I have to figure out this problem!

Discuss topics related to the CA18DE and CA18DET series engines.
cadet18
Posts: 226
Joined: Sun Feb 05, 2012 9:46 pm
Car: 89 s13 coupe ca18det

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So some of you have been apart of my many posts for my CA that has never been 100%. i have been putting a bandaid on the problem by using nistune the whole time. I have finally reverted my CA back to stock with the stock MAF stock 370cc injectors and a non socketed ECU 36F15. You can read through my older posts if it might help but i am just now starting to dig into this with a relatively stock setup. I still have the FMIC, non recirc BOV, 2860rs and the LS2 truck coils installed. I do have an ECU code, but its code 21 since the ignitor isnt there and have no spark issues. I have looked online and others are getting the same codes with no issues. Where i am at now with all of this is the car will not stay running after it cranks. it will start for about a second or two and blipping the throttle helps keep it running longer, but it will not hold idle at all. I have done a voltage drop test in the past which was good. I have checked fuel pressure and it is set correctly, my spark plug gap is set correctly. I have good battery voltage and a wiring specialties harness. my last compression test was a while ago but i will be checking that again today as well as new plugs again. I will also be trying another boost leak test when i can get a compressor at the house again (no leaks heard or agitated by spraying brake cleaner anywhere. Maybe you guys will say the one this i havent tried yet. i am by no means an expert but i do consider myself quite well versed in my abilities as far as automotive things go. Any help is greatly appreciated! Its been over 7 years and i have finally accepted that its needed to go back to stock to find this problem.

Thanks Guys!!!


cadet18
Posts: 226
Joined: Sun Feb 05, 2012 9:46 pm
Car: 89 s13 coupe ca18det

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UPDATE

checked compression 150 across the board #3 was around 148. new plugs are in and i have 6 ohms on all oins on dropping resistor. also checked for boost leaks and had a small one which was fixed. the car sounds smoother when it starts now but it will still shut off after a few seconds of running.

Its also probably important to note that all of my idle components are removed from the intake as well.

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float_6969
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You removed the idle control stuff and it won't hold idle and you're surprised? The throttle plate closes completely in stock form. With no idle control valves to allow air into the manifold, you have no way for the engine to breath and so it will die. There is a very small screw on the throttle body that the throttle pulley rests against when it's fully closed. It's kept from moving by a very small nut. You need to loosen the nut and thread the screw in. I would thread it almost all the way in. That should be WAY too much idle, but then you can start the engine and leave it running. now slowly back the screw back out until you get the idle down to about 1000 RPM. Then tighten that small nut back down. DO NOT OVER TIGHTEN THE NUT! It's very small and has very fine threads and it's really easy to strip out. With no idle control valves, this is about the lowest RPM you're going to be able to maintain and not have it die on you. The RPMS will drop when you turn on things like headlights, windshield wipers, etc. This is normal.

cadet18
Posts: 226
Joined: Sun Feb 05, 2012 9:46 pm
Car: 89 s13 coupe ca18det

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Thanks float! thats exactly how i ended up setting my idle. I think i have figured this out and it ended up being the power wire for the AEM UEGO being plugged into my fuse box for power. i have since ran a relay using the cigarette lighter power for signal and ran power and ground for the gauge directly from the battery. with all the stock components on the car is running wayyyy smoother. I have only driven it to the gas station and back though so time will tell. I couldnt believe that simply unplugging my wideband would fix this but it seems to have. HOPEFULLY after all this time i have finally found my mystery issue. If anyone else has ever had something similar to this please share. id love to hear of another issue like this.

Thanks all for the input on this forum from my beginning here. This truly is the best place on the web for CA advice. I lucked out and got the suggestion which was my fix from the CA18DET motor enthusiasts group on facebook. you get some prety decent help there as well.

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float_6969
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Yea, that's a weird one. I'm glad you got it sorted out though!

cadet18
Posts: 226
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Car: 89 s13 coupe ca18det

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i thought so. ive got it going on the tune from my tuner with my injectors MAF Coils and ECU back on. it will hold idle now but is super lean. it hits fuel cut when you roll into it though. my AFRS are very rich (10:1) with anything above half throttle. at idle it is off scale lean. this is with all my gauges disconnected except my wide band which is now wired directly to the battery.

Ken@PTUNING
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If it ran great before you put all the new stuff back on, I'd suspect your tune is off (improper MAF scaling, wrong injector scaling, etc).

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float_6969
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Yea, there's something wrong with the tune. The ECU is in closed loop at idle, so unless there's an O2 sensor signal problem, or your tune is way off, you shouldn't be lean at idle. Do you have the narrowband simulation signal going back into the ECU or are you using the standard O2 sensor to provide a signal to the ECU?

Buddyworm
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Joined: Tue Jan 09, 2007 2:55 pm

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^ECU defaults rich when it doesn't see the narrowband signal there Float. He shouldn't be reading lean if that sucker is the problem.

Cadet, if you've got Nistune try starting from a stock ROM and using Nistune's injector and MAF calculators to do the resizes yourself. Don't touch anything else and see how it runs. Nistune's calcs should get you well within the ballpark if you've done it right and it should start up with relatively little fuss.

Also, it's important that the base ROM file used matches the part number of the ECU. IIRC some folks on Nistune's forums have had some ECU's behave very oddly when flashed with a non-matching part number's ROM.

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r34 gtr
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Make sure to do the "big three" external grounds too. Grounding for the factory CA18 engine harness is about the worst I have ever dealt with. Mine used to die every time I pushed in the clutch to coast to a stop light. Grounded alternator body to fender, battery negative to fender, and intake manifold to fender and it never did it again.

I use the TB adjustment screw to crack it open a smidge for idle. Works great. Have to do that if you aren't running the factory idle control stuff. Sure it fluctuates between summer/winter but its usually between 800-1000. Even idles fine on startup in relatively cold temps, though its a fair-weather sort of car. Make sure you have capped all the vacuum lines on the TB if you are using the cracked-TB-for-idle mod.

I find mine idles happiest at around 12.5:1 AFR too, as I don't have any of the factory air control stuff. Might give that a try if you are running out of ideas.

Good luck out there.

cadet18
Posts: 226
Joined: Sun Feb 05, 2012 9:46 pm
Car: 89 s13 coupe ca18det

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ok sorry for the late replies ive been out in the garage pulling my hair out on this thing. heres my latest post on FB about the issue.

i have previous post to this regarding my car running lean at idle rich under boost. I t has been verified 110% no vacuum leaks so thats not the issue. i have reverted the engine to stock with the exception of a 2860rs. stock ecu has been tried with the same results. right now im just trying to isolate the lean idle. i feel all others will fall into place with this as the source problem. my question is will my car be running lean on the stock map with a 2860rs. im not going to buy a stock CA turbo for troubleshooting. im wondering if i am putting out too much air at idle with the 2860rs? fuel pressure is verified a dozen times over. all connectors are being checked for continuity and short to ground now (even though its a new wiring specialties harness). last thing i had was the wideband unplugged which took the CA from not holding idle at all to now holding a very lean choppy idle. If someone has some good experience it would be awesome to text/call with someone who knows cars quite well to bounce ideas back and forth. im 99.9999% sure all my sensors and fuel are working 100% correctly. its s stock tune so thats not bad. i have good battery voltage. any input is greatly appreciated as long as you dont tell me i have a vacuum leak lol.


ive got all the grounds listed above and more, i also have completely reverted everything to 100% stock excluding the 2860rs. i am using the stock narrowband for the ecu input wideband is a seperate entity. so with it being 100% stock setup now i have ruled out it being fueling, spark, or air. i also dont think its any of my sensors. i did get 10-11 Mohms of resistance when checking the battery cable to ground but i dont think thats enough to cause any of this. my battery is in the trunk too. im at a loss for what to check next. thanks for all the replies again i appreciate all the helpful feedback. One day i might actually figure this thing out and be able to enjoy the car.

Buddyworm
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No way the turbo is causing your lean idle.

Did you transcribe your resistance value right? 10-11 Mohms?? As in MEGA ohms?? That's gigantic! You should have fewer than 5ohms from any clean metal point on the body to battery negative. Engine block to battery negative should have almost no resistance.

That could be your problem right there. Excessive resistance might reduce the voltage available for opening your injectors, shortening the pulse.

Have you checked resistance to battery negative through your injector grounds?

cadet18
Posts: 226
Joined: Sun Feb 05, 2012 9:46 pm
Car: 89 s13 coupe ca18det

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i should have probably specified that was engine power wire checking to see if it had a short to ground. it had 10-11 Mohms

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float_6969
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I just realized that your ECU is for an automatic transmission. The auto ECU uses a switch on the TPS to tell the ECU that the throttle is completely closed so that it will go into closed loop idle control. The manual transmission harness doesn't have the wiring for this (and I doubt your WS harness has the wiring for it either). This may explain your running conditions. Can you source a MT ECU and see what effect that has?

cadet18
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Car: 89 s13 coupe ca18det

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i have the idle swiitch on my tps. my nistune lights up the idle signal when i release the throttle. i have a 36f05 as well. is that a manual one?

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float_6969
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That is a manual one.

cadet18
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tried the manual ecu with no change. i have cleaned the crap out of all my grounds and it runs better. it will hold idle now fairly well but, it still stumbles and doesnt have a clean idle. i have the plugs gapped at .8mm it will run close to 14.7 +/- a half point or so but then it will randomly lean out and then correct back to stoich again. it always recovers. one of the guys ive been talking with on facebook recommends putting the 440s and n62 maf back on now. I went and drove it and it drives smooth other than being rich under lower loads/rpms and lean at the higher loads/rpms. im assuming its because the bigger turbo spools slower than the factory t25 down low hence the rich. and obviously over powers the injectors up high. Does that sound like a safe assumption to you guys? also would you recommend going back to big injectors/MAF now or just starting it up and cruising around the neighborhood for a few days to check for consistency?

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r34 gtr
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I might give that a shot.

Did you do the wiring for this yourself?

I might get out a multimeter and check to make sure all sensors are getting the correct voltage at this point. I once had a similar problem that was caused by the O2 sensor getting inconsistent voltage

cadet18
Posts: 226
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Car: 89 s13 coupe ca18det

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its a wiring specialties harness. ive already checked continuity and for short to ground for all major sensors. right now it shows full lean on warmup but idles fairly well and when it hits operating temp it goes from 13.7-15.7 and never settles down. ive tried disconnecting the narrowband completely with no change as well. heres a link to the facebook page where there are some videos and more posts from this problem.

https://www.facebook.com/groups/1131997 ... tif_t=like

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float_6969
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Does Nistune give you the coolant temperature?

Buddyworm
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Sounds like you're making progress!

Check for vacuum leaks. Can be cause of lean misfire under vacuum plus rich under boost. Since youre AFR fluctuates so much I'm strongly suspicious of this. Heck, do you have any exhaust leaks upstream of the O2 sensor?

Also check ignition system. Are your coilpacks arcing out to the head? Are the boots clean? Are the little springs inside the boots in good shape? How's the coilpack subharness?

It might be a good idea to do new injectors after you've checked above. A CA18 with brand new injectors is a smooth idling thing of beauty.

cadet18
Posts: 226
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Car: 89 s13 coupe ca18det

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ive checked for vacuum leaks like 5 times now lol. im paranoid that im missing something bc it seems like it is a vacuum leak i know!(ive checked with the pvc cap with a valve stem trick/brake cleaner trick, and the soapy water trick with no leaks up to 15 psi) lol
there are no exhaust leaks that i can hear from that area or black spots. i am running ls2 truck coils converted to coil on plug ill have a look at the continuity of that harness here next time i go out to mess with it (busy at work at the moment, plus its cold here in delaware right now and my garage isnt heated). and yes float nistune gives me the coolant temp in F as well as C. it is consistent with the temp outside for the day here before startup and levels out around 160-170.

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float_6969
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Well I know this is going to suck, but maybe it's something to do with the coil conversion. Would it be a lot of trouble to put the igniter back in and put the stock coils back on?

cadet18
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Car: 89 s13 coupe ca18det

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actually no, its very easy i built the coil conversion to be easily swapped in or out by making a nissan to GM conversion harness(its not pretty but its awesome for times like this). ive been super busy with work lately and havent had time to mess with is but hopefully soon i will have time. for sure this weekend! Its running decent but i just want it to be perfect before i go putting anything extra into it so i can then be sure that it has to be my tune that is the issue. hopefully the rich down low is because of turbo spool time i cant be too sure without the facory turbo (long gone) being on there but at least that makes sense in my head. Thanks again all for the input, everything has been useful thus far to try and resolve this crazy issue. hopefully this is forward progress!

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float_6969
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With a MAFS based system, the change in air flow down low shouldn't matter. The ECU is measuring the actual mass of air entering the engine and injecting the correct amount of fuel. A bigger turbo that spools more slowly will simply ingest less air and so less fuel will be injected.

cadet18
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hmm it seems i have another issue to dig into then...

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float_6969
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OK, after re-reading this, I'm confused about something. You put it back to stock, but you have Nistune still installed. Do you have a completely stock, untouched ECU you can put back on there? You haven't really eliminated all of the variables if you still have Nistune installed on an ECU, even if it's a stock tune.

Also, it sounds like at some point you were running a stock MAFS and injectors on a Nistune tuned for a N62 and 440's. If so, that would easily explain the rich down low, and lean up high issue.

cadet18
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Car: 89 s13 coupe ca18det

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no i have the tuner license so i am able to swap maps or tweak them whenever i please. i have also tried with the 2 other untouched stock ecus and the car runs the same. anytime i had the stock components on the engine i flashed the stock map to it.

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r34 gtr
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You removed the vacuum stuff. Are you absolutely sure there are no air leaks around whatever block off plate you covered the holes in the IM with?

Is your PCV check valve on the back of the IM leaking a little bit?

Possible that the PCV horrible-nightmare-pipe-under-IM is leaking at one of its connections?

cadet18
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Car: 89 s13 coupe ca18det

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the intake held 10-15 psi with no audible leaks and passed the soapy water test there while pressurized it also doesnt change idle when spraying carb cleaner around the area while running.. ill check the pcv its less than a year old though (you never know with those things. ill look under the intake for a pcv pipe but i cant recall what your speaking of off the bat. i started it up today and it started up just fine then it did its normal searching for a constant afr and actually cut off on me twice while warming up as a result of running lean. I really wish i could find a vacuum leak somewhere but its not showing its head as far as i can see. at this point even it it was a $1000 part id be ecstatic to find out it was bad and was for sure causing my issue. im still working on it but im busy at work during the week. ill be out today trying to mess with the car. My cell is (229) 561-4678 is anyone has any revelations or just wants to shoot me some ideas. otherwise ill check here later on throughout the day. Thanks for all the help again guys! i cant say that enough.


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