Any 3VZ-E experts? Misfire problem

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Any 3VZ-E experts? Misfire problem

Postby hartster on Thu, 19 Oct 2017 9:10 +0000

Taking a punt here...

Vehicle: 1993 Hilux Surf V6 petrol 3VZ-E

It has a misfire / hesitation under load, at lower revs. I have researched this for hours on lots of different forums - particularly US / Canada - and the problem is described lots of times, but solutions are not forthcoming. Lots of guys have done the usual - new dizzy cap, rotor, HT leads, but the problems persist. Some have done this, then replaced all their vaccuum lines. Problem persists. I am very reluctant to throw money at it and repeat the same mistakes.

Vehicle had the head gaskets replaced under the recall. No coolant loss, no oil in water, or vice versa. No steam out the pipe other than when warming up.

Symptoms: when the vehicle is cold, it starts first time and drives away fine. As it reaches normal operating temp, a hesitation / miss starts under load, i.e. start of a hill. Sometimes the hesitation starts sooner rather than later. Once the revs have picked up the engine runs normally.

At idle, stationary, blipping the throttle induces a hesitation / miss right away. It's very obvious. Some days its much worse than others, and it stumbles a lot. Other days its a minor miss and not too bad, but noticeable.

Today I cleaned the rotor and dizzy contacts, and replaced the spring that controls the movement of the graphite electrode under the HT line into the cap, that sits on the rotor. I really thought that was it - problem solved - drove off coldish and was fine, but after 10 mins or so the miss came back with a vengeance.

A highly experienced mechanic told me that they can leak around the throttle butterly shaft and cause a flat spot. Again, reluctant to start taking it all apart unless there's some way of finding evidence.

Have checked throttle position sensor, air flow meter, vaccuum lines, etc. Would have simply replaced the HT side of things by now were it not for the reports that this hasn't solved it.

Do any of you fellas have a suggestion? Some experience of solving a low revs "load" type miss that didn't involve the HT leads, dizzy cap, rotor? Is there something else that I should be checking?

I know this kind of question is a bit vague, could be lots of things, but I'm always amazed at what this forum has been able to solve over the years...

cheers
Dave
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Re: Any 3VZ-E experts? Misfire problem

Postby Gipsy on Thu, 19 Oct 2017 11:55 +0000

After all you have done it only leaves the fuel system. Filters OK? Fuel pressure OK? Injectors OK? It sounds like lean mixture because it is fine cold, and hesitates on first load when hot then runs fine. Time for a diagnostics check methinks on the fuel system. Not sure if your model has obd2 compatible system but if you have/know someone with a scanner there's a good place to start. Not the end of the world to throw some new plugs in, then if this doesn't cure it try these

http://www.ebay.com/itm/For-Toyota-4Run ... 2000629592

$48 us for a set! For injectors, worth a try?
Cheers Gipsy :D
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Re: Any 3VZ-E experts? Misfire problem

Postby HK1837 on Thu, 19 Oct 2017 1:25 +0000

Has it ever had LPG on it? How many kM?
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Re: Any 3VZ-E experts? Misfire problem

Postby hartster on Thu, 19 Oct 2017 2:24 +0000

Thanks guys.

No LPG. 150,000 (genuine kms). New plugs recently. All leads checked. Earths too.

Fuel filter is new, but the fuel lifter pump was shagged after sitting for a long while, and the tank had a lot of congealed old fuel in it. So I cleaned it the best I could and fitted a new pump & sock. I haven't measured fuel pressure, and haven't pulled the motor apart to get at injectors. It's not OBD2, its the old school scanner port that you bridge with a split pin and read the blinks of the engine check light. No codes the last time I checked. Thanks for the link to ebay!

HOWEVER! I think the comment about it running lean is very close. I followed up a lead from my local Toyota dealer and pulled the cover off the air flow metrer. Turned it 4 clicks anti clockwise (loosening spring). Therefore adding fuel according to service technician and what I have subsequently red on the interweb.

Result: immediate massive improvement. Faster throttle response, miss is mostly gone, just a very slight hesitation in second when pulling away. So now I am just totally baffled as to why I would need to adjust the AFM. Somehow I managed to throw out my timing light during a move so can't check the timing would assume I would have to do so after fiddling with the mixture. Still more to be done but a step in the right direction nonetheless.

Now I'm gonna drink a beer and lament the disintergration of NZ politics now we have a minority government of utter clowns.....
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Re: Any 3VZ-E experts? Misfire problem

Postby hartster on Fri, 20 Oct 2017 8:59 +0000

Just finished a 200 km trip there and back and the truck ran just fine. Fuel consumption was 12% better than long term average as well. I am aware that if I'm having to fiddle with the AFM there may well be something wrong elsewhere. Not that I am going to be in a rush to find out as long as it keeps pootling along, it's just a local use / farm / spare vehicle after all.
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Re: Any 3VZ-E experts? Misfire problem

Postby Gipsy on Fri, 20 Oct 2017 10:04 +0000

Lift pump and other fuel problems raise a flag, check fuel pressure and that may be the problem, else more of the gunk has blocked the new filter? Also there may be water in the fuel somewhere?
Cheers Gipsy :D
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Re: Any 3VZ-E experts? Misfire problem

Postby Critter350 on Fri, 20 Oct 2017 12:10 +0000

From your description my thinking went straight to a flat spot / fuel mixture issue, seems to have been confirmed by the adjustment. Vacuum leak in throttle body- spraying crc or similar with a nozzle tube at the area with the engine running, if engine revs change it shows up the leak.


Cheers
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Re: Any 3VZ-E experts? Misfire problem

Postby hartster on Mon, 19 Mar 2018 6:49 +0000

Thought I'd post some feedback on this misfiring / rough running problem, which was eventually solved.

After fiddling with the AFM, the problem would improve but kept coming back after a few short trips. I saw that the plugs were carbon fouled which I put down to fiddling with the mixture (too rich) so I cleaned them and set the AFM back to stock and checked its function as per FSM and all good. I reset the timing to stock. I pulled off the throttle body and set up the throttle position sensor perfectly.

As mentioned before, this vehicle sat in the shed for 5-6 years. At some point during the process of getting it back on the road, I changed the plugs. This would have been after the initial process of getting it going, when it ran fine after I'd sorted out the old gummy fuel problem. Being a fool I didn't write down when I changed the plugs in the log book, so I can't remember exactly when I did it. It was probably the same time I changed out the coolant, PS fluid, brake fluid, which I did write down.

I had come across a box of six new NGK plugs still in their packaging with "Surf" written it, along with a fuel filter, oil filter. So in went the plugs, can't do any harm I thought. It would have been after that the symptoms started. But like I say... being a tit I didn't write it down so didn't put 2+2 together with the change of plugs and the onset of the bad running symptoms.

After pulling my few remaining hairs out trying to find the cause of the intermittent missing and rough running, I decided to go right back to basics. I re-tested the HT leads for continuity, re-checked the rotor and dizzy cap, igniter, etc. I pulled each HT lead off the dizzy while running and thought I detected a dead plug, #5. Took it out, swapped with #3, hey presto, its misfiring, nearly dead. But it's new, I said. Hmmm.

Looked up the number on the NGK website, went to get a new plug. Got back, compared to old plug. Different bloody part number!!!!

Turns out the plugs I'd put in were NGK BKR6EYA-11. Plug that I needed was NGK BKR5EYA. Off I went back to the store and got 5 more of the correct number, in they all went.... and you can guess the rest.

The BKR6EYA-11 is a colder running plug for use in 4cyl 16v motors. My old school 3VZ-E didn't like them at all and was not burning cleanly and pre-delivery fouling, the plugs were all carbon fouled again. My symptoms were exactly what was described for too cold a heat range on the NGK website.

Someone somewhere supplied me with 6 of the wrong plugs way back in the late-noughties I'd think. My fault? Maybe. Certainly my fault for not checking them when I put them in the motor. Incorrect lookup in the store by a numpty saleperson? More likely I'd think. I used to buy everything from the trade counter at Repco...

Anyway the truck is going like a Boeing now its got the right plugs, and I've fallen back in love with it all over again. It's been given a birthday big time, new rear coils and shocks, front shocks, steering damper, ball joints, recon'd front brakes, bearings, the works.

To think I nearly binned it. What a foolish decision that would have been!
Last edited by hartster on Mon, 19 Mar 2018 7:50 +0000, edited 1 time in total.
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Re: Any 3VZ-E experts? Misfire problem

Postby DeadlyBeast on Mon, 19 Mar 2018 4:27 +0000

Nice work mate.
A good reminder to maintain good records
Thanks for posting 8-)
If you're going through hell, keep going.
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