exporunner

I have been very hesitant to post the question on the grounds that I probably did something stupid. Also I posted the question on my build but it isn't seeing much traffic.

I recently 'finished' up a 5vzfe swap (JDM 5vzfe with taco donor parts) the engine was an auto and I mated it to my r150f with a 3.4 clutch and flywheel. My truck was a 3vze and ran decent when pulled. Did the wiring myself. The problem I am having is BIZARRE and I have searched everywhere for weeks.

The engine starts and runs although it idles a little rough slight bucking (assuming iat needs to be cleaned and maybe some minor vac leaks I haven't found). The issue I am concerned about is that the engine stalls under any load. For example I fire it up I can drive it on the flat in front of my house but it bogs under acceleration or when I try to go up a hill no matter how slight.

I read somewhere that the JDM motors have smaller injectors and the issue seemed fuel flow related so I pulled the injectors and put in 6 new ones.

Still same problem.

Changed plugs and wires thinking ignition could be the issue.

Same problem.

Ohmed out my coil packs. They are in spec. Ohmed out the crank and can see sensors they are in spec. Maf tested good but the problem screamed maf to me so I swapped it anyways.another note on the maf is that the wiring harness was from a 99 auto engine so I had to change the wiring on the maf whip to match the 98 computer I am running.

Same problem.

I pulled the timing cover balancer etc. To check the timing and it seems okay (Unless its 180 degrees off).

I had an extra computer so I tried that. No change.

I was thinking maybe fuel filter could cause this? So changing that today cause its cheap.

I can post videos if everyone else is as stumped as I am.

As for the wiring I did the tack mod but it still isn't working and I have a cable speedo so I wired the corresponding speed contact from the dash to the computer (but I don't think that does anything without an electric speed sensor).

I have not checked TPS but don't think it can cause this severe of an issue. Is it possible this could be an ignitor issue??

Help! Please I am stumped!!! I need guidance from some yota experts! TIA

exporunner

Forgot the most important thing.... 0 codes

exporunner

well that's awesome. I posted this from my phone and just now saw that it posted in offroad and not engine builds.... greatttt....

rworegon

Moved thread for you.

wyoming9

iTrader: (1)

How long did the vehicle sit not running??

Dirt on the fuel pump sock??

Restriction in the fuel lines . ( rust and dirt from sitting) kinked or crushed

Curious to see if changing fuel filters helps.

With the MIL not being triggered I would look at the fuel system

exporunner

That is my thought as well. it sat for about 2 months. After about an hour of toiling with the d*** filter i couldnt get the engine side off. I will try again after work tomorrow. It definitely has fuel though, its bizarre. Anyone else have any thoughts?

The rest of the fuel lines look good. I am starting to suspect one of the small vac lines under the manifold came unplugged or something weird like that

89934runr

Sorry for being so direct, but stop chasing parts & get into the diagnostics of it all- see what fuel pressure it has while running, MAF flow rate, O2s signal, etc. If it's something as simple as a vacuum leak U should be able to see that or try to find it while spraying starting fluid around the air tract / manifolds.

Codes are nice, but not often the real culprit.

Did you doublecheck that the plug wires are on right?

exporunner

Plugs are right. And I agree I hate chasing parts. I will need to check fuel pressures. I have been diagnosing for 3 weeks and am stumped which is why I have been chasing parts.

Can anyone tell me how the motor will run with no O2 sensors? I can pull mine and judge the response to see if they are the problem. Unfortunately my code reader is cheap so I cant view a/f ratios etc. through it.

Thanks guys.

vasinvictor

iTrader: (3)

Do you have power to the +B on "D" plug of your ECU? (from the ii3 16 W-L plug on my '98 FWIW) It's the most common and overlooked wire- will make your truck run just as you described. Also verify should also have 12v on the "D" plug at the "batt" pin, but that's an easy one.

vasinvictor

iTrader: (3)

Do you have 12v at the ignitor when cranking? Do you have power at the coils? 12v to injectors? Battery ground to block, to firewall beside battery, and from rear head to back firewall. Touch DMM lead to positive lead of battery and negative to ignitor chassis and verify you have it grouned properly. Are you crank and cam sensors hooked up? Do you cam marks line up perfectly when crank is at 0* tdc on timing marks?

exporunner

Thanks for the replys! Timing is dead on... Cams are perfect and crank is perfect. I have 12v at the ignitor and ground. This was one of the first things I checked when I thought it was an ignition issue. That's why I asked about bad ignitor symptoms.... Toyotas troubleshooting manual says "check ignitor: try new ignitor" thanks Toyota great way to test my old ones.. Buy a new one -.-

Also the +b pin was one I was suspicious of but its good as well so are my fuses (I did blow an efi fuse when I left my keys in the ignition and started pulling an grounding ˟˟˟˟ woops..m but that was last week.)

exporunner

F'in phone double posting

exporunner

Another small update:

I reassembled the timing cover crank etc. And pulled the whole intake manifold apart.... Again and found no cracked vac lines or anything else out of place.. I cleaned my iat while I had everything apart...... I am so stumped at this point. I was really hoping timing would be my issue. As soon as I load the engine it stalls. Fuel lines seem good no kinks. No check lights. Sounds like its idling off... Like missing but no missfire codes; injectors, plugs nd wores are newm there has to be something glaring I'm missing.

My speed sensor is cable driven. My ecm has a speed sensor input. Any chance this mismatch is causing the ecm to limit fuel (by thinking the truck is stationary) stalling it??? It has to be something dumb like that.....

Anyone?

vasinvictor

iTrader: (3)

The likelyhood of a wiring mistake is high. The likelyhood of a bad part is low. Do you have a pin swap sheet or something I can look at to check your wiring? Have you verified your camshaft sensor is hooked up? Crankshaft sensor? Where are you located?

exporunner

Yes I do! but it is in paper form it would take a little bit to organize it. That would be awesome though. Perhaps you can see where/if I made a bonehead mistake.

Cam and crank tested good and are properly wired (pretty sure is wont run if they werent)

If you suspect wiring it has a harness from a 99 auto that I repinned (yes I did make sure to rewire the MAF because they are different between 98 and 99). Another clue on that side is that the tach still doesnt work even after the resister mod. Also motor is non egr dont think I mentioned that.

I am located in WA.

Thanks!

SacRunner

I'm not sure what the result would be if you didn't have the speed sensor hooked up on your ECM, but on my 91 4Runner, the mechanical speedometer cable is hooked to the back of the gauge cluster, then there's some circuitry there to convert it to an electric signal (for the 3.0's ECM and cruise control), find that wire from the 3.0 dash harness and tie it to the speed sensor input on your 3.4 ECU.

As for your stalling issue, I'm stumped, I would assume it may be a fuel issue. Just to recap, you've already swapped the JDM injectors for OEM (US) injectors for a 98 Tacoma, replaced the 3.0 fuel filter, and checked all the lines for kinks? Did I miss anything?

How about fuel pump? Is your evap system hooked up (I doubt it, but who knows)?

Does it seem to be tied more to high engine speed or high vehicle speed?

Also, lets talk about that MAF re-wiring you did. A quick check of rockauto shows that the '98 3.4 uses the in-line "bullet" type MAF whereas the '99 3.4 uses the newer drop-in MAF, and for all I know they may actually put out a different signal based on the amount of air passing through. I know it may be a pain, but try to find (or borrow) the correct MAF and see if that makes any difference.

exporunner

Yep you're dead on. And no what I meant by all that maf mumbo jumbo is I have and inline maf (needed for the 98 ecm) the harness I had was wired for the drop in,which I also have sitting on the work bench, style (99), which contrary to popular belief is wired differently, same plug shape but different gold contact and wires 4 and 5 are swapped blah blah blah. I basically cut the connector off the harness traced the wires out and rewired the correct 98 plug for the 98 maf in. Previously it wouldn't start because of the issue (took me all of 5 secs to figure out why). I dont believe my current issue is at all related to the maf.

Last night I traced out all of the soft fuel lines searching for kinks and found none.

I wired the speed sensor exactly as you just described. the cable comes to the back of the cluster and I found the corresponding body cable harness connection for the converted speed signal and wired that to the "speed signal" contact on the computer. I was curious as to whether that was the proper way to wire the cable speedo style or not as no one talks about it. Would an error in this wiring cause the truck to stall?

The evap system is all hooked up. I believe I have a short in one VSV as it is HOT to the touch. I pulled the whole thing apart last night to look for cracks/leaks.

LOL "high speed" currently i can putt around in 1st and 2nd... any load like a hill or acceleration causes it to stall.

it stalls as if you were trying to start in 5th gear.... the engine just doesnt have enough power to spin the wheels.

Thanks alot for the brainstorming guys keep it coming!! I am terrified that the engine has blown rings or something like that. It HAS TO BE SOMETHING STUPID.

SacRunner

Ok, so MAF does match the ECM (good!) it was the harness that was different, but it has been modified to match a '98....good.

Have you done a compression test on the engine? You can typically get a free loaner tester from places like O'Riley's (you pay the $50 or so to "buy" the loaner tester, you use it, and return it to get your $$ back, ends up costing you $0). That would help you find out if something was mechanically wrong with the engine, a leak down test could then be used to get a better understanding of what could be wrong.

Also, maybe check the fuel pressure. I have no idea how to do this, but I've seen some threads where a T valve is attached to the fuel rail and a pressure gauge is attached to the T valve.

exporunner

I own a compression tester I have just been exhausting all of the potential small problems 1st (especially because I have the whole thing torn apart right now ).

I agree with the fuel pressure test it is on my list... but like you I have never done one and have no idea how can anyone chime in on that?

I like how you are revisiting wiring though. Do you have any thoughts on what would cause the fuel pump to not provide adequate pressure? As far as I can tell the FC computer contact is working but maybe there is something I am overlooking?

vasinvictor

iTrader: (3)

Get a fuel pressure tester that has a banjo bolt adapter in it. You can hook it in where you did the "fuel line flip". You may be able to connect it to the front side of the rail too, it may be easier to get at. Your fuel pump should activate when you actually crank the truck, or it might come on in IG2, depending on how you wired your COR. Factory way fuel pump comes on when the truck is actually cranking. You can use the Diagnosis pins under the hood to jumper your fuel pump on (FP and e1, I believe). If you get fuel pressure that way, then have a buddy help you crank the truck while your testing and see if you get pressure. This will tell you if the COR is wired correctly.

I mean the 3.0 was running before you yanked it, so I'm doubting fuel pump problem. Gonna be a wiring issue. Can you spray ether down the throttle body while cranking and see if you get fire? Be careful with that stuff though, spray while cranking, don't spray a pool of it then try to crank.