Still runs like crap!

[JNM240]

I just cant seem to figure this out!

So far i have:

replaced coolant temp sensor - throwing code, hard to start warm (dumping gas like cold)

replaced throttle position sensor - throwing code, would randomly die and not start back up

hooked knock sensor up - wasnt hooked up, now i have no codes at all

verified cam to cam and cam to crank timing - i installed the crank sprocket backwards, but now its all straight and holding 15* BTC at idle

retorqued cylinder head - ARP head studs and cometic mls head gasket problem apparently, not leaking anymore

verified ECU tune for 550cc injectors and reburned the EPROM

replaced Honda dropping resistor with brand new genuine Nissan unit

replaced wastegate actuator - stock one wouldnt hold vacuum, replaced with a HKS for SR t25, now i hold a good 23 in/Hg at idle

removed USA spec idle air control valve gaskets and used silicone to seal - USA spec gaskets left a space near the adjustment screw open, causing a vacuum leak

replaced cheap-o Ebay BOV with Greddy type RS BOV

But i still have a bad sputtering on acceleration! Im only pushing 6psi right now, and im fine with that if i can just get this running normally!! It still doesnt want to accelerate when cold. Start the car up cold, it idles good, but doesnt want to take throttle until its been revved up a few times. Even once warm, it wants to stumble on acceleration, so much so that i have to goose it a few times at a stop before i start moving.

WHAT IS GOING ON HERE?!?!?!? I need some CA gurus to chime in here, nothing seems to make this problem go away!!

Jason

[Buddyworm]

Try a different CAS? Maybe it's bad but not throwing a code?

Did you adjust your TP scale and TTPMax/TTPMin when you changed your K?

**Edit:

I programmed the EPROM based on the 550cc injectors only, meaning i adjusted all the fuel tables from the 340cc stock injectors down by exactly 340/550 (or 61.8% of original value)

Am I reading this correctly and that you adjusted ALL the values in the 16x16 fuel tables??
Modified by Buddyworm at 9:52 PM 3/28/2008

[r34 gtr]

Hows it idle when its cold? Is it hard to start? Sounds to me that one of those dumb idle valves is still not working all the way.

[JNM240]

Try a different CAS? Maybe it's bad but not throwing a code?

Did you adjust your TP scale and TTPMax/TTPMin when you changed your K?

**Edit:

Am I reading this correctly and that you adjusted ALL the values in the 16x16 fuel tables??

Modified by Buddyworm at 9:52 PM 3/28/2008

I adjusted the K value by 370/550, or 67.27%, then adjusted the boost tables at the bottom of both the High Octane Fuel map and the Low Octane Fuel map by the same percentage (the 340/550 was a number i had remembered when i first wrote that, but i went back and verified that is should have been 370/550). I did not, however, change the TP Limit nor the TTP max scales on the Global page.

I followed this exactly, from Boostruising.com:

Upgrading the Injectors is a rather similar story.. here's how ya do it..

On the CA18DET, you have standard injectors, and their size is 370cc.

I upgraded to RB26DETT Injectors, which are 440cc.

So you get the std cc value and divide it by the new cc value.

370 / 440 = 0.849

So you then grab your current K constant value, for example, 12A.

So in calculator, click Hex, type in 12A, then click decimal, and click multiply and enter 0.849.

So you'll have 12A (298) * 0.849 = 253.

Click back to hex, and your value is FD, enter that in ROM EDITOR as 00FA (zero, zero, F, A).

Also, I used the correction of 0.849 to all the values in the 'boost' section along the bottom of the fuel maps. You will find that once you adjust all those values, and then click Setup - Engine Specification setup, and adjust the Injector Blas-off quantity to the injector size that you are now using, all the values will come back to normal compared to the original map with uncorrected values and standard injector size spec).

Modified by JNM240 at 9:30 AM 3/29/2008

[JNM240]

Hows it idle when its cold? Is it hard to start? Sounds to me that one of those dumb idle valves is still not working all the way.

The idle itself is fine when cold, it just wont take any gas, it wants to die then. So i have to goose the RPMs up and rev it hard several times, for maybe a minute or two, until its decent enough to drive. I checked the Aux Air Regulator valve and it passes all the tests from the FSM. Unfortunately the one for the 88 Pulsar NX SE with a CA18DE does NOT fit the DET (i had special ordered it from NAPA a while back). And im suspecting the cold start valve less because it still sputters on acceleration when hot. And if i shut her down when fully warm, she has to spin over way more times to start that should be necessary.

I cant see how the CAS would effect anything, since its not missing and it has no broken teeth. Im gonna check the ECU for codes again today. It really feels like a vacuum leak or a bad MAF, but i am now pulling a very healthy 15-23 in/Hg at idle thanks to the new wastegate, and i cleaned the MAF last night after work with specialty MAF cleaner and nothing changed. If i didnt have to rewire it, i would swap in my spare KAE MAF just to check, before i go and plop $400 or so on a new one.

[Buddyworm]

When I bought my Silvia it had a bad stutter/stumble around 3000rpm. Guy I bought it from wasn't sure what it was and suspected it was a boost leak but said he couldn't find one it. It really did feel like one. I replaced the CAS and problem went away.

Mind you, it threw a code for me, but you never know. It could **** the bed and still not throw a code. The fact that it's affected by temperature makes me think not though.

What Diagnoses proceedures are you using from the FSM?

[JNM240]

Well i pulled the ECU codes today, and i came up with two: #12 Air flow meter circuit, and #43 Throttle sensor circuit. Whats weird is the TPS is a brand new Beck Arnley unit from O'Riely's less than 3 months old. Unfortunately all my tools are at work, so i wont be able to probe wires and check voltage till monday.

Hey Buddyworm, do you know a lot about ECU tuning? I was under the impression all i needed to do to change for larger injectors was change the K value, but should i be changing void blast off time (injector latency) as well by the same percentage? And no, i did not change TTP max or TP limit (there are no numbers on TTP min to change).

[Buddyworm]

I still don't know all the ins and outs, but injector latency is entirely dependant on the injector's, I guess you could say brand, but it is not necessarily related to their size. It's mostly for smoothing out your AF ratios at idle and has less bearing on the engine when it's revving out. If you google you might be able to find the latency of your specific injectors somewhere.

When it comes to TTPMax and TTPMin the CA .adr file with Rom Editor is whacked. They're actually two 1x8 tables that it accidentally combines into one 1x16.

TTPMax = 72, 72, 72, 72, 80, 80, 88, 88TTPMin = 179, 179, 179, 179, 179, 154, 154, 154

TP Limit is your boost cut. I'd leave that alone for now.

What you want to adjust, on top of your K, is the TP Scale (the series of numbers along the x-axis of your fuel/ignition tables. You adjust those by the same percentage as the injectors. I've heard of some people's cars running better without adjusting the TP Scales but generally it seems like the thing to do is adjust them. Try both ways, see how it likes it.

Definately get those codes cleared up though. It's tough trying to diagnose a car while you're also trying to tune something properly. You're never really certain what's causing the problem. It's why I sold my old engine setup (besides bad rings), I wanted to start from scratch and build/tune it progressively.

If you can I'd strongly recommend going back to stock injectors, get everything sorted, then set to work on tuning it.

**Edit: http://cherrypicker.tripod.com/id10.htmlAn invaluable resource. Pertains specifically to 300ZX's but the concepts are all the same.

[MeanGreenS13]

sounds like my car... will free rev VERY fast and very smooth... but under any load, it just hates life, once it "clears up" it pulls hard as anything ive ever driven lol

[progman]

Did you check you idle switch? I have no idea if it could cause this but it's easy to check. If you want you can send me your rom tune and I could compare it to mine. I also have 550cc injectors.

[JNM240]

It seems to be a wiring issue with my HKS Super AFR causing me some (hopefully ALL) of my current problems. The AFR splices into both the MAF signal and the throttle position signal down near the ECU. When i was probing wires at work today, i was trying to check voltage at the ECU while the car was running and i wiggled a wire and it started running better. So now i need to decided if i want to hardwire (ie solder) the AFR in or remove it. It would be super nice to have since is has the idle stabilizer function, to keep the car from dying when the BOV goes off (atmospheric). But if its causing me problems, i might get rid of it for the time being. And just cause i wiggled a wire and it got better doesnt mean anything is fixed yet. It just points me into yet another direction.

If you want you can send me your rom tune and I could compare it to mine. I also have 550cc injectors.

You've got mail!!!

Jason

[Buddyworm]

You sure it's the atmo BOV that was causing your engine to die? Mine just goes rich briefly and backfires out the exhaust. It's great

I'd get rid of any sort of MAF - ECU signal trickery device personally. Regardless of whether it's causing your problems. Find a romulator and a wideband to borrow (or buy, or something) and get your K set proper and then you won't have to mess around with any of those things.

[new200guy]

what kind of fuel pump are you running. you sure thats not gone bad? i am assuming your are running an upgraded pump? how about fuel pressure regulator. you sure diaphram not torn inside that?

[MeanGreenS13]

my car sounds like something out of the 1900s when im slowing down... BANG! BANG! POP! SNAP! BANG POW! lol

[ca18detgabby]

your running 6PSI? isnt stock spec 10psi? is the ECU tuned to run that way? could be running rich as funk.

the bumping the gas to getting it going......... sounds like a bad coil pack.

23in/hg? dang that is more vac than I have ever made.

I would try re-ciring your BOV and seeing if that cleans anything up..... it is very easy thing to try and wont cost much if anything. if problem solves itself............. then you know what the issue is.

[JNM240]

Ok, well i havent updated in a while and i feel like i should, as i have now sorted nearly all of my problems out. I even took her on a 2 hour drive down the beach today and she performed wonderfully.

It seems 99% of my problems were stemming from vacuum leaks. My wastegate actuator diaphram was blown so i replaced that with a HKS wastegate actuator. That was a massive PITA, since i had to reuse the OE actuator mounting bracket, which required seperating it from the actuator and drilling holes to bolt the new HKS unit to, and using the original threaded actuator arm, as the new one was way too short, and then having to cut the arm about an inch to get it to fit properly. But now its on and, before i put in the manual boost controller, i was pulling 7.5 psi, extremely acceptable to me as i believe 8 pounds is stock. Now with the MBC i am pulling 9, almost 10 pounds of boost.

My cheap ebay BOV was also leaking, whistling at idle. Replaced that with a genuine Greddy type RS and i havent had a problem there since. Plus the Greddy sounds wicked cool.

I am actually pulling 15 in/Hg at idle, i just seemed to recall that 23 when i wrote it, but i am really pulling 15 at idle. The car, once warmed, performs exactly like any normal car. Used to have to blip the throttle once or twice to get the RPMs up before i could start moving (like from a red light), now i dont have to do that at all. It just goes, exactly like a normal car. Pushing 9 pounds of boost now is awesome, this car is freakin fast.

The ONLY running problem i am having is when she is cold. Cold starts i still have to race the engine and feather the throttle to get moving, and she back fires at a lot. I really feel this might be related to the Pressure Regulator Solenoid Valve, since i dont have that installed. Im going to mess around with that at work sometime this week.

One of the two stupid minor problems i still have, that dont have anything to do with how she runs, is my coolant temp gauge seems to be slowly drawing a current from somewhere. It will climb slowly after driving for a while, but if you hit the brake, or work any other electrical accessory (lights, turn signal), the gauge will pop back to normal, then slowly start climbing again. Im sure its a grounding issue, im just not sure where to begin looking.

The other minor problem is totally my fault. When i swapped in the DOHC tach, i had to remove the needle and face from mine (i have HUD and the HUD tach and needle are slightly smaller than the analog) to swap over, i didnt set the needle on right. Basically it says i idle at 1600 RPMs (its actually a really nice 750). In fact, turn the key on without starting it, it shows 500 RPMs. Its just such a pain to remove the cluster and try to reposition the needle.

But i just thought i would take a moment and let everyone know that im just about 100% finished here. She's running like a champ and im loving every second of it. Boost is so addicting im wanting to get an electronic boost controller (Blitz single solenoid) so i can up the boost from the drivers seat. And im looking at turbo upgrades. The gt2871r looks REAL nice, well except for that $1200 price tag. Before that i probably need a VLSD, since even at 9 psi, wheel spin is starting to be a problem.

One day im going to clean her up real nice and take some pics for you all. I am very proud of her, as ive owned her for the last 14 years and only just recently went CA. Just goes to show she's never too old for a makeover.

Jason