Breaking up in the top end, but boost problem fixed, any ideas?

[progman]

Maybe check the timing again. Perhaps the CAS is doing weird things.

[KEMP]

Dude I have said the timing is fine the cad is fine. It's not that as I stated

[Myetball]

I don't have a CA18DET but a C20GET, Brazilian 2.0 SOHC turbo. Was having almost the identical problem. It's got a 3-speed auto and it shifts at 5600. As soon as it would hit 5k, in all gears, it would break up and spit and sputter.

Over may months I checked and rechecked everything. Ignition was not the problem. Air flow was good. Ended up having to replace everything related to fuel delivery to get it squared away. Replaced modded fuel rail w/AEM FPR with stock rail and FPR and forked out the dough for a set of TOMCO rotary disc injectors also a new MAP sensor...the 20 year old sensor was getting a little long in the tooth.

The biggest problems were the bad AEM FPR and the old azz injectors. Yeah it was holding fuel pressure at idle but wasn't climbing as the boost pressure was applied to FPR. Injectors were just old and couldn't put out what the duty cycle required.

Do you have a wideband O2 sensor? Will tell you if you're maxing out your injectors. Of course you can spend countless hours and money, like I did, replacing everything or get it onto a dyno with a wideband sensor and find out what's really going on. It's the best way to be sure and will probably be cheaper in the end.

[KEMP]

See that is similar. But when this happens it shoots tons of black smoke according to my friend driving behind me. I'm putting in a nismo for soon. I still don't think it's fuel

[Myetball]

Okay, if it's shooting tons of black smoke then you're dumping too much fuel into the cylinders. Go into your SAFC and start pulling back on the fuel at the top end where it's breaking up. The biggest problem is probably that you've put larger injectors in without the correct fuel map. If you're motor is mostly stock and all you did was crank up the boost you may be better off with stock injectors and a little fuel added at the top end.

You'll probably need to pull back the fuel across the entire band. Either that or put stock injectors back on and add a little fuel.

Again, a wide band and/or dyno tune will tell you exactly where it's getting too rich.

[KEMP]

Okay, if it's shooting tons of black smoke then you're dumping too much fuel into the cylinders. Go into your SAFC and start pulling back on the fuel at the top end where it's breaking up. The biggest problem is probably that you've put larger injectors in without the correct fuel map. If you're motor is mostly stock and all you did was crank up the boost you may be better off with stock injectors and a little fuel added at the top end.

You'll probably need to pull back the fuel across the entire band. Either that or put stock injectors back on and add a little fuel.

Again, a wide band and/or dyno tune will tell you exactly where it's getting too rich.

its not stock at all, read my sig...

[Myetball]

Sorry, by stock I meant anything that would require bigger injectors like high lift aftermarket cams. Anyway, good luck, this will probably fall into the category of the 99% of problems that can't be solved over the internet.

[KEMP]

A big *** turbo requires many non stock things like injectors

[float_6969]

Did you get this figured out yet?

[Desert Fox]

I am having this same problem. Car is hitting fuel cut at 14/15 psi.

I have a manual boost controller, and its turned all the way down. I think the hks wastegate is boosting too high, and its a crappy boost controller.

Any Ideas on why?

[float_6969]

If you've got an HKS wastegate on there, you're gonna hit fuel cut. No way around it. You need bigger injectors, bigger MAFS, and a chip tune.

[Nali]

CA18DET, breaking up at higher boost levels. And at Full throttle.

Ive got the exact same problem, i thought i was the only one feeling this unresolvable pain.I can run all the way to redline aslong as im not at full throttle, once i full throttle it, the car breaks up at about 4k, then after the small break up jumps back on boost and continues all the way to redline.

But lately for me the problem has been getting worse and i suspect its a fuel cut or grounding issue. Im gonna reground and get a fuel cut defender soon.My car actually wont go over 4k at full throttle if i reduce throttle by like 30% it goes just fine.And during breakup i get plumes of black smoke out the back.I checked all the obvious things too. Its just grounding and fuel cut which i haven checked yet.

Im gonna keep my eye on this thread, if a solution comes from it i will be ecstatic. I post my results after the reground, and ignition test.

[ca18detgabby]

I will throw my 2 cents in on a few ideas.

first have you checked and cleaned your plugs? I would try running hotter plugs maybe least they would ignite faster...... with the black smoke it shoulds like you are extra rich.

second I would look into leaning it out with the SAFC, just at the top end. Flooding it will make you stumble real quick.

have you considered spark nock?

are you running an auto to manual ECU?

lastly, engine issues are frustating and all of us have experienced one problem or another. You need to chillax a bit help us help you. there are only so many components in an engine, so when you tell us "thats fine" it makes it difficult to diagnose. a video would be cool as well..... hell my cell phone can do it......

if we rule out the over fueling with the 444s, then you come to very few components left to look at. Vac, ignition, and timing.......

I have to think Vac is a omni prominate issue and since it is just in XXXX RPM band, that it probably isnt the issue. less there is an issue with running the turbo outside its comfort zone(possible).

timing-assuming you have it straight..... less there is slack on the belt I cant see it having issues at just 1 point in the RPM band. It doesnt seem likely that is the problem.

Then you get to ignition- plugs, wiring, and coils- coils usually an omni present issue at a given RPM band pre-boost, but I suppose it could be across the board. plugs? maybe carb build up....idk. then wiring, always worth a 2nd and even 100th look at, things wear over time.

so please help us help you.

[KEMP]

bought 4 new coil packs for a pulsar, through a friend at autozone, i got a little deal, so i popped em in, and it runs quite great, i trid eliminating it to just one coil, but all my coils were weak.

it breaks up a bit but revs to redline and spins so hard 1st and second gear are worthless.

so at this point, it is tuning to fix my small break up, coil packs were my problem. also for futrue referance, go to autozone for your oil packs, they are $42 a peice there, and about $70 everyother place.

[Nali]

bought 4 new coil packs for a pulsar, through a friend at autozone, i got a little deal, so i popped em in, and it runs quite great, i trid eliminating it to just one coil, but all my coils were weak.

it breaks up a bit but revs to redline and spins so hard 1st and second gear are worthless.

so at this point, it is tuning to fix my small break up, coil packs were my problem. also for futrue referance, go to autozone for your oil packs, they are $42 a peice there, and about $70 everyother place.

Coil packs aye.

I just changed mine.I think my problem must be fuel cut. Because its just too clock work how my car stops revving 4k with full throttle.I might get new coil packs just for the sake of it

Last time i had break up like this it was Vac Leak, this time i dont know. Why would my car be Fuel Cutting at stock boost pressure? Any ideas.

[Ca_Silvia]

bought 4 new coil packs for a pulsar, through a friend at autozone, i got a little deal, so i popped em in, and it runs quite great, i trid eliminating it to just one coil, but all my coils were weak.

it breaks up a bit but revs to redline and spins so hard 1st and second gear are worthless.

so at this point, it is tuning to fix my small break up, coil packs were my problem. also for futrue referance, go to autozone for your oil packs, they are $42 a peice there, and about $70 everyother place.

'88 pulsar nx coils?

I never knew they were interchangable or could be bought new....

[rico05]

'88 pulsar nx coils?

I never knew they were interchangable or could be bought new....

I have three in my car right now

[Desert Fox]

I fixed my problem with the fuel cut by changing the lines for the boost controller. Apparently my friend showed me the lines for the wastegate and for the b.c. were on the opposite ones they were supposed to be. I also found a hole on a weld on my bov. Seems like the Previous owner didnt know his head from his butt. And since I just got it a week ago, we've been diagnosing it.

After we got that all taken car of, I was running it and I started backfiring, and something fierce of backfired at that. So we pulled over and checked under the hood. I wasn't building boost anymore, and something sounded like an exhaust leak. I had my friend rev the engine, and I could see that it was backfiring out where the turbo connects to the exhaust manifold. When it got turned off we looked and saw the gasket sticking out the side like it had been blown out. I figured that was the problem with boost and drove it home.

We took the ex. manifold off and found only two of the studs were tightened on with nuts. not even very tight at that. We tried to go to autozone and get the part for a 300zx since they had a t25 as well, and from what I searched that would fit. But it turns out that they dont have 90-96 turbo gaskets for those cars. I went and ordered it off a site I found in a search, and Im waiting for that. while we were waiting, I tried doing the gasket with high temp rtv. after I put everything back together, It smoked for a little bit, and still had the exhaust leak noise. I took it down the block and back and I still wasnt getting boost. I tightened it all and did that 2 more times. The last time I was informed I was blowing blue smoke. Pissed off I pulled back in the garage and started taking the headers off. Im pretty sure that the exhaust gasket had a leak, and that the rtv wasnt holding either. So I went and got a new exhaust gasket as well. Now im jsut waiting for the turbo gasket to come in, so I can get the car running. In the meantime Im painting it. Blacktop maroon.

My question is since it was blowing blue smoke, is that cause there was that leak so the turbo couldn't spool to boost anything over 0 psi, so the cooling oil just was cooling a not spinning turbo? Cause when I took the headers off, I could see oil all over the inside of the turbo that wasn't there the first time I took it off. Im new to the whole forced induction thing, so im a little confused here. I cleaned the oil out and filled up a bit more, so it should be more. I appreciate the input.

[KEMP]

i have had a turbo bad enough to where it wouldnt spool

shaft play?

[float_6969]

If the turbo isn't building any pressure internally, I suppose that it's possible that the oil could push past the seals.

[Desert Fox]

Yeah, there is a little shaft play, but it still spins. I dont think it would just crap out and not work at the same time the turbo gasket blows.

Or is it cause the turbo is dead?

Sorry for hijacking the thread though.

[KEMP]

Yeah, there is a little shaft play, but it still spins. I dont think it would just crap out and not work at the same time the turbo gasket blows.

Or is it cause the turbo is dead?

Sorry for hijacking the thread though.

bad, gummed up and leaky seals, cause sahft play, which in turn leaks more, wearing seals/bearings down faaster, eventually going to the turbo is pissed at spinning, and screws up blades, and not letting it compress air in the compressor housing.

[Desert Fox]

OK, and I'm guessing my turbo either died, or is pretty close to it right now then?

[KEMP]

uh, yeah