagle 028 15x7's with 215/50/15 Dunlop SP5000's, Eibach springs with KYB struts. Sits nice and clears everything including the front air dam. Car dropped about 1 1/2" with springs. The Dunlops measure only 22 1/2" tall and with the T5, it makes the first two gears too quick in my opinion. Good luck.

Will do Sleeper.

Ok. Update...broke out the meter last night and started checking the head temp sensor. There's definetly something wrong...but it's not with the sensor. I did the tests exactly how the FSM says and the readings it's giving me are right in the curve it should be at different coolant temps. Here's the catch...When i plug the 16 pin connector back into the ECM with the ignition off, the reading stays the same. When i turn the ignition into the run position, the meter turns to OL. Same thing happened when i started the car up and ran it...no nice readings to the ECM like it does when the key is off. Also, the readings off the back of the sensor with the plastic plug unplugged are right in the zone so i know it's working properly. So, i started doing some investigating and found that if i put one leg of my meter on the black wire off of the head temp sens and the other to the neg side of the battery, with the key off, it has continuity BUT...say i put the headlights on....now i lose continuity between the battery neg and the black off the head temp sensor. Strange huh? Anytime i pull power from the battery or cause more resistance on the ground circuit, the black head temp wire gets a major increase in resistance. And of course, when i turn the key into the "on" or "run" position - running or not, and components start drawing from the battery (fuel pump, relays, gauges...etc), the correct signal from the head temp sensor wire (yell/green) never reaches the ECM. So now i figure it's got to be some kind of ground issue and start grounding everything around the entire car - ground wire from battery to engine to frame to body to intake...everywhere and it really didn't make much of a difference. It did a little but not much at all and didn't help with the values coming out of the HTS. This is what i DID find...I yanked my battery out and found that it basically blew it's load and is leaking acid down the back side of it, all down the nice new firewall i just welded in there a couple of months ago. Nice huh? So, this is what i'm thinking...The battery's got a dead short in it and causing my problems. Sound good? Yeah right...i'm wishing it were that easy but, i am going to put a new battery in her tonight. I'm also hoping it's not a wasted ECM, which i ripped apart last night and didn't see/smell any burnt components. I know, it doesn't mean everything in there is OK but it makes me feel better for the moment So...any ideas out there? Has anyone else put a meter on the yell/green and black wire off of the head temp sensor wire while it was running? If so, was it showing the resistance it should or close? Thanks in advance.

Thanks for the input and thoughts Afshin, and everyone else that's subbmitted suggestions. Now i'm hoping Head Temp Sensor. We'll see what values it reads tonight.

Sorry Afshin i didn't reply to your previous post..guess i was posting at the same time. Anyway, I did not put a meter on the HTS to check it but i did pull it off while running and she died instantly...which doesn't really mean much. The only reason why i didn't meter it is because i figured it really shouldn't have anything to do with the vacuum problem...And now reading your second post, maybe the vacuum problem is the effect, not the cause. I'm thinking the low vacuum is causing my low, eneven idle, rich problem but i think i've exhausted every possibility air wise, except for maybe a valve issue so, now i'll be going home checking the HTS with my meter. I did the ECU/harness unplug/clean job on all three connectors and at the AFM. AFM flap operating smoothly but did not manually open it up a little more while running. I will check the HTS tonight with my meter. Thanks for the input.

Checked/cleaned/adjusted TPS. Working good - on and off. Fuel pressure is good all around. What gets me is the fact that if i create the vacuum leak, it creates more vacuum on the gauge and runs perfect. Also checked the (stock) FPR and it also is working properly. I understand what your thinking Forrest - too much fuel pressure and she'll run rich at idle. But would this create less vacuum in the intake?

Sorry so late and i know you're past this but, i found a pic of the front of the L28ET when i was doing the swap, which kinda shows where the BOV is mounted. The pic was located on my website. DUH! haha. Here ya go...

Nope, not yet. Shoot, i have your "lag/stumble" problem on my mind! haha. I really haven't had "garage" time lately and with all this rain here in NJ, i've just been driving my truck around. I just got back in from the garage (2:19am) Checked for leaks, none. Vacuum on gauge still reads 19hg and runs poorly and VERY RICH at idle. It actually burns my eyes when i'm under the hood...with F.I.!! ha! When i used to tune my SU's, i used to get the rich/eye burn but i never figured i would with a closed F.I. system! My luck i guess. If i pull a capped plug off one of the intake ports and create the vacuum leak in the intake, idle comes up to 800rpm, vaccum increases to 21hg, it runs less rich and idle smooths right out. Go figure. Checked and cleaned all harnesses, no help. Checked O2 and harness with meter, working properly. Good readings. Only thing i can think of right now is valves. I think that'll be the next thing i look at and check. Everything electrical and hose-wise in the engine bay seems to be fine. Either i'm completely missing something or it's under the valve cover...or even worse, inside the cylinders, like rings, causing low compression.

525 - you don't have an I.C. installed yet, right? If not, i dont think what you're experiencing is lag...because there's not much of it without an I.C. You mention race fuel that the guy before you, that owned the donor car, ran through it. This has me thinking. Did he race the car? Why was he running race fuel? Did you ever get a chance to do a compression check on this motor? My brain is working hard on your problem and i really want you to get it figured out. You've been so pumped up and excited about this Turbo swap and have posted about 3000 times in the last 2 months, i really wanted you, of all people, to have a good experience and get the real thrill of a T3 strapped on an L28...and it just aint happenin! Hopefully it's just a timing issue. We'll keep working on it..from a distance. Wish you lived closer to Jersey...damn.

That's exactly the info i needed John. Thanks bud.

Len - i know they're DOT approved but i wouldn't drive around with a much bigger tire on the rear than the front. i like the way she handles being nice and level But it looks like i'm going to have to do the tire swap deal for the track. I have a extra set of the 14" star ZX rims...guess i could slap like a set a 235/60-14's on them. That should be around a 25" radius tire compared to my current 22 1/2" radius. That should be right around what i need. Funny stuff - laundry, jack, tools...you run like me! haha. Mudge - I dont think i'm putting down much power, i just run through the gears REAL quick right now and topping out 4th across the trap @ 106mph and 6200rpm! Way past the limit of the T3...in my opinion. The 3.36 wouldn't be enough of a jump i'm looking for from my current 3.54's now anyway. I didn't know that they were that hard to find. I cant believe datsun/nissan didn't put a R200 or R180 with a 2.90, or something close, in any of thier vehicles over the years. I know my '88 pathfinder had a R180 front diff but they were something like 4.11's. There's got to be something out there. Possibly mix a ring with a different pinion to get lower....hmm. Thanks again guys.

Thanks guys. Damn. Yeah Len, that was my original thinking...to go with a drag slick in a bigger size then i thought, i like to drive the car on the street exactly how i run it at the strip. So, i was trying to keep the 215-50-15's on and lower the ratio but, no good i guess. Thanks for the replies guys.