LScowboy

hopefully this will solve a huge issue that is frustrating the hell out of people here!

I have a 1986 300ZX normally aspirated and had a problem for many years with the car intermittently cutting out, sometimes almost to the point of dying in the middle of the road, and it was becoming quite dangerous because it happened without any pattern.

So at any given time, my 300ZX could suddenly start this cutting out terribly, and it nearly got me in a wreck several times on major highways to the point I was becoming afraid to drive the car at all.

Well over 8 years, every 300ZX expert in 3 states looked at it, and everything under the sun was suggested and replaced, from coils to engine head temperature sensors to cap to rotor to fuel pressure analysis, igniter/ignition module, relays, cam and crank sensors, and on and on and no change!

finally, in desperation, I thought to myself, hey "what do you do for a living?" and one of the things I do is repair ECU's (replace the capacitors) in Lexus LS400's and other Toyotas, so I thought, what the heck, why not try it?

So I replaced the 3 electrolytic capacitors in my ECU with modern high temp, low-ESR equivalent caps from the 4 premium capacitor companies, namely Panasonic, Nippon Chemi-con, Rubycon and Nichicon and VOILA! - the problem I chased for nearly 8 years has been GONE for over 1 year!

so if an intermittent cutting out problem is making you crazy - let me know and I will fill you in on precisely which capacitors I used.

for those who would like to do this yourself, please see my famous post at Club Lexus for how to replace the capacitors on an LS400, as this is basically the identical job!

ch33z3x

Awesome! Thanks for the tip! Have you done any ecu programming? Have you heard of the Pocket Romulator?

Donn144

With my first Z31 it was fine as could be. I was filling up at the gas station and when I tried turning on the car..I could not start the car for anything! I said to the station guy "what the hell do you have in this gas?"

Well, it was the AFM. I bring this out because it is somewhat similar to the stall feeling you describe, where you haven't a clue what the hell happened and it comes out of nowhere.

Z Pal

What capacitors did you use? Where on the circuit board did you replace them?

Delecroix

I would like to see this done up as a DYI sometime, would be nice. Everyone with a Z, or any number of cars, could certainly benefit.

zxguy1986

Good post, cowboy. ECU is always the last thing I think of. It's got no moving parts so you think it can't wear out. Looks like a Nissan factory fail if included capacitors that die early like yours did.

I'm wondering if the failure could have been caused by an external factor like moisture or water inside the housing - or a short somewhere - or a switched battery cable.

Spencer

Hello, I was reading this thread and wondered if maybe this was causing my issues. I looked at the board and noticed only two things.

1. Glue everywhere. Seems like glue anyways.

2. Weird gunk next to some capacitors. I'm no chip techie, so it could be actual adhesive, or heat displacement. IDK.

Pictures were too large to upload here. I posted them on my IMGUR page. I cant remember, can I post links on here?

Spencer

Here is the link... aflyingcake's uploaded images - Imgur

pretty sure I can. If not I guess this comment will just get removed.

zxguy1986

That link says your images are not available.

To post images here, sign in, click Post Reply to this thread, click Go Advanced under the text box, under the next text box click Manage Attachments, click Browse to select fotos on your computer to upload, click Upload, put your new text in the text box, click Submit Reply. Should at least get clickable images in your reply.

Also, back to your orig post - why did you not first think of getting a used ECU to check out. There are a lot of them around and you can plug one in in 5 minutes. Was it just the charge you get from plugging in components?

Spencer

Try it again. Think I fixed it.

My photo sizes were too large. I took them with my good camera, so the file sizes were +6 MB.

PredatorZ

I will offer my soldering skills for free to anyone wanting this mod done. PM me and you can send your ecu to me, ill replace the Caps, and check out the board for cold solder joints or any other issues. A lot of capacitors have a life span of 5 years or less, the better brands 10 plus years before you might see issues. A quick check for visual inspection of caps, they look like a beer can, on top will be an X or Y pattern stamped in the top, when the Cap starts to fail, it bulges up and distorts the top cover. If you have a cap like that, it is near failure or already has failed. My 84 had a mysterious stutter that would come and go, never figured it out. My 84 is totaled, I have already pulled the ECU, Ill open it up, find out what parts are needed and do a write up.

Spencer

Money sake. I know its not a big difference. But paying 100 bucks for another ECU vs replacing some capacitors seemed like an easy choice.

zxguy1986

OK, looking at your fotos, that goop on the foto's upper end of the ECU is not Nissan OEM goop. Nissan didn't put that goop there.

So my guess is a damaged ECU. You had the skill to get it working again which is very cool. So if your Z is running 100% now, you win. If not, check out a replacement ECU. Consult the z31.com resource at resources:z31_ecu_list [Z31.com] and maybe car-part.com.

BTW I had the identical cutting-out problem with my '86na. But it was water leaking in to the ECU, not extraterrestrial goop. Without a happy ECU, we have nothing.

Spencer

Are you saying "Goop" in regards to the yellow stuff, or the glue looking stuff?

zxguy1986

That bubbly stuff upper left in your first motherboard foto. What the hell is that.

The yellow goo stuff looks like a factory slip-up - but since it's insulation goo, I don't see the problem with it. Just a waste of material. Was probably done on Monday morning just before coffee break. Assembler had a rough weekend, jittery hands... Donut time!

Spencer

I initially thought it was glue. Not entirely sure.

As far as getting another ECU. Mine is the 84 manual turbo. Cant find anything under $300.00

zxguy1986

PredatorZ: Very cool. I would send you an ECU in a minute if I knew what probs it would solve. At this point in time, I would bet that no '84-'89 Z is still at 100%. Something in it, no matter how small, isn't working right any more.

When they were designed, computer diagnosis was in its infancy but the cars themselves were growing increasingly complex, much more dependent on electronic management.

It's a testament to the skills of guys like the ones on this site that they run well or at all now. Nissan's best in '84-'89 now needs serious mechanics' best to keep these beautiful vehicles on the road. Well done, ZDriver.

PredatorZ

You can pop the cover on the ecu, take a look at the caps as I described above, if they look flat on top its no guarantee, but its a good sign that they are good, if they are bulging or leaking, then its an obvious problem.

zxguy1986

Check out car-part.com, enter your data, search USA only and sort by distance. There looks like a lot of them around - and way less than $300. As the car gets rarer, the prices fall. They just want to sell the part but the market is shrinking away.

Hard to work out a warranty for used electronics - but do your best. Great if you can drive there to pick it up. Smile a lot - and be willing to accept a store credit if you have to return it for some reason.

But if you don't need another ECU, no prob.

PredatorZ

That goop on the ferrite filter is probably normal, but that sticky stuff on the edge on the last ecu pick needs to be cleaned off, wipe it off, try alcohol and a rag or q tip, and find out what is causing this.

Spencer

Found an ECU for 150. The guy shipped it out already so I can expect it Monday.

Spencer

Sad day. Replacing the ECU did nothing to fix my issue. Looks like more trouble shooting in my future.

PredatorZ

With your car broken, unless you can swap in a known working ECU you wont be able to know for sure. That's one of the major issues of buying used old parts, especially electronics. I wish you lived near me, I have a turbo and NA ECU you could borrow to test out. The one you got might need the caps replaced also, which is the essence of this thread, which kind of got hi-jacked by us.