I can't remember the manufacturer, but they've made VH pistons before. All you gotta do is give them the bore/compression ratio and they'll make you a set for ~$1k. The rods should be good for a lot of power...

Don't think like that! You'll get her running.

Well I'm getting my hands on a leakdown tester this weekend, I did however pour some ATF in the cylinders last night and cranked it over, ran the comp test 3 times and let it sit the third, it got 90psi of compression, but the thing is it held that 90 psi for like 3 hours. I didn't check it this morning but I'm willing to bet that the gauge is still showing 90. As soon as I the leakdown gauges I'll see if it holds at 210 which should be about operational compression + safety factor. I'm really stumped now as to what would make my comp so low and if it doesn't fail the Leak-down then I'll really be surprised.

While doing my rebuild I found a few places that can make custom pistons for any engine for about $500-$600 a set for forged for a V6, so 1K for 8 sounds right.

Hmm, that's weird. You got 90psi across all cylinders? For 3 whole hours? .

Well, if you ever need help with the VH let me know. I'd be happy to give you dimensions for the crossmember/oil pan modifications/header modifications.

Like I said I'll come to you first if I ever get involved with a VH and yeah dude the car wont make more then 90psi on all 6 cylinders but all 6 are withing like 2psi of each-other and there is no drop in pressure, NONE. I've been for a couple weeks now because everything seems as it should except I got low comp on all 6 and #5 isnt firing but the coil and plug are good and its getting signal and power, ptu is brand new and tested FUUUUUUUU I'm going nutz.

NolimitZ32 wrote:Like I said I'll come to you first if I ever get involved with a VH and yeah dude the car wont make more then 90psi on all 6 cylinders but all 6 are withing like 2psi of each-other and there is no drop in pressure, NONE. I've been for a couple weeks now because everything seems as it should except I got low comp on all 6 and #5 isnt firing but the coil and plug are good and its getting signal and power, ptu is brand new and tested FUUUUUUUU I'm going nutz.

#5 could be an injector if it's getting spark

The low compression definitely sounds like an internal issue. Good luck demon hunting

Injector is good too (ohmed and tested with screwdriver/tick test), that's the thing I've tested everything except leak-down, I even went as far as to figure out the actual decrease in compression an oversized HG would make (not that I ordered one but maybe I got sent the wrong one). BTW as far as the physics of it are concerned a TT engine should only make 125psi of cylinder compression max, so its interesting for me how they are shown to make 175+ psi @ 500-1000rpm? when 8.5 (DETT comp ratio) x 14.7psi (atmospheric pressure) = 124.95psi (cylinder compression pressure)

on a somewhat unrelated note this is becoming less of "Nolimit's rebuild thread" and more of "Nolimit's amazing wonder of engineering/WTF happened to my engine" thread lol.

so update on what happened??

I have been dealing with some personal things lately, on top of that I have been out of town a lot guys so the car has been sitting for about a month and a half, aaaand my WRX decided to almost catch fire on me 2 weeks ago (electrical fire). On the Z I believe I narrowed it down and it seems to me like what happened was the timing jumped once, then without knowing it I reset idle to 15BTDC (with jumped belt) and then the TB jumped again. At this point the number of cogs between all of the gears are correct but the TB lines don't line up with the gear marks, I will maybe hopefully get a chance to reset the TB this weekend. And from there we will see whatsup. I still dont see how i can be getting such low comp numbers but until I reset the TB I wont be able to move forward so, hopefully updates on monday.


Dan thanks for checking in man.

Back from the dead BUMP: It runs once again! the low compression numbers turned out to be a bad Comp Tester and not bad rings haha, found this out when I finished the rebuild on my STI engine and went to test the comp to only get yup you got it 60 psi. So I traced the problem to a s*** connection in the Brand new engine harness, between the MAF and ECU. I have been driving a little bit around the neighborhood with the MAF unplugged and its running great so once I figure out where the bad connection is or replace the wire I will be taking it up to Dane Miller to get the Nistune put in and street tune the beast. More pics and Vids coming soon.

NolimitZ32 wrote:the low compression numbers turned out to be a bad Comp Tester

Whell that will f*** your day up proper!

Glad she's alive again.

Could it be the actual MAF has an issue?

It may be the MAF, I'm borrowing one this week/weekend just to make sure. but it would be weird since the NA ran with this MAF and its spent a few years in a box but hasn't been handle/dropped/damaged physically but anything is possible.

Awesome!

wow talk about a roller coaster of a build thread.....holy jeez

hey man good luck and im soo glad for you that you dont have to break her down again...

Yeah man, its been one wild ride, but I think this is all coming together at the best time, I'm graduating with my bachelor's I turned 25 in Jan, I just became happily single, I just got a great job in the industry for which I am in school and love it, and now this was just the icing on the cake. I felt this was going to be a good year when I celebrated my 25th bday and its definitely turning out to be.

So, I finally sat down and read this thread from cover to cover and it's been a hell of a ride lol. My heart sank when I read about your disaster! I will soon be in the first start up phase too and I am praying to the Z gods that everything will be according to plan. I'm glad that you have your problems figured out and I'll bet you were so pissed/relieved that it was just a tool malfunction! Oh and I really like the copper color you decided to go with by the way

Thanks man, yeah I was more ecstatic then anything to find out the comp gauge was bad because I was really not looking forward to doing a full rebuild again. thanks man, it took a lot of contemplation to end at that color. And during your build if you got any questions feel free to give me a shout.

Wow, great to see that you will be back in business again!
Looking forward to seeing you get it all going again, and without any problems with the internals.

Ok guys I got a question for all of you that have ever had to chase gremlins. My Z drops off idle and dies when cold or when coming off the gas and misfires under load. Tming is set at ~15*, Power balance shows that all Injectors and coils work. readings (through AVC-R and SAFC) on injector DC and all other components show correct values, SAFC is hooked up only to read sensors the MAF wires are not hooked up so it does not alter the MAF signal. I have tested the following connections, wiring and components themselves: MAF (shows .465V with ignition switch in ON position and .8-1.5V at idle), Coolant temp sensor shows good readings, TPS shows good readings, AAC shows 11 OHMs (1 ohm too high but should not make the car undrivable) ECCS/EGI relay switches and shows good readings, all wiring has continuity and no resistance (brand new Engine Harness). So I am lost, I have gone through EF EC section of FSm from page 42 to page 190, gone through all of the tests and everything, I mean everything comes up as it should. The ECU was throwing a 12 (MAF code) but after screwing with the wiring and testing everything it lost the 12 (without disconnecting power) and now shows 55 (all good). If you have any ideas of what the hell it could be please throw em my way, I don't believe its the ECU because all the inputs/outputs on all the sensor channels are as they should be and a bad ECU would usually provide bad inputs/outputs to the components.

Thanks
Anton

What did you use to set the timing? Coil pack connection or PTU loop?

Have you checked fuel pressure? Sounds like an issue with your fuel pressure. Could be the pump itself, or the regulator. IMHO, get a cheap mechanical pressure gauge and check the FP after the filter before the hardline to see if you have 33ish PSI at idle. Then disconnect the damper vac line and see if it goes up to 48ish. If so, then you don't have a fuel problem.

After that I'd check plugs, check the gaps and color of them.

When you say you messed with the wiring for the MAF, what exactly do you mean? IMHO, I'd swap the MAF with a known good unit, or at the very least clean it with some MAF cleaner and let it dry thoroughly.

Wiring has good continuity is good, no resistance is bad. That would be an open. So I think you mean no unusually high resistances or opens (infinity resistance).

That's all I got now of the top of my head. Where are you located again?

Thanks man,

Timing was set by using coil # 1 and checked with black loop, they showed within a few degrees of each other so I went by the sound and behavior of the engine to get it down to the wire.

Fuel pressure is good, in fact its running a bit rich. but I will do the damper vacuum disconnect to see if I can get some kind of result.

Plugs are fresh, picked up from IPP last week and they are already getting covered with carbon (rich)

I tested all the MAF wires for signal in different situations (ignition on, engine running at idle, no power etc..) by the FSM. Also swapped the MAF with Matt's (Legion) last week and nothing changed.

Every wire I tested has continuity and very very low resistance (tested resistance to make sure nothing magically got corroded over the last year) Its a brand new OEM wiring harness.

And finally I'm in Houston, I've talked to Dane and Kyle but I don't want to be a huge burden on them, plus fixing and modding these cars is what they make their living off and I just don't feel right constantly bothering them for answers when I'm not a paying customer, but I want to figure it out myself, its one of those I'm a man I don't need direction even though we are lost type of things hahaha.

Really the way it's behaving the problem is either in the TPS or the AAC, the problem is that when tested they both come up good unless the AAC showing 11OHMs instead of 10 is enough to screw the car up that bad. Other question I got is why the hell does the TPS have 3 pins on the connector thats on the body of the TPS and the incoming harness has only 2. And why the hell is there a $80 price difference between the NA and TT TPS?

NolimitZ32 wrote:Really the way it's behaving the problem is either in the TPS or the AAC, the problem is that when tested they both come up good unless the AAC showing 11OHMs instead of 10 is enough to screw the car up that bad. Other question I got is why the hell does the TPS have 3 pins on the connector thats on the body of the TPS and the incoming harness has only 2. And why the hell is there a $80 price difference between the NA and TT TPS?

I have a known good TPS you can use to test if you want. If it's adjusted correctly though, and reading the right voltage, then I'm not sure that's the issue.

How about the CAS? Do you have Datascan or another means of checking the output of the CAS? There is someone on TT.net who did a teardown and cleaning of the CAS to improve the signal quality. That's something I wouldn't try until you've ruled everything else out.

Do you have a FP gauge on the system? How do you know the FP is good? Just because it's running rich doesn't mean it can have weak pressure when the demand increases. I'm asking because you didn't mention a FP gauge in the post. You are using a TT fuel pump right? Sorry I don't have time to re-read the whole thread. TT ECU as well? And did the car ever run correctly after the rebuild and reinstall?

3 pins vs 2 pins is for Auto Vs Manual. Third pin is for the auto kickdown switch, IIRC. I'm unsure of the reasoning for the price difference.

I do have a gauge, well not currently but It was there for a long time just took it off recently because I was trying to eliminate everything not stock on the car. Also it misfires and runs poorly at all rpms even with low load where fuel pressure shouldn't be an issue as much as under higher demand.

CAS seems to be in good condition because the car idle fine in limp mode (achieved by disconnecting the MAF) and if I warm it up in limp mode and then turn the car off, clear memory, plug the MAF back in and start it I can get it to idle almost perfectly by holding it up with my foot for maybe 20 sec and letting it find itself then just letting it sit and rumble.

Its a Walbro pump since this is a swap car. TT ECU with EPROM written for NA.

The car ran for maybe 6 to 8 miles after I built it just cruising around the neighborhood watching for inconsistencies and bugs and such it started misfiring like crazy, dropped into limp mode and has been acting all FUBARed ever since.

Thats interesting about the TPS since Courtesy doesn't list Manual vs Auto TPS only NA and TT.

NolimitZ32 wrote:I do have a gauge, well not currently but It was there for a long time just took it off recently because I was trying to eliminate everything not stock on the car. Also it misfires and runs poorly at all rpms even with low load where fuel pressure shouldn't be an issue as much as under higher demand.

CAS seems to be in good condition because the car idle fine in limp mode (achieved by disconnecting the MAF) and if I warm it up in limp mode and then turn the car off, clear memory, plug the MAF back in and start it I can get it to idle almost perfectly by holding it up with my foot for maybe 20 sec and letting it find itself then just letting it sit and rumble.

Its a Walbro pump since this is a swap car. TT ECU with EPROM written for NA.

The car ran for maybe 6 to 8 miles after I built it just cruising around the neighborhood watching for inconsistencies and bugs and such it started misfiring like crazy, dropped into limp mode and has been acting all FUBARed ever since.

Thats interesting about the TPS since Courtesy doesn't list Manual vs Auto TPS only NA and TT.

*edit* just read up, a single Walbro (255 lph) flows less than a TT pump. What are you using for a fuel pump controler?

*edit* I see that you did get to drive it some. IMHO, I'd skip the SAFC as it's a band-aid tuning device. Especially if you have a tuner semi-local to you. I'd run everything direct to the ECU until you get the issues worked out

This confuses me:

TT ECU with EPROM written for NA

That 6-8 miles sounds like the ECU running in learning mode. Then once it figured s*** out, it barfed because something ain't right. Perhaps you over oiled your air filter? That's pretty much all I got. I'd also check for boost/vacuum leaks, as you were getting 17in/hg in vac right? I'm getting 22in/hg at idle, I'm unsure what the factory specs are. Not that I think a 5" difference would be the cause, but it never hurts to be TIGHT!!

IMHO, if you get to your wit's end, I'd contact Dane and see if he can fit you in for an hour diagnostic session. I'd also document (bulletized) everthing you've tried so far, so that he has a better idea of what's been looked at. That way you get the most for your money.

Hahahah I meant Auto TT ECU with 5SPD TT Eprom hahahah my bad

The SAFC is only hooked up the the sensor wires, the 2 MAF wires are unhooked, I have it on there so I can read realtime parameters of the car, Its not being used to tune anything.

Yes the walbro does flow less than a TT pump and I am running the NA controller but from talking to a few tuners this shouldn't be an issue especially with my setup and the demand for fuel not being high enough to max the injectors/pump.

And it looks like I'm getting close to that wit's end point, just really wanted to figure it out myself. I'm picking up a Nistune from Dane tomorrow with a base map written by Dane because my suspicion is that the map on this EPROM is not a good one.

Thanks for all your help man.

NolimitZ32 wrote:Hahahah I meant Auto TT ECU with 5SPD TT Eprom hahahah my bad

Thanks for all your help man.

Doesn't feel like helping if I didn't solve the problem

Auto TT ECU with 5SPD TT EPROM... I *think* that should work, but I'm not sure. Hopefully Nistune solves your issues. Then you can get rid of the SAFC I had a bunk one that caused my car to die, so I hate them. Also learned more about how they add fuel and what they do to your timing, it's not the best method. Nistune can be a monitor as well, IIRC.

Yeah I bought it before I knew how it worked and when I found out why all my DSM friends were popping engines running SAFCs the MAF signal got disconnected, like I said I use it purely as a display to monitor my knock and certain other parameters. the two MAF signal wires are just wrapped in E-tape tucked away under the dash.

As far as the Auto ECU with 5spd EPROM, from what I understand there is no reason it shouldn't work, whats more i know of people running such combos and every tuner I've spoken too says there is no problem so... Yeah I hope Nistune fixes everything too cause if it doesn't I'm gonna go beat my head against a effin wall.

And its the thought that counts, you read the problem and then thought of possibilities to mend it, then spewed some info at me, that counts.

I got it running with no faults and codes, it still runs rough but I'm thinking its the tune, no more codes either. I guess there was a bad connection somewhere and me going through unplugging and plugging everything back in fixed it. Hooking the Conzult up to it later tonight to confirm good readings on everything, if all checks out, I am tapping and wiring in dual EGTs and putting my LC-1 in this weekend and off to HoustonZ for Nistune next week. I am so tired of chasing gremlins and so ready to go topless cruising down Seawall Blvd.

So I tried 3 different ECUs yesterday, had the car hooked up through ztalk, conzult and OBDScan, Here is what happened: I have 3 ECUs: 1 8bit MT TT, 1 8bit Auto TT, 1 16bit MT NA and 4 chips: Stock MT TT, Stock Auto TT, emance custom MT TT (for my setup) and JWT MT TT clone (370cc 14psi). Here are the results of ECU diagnosis, The car was not started on any of these except the Auto TT w/ MT TT custom chip.

- I can get the NA MT ECU to connect just fine and the readings are dead on for all sensors in Conzult.
- Both TT ECUs with any chip other than the custom Emance chip do not connect to the software at all, whats more the AUX fan turns on as soon as the ignition switch is in the ON position.
- Auto TT ECU with Emance chip connects to software but with the car shut off shows erratic readings as if the sensors are working ie. TPS, A/F, CTS, Injector pulse, etc jumps up and down and shows figures outside of the regular operating range of those sensors such as -90 degrees on CTS and -14V on TPS. When I download the fuel maps from the chip the AFRs are all over the place, its not a smooth transition form mid 14s to mid 10s but rather (Top Row of Map: 14.xx, 14.xx, 14.xx, 11.xx, 12.xx, 10.xx, 10.xx, 10.xx, 14.xx, 13.xx and so on).

After exhausting every possibility of a bad sensor/valve and making sure all injectors and COPs work, after testing continuity on the harness and making sure I have correct fuel pressure, I have exhausted pretty much every possibility other than the ECU, so tell me do these results prove that its a bad ECU or is there something else afoot here. Any educated responses are greatly appreciated and all options that have not been tested will be considered and explored. I WANT MY f*** CAR RUNNING! please help

Man, what a nightmare...hope you get to the bottom of this.
I also have a strange gremlin that seems to be somewhere in your mix, I am watching this with interest to see what ends up being your issue so I can look around myself.
My NA also has some idle drop off issues when very cold (less so the warmer the outside air is), and a time during driving with accessories on where I lose the throttle when slowing down (engine is all loaded up and slows down, I press more throttle and nothing; I "pump" the throttle and eventually it will catch and accelerate roughly just like an injector or two is bad) for about 2-10 minutes on and off until it magically returns to norms although by the end of a drive (30-40 minutes) the engine feels loaded up period. Oh, and BTW with no accessories on this will only happen maybe once for a minute or so and then no problems and no "loaded up" feeling after a drive. Battery and alternator were just replaced, also.
I have checked much but not all of what you mention above except codes which my Z guy has checked, and my Z guy says he thinks he can tune it out which is where your ECU info/concerns also come in for me. I also had a 5-speed swap done before this issue, but still have the AT ECU which I thought needed replacement for the MT?
Anyway, good luck and keep us posted!

^^AT ECU can be used for the MT.

Sounds to me like the tune could be corrupted. Is there any way you could get a reflash on your ECU? Those AFR numbers are nowhere near correct.