Intermittent miss up to 2k and idle when warm NA-T
 

Hey guys. Having a small issue with my Na-T on my 70k miles 2jzge I am running the 4 runner cap on stock dist. To clear turbo. Although still touching intake pipe. Car idles and runs amazing until it gets a little below mid operating temp then it starts to stumble on idle goin to almost 16 on afr. And I loose vac. Down to about 10. Sometimes if I shut it off and start back up it goes away until I warm it up again. It stumbles and hesitates up to about 2k rpm. Never had this problem before the NA-t I haven't really boosted until I get this sorted New cap, New 2j rotor new wires. Will be pulling plugs today. Gone through all connections. No vac leaks, have sprayed everyone. Help me I'm stumped. I have inspected the Bov, and wastegate diaphragms which are in good shape.


Edit..... Car is 95 Supra SE. 70k miles. Stock HG, stock fuel system. New o2 sensors. There is no Check engine light or codes.

Update. I took it for a ride at lunch. This time it started missing and stumbling before even 1/4 to temp. I have no idea what is goin on. I did find that my O2 sensor plug was melted but it is and was still making contact. Any ideas at all. Also I sprayed again every vac Lin and intercooler line with starting fluid including the throttle body. No leaks found at all. I'm lost. Please help

Pretty sure this problem is with my Ignition system. I did have to order a set of spark plug wires so i could run the 4runner cap, i needed #2 wire in the #1 spot for length. While it was idling yesterday i pushed on the plug wire at the dist. and BOOM shocked the hell out of me. I changed it to another one from the "new" kit and it seems to be running better but still intermitenttly will miss and stumble but not near as much. Does any one have ideas??:dunno:

Okay. Its not the ignition system. I built some MSD wires for it another new cap and rotor from Toyota this time problem with missing got worse and afr are even leaner now. So I went to the fuel system, I unhooked the vac line off the fuel regulator and capped it and it smoothed out a bit but still in the 15s instead of 16.5 on the afr. It also does not take long at all for this to start happening so the problem is getting worse So I am ordering a fuel pump. :crazy2

Apologies for the delayed response...and thank you for posting your question.

To begin with, please note that I'm much more familiar with the 2jz-gte...so you may take my advice with a grain of salt.

Here goes:
Just offhand, this doesn't seem like a great idea. Is there any way you could re-route the intake pipe to completely clear the distributor? Also, is the 4 runner cap a standard solution for an na-T Mkiv?
Is your Supra an Mkiv? If not, this question may be in the wrong section...

What spark plugs are you using? How long have the spark plugs been installed?

Fwiw, I don't think it's the fuel pump. You should check the fuel pressure before replacing the fuel pump. If anything, replace the fuel *filter* first.

That's it off the top of my head, for starters. Please let me know your thoughts about these suggestions, and any updates you have for us.

Take care,
Phil

Yes my car is a 95 mk4 SE na. I have not yet updated my signature.

Spark plugs (Bosch copper super plus 7956 gap at .028) were changed when I built the new MSD spark plug wires. Old ones were in great shape but did show a lean condition due to this problem. Also when I changed to the new plugs I bought another 4runner cap this one from 91 as the 92 had the lock tabs for the factory supra wires and the new wires are the slip on style like the 91 4 runner which match the ends of the 8.5mm low resistance MSD wires..

Both yrs of The 4 runner cap are very successful and idely used solution to clear a the turbo intake. I got the idea from Club Na-T FAQ. The only other solution is to run a 7m cps and COP which requires intense more amount of modification.


Also note that after I replaced the Cap for the second time with new proper working spark plug wires my AFR went even leaner. Almost maxing out my AEM Uego.

Fuel filter has been replaced 5k miles ago.

I have also considered the thought of maybe a bad batch of fuel.
.
.

Update--- Installed fuel pump and no change.

What are your thoughts on pullin the turbo and manifold off plugging the oil feed and drain putting na header back on and then trying to trouble shoot. A lot of time I kno but am sick of dumping money and getting nowhere.

I agree with your plan to temporarily put it back to n/a to troubleshoot.

As a test, could you remove the turbo intake and put the oem distributor cap back on? As long as you don't run the car in a dust storm and you don't have frozen chickens falling from the sky nearby, running the turbo wide open to atmosphere isn't all that risky.

Lastly, have you *pressurized* the intake yet? You do n/a vacuum testing with spray (or smoke), but pressurizing the intake (with an air compressor, for example) is what's needed for a turbocharged intake system. It should be able to hold about 50psi cold. Clamp your air hose adapter in there tight or it will turn into a cannon. (amhik)

Well after driving the car today I finally got a check engine light- Code 26= running rich. So Im leanin towards possibly a fuel regulator. Checking the fuel pressure on the GE is hell due to all the egr and related parts being above the feed line. I looked around for another port before the regulator but see nowhere else to go other then the banjo on the fuel sender but that is far from accurate.

I bypassed the turbo system and hooked up the afm directly to the intake mani with all vac lines hooked up. Fired it up, but still idled badly so I went back to find a vac line from the Bov still un capped. Oops! Then my great friend of mine without asking me unhooked my battery clearing the code so the cel went out. Not what I wanted to do. I wanted to see if the light would go out on its own.

Anyways, fired it up and it running rich right now with the cel cleared.

Afrs now at idle are 13.0-13.8 and at 1500 rpm no load afrs go to 11.8-12.5. And runs smooth no hesitation at all. But I'm sure as soon as I went down the road it would start droppin off lean again.

Any ideas greatly appreciated! The current set up jerry rig intake I made does not allow me to close the hood at all so I'm working on another setup to drive with. But those afr do not sound right to me.

I pulled the 4 runner cap off today to look at the spark trace on the cap poles, everything looked good. I am lookin in to getting a fuel pressure gauge if that checks out I will be doin a compression test aswell as leak down test. Really hoping there is a fuel problem thou!

What about an inline T sensor adapater right after the fuel filter? That's where we splice in on the MKIV TT...
Speaking of BOV do you have the output of the BOV routed to atmosphere or is it routed back into the intake system? If the main BOV itself is leaking, that could explain your rich condition (since the air ejected through the BOV has already been metered by the MAF)...Agreed.
Are you still planning to replace the oem distributor cap, just as a test?

Also, a short run with no hood shouldn't be too big of an issue, right?

Update!

I bought a new Mac tools pro fuel pressure test kit and it had a banjo bolt adapter that I hooked into the top of the fuel filter...

Results- with Vac line disconnected and plugged 51psi. Factory spec 38-44

With vac line hooked up 42psi. Factory spec 28-34

1500 rpm 55psi with vac line hooked up. That is out of factory specs so I will be replacing it.

I apologize for not adding the info about the stock distr cap. I reinstalled the original with no change. Although I did have to change plug wires back to OEM as well. So I put the 4 runner stuff back on and doubled checked that the timing is at 10btdc.

Is it possible that the added pressure from boost could damage the factory fuel regulator?? Should I stick with OEM or go to an aftermarket in your opinion.

My BOV is an HKS SSQ that I bought a recirculation nipple for so it has been blowing back into the intake post MAF, pre turbo!

Regarding the FPR, I'd try with one from an Mkiv TT if it's a different part number and if it fits. You could even try a used one (yours is the first I've heard of one that has problems). Just a thought - do you think your fuel return line could be blocked/kinked/crimped in any way - that would raise fuel pressure regardless of how well your FPR works. You could always go to an aftermarket FPR (a lot more expensive, especially after the adapters, braided hose, etc.) if a different oem fpr doesn't do the trick.

To bad you don't have a fuel controller (eg. A'PEXi AFC) - you could just dial down the fuel at idle based on the higher fuel pressure, then the additional fuel would be available under boost. Capiche? :)

I actually have a friend sellin a AEM ems v2 for the ge for $1000 with COP setup and a gm 3 bar map. I've been consodering but I have spent a lot of money this year! Buying a 32ft boat didn't help either.

Like you I have never had a regulator go out on me and the Walbro 255 is cheap insurance. Not to mention was way cheaper then the fuel press. Kit I bought!

I was just lookin into the gte regulators from what I have read they are interchangeable. I will be ordering one in the next few minutes. Thanks for your help Phil!

I'll keep ya posted if this resolves my issue for good!

Okay. I installed an aftermarket Aeromotive regulator with steel braided lines set within factory specs.

All seemed great yesterday afrs were where the should be around 14.7 so I parked it and then while driving to work this morning guess what came back! The lope in the idle.

Agghh. The CEL did come back on and I will be checking that at lunch time and will update that info. I have no idea what's goin on.


Is it possible my headgasket is seeping? Although I am not missing fluid.



I put some new fuel in it with some injector cleaner so time will tell of that helps at all.

Per my post above, have you checked for boost/vacuum leaks yet via pressurizing the intake yet?
One potential issue is a split vaccum (or charge air) hose that weakens with heat. A boost leak check will detect this (and an ordinary smoke test won't).

Here's another thought (while we're on the topic of split hoses):
http://autos.groups.yahoo.com/group/mkiv/message/230604

I have not yet pressurized the system I will do that this evening after building an adapter.

I pulled the code ==== 25 lean condition?? Fuel pressure is within spec.

I am starting to think possibly a bad MAF. I am running out of money fast throwing parts at it. Do you kno how to test the MAF on a ge??

Also at lunch today the check engine light went out on its own. At times my afr are perfect idling at 13.9 then all of a sudden just fall on its face down to 16-17. I unplugged the maf and it did not change the way it was missing???

I am also goin to ohm out the injectors this evening as well.

The easiest way is to swap it out with another Supra. I agree this is a possibility. One of my Supra buddies did have a MAF go bad.

Do you have the TSRM? I know it's a few bucks, but it's money well-spent that will pay itself back over and over again. The MAF test procedure and thousands of other useful procedures are detailed in it.

I do not yet have one but do plan on buying one.

Update- I pulled the turbo system off and put the stock na header back on with the sane 4runner dist cap and msd wires. Car runs AMAZING so far it made it all the way to work and didn't skip a beat for the first time in a while!

So two things I'm goin to do. In order to run my afr gauge I am only running one o2 and jumped the wires for the second into it. I am goin to switch it to the rear bank after work to confirm I ge the same results. If I do then I will be doin the pressure check on the intercooler piping. If that checks out the I will install the turbo and check it through the intake of turbo pressuring the entire system.

My question to you is should I dis connect it at the throttle body or will it hold 50psi??

Update :(

I switched the o2 sensor to the rear bank and what do ya know it started acting up again stumbling on idle just like before afrs drop lean.

So I ohm'd the injectors they all checked out within limits.

So tomoroow I will be gettin a new leak down tester and an adapter for my compression gauges as I didn't receive it back after I loaned it out.

Fluid levels still look great. No mix in any fluids so I am starting to wonder about my piston rings. ??

Everything should hold about 50psi bone cold. This is the equivalent of about 25psi running hot under boost. If things pop apart at 50psi or less, it just means you need better t-bolt clamps & couplings.

Maybe a silly question, but if it runs great using the O2 sensor to the front bank then maybe the problem is related to the rear O2 sensor (i.e. not anything else like the piston rings)?

I used the same o2 sensor for both tests just switched locations with my wideband afr.

I did a pressure check on the intercooler and piping but with the turbo pulled off I couldn't do it through the intake of the turbo yet.

Could still possibly be a clogged injector but the compression test will let me kno that tonight.

If it is rings I won't be rebuilding the GE. The limits are so tight on these motors I don't trust it with just a plasti gauge and don't have any better or special tools for that. So I will be looking into a 2jzgte swap with my single on it and pull the jdm twins. But would much rather not have to do that. Hopefully its not a compression issue in the bottom end. I will keep you posted!

Okay, but which O2 sensor was the oem ecu using to regulate the a/f curve? Since it ran fine when you flipped the wideband...

1. Quote:

   Originally Posted by Travis89Turbo (Post 104368) ...I pulled the turbo system off and put the stock na header back on with the sane 4runner dist cap and msd wires. Car runs AMAZING so far it made it all the way to work and didn't skip a beat for the first time in a while!...

2. Quote:

   Originally Posted by Travis89Turbo (Post 104368) ...I switched the o2 sensor to the rear bank and what do ya know it started acting up again stumbling on idle just like before afrs drop lean...

...then it seems that troubleshooting should focus on something to do with the O2 sensor?

If this is a dumb suggestion, please ignore. It's REALLY hard to provide third-hand advice over the internet...

The GE originally had two single wire narrow band o2 sensors from the factory. About 6 months ago I bought an na header that had screw type o2 instead of the 2 bolt so I bought two brand new bocsh screw type o2 sensors. Ran great with no problems.

When I put he turbo and downpipe on I ran the two new o2 sensors. When the problem started o2 sensors were ny first thought so I pulled those two off and exchanged them under warranty. Installed them both and same problem.

The wideband is strictly for my AEM AFR gauge.

The current set up just so u understand how I have it hooked up is my wideband hooked up in one of the banks and then 1 of the new o2 sensors with both o2 sensor wires ran to it. When I have the ecu o2 sensor hooked in the front bank and wideband in the rear the car runs flawlessly. It certainly doesn't feel like im down a cylinder.

When I switch locations of the wideband with the same ecu o2 sensor now in the rear bank still with both wires hooked to it goes lean as soon as I fire it up.

The single wire o2 sensors have less then 15 miles on it.

Results= Bad News!

Compression test results done on warm engine. Done 3 times and averaged.

#1- 170
#2-171
#3-171
#4-172
#5- 168
#6- 140----- with oil in cylinder 192. :crazy2:

Lesson learned- never boost an na without thicker headgasket. Even under 5 psi! :dunno:

Gosh sorry to hear that. :(

Y'know, there still might be a problem with the air:fuel tuning too. Since it actually ran great a few times for you, it's tough to explain that if #6 is broken. Maybe with some heavier weight oil and a new oil filter you could keep troubleshooting - just until you get your shortblock swap squared away? Just a thought - maybe a bad one. *shrug*

I agree with pwpanas still might be a problem with air/fuel.
Is the car smoking.

Well I have an update for everyone. Unfortunately this problem is not gone, however i do now have proper compression, and a TT headgasket giving me a more boost friendly compression ratio of 9.2-1.

So... the problem still is it runs rich at start up avg. 12.5+/- It will run in that range for a while approx 5 min. Then drop off carzy lean 17+ at times my AEM AF gauge wont even read it. I have only ran the car for few mins at a time and is not off jack stands so im not going to drive it and do damage with the 17 AFR. The time frame in which it starts to bog and miss (when it falls to anything more the 15 AFR) has gone down drastically from when the problem very first started. Im out of options other then swapping parts. Which luckilty have a friend with a 2jzge in his mk2 that is nice enough to let me use his good parts. Im hoping for a bad MAF

I have a friend coming by the house in a couple hrs to let me try his MAF. If that is not the problem what else would you reccomend swapping to try and troubleshoot??

NEW O2 sensors as well.

Intermittant miss up to 2k and idle when warm NA-T
 

Hi! , Reading through the history chat , I noticed you mentioned that the spark plugs have been changed , - Question ? - was the engine misfiring before you changed the plugs ,or after ? .
My history , Years ago - my mate changed his spark plugs for new ones only to find he had misfires , I convinced him to put the old ones back in , misfires gone - the NEW plugs were the problem ! , recommend changing the plugs for KNOWN good ones , - just a suggestion! ,sometimes the simplest things cause the most problems , NEVER be convinced that new plugs are blameless .
An old test is to disconnect one plug lead at a time ( at the coil /cap if plugs are hidden ) and run the engine each time and see if there is a noticeable change , thereby highlighting the offending cylinder ( misfire problems ) .

Yes the problem was present before the plug change. I changed them hoping they were the cause with no luck.

I do now have a Map.ecu that has a built in map sensor. I may just throw it on with a base map and hope it goes away. My good ol friend didnt show up yesterday to swap maf

1) Thanks for the update - much appreciated!
2) For what it's worth, I wouldn't call 9.2:1 "boost-friendly". Oem 2jz-gte is 8.5:1, and even that is only good for 15psi or so on 93 octane pump gas.
3) Ime, 12.5:1 a/f isn't really all that rich for cold-start. *shrug* However, I agree with you that 17:1 is crazy-lean - I'm guessing that's where your problem is (i.e. not the 12.5:1 on cold-start).
4) If you can obtain some sort of fuel controller to modify the maf signal (eg. APEX'i S-AFC or MAP ECU), you could try richening the fuel curve that way (above idle) - just as a troubleshooting step.
5) Guesses: Test for vacuum leaks. Bad IAC. Dirty injectors. *shrug* - I'll ponder it some more and re-post if I think of anything else. In the meantime, please do keep us updated.

Note: You can pressurize the intake with an air compressor to test for vacuum/boost leaks.

Okay have a few more updates. And they are not good news.

I pulled off my MAF, Coil, and igniter and tried them on another 2jzge together and individually and it ran great no miss or hesitation at all.

So I got thinkin about the compression again. I do know that the GTE is at 8.5 but there has been gray success running 9.2 on the ge at lower boost levels. I'm only shootig for 350hp with a t70. Anyways. I ran the car for a bit a couple different times to burn any oil from assembly out of he cylinder. Re dis compression test and wouldn't you know. 145 across the board until #6 which is 129. Now I know the compression would go down with the 1.3mm headgasket but everyone else says they are around 170 with the thicker gasket.

What I did to originally repair the compression is pulled the head off. Replaced rings in 6 cylinder all others were 170ish. I also replaced valve seals on all valves. However me not thinking did not pull the valves out to inspect them. I am wondering if I have slightly bent valves possibly?? I am almost to the point of pullin the motor and swapping to another GE. Or would u suggest just a head change? I really don't think its in the bottom end myself. But I am out of ideas.

I do have a map.ecu. But I would much rather get it running properly on factory ecu. Although I may try it. But the compression numbers are depressing. I am picking up a leak down tester to find out where i am loosing my pressure.

I have done the pressure test at 50psi. All checked out okay. I will wire up the map.ecu and try to play with it.

I'd assume you didn't notice any cracks in the #6 piston's ring lands (this is common when compression is low). A bent valve is unlikely, unless your previous config was interference? A bent valve on the top side almost never happens with the OHC+bucket config. A leak tester is an excellent next step. Good luck with it, and please keep us informed. If I were to just guess (which I don't like doing), consider replacing your #6 piston (i.e. not the head).

Okay. Results of leak down.... I have only done cylinder 5 and 6 for the time being due to the cross over intake mani. And it was gettin late.

#5= an average of 25% leak. No leaking out of valves with small blowby past rings.
#6=an average of 85% leak! Blowing pressure out of intake and exhaust with very very little blowing by piston.

The ge is still Non interference motor but I'm assuming the added pressure from boost and high compression. May have tweaked them. It's not a massive bend cause it looked flush. I had done quite a bit of research before my tear down just tryin to find troubled areas on the GE. And like you said the cracks in the piston ring glands is a common problem. So I inspected the piston thoroughly and it besides the slight carbon (more then I expected at only 70k) the piston looked flawless as did the rings I pulled and measured within limits per factory manual. Although I replaced them anyways. The GE pistons are coated just as the GTE so I stayed away from the wire brushes.

I forgot to add that I found Volume 1 and Volume 2 of the factory service repair manuals on eBay for an insane deal of $45 shipped. Some were sellin for over 100+ These manuals are great. They cover everything you could think of and then ten times more! Thanks for the advice to pick those up!

Hi! , The high blowby through the in and ex ports makes me believe the valves are on overlap - exhaust closing and inlet opening , may be an idea to retest with the crank in different positions to thoroughly test cylinder no 6 pressure .

Only thing I can think of that is left would be ECU possibly. Hopefully I can talk my friend with the mk2 to let me swap ecus.

http://www.toyota-supra.info/forums/mkiv-supra/20746-intermittent-miss-up-to-2k-and-i
 

Hi! , No problem ! Question ? : is the engine a high miler from new without top-end overhaul ? -- The valve seats and valves may have some pitting and this is letting the pressure through , my 7MGTE head needed an overhaul ,the seats and valves desperately needed recutting/refacing following a BHG as they were severely pitted ,a leaking ( oil ) turbo and general clean-up . I've had two engines where the inlet valves have split at the seat and burnt away , one was nearly new , the other a high miler . both were misfiring .

How is your valve shim clearance?

True. I've seen a VERY badly pitted head from running higher boost on pump gas. In fact, (among other damage) it punched right through from one combustion chamber to the next! Lots of welding and machining was required to get that head back in shape.

I checked valve shim clearance and all were to the lower side of the limits per FSM.

Mileage is only 71,000. I purchased the car from an elderly man that was original owner. All factory service records.


I have an idea. Thinkin back a few post when I had pulled all my turbo stuff off and put the header on to determine which bank of cylinders was giving me trouble. I am wondering if its just the differential pressure between the rear bank that causes the ecu to go hay wire.

What if I weld an 02 bung pre turbo on one of the front bank cylinders to trick the ecu. I know this would cause 6 cyl. To run rich but it should keep the ecu out of lean mode. And the worse that could happen is I blow a motor that I am ready to pull out anyways.

Looking way back when I first bought my na header way before the turbo kit I noticed 6 cyl. Was not near as colorful (almost ss still) compared to the others. I think that has been a weak cyl. For a long time? But the turbo pushed it beyond the ecus threshold after the boost. It did run great and not skip a beat when I was running o2 on the front bank.

If the #6 valves are bent, you could get 4 new valves, seat them with lapping compound, and then re-shim just those four buckets. *shrug* just brainstorming ... like you said, it's a good time to try options since you're at the point where the engine may have to come out anyway.

Well here's where it gets even trickier. I was doin the leak down on the wrong stroke. I turned engine 180 and then leakage was in the 30s?? No blowby past the valves but some out of the bottom end past rings. The motor hasn't even ran enough for the new rings on 6 to seat. So now I don't think its a valve issue anymore. Lol. This dang thing.. I'm determined to figure it out.

What I did last night is pulled all the turbo equipment off and put my NA header back on with the ECU's Narrow band O2 sensors wired into the front bank. And then My AEM wideband in the rear bank. And wouldn't you know it. Ran perfect. Doesn't skip a beat or run rough at all. And like I was figuring the rear bank is running just slightly rich 13.4 vs before issue idle was about 14.5. I was able to run the engine up to operating temp hoping to help seat the new rings. Although I found my brand new cam seals are leaking like crazy so I am addressing that issue first today.. And I mean leaking bad. Wondering if I blew them out with leak down test? But not a big deal to change.

So what I am goin to do to for a more permanent fix is weld the o2 sensor bung into my number 1 cyl. Pipe on my turbo mani pre turbo to run my ecu. I got thinkin about tuning after that and figured the best way to do it accurately (except for 6) is to weld an additional o2 bung in either 1 or 2 for my wide band. Allowing me to tune accurately to 5 cylinders and 6 be slightly rich due to lower compression which may go up with some break in. Although it will technically only be tuning to one cylinder but the others are within a few psi of eachother and the low amount of boost/power I am aiming for and just daily driving it not beating it up I believe it should work.

Then the thought of passing the emissions smog test. Luckily its obd1 so its the sniffer. How I plan on makin it pass is with a separate tune I will add only for smog and load it to the ecu at the smog parking lot. Is move my wideband to the downpipe after turbo and de fuel the other cylinders to make My exhaust fall within smog limits. What do u think? To pass smog based off other vehicles I have tuned is around 14-14.7


I will be doin tune with MAP.ECU1 with built in map sensor and runnig an IAT sensor. Deleting MAF.

Hi! , Excellent news! just a bit of tweaking now , had us worried for a while .

Agreed.

Thanks for the update! Please keep us informed.