'87 300 ZX cuts out (and back in) while driving, all speeds

[dJohnn]

While driving or at a stop, I get a loss of power, ie, lack of power means no gas (the electrical system stays OK, radio, lights etc. stay on), the tach dies. If freeway driving and I keep my foot on the pedal, the vehicle might surge in and out of getting fuel. I can drive for 10 miles, maybe more, often less and it will cut out. The car does not always restart right away, then sometimes it does.I replaced the fuel pump, fuel filter, rotor (distributor & wires are OK), checked all engines compartment harness connections, new plugs, air filter, battery & cables, the coil is good, the oxygen sensor is OK, no discernible vacuum leaks, timing is set right, the idle mix is a little rich...There is the possibility of a wire casing cracking and shorting but I have not found that yet (the engine wiring harness is rather brittle). I have a distance to drive to get to the university and missed most classes last week, this is not good.I'm stumped, any help is greatly appreciated.

dJohnn
Modified by dJohnn at 10:05 PM 2/6/2010

[evildky]

have you checked the ecu for codes?

the distributor in these cars is optical, and can fail intermitantly, when the car dies is when you need to test for tuel and spark, intermitant failures can be tough to track down, intalling a remote fuel pressure gauge can help you determine if you loose fuel pressure

[dJohnn]

I have not checked ECU codes yet, I only figured out yesterday that I did not need a reader for that. This will be done in the morning (Monday) as well as a complete harness inspection. I understand that even with a working pump if the pressure is not right or drops I can get a problem like this.I will have to check into a pressure gauge.Any plug wire will do for checking spark, right?Thanks

[evildky]

yup check for spark at any plug, when it stops running you need to determine what you aren't getting, seing as it's intermitant I think we can rule out any physical problem with the motor, that means ignitin or fuel, and while verifying fuel pressure doesn't rule out injector issues it will verify the pump and fpr are doing their jobs

[dJohnn]

Unfortunately the car won't start at all at this point so an ECU reading won't work. It rained today so I was not able to work on it.I did find this link for troubled shooting hesitation/cutting out:http://www.ttxtz.com/tech.html#fsGenerally it covers almost every component that may be causing the problem; this is what I figured had to be done, one by one, until the problem is fixed, then I may get lucky and it will fire up again so OI can read out the ECU codes.I have owned this vehicle for over 6 years now and she's been great with almost no problems until now.Thanks for the info though.

[evildky]

with the car not starting it's a great time to test for fuel pressure and spark, if it won't start it's easier to diagnose most problems

[dJohnn]

I did an ECU check, at first I got a 21 (primary ignition reference), checked coil spark, a friend did not get a spark, I did (it was at night); replaced the coil. Back t0 the ECu, the next reading was a 44, no malfunction.Spent the day on fuel and emission lines. There was a problem, the routing was off, most likely the inlet and outlet lines had been swapped (reversed? I did not create that problem; the 'why' is too lengthly for here). Put a fuel pressure gauge on it after failing to start after the work done today. The psi readings were correct.These items have been replaced or swapped: EGR valve, air regulator, fuel filter, pump, rotor, exhaust gas sensor, coil and some hoses (and some harness connectors rotted by age). Most of these components I had on hand, some new, some not, money has been put out but not a lot so far.Plugs, distributor cap, wires and timing are recently new or correct (2 to 3 months).It still cuts out within 6 to 12 blocks of first start up (if it starts), then stays okay for ten miles or so on the freeway, then cuts in and out, sometimes having to pull to the side, waiting 1 to 5 minutes before starting again. It will be okay for the 20 to 25 miles home after that (usually/over the last week). When stalled, it may start right away, or not.I checked spark from the coil after no results from doing the fuel line work today. NO SPARK.

Would I be spinning my wheels and wasting money on a full diagnostic at a garage?

[dJohnn]

if it won't start it's easier to diagnose most problems

I did not really understand this line?(as I scratch my head=huh?)

[evildky]

check the ignitor, it could still be in the distributor but you need to test the 2 output wires for 5v square wave

it's easier to diagnose a problem when it's persistant, an intermitant problem can be very tough to diagnose

[dJohnn]

At least the field is narrowing down.Not getting spark from the coil kind of threw me last night, especially after spending hours on the fuel lines. Checking the forum earlier I was thinking it seems to come down to a few things: PTU (igniter?) and CAS.You just suggested the igniter. Considering this is the problem, is this unit apt to work at one point and then not work (the intermittency of my problem).Both are easily gotten at the wrecking yard, getting there is my problem right now.Since there is no spark at the coil, is there anything else it might be? I might as well get what might be needed while I am out there. This would be the 4th or 5th trip there for this problem.Another day of classes of classes missed, at least I am learning something throughout this process.Is there a procedure (for dummies) on checking the CAS? I have seen some write ups on it but those have been for later models than my '87. I want to check this after testing the igniter.My next search is the proper procedure for checking the igniter.

As always, it is not too difficult correcting the problem, it is the finding of the problem. Thanks again. I do appreciate your feedback on this.

(Just an added note: The fusible links appear to be okay. I am not sure how to check the relays up front on the passenger sidewall of the engine compartment.)
Modified by dJohnn at 9:49 AM 2/16/2010

[dJohnn]

I got the PTU from an '87, same year as mine, but it looks physically differentHere links to 3 photos. The 1st pic is what is on my auto right now, the 2nd one is what I just got at the yard and the 3rd one is from an online source showing the PTU for an '87.http://farm5.static.flickr.com...o.jpghttp://farm3.static.flickr.com...o.jpghttp://farm3.static.flickr.com...o.jpg

Will the unit I just got work as the replacement?

[dJohnn]

Not counting the anxiety of missing classes at the university, this has been interesting in what I found that was not wrong and not causing the stalling and cutting out. This would include about half of what was done, there is a noticeable difference overall. The most puzzling is the fuel linbe and the return fuel lines being backwards and the car still ran! It is/was the PTU. Put it in and immediately it started.

Thank you for your information and help with this.

dJohnn

[evildky]

glad you got it worked out, the ignitor is a fairly common issue andis easy to test if you have the right equipment, most people don't have the right tools

[dJohnn]

After replacing the igniter, the car started right up, I drove it a bit without any hesitation or cutting out, everything seemed to be working okay.Went to Taco Bell last night and it died on me several times in the drive thru. Same thing but worse (? so it seems). It cuts out more frequently than before, sometimes it dies again right after firing up, other times it might start after few minutes of waiting.

This is what I have done so far:I have checked most of the connectors on the engine harness, cleaning all of them from any corrosion or replacing as needed; changed out the fuel pump, it delivers past the fuel filter (at the least, to that point); put a fuel pressure gauge on it after the fuel filter and got the right pressure readings; rotor cap; EGR & its solenoid; coil; igniter (PTU); air regulator. There are no apparent vacuum leaks.I found that the line from the fuel pump and the return line from the fuel pressure regulator were actually reversed at the pump (determined by turning the ignition on so the pump would build pressure, when this was done gas came through the hose which was running from the bottom of the FPR to the tank. This may have happened several years ago when the pump had been replaced~~I am still trying to wrap my brain around that, how could it have been running at all with the lines hooked up like that?); the plug wires and distributor cap are only a few months old, plugs are only one month old; new battery cables and changed out the throttle valve switch.

I know these might or can cause this (these have not been checked yet): Pressure regulator (with fuel temp sensor) and CAS.

If you would indicate if any of these other components be could contributing to this problem, please let me know. I have most of them on hand and can swap each one out as necessary:exhaust gas sensor, vacuum control valve, cylinder head temp sensor, FICD, Idle up solenoid, pressure regulator control solenoid, Air flow meter (MAF?), the pressure regulator control module (under the battery tray), is there a PCV valve on this year?

I am sure it is getting fuel yet, could it be the FPR? The fuel is not being ignited so the only unit left to check would be the CAS (correct me if I am wrong) and I have another on hand. At this point I am ready to start stripping the outer harness wrap to check for cracked wire casings which could be causing a short (and swap the CAS out).

Just one more thing: The plugs were changed about a month ago, there had been a small miss or flutter before then, it seemed to be a little more pronounced afterwards (these are the Bosch split fires). Two shops I deal with cannot get me in for a diagnostic until next week and both want me to leave the car for a few days. This is my only vehicle. The loss of attendance at school is almost certain to kill this semester. That cannot happen.

(added note)O I have checked the relays and fusible links & fuses, all of which obviously would cause it not to start at all if they were bad. Is there a way to check if a relay is going bad (can that cause this?).(2nd added note) A clogged catalytic would not cause this,would it?

Thanks for reading.

John
Modified by dJohnn at 1:20 PM 2/18/2010

[evildky]

does the car only die when ideling? or when you let off the gas? if thats the case then I'd suspect and idle air issue

[dJohnn]

It will die anytime, on the freeway at 70 mph, city streets, waiting for a light, reverse, etc., it's not picky.

Then it might start right away or take a few minutes before it start again.Spark from the coil is still intermittent. This being the case it should rule out the CAS.Today I am looking for any problems with the harness and the connectors.

[evildky]

the cas can fail intermitantly, it's not unususl to fail intermitantly in earleir cars

[dJohnn]

I hesitate to say that the problem is solved. I ran it for some short errands earlier without any stalling or cutting out at all.The final step was changing the spark wires, it's nice that they are life time warranted.Hopefully, this is it, but I did find a few things that were out of whack during this whole process.

Thank you evildky for your help.

dJohnn

[dJohnn]

ha ha, lol, lmao, rofl, wtf!!Yeah, it's a kick myself in the but thing ANDthe problem persists. So what do I know at this point in time:There is an intermittent loss of spark, it is before the distributor. When I have taken the coil wire off the distributor cap, checking for a spark that way, there has been some times when there was no spark and other times when there has been a spark. I may have gotten lucky one time when checking the ECU and there was a read out of 21, i.e., there is a problem in the primary ignition circuit.

In my previous posts you can see what has been done already, what has been checked already and what components have been replaced/swapped out. Please read those first before replying if you are new on this particular thread. If you then see something I have missed, please HELP (!) and let me know.

I am disconnecting the stereo, just to rule that possibility out since it was recently installed (although it has been in the vehicle for a few, months (2 or 3) before this problem started

[evildky]

distributor, ignotor, it could also be the ecu but most likely it's the distributor or ignitor

[dJohnn]

There isn't much left to check for the no spark problem. I have an extra distributor from one of my last wrecking yard visits. Changing that is the first thing to do tomorrow afternoon. Or run a wire from the positive starter connection to the positive coil connection and see if the problem persists or not. There is also a test from the FS Manual for the igniter that can be done. And one more inspection of the wiring for the ignition system. The second from the last thing to do is checking the ECU in accordance with the FSM, something like 4 or 5 things to check there, probably more. These are the easy checks to do.The final step is to pick through the engine wiring loom, a task I am sure to dislike.Should the problem disappear, I will post the solution here.Since the majority of my time has been spent on researching this problem and on the actual work done over these past three weeks, I now have an all nighter session to catch up on 3 weeks of missed studying. I have an exam in a little over 8 hours from now.

[evildky]

a part failure is far more likely than a wirng issue

[dJohnn]

Ever get pigheaded? Just stubborn and set against doing a particular thing; without a good reason?This is me with the CAS.The problem was the CAS and the rest, a** (<---me).I also did a clean up of contacts in on a dozen so connectors, fusible links, replaced most of the vacuum hoses that were hard as rocks, some with cracks and replaced 3 connectors in the engine harness.It was the CAS.Other than routine maintenance, replacing the timing belt & tensioner and fuel pump before now, this car has been a dream for 6+ years. I learned more about this car during the last 3 weeks than all the years before; never had to do anything more than maintenance until now.

evildky, thank you again for your assistance and knowledge, I do truly appreciate your time spent helping. I also apologize for using more of your time by not doing the CAS sooner.

As Willie would say, 'On the road again...'

Thanx,

dJ

[evildky]

lol, well at least you got it fixed

[dJohnn]

There are still some adjustments to be made since this turned into a 120,000 mile service with all the components that were swapped out and a lot of other things were also taken care of such as, radiator hoses, trans cooling hoses, vinyl dash pad skin and so on. Even though it needs to be retimed & the idle/mixture set (blah, blah) I have already noticed much better mileage. This used to get 30+ mpg straight freeway driving then it dropped around 23 mpg over the last 18 months.I see non-turbos w/auto trans get rapped on kind of hard around here, regardless, mine is still a sweet machine (once again).I will be back, maybe not asking for help but the other way around.

Thanks,

dJ