ca18det spluttering and choking up upon acceleration/revving

[jakry001]

hi, really want to get this sorted out. probably a really easy solution (hopefully anyway)...

every single time on cold start, or when the car has cooled down, when i start the car and go to accelerate/increase revs, it will splutter and choke up, coming close to dieing on me. if i take my foot off the accelerator, back to idle, it will be fine... or after a few hard revs, the spluttering will go away, and be fine, until another start up when engine is cold, or cooled down a lot.

i have noticed when i rev it, at the point where its starts spluttering and choking up, i can clearly hear a rapid number of clicking, probably from the injectors...

any good ideas to what the problem is? its the same thing over and over...

thanks heaps

[JNM240]

I am having this EXACT same issue. To let you know, i finally wired up my knock sensor, so i have exactly zero ECU codes. I have solved my grounding problem (body ground on the negative battery cable fixed). I have re-torqued my cylinder head (cometic hg and ARP head stud issue). I have verified that cam to cam timing is 100% correct (havent been able to pull the crank pulley at home). The only way the car will run is for timing to be set in the neighborhood of 30* BTC. When set at 15*, it falls flat on its face and barely idles. CAS is good, no broken keyway or pins or anything.

But its exactly as described: when cold, its almost like i have to blow stuff out with several hard revs until it'll run right. Also, even once warm, there is the occasional sputtering or slight backfiring in the exhaust. She runs good enough for around town, but i want to get her 100%.

Mods are: 550cc injectors, tuned ROM, Cometic hg, ARP head and main studs, removed & plugged secondary butterflies, stock CA T25 turbo, el-cheapo BOV.

Any light shed on this subject would be greatly appreciated!

Jason

[Indecisive]

*looks for sign-up sheet*

same problem on my old S12. On a cold morning, or the very first start of the day(unless it's been sitting all day in the sun), when I give it some gas, it sputters and will want to choke out.

After it gets going and I start driving, no problems.

I think it's just a cold start issue with our engines...

I have a new engine in the car now, and I'm picking it up on monday. If it has the same issue, I'll post up.

[ca18detgabby]

crazy question......... do yall have the aux idler port in the bottom of the TB attached to anything or blocked off?

[JNM240]

If you mean the vacuum nipple of the bottom of the throttle body, it is blocked off on mine. If you mean the Auxillary Air Valve, which regulates the cold start up, it is hooked up correctly, and to the best of my knowledge working correctly. It passes all the tests per the FSM.

But the thing is, it still hesitates and slightly bogs down on hard acceleration once its warmed up too. Its just REAL noticable when cold.

[ca18detgabby]

I do believe the discussion a few weeks back was that the nipple below the TB was a secondary aux idler......... and w/o it attached to vac it was rough start on cold starts.

[jakry001]

i have my auxillary on, and it closes and shuts properly.

im thinking this problem may be fuel related. maybe the fuel pump is stuffing up, it is approaching about 20 years of age now...

[JNM240]

I doubt its a fuel problem. Was doing this exact problem before i installed a Walbro 255lph fuel pump, and its doing it still. I do have 550cc injectors (ECU tuned for them), a Z32 fuel filter and a Nismo adjustable fuel pressure regulator, and monitor my fuel pressure via an electric Autometer gauge under my stereo, so i really dont think its fuel.

As far as the vacuum under the throttle body, im having a hard time finding the vacuum diagram i used when i ran the vacuum lines, but it specifically said to block off the one on the TB.

[bias]

I'm having the same problem. I have stock ca18det no internal mods, t28bb, 450cc, z32 maf, Q45 fuel pump, eprom for mods, 3"exhaust/downpipe, front mount, iridium plugs(6s) Apexi filter, 300zx fuel filter, and elecric fan. My car has problems warming up and it pops and seems to bumple in boost. I checked all vacuum lines and everything looks good. It runs good but I would also like to be at 100%. We have to all have the same or very similar problem.

[jakry001]

its definately not an obvious problem... ive checked just about everything under my hood and all seems fine, but obviously some componenet has decided to throw the towel in.

im really thinking its poor fuel pressure, or a weak fuel pump. im going to check those parts out.

[bias]

I was thinking fuel pressure too. I have the stock regulator now but I'm not sure if it's where it should be. I'm only at 30psi at idle. Has anyone tested there tps? I tried but I'm not sure if I did it right.

[JNM240]

Well i doubt its fuel pressure. Im getting 36 psi at idle with a brand new Nismo FPR and a brand new Walbro fuel pump. So i know thats not a problem for me, and since we are all experiencing the same problems.....

And i have already replaced my TPS for another reason (was throwing the TPS code and the car would randomly die on me and not want to start back up). I have also replaced my coolant temp sensor, again because there was a code and it didnt want to start (dumping tons of fuel on start up, ECU thought the car was -176* celcius!!!). And i have wired up my knock sensor. So right now i have no codes at all, but i still sputter and bog on acceleration.

Driving it today im seeing it happening even when warmed up. And if i shut her off when fully warmed up, she's kinda hard to start up again right away: has to turn over a lot more than would seem usual.

It really seems like some kind of sensor or valve or metering device is faulty somewhere.

[ca18detgabby]

coil packs going will give a rough idle and spudder on accel or at different points in the RPM end.

[bias]

Did some searching and i'm starting to think coil packs too. I will try and test them tomorrow and see what happens.

[ca18detgabby]

could be the plugs....... or the packs......

the packs go more often then I would like, but atleast it is an easy fix.

[jakry001]

i really hope its the packs. i will swapping my stock coil packs (and never using stock coil packs again) out for a set of either bosch or msd. over here in australia its very common for guys to run externally mounted bosch coil packs, some use msd as well, but they are more expensive here.

at the same time ill also be changing my ignitor to the q45 ignitor, as its a common failing point on a ca18det as well.

[JNM240]

OK, HUGE update for me here:

I checked out my coil packs, should be .7 ohms between terminals A and B, and 7000 ohms between terminal C and the spark plug connection. Well, i was getting between .7 and 1.2 ohms, and OL between C and the plug connection. Not sure at all why, so i pulled it into the shop today to recheck with another techs (much better) multi meter. Instead i wanted to recheck cam timing, mostly for my manager to see. Well, cam to cam was perfect, so i yanked the crank pulley off, and started inspecting....

Turns out i had installed the crank sprocket backwards!!! I had just set the timing belt to the keyway pointing up, not to the dot on the sprocket.

So now im gonna put it all back together. This should at least fix my timing issue.

[dattodude]

oh man. that's one of those things people would expect you had gotten right. :-)

Cam timing makes a huge difference, you must have been close though, or you'd have seen other problems.

[trevr]

Same problem as above, problem goes away with about 5 mins of idle for warm up. Tried all the same remedies, coil packs, igniter, knock sensor... the only thing I haven't tried was re-gapping the spark plugs. From what I've read, you need to fine tune the gap and see what will work.

[JNM240]

Ok well, not resolved yet. So all the timing belt issue resolved is why i had to run 30* BTC timing to keep her running. Now im down to 15* BTC.

So i yanked out all the plugs. They were all caked in carbon, obviously im running rich. So i dropped in some cheap NGKs (im cleaning up my NGK iridiums for use when i solve this problem) to burn up while i tinker.

The new plugs actually helped out a lot, the sputtering was gone, for all of about 5 minutes.

So apparently im running very rich. Ok, but why? I guess the next suspect is the O2 sensor. Gonna check that out tomorrow.

Jason

[ca18detgabby]

Ok well, not resolved yet. So all the timing belt issue resolved is why i had to run 30* BTC timing to keep her running. Now im down to 15* BTC.

So i yanked out all the plugs. They were all caked in carbon, obviously im running rich. So i dropped in some cheap NGKs (im cleaning up my NGK iridiums for use when i solve this problem) to burn up while i tinker.

The new plugs actually helped out a lot, the sputtering was gone, for all of about 5 minutes.

So apparently im running very rich. Ok, but why? I guess the next suspect is the O2 sensor. Gonna check that out tomorrow.

Jason

after re-reading a few of your posts 2 things come to mind...........

your BOV is recirced or Vent to ATM?

also you have an Eprom..... is the burned chip from a tune when the crack sproket was backwards? Thus not it is running to the specs of the backwards crack sproket? Or maybe the chip has come loose(which there have been a few people have issues with it shaking loose) this also would make the 550 injectors dump excess fuel.

lastly and a total shot in the dark........... did you consider going back to your stock FPR just to single that out of the equation of issues? there have been people(specificly boost boy) who have said the stock FPR is stronger and more reliable than the Nismo unit.

[trevr]

^^^ That's alot of work, to save time, I am running stock ECU, stock fuel pump, stock FPR, Q45 igniter, KA24e MAF, 2.5" IC Pipe, and recirc BOV... same problem. I still suspect plug gap, and now that you mentioned it O2 sensor.

Is the ECU on the CA self learning/adjusting?

[superJoy]

I am running stock ECU, stock fuel pump, stock FPR, Q45 igniter, KA24e MAF

Unless you're ECU is chipped and programmed to use the KA24E MAF, it's probably causing the problem. (Or certainly not helping it, haha) The CA MAF and KA MAF are NOT interchangeable without switching VQ tables. See here:

zerothread?id=241331

[JNM240]

after re-reading a few of your posts 2 things come to mind...........

your BOV is recirced or Vent to ATM?

also you have an Eprom..... is the burned chip from a tune when the crack sproket was backwards? Thus not it is running to the specs of the backwards crack sproket? Or maybe the chip has come loose(which there have been a few people have issues with it shaking loose) this also would make the 550 injectors dump excess fuel.

lastly and a total shot in the dark........... did you consider going back to your stock FPR just to single that out of the equation of issues? there have been people(specificly boost boy) who have said the stock FPR is stronger and more reliable than the Nismo unit.

OK wow good questions:

BOV is atmospheric, but i totally undestand that when it goes off it will want to die because metered air has just been vented to the atmosphere. Im ok with that right now, it just means that when im slowing down i either need to engine brake or slow down enough that the BOV doesnt go off.

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); the crank sprocket being backwards only affected cam to crank timing (which was ultimately only 1 tooth off), and has nothing to do with the ECU tuning. And i am using a quality ZIF socket so there is no chance of the EPROM coming loose. Besides, ive run a Stanza ECU with ZIF socket and burned EPROM for over a year on my built KA with no problems, so im 100% confident in this set up. Good question tho...

I havent even triend the OE FPR, but like i said, im still seeing 36 PSI of fuel pressure at idle, and with the Nismo FPR i can make that go up or down at will.

Im becoming more convinced its something that is allowing the car to run rich, like an O2 sensor (cant be coolant temp sensor cause ive already replaced that). Im gonna test some more stuff tomorrow. Ive just narrowed down to NOT cam to crank timing, ignition timing, or fuel at this point. It still could be the coil packs, they were giving me some strange readings this afternoon, but then again, im not 100% sure of my ability to use a multimeter at this point (hahaha). I would just rather replace a $21 O2 sensor than $240 worth of coils.

Everyone else having this problem, pull your plugs and look at them. Are they black and carbon fouled, like its running rich? I want to know!!!

Jason

[trevr]

Unless you're ECU is chipped and programmed to use the KA24E MAF, it's probably causing the problem. (Or certainly not helping it, haha) The CA MAF and KA MAF are NOT interchangeable without switching VQ tables. See here:

zerothread?id=241331

I've seen that before in my searching endevours. Plan on upgrading ECU, injectors, and MAF this summer, hopefully it will remedy the ailment. Although, I believe it is something else. because difference between MAF's is more prominent as the percentage of air flow increases.
Modified by trevr at 11:51 PM 2/27/2008

[ca18detgabby]

btw when one of my coils goes........ the easiest way to tell is that it is usually the cleanest plug pulled. This bad plug will give you an ugly idle(similar to a vac leak) but cleans up higher in the RPM band when the duty cycle of the other 3 plugs increase. if you have black plugs...... I would think something else is wrong.

it could be the 02 sensor causing the running rich.......... there are only so many sources telling the ECU how much fuel to pump

temp sensorsFPR02 sensorsMAF (maybe it is dirty?)throttle cableinjectorsECU

all I can think of......... at this hour.............. (but you know the issue so as you eliminate one you can move on)

btw, for the 2 seconds it would take to check the ECU....... I would save my 21 bucks and check the ecu just for ****s an giggles as it doesnt cost anything and is a simple fix.

I know my car is running a tad rich from over cooling, but 13.4:1 at idle is something I can fix this weekend....... I need to remix the coolant and water with more water this time

Ps if you have tuned the car to run these items....... was there a point where it was running ideal? just curious if this is a first test or something that is just now starting to have issues.

I have never heard of running a stanza ECU.......... why?

[jakry001]

UPDATE. i pulled out my spark plugs and coil packs.

my plugs were blackened on the ends which means im running rich.

but my big question is this: why am i running rich if diagnosis mode 1 and 2 both show my o2 sensor is operating correctly?

i cleaned my plugs as best as i could, as well as the coils (were not very dirty). put the plugs back in, and re-arranged the coil packs so they werent in the same position as before... now the spluttering has gone away. therefore, this must be a spark plug and coil pack related problem.

which leads me back to my richness? why?

all diagnosis modes show no errors. is it possible to be running rich bcos i havent had a tune in ages, and have a full 3" exhaust system, including a pod filter with hard intake pipe? i remember hearing somewhere that an exhaust can increase richness...

i get about 300km from a 50lt tank. thats quite poor, should be around the 400 mark.

furthermore, maybe the richness is due to the coil packs not functioning correctly anymore? anyhow, i will be putting 4 msd ss blaster coils on my ca soon, with a q45 ignitor. hopefully this will eliminate these problems forever.

anyone have any experience with msd on a ca18det?

[Cams]

hi all, I'll jump into this discussion as I'm having the exact same issue, and it's been going for a while. Car won't fire up when cold, unless I stay over 20 seconds on the ignition with the accelerator fully pressed. Once its on I have to keep the revs above 1Krpm until it stops studdering and the failure seems to be gone. Once warmed up would start again without major issues. Other issues I have are Valve Seals (still smokes white after turbo replacement, intercooler pipes are clean) and stuttering on high boost over 4,500rpms.

Car was bone stock when I bought it, with a Factory installed CA engine in it. The first thing I upgraded was to a custom 2.5" exhaust, but I dont think I was having start up issues before that. Was happening with factory everything, and since this car is the Latin America version it never had a Catback, and it never had an O2 Sensor so I doubt is that.

Now I have FMIC, K&N 57i intake with custom pipe, NIsmo FPR, WalbroHP, T25G, 1G DSM BOV recirc.

Intake manifold emission system is somehow gutted, blocked PCV, and temp thing unhooked, yet lowest temp here ever is like 24°C (at night) so it's not extreme cold.

Sparkplugs came out Black, so Im running rich too. Replacing them solved the issue for a couple of hours, maybe days.

Last thing I did was remove Fuel Injectors, took them to the lab and they were tested and had the internal filters replaced. Started right away once I installed them, solved the issue for a couple of hours.

Will be checking for codes in the next days, plus verifying vaccum lines and intercooler/intake pipes, and cleaning the MAF (to see the high boost issue is gone). Vaccuum is always at 20 so I guess this is ok.

Still think is the coil packs, but don't want to mess with those yet.

[bias]

This is crazy how one proplem can be getting all of us. I don't get it? Today it was really cold and my car ran strong no problems, well maybe a pop or two when I ahifted but no hesitation or stall? Has anyone changed there alternator? I know we have been thinking coilpacks but the alternator runs the car. I noticed when I use my lighter the interior lights die down. I don't have anything in my car but a boost gauge, timer, and factory heat/ac controls? What do you all think?

[JNM240]

...for the 2 seconds it would take to check the ECU....... I would save my 21 bucks and check the ecu just for ****s an giggles as it doesnt cost anything and is a simple fix.

After i hooked up my knock sensor last week, i check the ECU codes. Then i checked them again the next day after driving it a while. Still getting no codes.

Ps if you have tuned the car to run these items....... was there a point where it was running ideal? just curious if this is a first test or something that is just now starting to have issues.

Basically first test. Ive been sorting through my running problems since i finished putting the motor in last November. I just keep eliminating one problem after another, it just seems this is the last one, and the hardest one....

I have never heard of running a stanza ECU.......... why?

Its only on the SOHC KA. Nothing to do with the CA18. Just making the point that im not new to ECU tuning, thats all.

Has anyone changed there alternator? I know we have been thinking coilpacks but the alternator runs the car. I noticed when I use my lighter the interior lights die down. I don't have anything in my car but a boost gauge, timer, and factory heat/ac controls? What do you all think?

Not sure, but wouldnt you think that if the alternator has enough power to keep the car running and the battery charged, then it wouldnt affect the ignition, since all those components are seeing the 12V they require? And if your lights dim when you use an accessory, your alternator may not be putting out the voltage required? Only time my lights dim at night are when she wants to die coming down to idle, sputtering the whole time.

Today i was kinda thinking about my ECU tune as a possible suspect, but if no one else here has tuned their ECU, then thats probably not the problem. But im still going to check the fuel maps one more time.

What about heat range of the spark plugs? Im pretty sure mine are standard heat range of 6, but what about changing to a hotter plug?