Club-S12 International S12OC United Kingdom ClubS12 France S12Silvia Australia S12.org.ua Eastern Europe S12 of Sweden S12 Japan BBS
Please login or register.

Login with username, password and session length

Author Topic: The story of my Silvia in my tiny little garage  (Read 3053 times)

Offline Cajun1guy

  • Old fart (pedoro numero uno)
  • Full Member
  • ***
  • Location: Mandeville, Lousyana
  • Posts: 750
  • Vehicle: 1984 Nissan 200SX
Re: The story of my Silvia in my tiny little garage
« Reply #40 on: 09:40:38 PM / 21-May-17 »
Love that description! I can just imagine the vibrations and resonations going on.

Offline CzechSilvia

Re: The story of my Silvia in my tiny little garage
« Reply #41 on: 04:39:47 AM / 04-Jul-17 »
Alright, here's an update: I have done some long due servicing - I have replaced the spark plugs (my choice were the NGK BCPR5ES-11 and BCPR6ES-11), NGK sparkplug wires, NGK/NTK O2 sensor and a new distributor cap.

Right after I changed these I started to get engine hesitation at random RPMs, when it happens I get 0 power for a few seconds but at that time it happened only twice during 3 drives. I thought it's a bad electrical connection at the fuel pump because when I bypassed the ECU so that the pump is always running when the key is the "ON" position, I only twisted the wires and didn't bother to solder them.

Well, to get the connection soldered I had to get to a friend who actually has a soldering iron, the car almost died 6 times before I got there and that was only about 4km drive. I soledered the connection and the drive back was without a problem. I did one more test drive and found out, that the engine hesitates at 5k+ RPM, I thought that's a separate issue but looking back, it's probably still the same one. Anyway, I suspected the coils so I tried the dual coil mod but that didn't help at all and the hesitation at random RPM came back.

This really pisses me off, I wanted to go on a two-day trip in the s12 tomorrow

I really don't know what can be causing it, is it the new dizzy cap? bad ecu? bad fuel pump? or a dirty fuel filter? probably not the fuel filter, it seems more like a electrical problem... Am I missing something?
But what do I know? All I know about cars I learned from youtube...

Offline JonB

  • CONTRIBUTING MEMBER
  • S12 Guru
  • *****
  • Location: SW Pennsylvania
  • Posts: 2,552
    • http://
Re: The story of my Silvia in my tiny little garage
« Reply #42 on: 08:48:40 AM / 04-Jul-17 »
I'm usdm so.

No codes? Don't think the ecu says much about the ignition.

Check the values on the power transistors. These failed on me at about 5x the rate of coils, but my stuff was getting hit with an msd and an amp.

The way to go for plug heat range is read the plug. It's about the cylinder temp. If the air outside is cold, there's more oxygen in every cubic foot of air, so you'll make more power, if it were carbureted, it make make it lean when your in it, which means hotter chamber temps, which you deal with from there - read the plug, change the plug range if it's not correct. You have fuel injection - it should keep it pretty close to correct a/f even in cold, possibly, you'd just have to rev it a bit when it's freezing ass cold.

I upped my compression, ran a used intercooler, went from, t2 to t22, and ran a euro cam, here in pa, where we have 10F days, I never had to change the plug range on my car. It'd feel a little slower north of 5500rpm, but the head sucked, but it wasn't slower up there.

Anyway, I digress. It's not easy to find problems in these things sometimes. Good luck


Offline kelso840

Re: The story of my Silvia in my tiny little garage
« Reply #43 on: 09:21:24 AM / 04-Jul-17 »
This sounds like an issue I've had before. Did you by chance loosen your distributor when changing the cap? I'd double check your timing.

Also try cleaning the grounds on both coils at the terminal and where it contacts the body. Can't hurt.
Infrequently driving an s12.

Offline weitrhino

  • Full Member
  • ***
  • Location: North Texas
  • Posts: 429
  • Vehicle: 1985 Nissan 200SX
  • '85 Notch just cracked 40k miles! RIP '86 Notch
    • Blue Mouth Promotions LLC
Re: The story of my Silvia in my tiny little garage
« Reply #44 on: 11:15:23 AM / 04-Jul-17 »
I think I'd focus on the wires and cap because these were changed just before the issue showed up. Put the old wire set back in and see if anything changes, then do the same with the cap. At the very least you can get back to square one and take your trip.
« Last Edit: 11:15:57 AM / 04-Jul-17 by weitrhino »

Offline rednucleus

  • Old Fart #2
  • CONTRIBUTING MEMBER
  • Sr. Member
  • *****
  • Location: Marysville, WA
  • Posts: 2,020
  • Vehicle: 1985 Nissan 200SX
Re: The story of my Silvia in my tiny little garage
« Reply #45 on: 12:19:24 PM / 04-Jul-17 »
Please verify this condition did not exist prior to the work you did?
If so, replace only one component at a time with the old part to try and isolate the problem.  Good luck, anxious to hear you report back. I have other ideas if this doesn't give you the answer.

Offline CzechSilvia

Re: The story of my Silvia in my tiny little garage
« Reply #46 on: 12:26:18 PM / 04-Jul-17 »
This sounds like an issue I've had before. Did you by chance loosen your distributor when changing the cap? I'd double check your timing.

Also try cleaning the grounds on both coils at the terminal and where it contacts the body. Can't hurt.

no, I didn't losen the distributor so the timing should still be on the 18° I set it for about a year ago but I doubt it's timing problem because the car runs fine most of the time and then suddenly combustion just doesn't happen for a moment - usually about two seconds. If it was timing issue, I think the engine would run bad at all times. Cleaning the grounds sure wouldn't hurt anybody but the engine shouldn't act like that since I did the dual coil mod, unless the coils share the same ground of course...

No codes? Don't think the ecu says much about the ignition.

I completely forgot that the car is smart enough to talk to me.

Check the values on the power transistors. These failed on me at about 5x the rate of coils, but my stuff was getting hit with an msd and an amp.
If I'm not mistaken there are two independent transistors, one for each coil, so it probably should be the same as with the coil grounds, not really probable that both transistors would fail the same way in the same exact time. This is the same reason I think the sparkplug wires are not the cause. The distributor cap, I'm not so sure now... Although it's brand new, if it's fucked up in some weird way, it might be causing symptoms like these. I'l try changing it as Weitrhino suggested as soon as I get back home from night shift.

Please verify this condition did not exist prior to the work you did?

I don't think it did but I'm not 100% sure, I don't drive the car very often.
But what do I know? All I know about cars I learned from youtube...

Offline rednucleus

  • Old Fart #2
  • CONTRIBUTING MEMBER
  • Sr. Member
  • *****
  • Location: Marysville, WA
  • Posts: 2,020
  • Vehicle: 1985 Nissan 200SX
Re: The story of my Silvia in my tiny little garage
« Reply #47 on: 12:50:52 PM / 04-Jul-17 »
New rotor too?  Make sure rotor bolt is secure.

Offline CzechSilvia

Re: The story of my Silvia in my tiny little garage
« Reply #48 on: 02:10:10 PM / 04-Jul-17 »
New rotor too?  Make sure rotor bolt is secure.

I changed only the cap but I'll make sure to check that
But what do I know? All I know about cars I learned from youtube...

Offline rednucleus

  • Old Fart #2
  • CONTRIBUTING MEMBER
  • Sr. Member
  • *****
  • Location: Marysville, WA
  • Posts: 2,020
  • Vehicle: 1985 Nissan 200SX
Re: The story of my Silvia in my tiny little garage
« Reply #49 on: 04:26:10 PM / 04-Jul-17 »
Always change rotor with cap change. I have had two S12 rotors that had an intermittent short down thru the distributor shaft.

Offline CzechSilvia

Re: The story of my Silvia in my tiny little garage
« Reply #50 on: 05:49:39 AM / 05-Jul-17 »
I took the distributor apart and all the parts seem to be in pretty good condition. Also, upon closer inspection of the distributor rotor and cap, I must rule out the ignition system as a suspect because the exhaust side and the intake side ignition systems are completely independent systems all the way from spark plugs to ignition coils. Now that I did the dual coil mod, I can't think of a way for both, the exhaust and the intake, sides to fail to deliver spark at the same time.

I also asked Silvia what's wrong and she said 23 and 31 so TPS and AirCon. I replaced the TPS with one that I dug out from my stash of old spare parts and tried to set it up but I still get the code 23. Well, the TPS throwing codes remains an issue but I doubt that the little piece of shit is so important that it would be capable of something major like stalling the engine when driving. As for the code 31, the instructions on the ECU say that it's ok to get the code for AirCon if the car doesn't have it (which it doesn't).

I took her out for a drive and now I'm pretty convinced that it's a fuel delivery issue. What I noticed is, that the fuel pump noise changes depending on what electrical stuff, like the fans etc., is turned on. (Mind that, there's more than enough juice at all times, I always measured more than 14V at the battery when the engine is running.) But the weirdest thing is, that the fuel pump noise gets weaker the more I press the throttle pedal while driving. Occasionally, when I go full throttle, the fuel pump stops completely, that kills the engine and the revs go down, sometimes, the engine comes back to life by itself and at other times, I have to lift the foot off the throttle for the fuel pump to start doing its thing again.

Is it a bad pump or can something else cut the fuel pump power supply like that? Also, how the hell can throttle position influence the behaviour of the fuel pump? And can the TPS issue be related to that? Well, the only thing certain is, that we're doing the today's trip by train...
But what do I know? All I know about cars I learned from youtube...

Offline iceageg

  • Full Member
  • ***
  • Location: Denver, CO
  • Posts: 604
Re: The story of my Silvia in my tiny little garage
« Reply #51 on: 11:00:44 AM / 05-Jul-17 »
I don't know how the TPS can impact the function of the fuel pump directly.  However, our pathfinder had/has a similar TPS related issue that took some time to diagnose.

After 25 years the plastic connectors for everything under the hood are brittle and require great care when being plugged/unplugged.  The harness side connector to the TPS is one that has had part of the retaining clip break off.  The other half of the clip holds it in place and since the male and female parts of the connector still fit snugly so it has never been an issue.  Until one cold day . . . My wife drove to work and the truck started cutting out fairly violently.  She coasted it down the hill and nursed it into a gas station.  At low speeds it was fine but at any significant throttle position it would randomly alternate between idle power and correct power.  Her description of the problem was terribly inaccurate which is important because by the time we had towed it the few blocks home the problem had self resolved.  I did not get to experience it myself.

Fast forward one problem free year and it happened again on cold winter day, but this time I was home to experience it for myself.  Turns out when it is very cold outside the plastic shrinks just enough for the TPS connectors to wiggle part way loose.  Not having an extra harness handy I simply secured the male and female connectors with a couple zip ties temporarily and the issue disappeared instantly.

I am not sure if this will help in your situation, but for me the TPS was telling the computer to cut fuel back to idle flow even though the throttle was half/wide/partial open, then suddenly getting the correct reading and adjusting the fuel back to correct, then back to idle, then back to correct, then back to idle.  All without ever moving the throttle.  Simple enough to test with some zip ties.
I was afraid all the five gallon buckets of pain stacked four high were going to fall over

Offline CzechSilvia

Re: The story of my Silvia in my tiny little garage
« Reply #52 on: 01:48:40 PM / 05-Jul-17 »
The TPS connector on my s12 is secured by a metal clip which I have in place and the connector itself also seems to be in good health, plus I don't think it's possible for the TPS or the ECU to shut off the fuel pump. The ECU doesn't control the pump on my car anymore, I have it bypassed. The ecu could possibly cut the fuel delivery at the injectors but that wouldn't explain the trouble with the fuel pump.
But what do I know? All I know about cars I learned from youtube...

Offline CzechSilvia

Re: The story of my Silvia in my tiny little garage
« Reply #53 on: 12:51:29 PM / 24-Jul-17 »
I finally had some time to spend in the garage and troubleshoot the fuel system today. I removed the fuel pump which had collected some surface rust over the time and didn't look very healthy overall, I found out that it's not the original pump but it's probably from a comletely different car. I replaced it with what seems to be a Ford Mondeo fuel pump, I had this pump lying around and it happened to have the same style of connector as the one I took out of the tank so the change was easy. The Ford fuel pump is noticeably quieter than the old one.

I did a short test drive and experienced only a short hesitation just before I pulled over to a petrol station but I really, really hope that was just the car running out of fuel. The rest of the drive went without any problems. It seems that the hesitation is gone but I don't want to jump to any conclusions, the problem was hard to replicate even before the fuel pump change and now, when the pump is quieter, I can't monitor the fuel pump noise while driving.
« Last Edit: 12:53:41 PM / 24-Jul-17 by CzechSilvia »
But what do I know? All I know about cars I learned from youtube...

Offline weitrhino

  • Full Member
  • ***
  • Location: North Texas
  • Posts: 429
  • Vehicle: 1985 Nissan 200SX
  • '85 Notch just cracked 40k miles! RIP '86 Notch
    • Blue Mouth Promotions LLC
Re: The story of my Silvia in my tiny little garage
« Reply #54 on: 03:15:02 PM / 25-Jul-17 »
I'm sure it will run perfectly until the first time you go out of town.  :evillaugh:

Offline CzechSilvia

Re: The story of my Silvia in my tiny little garage
« Reply #55 on: 08:09:41 AM / 14-Dec-17 »
Haven't updated the thread in a while because, sadly, there wasn't anything worthwile to talk about. The problems with fuel delivery I was having seem to be fixed by that random Ford fuel pump and that's about it, nothing new happened...

However, I have not forgotten my s12, actually, I've been saving money for the s13 front conversion and BC coilovers. I already have most of the stuff I need for that home but I don't think I'll be putting it on the car before the spring comes. Anyway, while sourcing the s13 parts for the conversion, I also bought an old t25 turbo from ca18det so my long-term plans now also include getting the t25 rebuilt and slapping it on the car along with an intercooler and custom exhaust. But before that I'm also planning to address the shabby exterior of the car and to install a new fuel pump with an aftermarket fpr because I'm obviously not happy with the current setup.
But what do I know? All I know about cars I learned from youtube...