benchernif

Heads up - I also had this same code 14 issue on my 1995 3VZE. About a week before this happened I had a code 27 appear - my truck is a California truck and has 2 O2 sensors - one pre-cat. and one post-cat.

Anyway, when you get a code 27 it means there's something funky going on with communication between the post-cat o2 and the computer. I noticed some weird acceleration issues, so I decided to order 2 new o2 sensors to replace.

While waiting for my new o2 sensors in the mail, code 14 began, and the engine would just randomly lose power and die - mostly at stop lights, idling, etc.

Finally I discovered the cause: I wired my own post-cat. o2 sensor, and the wiring had gone bad, intermittently shorting the EFI and killing the engine/pulling code 14.

After replacing the post-cat o2 sensor with a pre-wired/harnessed unit, all was fine.

So glad it wasn't anything more than that!

LONG AND SHORT: be sure to wire your o2 sensors correctly!

Ben

bdcurnutt

I've looked at multiple threads on multiple forums and can't find anything that exactly describes my issue...

This started happening last year and it seemed like, at 206,000 miles, it probably needed a new fuel pump. Put in a new Denso (OEM) pump and changed the fuel filter and the problem got better, but wasn't completely cured. Put on new distributor cap and rotor and problem got better for quite a while. Now, about a year later, it started having fail-to-start problems again. My first thought is a bad fuel pump, but after bypassing the Fuel Pump Relay (COR?) I could hear the pump running and it started running fine... for a few days. I also checked the EFI relay and it had continuity on my ohm meter. One new symptom was that it started idling lower and a little rough at about 400-500rpm, when it's normally in the 750-900rpm range. I cleaned the throttle body and that seemed to improve the rough idle issue. (NOTE: I kept reading about cleaning the MAF sensor, but found out the Gen3 has an Air Flow Meter, not an MAF, and there isn't anything to clean. Most people that tried, damaged it by pulling out the wiring. However, I did take the unit off and make sure the "flapper" opened easily and smoothly and it looked okay. Also, I also kept reading about the Idle Air Control valve and that seems to only exist on the 4cyl, not the 6cyl).

In the meantime I had ordered a new fuel pump relay (since it showed a little resistance on the ohm meter), but it still had no-start problems even though I had bypassed it in the diagnostic port. I also checked spark and found that if I pulled the coil wire off the distributor and let it ground to the body, it seemed to have strong spark, PLUS it would start right up and run fine for a day or two. A new symptom showed up - my son called and said it died when turning a corner, but it started back up and he was able to drive on. Later that evening it wouldn't start and left him stranded.

I put on the new fuel pump relay (Denso), checked the spark and it started right up. That evening it failed to start again. I checked the spark and it looked okay (whitish-yellow), but this time it wouldn't start at all - just cranks away. I decided to replace the coil, but that didn't help either.

NOTE: It never has generated any codes.
Here's what I haven't done (please tell me what I've missed, if anything):
1) The plugs and wires are 70,000 miles old, but if they were bad it would be idling rough, right?
2) EGR is original, but shouldn't it have caused a rough idle sooner?
3) Throttle Position Sensor???
4) Ignitor/Ignition Control Module (but there is spark...)?
5) AFM signal problem?
6) ECM???

I'm going to check the fuel pressure tonight, just to see if the pump is a lemon (it only has 2,000 miles on it since new).

Honestly, I've been trying to get it ready to sell because I don't need a 4x4 in Dallas traffic and I have a better option, but I DON'T want to lose money on it because I can't figure out this problem nor do I want to dump problems on someone else (guilty conscience...).

Scrussanation

1) you ever sale let me know i might be contender especially since you have exact engine as me

2)have you checked your TPS??? whats your ohms reading??

3) whats your timing set at? It never hurts to change plugs and wires just make sure they are a decent brand, I bought imports a week ago and the boots made very poor contact and caused numerous issues, needless to say replaced with NGK wires... check your o2 sensor as well. check for alll the simple stuff leaks, airflow restriction, vacuum, lines. also dont use bosch anything on these things.. i hear horror stories lol.

4) you being in dallas not too far from me being close to tyler and all. I've never had any major issues with mine and I love it. hope this helps point you in the right direction

http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml this is for your tps checking

http://personal.utulsa.edu/~nathan-b...92volumeai.pdf this is to check your AFM not to be mistaken as a MAF... basically same thing imo but whatever

and a guide to your 3vze http://personal.utulsa.edu/~nathan-buchanan/93fsm/ just make sure you pick the right document when looking for what to check. their are resistance values different from the 22re then the 3vze.. I know i made the stupid mistake once.

hope that helps buddy!

scope103

There is no component in your truck that is (intentionally) sensitive to turning corners. Given that you have so much that comes and goes, I would say that you have a wiring problem. Somewhere a wire shakes loose, and then re-connects.

Rather than switching parts on spec, you would benefit from basic diagnosis. Use a timing light to a) check timing, b) on each plug wire to confirm spark. Use the FP terminal and listen to confirm power to the pump; don't waste time swapping relays that are still working.

But in the end, a broken wire somewhere can be hard to find. Good luck!

bdcurnutt

Good stuff! I'll work my way down your list and see where it takes me. The University of Tulsa guy's post is where I found out how NOT to ruin my AFM, thankfully.

I've decided to stick with the Japanese stuff; certainly for all the electrical stuff.

P.S. I'll let you know when I'm ready to sell. I've loved it and my kids told me to sell the other car, but the "logical" thing to do is sell this one. I've done a ton of work to it and it is above average, but I've got to solve this problem first.

Thanks again!!!

Scrussanation

let us know how it turns out. lots of people hate the 3vze. me personally i see lots of potential and with the proper tlc it can be just as good as some others... still waiting to go past 85 mph tho lol

bdcurnutt

Isn't THAT the truth!!! 3000rpm at 65mph, 3500rpm at 70mph; and for every 5mph faster goes 2mpg lower! Actually, that made it a great vehicle for my first boy. He said he drove like a grandma to keep it above 10mpg in town. ;-)

Scrussanation

lol yeah.. one guy actually put a turbo on his... and then i stumbled across a performance made 3vze for 7k... ill just fix it as it breaks lol not one to want to swap out the engine because you just dont see originals anymore

bdcurnutt

Last night at 12:25am, and even this morning, I was preparing to add a "victory post" to the thread, but then I had another "incident" this morning.

I took your advice and quit throwing parts at it. I had to push it into the driveway (with some help) and for fun, tried to start it since it hadn't started for 4 wks. IT STARTED; rough idle, but when on the pedal, it ran fine. Once I let off the pedal, it idled rough and then died and wouldn't restart. I decided it had to be fuel related, not spark.

I did some more research and decided to get a fuel pressure tester. I was only getting 12psi and on the forum it said to pull the fuel return hose of the fuel pressure regulator and if it was flowing freely, it was a bad regulator. It WAS flowing freely. I picked up a new regulator and thought, this will be easy since everyone talks about replacing theirs. WELL, when I loosened it and tried to unscrew it, the nipple for the return line hit the intake manifold (V6). I took me an hour to decide my only option was to pull the throttle body and try to get the fuel rail off. Then I realized you can't get the nut off the front on the rail because it bumps into the intake manifold too.

In the end, I was able to loosen the rail enough for it to pull up so I could get the nipple above the manifold. So now I have a new TB gasket, plus I found a small leak in the coolant hose to the TB, so it was worth the pain.

VICTORY - It started up, although it still ran a little rough at idle. Ran a couple of miles (ran fine a higher RPM), came home and went to bed. Started it this morning; a little rough but ran fine at higher RPM. In church a couple of hours and went to get food. Ran alright. Came out - WOULDN'T START. Pushed it out backward and turned it around to point a little downhill in a different spot (thank goodness for big teenage boys). It started and we drove home.

WHAT NEXT?!? Vacuum, faulty air flow meter, ??? Any ideas are welcome.

scope103

Uh, welcome to Yotatech? The fuel return hose from the Fuel Pressure Regulator has to have fuel flowing freely at all times. (Once the flow stops, how is it going to hold up the pressure?) So be careful what you read, if it doesn't have a citation to the FSM (heck, even if it does!)

The good news is that 12psi is way, way too low. I'm surprised it ever even fired. The right pressure is 38-44psi. http://personal.utulsa.edu/~nathan-b...28fuelpump.pdf (Note that it drops with the engine running.) While the FPR can certainly be the cause of low fuel pressure, my guess would be fuel filter followed by pump followed by fuel lines. Which one is it? Certainly you checked the fuel pressure after you replaced the FPR?

By the way, how did you measure the pressure? The manual suggests doing it through the CSI, but it's easier to get a 12mm adapter, which would mean attaching it to the rail near the FPR.

bdcurnutt

Apologies - I was in a rush and didn't include enough details. Also, this is the farthest I've gone on DIY with this vehicle. It's more complex than my Suburban/Tahoe/325i, and the Civic hasn't broken yet... (knocking on wood).

I rented a Fuel Pressure Test kit. At 12psi, the FPR was letting gas pour through, so I was confident that was the problem. After installing the new one, the pressure was at 40psi and I didn't think I needed to pull the return hose after that to find out how much gas was going back to the tank, but I presume it should have been less.

In my earlier post I stated that I replaced the fuel pump (with a Denso) and the filter about 2,000 miles ago and initially that seemed to solve the problem. Then it recurred and used a jumper to bypass the Open Circuit (fuel pump) Relay to test it and that seemed to solve the problem. So, I ordered a new Relay, only to have a start problem again within a few days. Then I thought "spark" so I replaced the coil (since it has 206K) on it. No luck. That's when others recommended more diagnostics before spending more money (since I was about tapped out, that sounded good). With the fuel pressure where it is now, I don't think there are any more problems getting it to the rail, but that's where I get stuck. This car has only been in Oklahoma and Texas, so there aren't any rust issues around the tank/pump, etc. - it's all very clean.

I did some more research last night and I'm going to test the impedance on the Throttle Position Sensor and the Air Flow Meter. Like I mentioned before, it's running smoothly at higher RPM. Even turning on the AC, kicking up the RPM to 1100-1200, makes it run smoother. It's during idle that it gets rougher.

scope103

What is your timing set at? The test is very quick, the timing light costs less (~$20) then any one of the parts you've unnecessarily replaced, and mis-set timing would explain your symptoms.

bdcurnutt

I had not done that; so I bought the timing light (my Dad has two, but is 250 miles away...) and a feeler guage. I followed the FSM and checked the Air Gap in the distributor, and jumpered the diagnostic port.

Ironically, after all this trouble, it reluctantly started up and then idled at 1100rpm with a tiny bit of roughness. After revving it a few times, then messing with the throttle cable, it moved down to about 850rpm and it was on 10 degrees BTDC, as it should be. The last recommended check was to remove the jumper and was supposed to advance to 8 degrees, but it didn't. It stayed around 10.

I decided to mess with the distributor anyway and see what happened. As I moved it counter-clockwise it went to 12 degrees, the idle picked up and it seemed to smooth out. As I moved it the other way, it went down to about 5 degrees and the idle went down and the roughness increased slightly (but that's been the case all along).

My understanding is that if you advance it too far (lower than 8 degrees?), it will start pinging with predetonation. It has pinged in the past, but I presumed that was due to carbon build-up and I've run Lucas, Seafoam, and Gunk Regane through it over several tanks of gas and it seemed to help.

I shut it off while I reviewed the FSM more and when I tried to start it, it just cranked and wouldn't start again. It seems like the no-start problem only occurs when it's hot now that the fuel pressure regulator has been replaced. The roughness at idle could be due to old plugs and wires which are at least 80K miles old.

I did go ahead and check the impedance on the coil wire to the distributor, then the distributor, and then the coil (which was new - just to make sure I was reading my meter correctly). They all checked out.

Next?

scope103

Vapor lock is a possibility with no-start-when-hot. There is a fuel pressure-up for just that purpose. http://personal.utulsa.edu/~nathan-b...ne/41fuelp.pdf Note that it plumbs into the vacuum line for the FPR; if you did not hook up the FPR correctly it will contribute nothing.

bdcurnutt

Now that I got my oldest kid off to college, I decided I need to get back to work because I don't have his car as a back-up anymore and the other kid doesn't want to share his as much (although he said he'd drive the 4Runner if I get it fixed. HA!)

After reading more posts, I worked through a couple more "procedures". Even though the CEL hasn't been on, I jumpered the Dx port and found there were two error codes: 24 and 31. 24 is related to the Vacuum Switch/Control Valve and 31 is related to the Air Flow Meter. The Haynes manual walked through the diagnostics and I found that the VSV was clicking on and off, but apparently the valve was sticking. With power (12VDC) applied, I was able to blow air through the filter side, but when power was removed, wasn't able to get air to blow through the other side like it described. Also, it should have registered 20-50 ohms across the terminals and I got 0, so that's that. I then checked the resistance on all the terminals on the AFM and found that the E2 terminal test isn't registering any resistance, so I guess it's faulty too.

Ironically, after I messed with both of them, it started up even when hot and I drove it around without a problem, so I suppose there aren't any catastrophic issues, but I must have jarred the VSV loose. I doubt that is a sufficient cure though.

I'll replace the VSV first and see how it does. Any words of wisdom are welcome!

scope103

The ECU "starts" as soon as power is applied. Is that your question?

bdcurnutt

Now I'm confused (again). I pulled the VSV off to get the right part # and try to hunt one down. NOBODY in Dallas has one and most are pointing me to the dealer because they can't get one. Well I drove it today without the VSV and it ran okay. I attempted a restart after I got to my destination and it started right up. Came out almost 2 hrs later and it took a long time cranking before it started. That leaves the AFM error code (31), caused by no resistance on the E2 terminal, as the next possible culprit. HOWEVER, when searching the site again, I saw a post that indicated the IAC or the coolant temp sensor could also cause the problem.

I'll check both of them next. This is painful, and since I can't trust it, I can't drive it to work - not good...

P.S. The exhaust smells like it's running rich. Also, the local dealer said they'll do a diagnostic for $133. Maybe I should just cough it up.

scope103

I'm missing something here. My manual http://personal.utulsa.edu/~nathan-b...85diagnosi.pdf says code 24 is the intake air temp sensor; that has nothing to do with any VSV. That sensor is in the VAF, the same (potential) source of code 31. Did you run the test on the VAF http://personal.utulsa.edu/~nathan-b...92volumeai.pdf , or is your reference to "no resistance on the E2 terminal" just a paraphrasing of the diagnostic code? Your problem could be as simple as a loose plug connection to the VAF (which would account for both codes, and would certainly make the truck run very badly).

Before you go too far, remove the EFI fuse for 5 minutes to remove any stored codes. If you have a bad VAF you should get those two codes back as soon as you try to start it. If the problem is intermittent, you might try tapping on the VAF and wiggling the wire to see if you can trigger it. (You can also remove stored codes by just disconnecting the battery, but that also takes out your radio presets, etc.)

bdcurnutt

My bad - Code 24 is what you said. I've looked at too many different site and threads and in some cases they were talking about the 4cyl (but I think I just got confused). I reread everything and was relieved, in a way, that both codes relate to the same thing, so if I have to replace the AFM, I kill two birds (both codes) with one stone.

I did check the plug on the AFM; in fact I've pulled it off several times to recheck and all the connections look clean and tight. When I rechecked the AFM, the E2 to VC and E2 to VS were within spec, so I think I have an intermittent issue; probably a failing chip on the board. I haven't reset the error codes, but will pull the battery terminal tonight and then I'll recheck it (the presets are already messed up...).

I finally had the guts to drive it a little while last night and it did fine, so I drove it 12 1/2 miles to work today without a problem, other than a misfire and it still seems to be running rich. I tried to restart it hot when I parked and it started hesitantly. Hopefully I'll get home too. I suspect the dying-while-driving problem was the fuel pressure regulator, since I know it was weak (at 12psi and now at 40).

I appreciate your "challenges". I'm still on the learning curve, but I've learned a lot and just as importantly, probably saved some money so far.

P.S. Do you have any recommendations on what or what not to buy regarding AFMs? There are a lot of choices for refurbs and even NAPA has a semi-reasonable price compared to other local places.

scope103

Did they even have chips 20 years ago? Well, yes, but not in your VAF. I've never disassembled one, but I'm 99% sure there's nothing in there but a rheostat, a reed switch, and a thermistor-type temp sensor. But those are mechanical components, and after 20 years something could have shaken loose.

What catches my eye, though, is the getting BOTH code 24 and 31. What would break INSIDE the VAF to take out both of those? Before I dropped $250 on a rebuilt VAF, I think I would carefully take mine apart to see if I could find a broken E2 wire or something. Your problem could be in the harness.