intermittent Bad running stalling

I just can't figure this out. My car will run fine for a little bit after it starts up but then it'll have trouble going over 2200RPM with or without load and it will sputter on the way. Also while if you drop it to idle it starts doing that it'll idle at 500 RPM and eventually die if you give it a minute. It seems to do it more often when the car is warm but it seems independent of coolant tempature

Unplugging the MAF sensor will make it idle fine. It smokes a little though when you do that (rich mixture I have a very short exhaust)

I have no idea what it could be. I've replaced the MAF sensor. Both coils have been replaced with MSD blaster coils (they are wired correctly) plug wires and the plugs (the ignition stuff was more of an upgrade but I hoped it would get rid of the problem)

Mind you this is an absolutely new problem I did not have anything of this kind before I put the turbo and everything on.

the idle sounds like it could be a vacuum line...are you running an aftermarket cone filter, or aftermarket intake lines...also has it been doing this ever since you did the turbo, or just rescntly??

sounds like a afm problem..........have you checked for codes? If it's an afm problem it should throw a code.

check vaccuum lines...FYI..my 88 SE is doing this too..when i first start it, it trys to stall for the first 5 minutes..so long as i get in an go, its ok, if i let it sit, it dies...i have no codes..new vaccuum lines, plugs, wires...im gonna re-do my engine/chassis grounds soon, hopefully that'll fix it.

The car ran perfectly fine before I changed the turbo. This is exactly every last thing I have done, turbo install wise, to the car. This is going to be long

The car has a cone filter and had one a month before I started taking it apart

The turbo appears to be a T25 similar to one found in a Z32 300ZX TT. It is fine. All difficulties in installation were sorted out.

The turbo was bought off ebay and had a custom downpipe and had an O2 sensor with it. The o2 sensor's wiring was frayed so I decided to use mine. I had to lengthen the wires in order for the o2 sensor to connect to the harness.

volvo 740 I/C simple install two holes in the frame and then piping this was pressure tested to 30psi and it did not leak.

Custom 2.5" I/C piping these were bent at an exhaust shop.

There are two sections for the intercooler inlet pipes. The compressor outlet has a 2-2.5" transistion hose made from reinforced silicone. The hose coupler is the same material. Both the intercooler inlet and outlet couplers are rubber.

There are three sections for the intercooler outlet pipe with two of the same silicon coupler as the inlet. The last section of pipe has a 1g DSM BOV welded on it.

The port for I.A.A. unit was taken from the old pipe and welded to the same pipe as the BOV. The stock hose was trimmed down (too long) and used again

The BOV gets it's true pressure source from the same place as the boost controller. (I'll get to this in a sec) The boost gauge also get it's pressure from this location.

The BOV's dump pipe goes into where the stock PCV hose went. The PCV route's new exit is a filter.

The boost controller gets it's pressure source from the hose tee right next to and below the throttle body. The other item above are teed off of the boost controller line.

For the boost controller to control boost it has a solenoid valve. One part of this valve gets the pressurized air from the compressor outlet housing. The other part goes to the wastegate actuator

The Compressor inlet side of turbo requires something to be bolted to it in order for a hose to go on it. The part that came with the turbo had a 90 bend in it and was worthless to me. I had an exhaust shop weld a 2.5" diameter pipe onto a flange that would work. The flange looks almost exactly like the old one without the pipe.

In order to get the compressor inlet side hose setup quickly I had to trim some of the stock hose to shorten it so that it wouldn't kink and so the filter would fit . I trimmed it from the filter side. In order to keep the vacuum fitting that goes into that side of the hose I made a hole for it to go in.

To try and fix the problem i have already checked for codes. There are none I have repeated checking for codes before and after letting the problem happen. I have not done a real time diagnosis yet.

To fix the problem

Thinking the ignition was faulty I installed MSD SS blaster coils, Magnecor spark plug wires and NGK iridium spark plugs. 160 bucks worth of.... Nothing but an upgrade none the less

I have replaced the MAF sensor. 150 bucks worth of.... Nothing :kicknuts:

Another help of diagnosis.

When the car first starts it first idles at 1000 RPM for 2 seconds then drops to about 600. The Air regulator is stuck closed the car had this problem when I bought and still has it now.

If the car is driven and no adjustment have been to the boost controller it will boost 5.3 psi of boost at full throttle by 3000 RPM.

Continue driving approx. 3-4 miles the car will start showing the symptoms i have described.

If the car is not driven it will idle for 15-20 minutes before the symptoms show up.

Shutting the car off and restarting it will make the problem go away for a few seconds and then it will do it again.

The car will idle until the forseeable end of petroleum usage if the MAF is unplugged at this point. But it will start smoking. It did the same exact thing before and after I put in a new maf sensor.

Things I will look at next...

Vacuum lines (my dad is also saying itis a vacuum related thing)
O2 sensor
power transistors for ignition
Perform real time diagnosis to see if CAS could be causing this

the vaulve cover breather is part of the engines vacume, under idle and light revs. when the car is in idle or light revs the PCV vaulve is open and sucking air from the block and with the breather filter there it will be sucking unmeatered air through. Block the breather under idle and see if that helps.

My car runs perfectly fine with the valve cover breather so I doubt thats the problem.
I am still leaning towards, bad CAS, or bad AFM.
I've had both go bad......and with the bad CAS it would run fine for about 20-30 minutes, then stumble, back fire and die.
With my bad AFM I couldn't rev over 2000 anytime...but you say you can for the first 20 minutes after crank-up?

Could be fuel ... make sure your pump is getting a good signal.

But yeah, if unplugging the MAF makes it work, your ECU could be on the blinky.

My 85 Turbo is doing the exact same thing. At first it would just die and I could turn the ignition to off and crank back up and go. The problem got worse and worse untill I couldn't even get out of the driveway. It would stumble and die some times at idle but as soon as I put it under load to back out it would die. I towed it to a friend's place I'll mention later and he messed with it, un-plugged the vacuum line from the solinoid ontop of the fuel pressure regulator and it ran fine. He drove 1/4 tank of gas off, I drove it home, to work, and all over the place that night and next day. Then it started up agian. Now it won't start. It is bone stock except replaced plugs w/ NGKrs and replaced Rot and Wires w/ regular replacements.

At first I thought it was a fuel problem, either fuel presser regulator or fuel pump itself. I had a mechanic friend of mine take a look at it and he diagnosed it as multible giant vacuum leaks. I've replaced most vacuum hoses but when I spray carb cleaner down next to the intake mani and tb it idles smooth as can be. Right now it's not even starting unless I drench that area w/ carb cleaner. I'm going to pull the tb off and intake mani and replace those gasgits over the next day or so. We'll see what that does.

Your problem and mine sound alot alike, they both sound like a few things. The CAS or AFM, also the vacuum leak sounds plausable in my case because of the effect of the carb cleaner. If you haven't tried that already give it a shot see what it does.

I'm going to choose to ignore Mr. 200's post on the ECU, I'm in denial of that... To broke :P

check the "resistor box" under the ecu i had a loose connection on that once before and it had the same problems

Unplugging the O2 sensor seems to have fixed it. First I tried disconnecting the Fuel pressure control solenoid and it made it idle higher but I didn't have anything to plug the solenoid and the hose with so I put it back.

Then I just went out unplugged the O2 sensor. Then I drove it 7.4 miles. Not one hiccup or problem.

It has one hell of a boost spike though but the controller clamps down on it quickly. (like I said really short exhaust which is probably why it's spiking )

Other things

On first start up it idled perfectly fine except it was a little low. (and for some reason the car shook a little bit).
Again it boosted to 5.3 psi.
It spiked to 8 on WOT throttle application in high gear
max speed on test 80 MPH
max RPM on test 6400 RPM in 1st gear
when I got back home it idled perfectly fine.

Unfortunately the stupid connector for the harness side of the sensor fell onto the down pipe. :wall: oh well.

So the O2 sensor seems to be the problem now. How the heck could the stupid thing have that much control over the car? oh well I try it again to make sure it wasn't a fluke.

it could be the TB gasket, but I dunno, it takes a pretty godawful vacuum leak to shut a motor off.

A failing 02 sensor on these cars can do that. I had a bosch 02 sensor that failed on me and the car ran so rich it wasn't even driveable. I disconnected the sensor and it ran ok but richer than it should be with a working sensor. A new NGK 02 sensor and haven't had a problem since. Also notable is that removing the coolant temp sensor connector also disabled the 02 sensor problems so it seems the 2 units work in conjunction.

It was the O2 sensor most definately. I went for another slightly shorter drive. and even decided to play with the boost a little bit. It put it up to 7.8psi. and it went there with no complaints

I won't take it higher until I get better gas in it and my exhaust on but it won't matter anyway cause I have new problem now :cry:

For some reason now under full boost in 3rd gear or higher. The revs seem to go up faster than the speedometer :p

MUHAHAHAHAHAHA!!!!!
AHAHAHAHAHAHAHAHA!!!! :devil:

Thanks for all your help guys. See you in NC :burnout:

... it takes a pretty godawful vacuum leak to shut a motor off.

My old (i do not own that P.O.S. anymore) 94 tempo had a vaccuum line just completely break once...couldnt even start the thing...lol..it ws the line that went into the Intake..dont know/care where it came from, it was a FORD, and i hate it simply b/c of that...

Ok the following question proves why I'm not a mechanic. Were might I find this o2 sensor... I want to check this because it's alot cheaper then all the other things I've been looking at. I'll look around for some info on were to find it but if some one wants to support my lazyness by letting me know I'd appreatiate it ;)

sure, it's in the 02 housing. Look under the hood, on the driver's side, underneath the brake booster, attached to the back of your turbocharger assembly. There will be a 3 wire connector attached to the sensor. It looks kind of like a spark plug screwed into the back of the turbo.

sure, it's in the 02 housing. Look under the hood, on the driver's side, underneath the brake booster, attached to the back of your turbocharger assembly. There will be a 3 wire connector attached to the sensor. It looks kind of like a spark plug screwed into the back of the turbo.

Cool, thanks :) I'll go unplug that bugger right now and see what happens.

Well, I couldn't unplug it because the prev owner had let it tough the turbo or somthing down there and melted the plug all to crap. They then wrapped it in electical tape which melted agian... yay. So I figure I need to replace the plug anyway or just hardware it so I cut it out. Still won't start and now I get code 22 and 23. 22 is fuelpump circuit and I have no idea what 23 is altho I would assume it's 02 sensor. So I don't think that was my problem. Question is, if my CAS was bad would it throw a code? When I say bad I mean bad enough to keep the car from ever starting.

**Edit**
Is 23 bad idle somthing?

a botched up o2 sensor will not keep the car from starting. my 86 never had one hooked up and ran (on boost) for a year like that.

a botched up o2 sensor will not keep the car from starting. my 86 never had one hooked up and ran (on boost) for a year like that.

I wouldn't think it would but I didn't know for sure. Does every one think this sounds like a CAS? Were is this sensor located?

code 23 is the TPS push the accelerator right down and this should turn the code off when the motor off and the ignition is on of corse:burnout:

code 23 is the TPS push the accelerator right down and this should turn the code off when the motor off and the ignition is on of corse:burnout:

Is this somthing that would stop the car from starting? It's wierd that it just started throwing it after I disconected my o2 sensor...

no the tps wouldn't keep the car from starting. It just tells the computer when the throttle is close to reduce fuel for idle (on the CA18ET). On the CA20 it also is a WOT swich but the only function on the CA18ET is for idle purposes.

The CAS is within the distributor unit......you have to take off the cap, and rotor to gain access to it.

The CAS is within the distributor unit......you have to take of the cap, and rotor to gain access to it.

Thanks for the info, any way to tell if it's buggered w/o just replacing it? Ie w/ voltage meter...

perhaps the fuel pump circuit is the cause of your no start problem 8). Do you have a manual? If so follow the procedures for checking the fuel pump circuit.

Thanks for the info, any way to tell if it's buggered w/o just replacing it? Ie w/ voltage meter...

The CAS operates too fast to use a multimeter to check it. You need a reasonably good oscilloscope to see its output (preferably at least 20MHz, my 1MHz hand scope has problems). The easiest place to measure it is probably the computer, at the back of the plug.

If you do go pulling it apart be very careful not to damage it, especially the internals. The CAS is a very delicate and precise instrument, it is critical to the safe operation of your engine, it can be damaged very easily, and if you damage it at all then you will have no choice but to replace it.

Your problem sounds heat-related, and I (recently) had a mechanic mate of mine tell me about a heat-related CAS problem - the engine would heat up then play up then stop, and all problems disappeared when the CAS was replaced. I don't know how much it would cost you for a new (or at least 2nd hand with guarantee) CAS but seeing as how you've already spent $310, a few more won't hurt :)

fester are you speaking about my car or gothrax's my car's already fixed it's the O2 sensor. Gothrax has a no-start condition

Oh and CAS's are MOTHER****ING EXPENSIVE. I've heard of getting the module itself from nopi or something for $70 but I haven't tried that. Otherwise bring a shit a load of anal lube when you go up to NISSAN cuz that's the only place besides a junk yard you can get one.

Oh and you have the same odds of finding another turbo model in a junk yard (at least by me) as you do by getting struck by lightning 5 times, consecutively mind you, and living, and being able to ask christ himself where you can find one at.

I would continue but there's no point.... :disgust:

Oh and CAS's are MOTHER****ING EXPENSIVE. I've heard of getting the module itself from nopi or something for $70 but I haven't tried that. Otherwise bring a shit a load of anal lube when you go up to NISSAN cuz that's the only place besides a junk yard you can get one.

I don't like anal lube, I like NOPI (http://www.nopionline.com/nopistore/dsp_part_detailos.cfm?vmakeid=270&vmodelid=110&vcatyear=1985&vnopinum=924%2B0208&vTitle=NISSAN%20200SX%201985)

924+0208 Ignition Module O.E.M. Crank Angle Sensor, ALL 1.8L (CA18ET) Series Engines. $70.59.

Fester I don't have an oscilloscope nor do I know any one who does so thats out of the question. I might aswell buy a new one from NOPI and replace it, it really sounds like the problem.

**Edit**
RE Whoever mentioned the fuel pump code. I know I know but this is my rational for not exploring it and it is really dumb... 1st off, no I don't have a manual and yes, I really really need one. 2nd, I don't have a way to test the pressure it's putting out nor do I know what it's supposed to be. 3rd, this is the dumb part, I can hear it running when I turn the ignition on. Lol, is that not the worst way to certify the integrity of an engine part ever? :mrgreen:

My CAS was acting up with heat...........it would run fine for 30 minutes or so, then just die with no warning. It would turn over, but wouldn't crank until the engine was completely cold.....then it would crank right up and run for about another 30 minutes...then same thing. It finally got to the point where it backfired and shot a huge flame out the tailpipe (according to my wife), then never cranked up.....had to get it towed to Nissan who raped me for a good $500 bucks for a new distributor and labor to put it in!! Ouch....this was back in '96 and way before I had my FSM, and didn't know much about the car, so I had no other option than to take it to the dealer.

I'd get that NOPI unit. I have one myself and it has worked fine for over a year now. It's not hard to replace either and way way cheaper than having to buy a whole distributor from Nissan.