1jz vvti misfire under load only? Any ideas?

[sambo91]

Hey guys.
I recently bought a Cressida with a 1jz vvti conversion and ever since I have had it, when under load it misses and just doesn't work like a 1j should.

The only mods done is a pod filter, FMIC, bigger fuel pump ( unknown brand or type), 3 inch from the dump and a manual boos controller which is wound right down to stock boost.

I have replaced the coil packs, and the spark plugs with .8 twin tips and now I'm lost.
Has anyone had this problem also or does anyone have any other ideas as to what it could be.
I would love to wack it on diagnostics but am unsure on how people do this. Do you have to buy the reader or is there places that will have the gear already.

I wouldn't mind trying the ignitor or another ecu either just to rule it out. So if anyone knows a friend or has one sitting around that wouldn't mine lending or selling for a test it would be greatly appreciated.

What's everyone's thoughts on the matter? It's got mechanics I know boggled :/

[Daddio]

I'd look at igniter first...its easiest to swap out and can be found for under $50
Then ECU...

[rob]

are the spark plugs copper or platinums?

try some copper ones

[dumbass]

I would buy check Ngk std tip plugs and reduce gap to .8mm
Try that

Is it a miss only on one or two cylinders or is the whole motor having a miss at a certain rev

These can have misses at 2500 or 4000 if not wired right
Igniters are hard to find for vvti 1js as they r different to normal 1j igniters

Also check your ecu for stuffed caps. But I doubt it would be that as its newer
But best to check anyway
Try putting gear lever in 2nd and see if miss goes away

[midnight_purple_GA70]

BKR6E spark plugs... come standard .8mm gap work fine for non vvti 1j and 2j... at a guess ide say will be fine for vvti...

[sambo91]

Hey guys. Thanks for the quick responses. The ones in there are the standard bkr6e .8 gapped. It's the whole motor missing for sure. I'm pretty sure it is between those rpm's, usually just as soon as you go to get any power out of it. Yeah I have been looking for one but no luck so far

Ok I will have a look tomorrow for the ecu caps. And also try 2nd

[allencr]

What's the compression?????

Always been this way or happen suddenly? Do ANYTHING or pressure wash before this happened?

Look for the code/s!

The narrower gap with identical symptom/s suggests that the ignition is ok, so what's the fuel pressure and what does 'missing under a load' mean? Symptom/s? What gear,rpm & range,throttle position-steady state & accelerating & WOT?

[Cuts]

I had a JZX100 for a couple of years (sold it at the start of this year though ) one thing I found is that (mine at least) hated copper plugs, as soon as I would put a set it it would miss. This happened a couple of times so it was no fluke. I ended up using stock twin tipped platinum, I know they are more expensive but it was like a dream with them.

Another thing to consider which you didn't mention replacing is the leads, because of the angles they sit at, and how they sit in the warm cam valley they do tend to degrade and arc out, especially after being removed and installed a few times.

[dumbass]

did u buy it with the problem
hope u only paid afew bucks for it then hehehe

[sambo91]

I had a JZX100 for a couple of years (sold it at the start of this year though ) one thing I found is that (mine at least) hated copper plugs, as soon as I would put a set it it would miss. This happened a couple of times so it was no fluke. I ended up using stock twin tipped platinum, I know they are more expensive but it was like a dream with them.

Another thing to consider which you didn't mention replacing is the leads, because of the angles they sit at, and how they sit in the warm cam valley they do tend to degrade and arc out, especially after being removed and installed a few times.

I will have to get some of the platinum plugs after this I think. It's getting out of hand, thanks mate. Might as well do all the cheaper things first.

I have some leads on there way from Japan so I'm hoping this could be it because when I changed the coilpacks it did it a bit less than before.

[sambo91]

I'm unsure of the compression as my tester was to short and havn't had a chance to check the fuel pressure.
I don't have a reader so I can't check the codes.

Didn't do a pressure clean or anything.

Missing under load means under a lot of acceleration on a flat or up a hill it will just retard and drop power and struggle to go any higher in the rpm range. Boost drops a a few psi. It doesn't matter what gear you are in, if you demand so e power it will miss.

[dumbass]

sounds like ecu or maf
pity i just sent a job back the other day
i had a jzx100 ecu and loom

does it have the odb2 plug wired up to it
or just the general rectange toyota plug in the engine bay

if its an early vvti one i think they run the half circle diag plug under dash
so just get someone with a scanner that can do that

ive got 2 scanners that can do most toyotas

or use the diag plug in engine bay and bridge out te1 and e1
thats only good if your check engine light is working in the dash

[YGO 08]

hey guys yeah ive owned this car before and it done it to me when i bought it. runs like a dream until on full boost. i how ever swapped the plugs and it went away and run 13psi fine the whole time i owned the car. as ive said to sambo it cant be nothing to bad but its just a matter of working out what the hell it is lol. as someone said the (leads) between the coils and plugs might be the problem as when i swapped the plugs maybe it turned or something and made it happy for a while and then over time just came back??? anyway hope you get it sorted buddy and able to bring it on the cressy cruise next month as its a clean car. keep me up to date and feel free to ask any questions?

[[email protected]]

Hey guys.
I recently bought a Cressida with a 1jz vvti conversion and ever since I have had it, when under load it misses and just doesn't work like a 1j should.

The only mods done is a pod filter, FMIC, bigger fuel pump ( unknown brand or type), 3 inch from the dump and a manual boos controller which is wound right down to stock boost.

I have replaced the coil packs, and the spark plugs with .8 twin tips and now I'm lost.
Has anyone had this problem also or does anyone have any other ideas as to what it could be.
I would love to wack it on diagnostics but am unsure on how people do this. Do you have to buy the reader or is there places that will have the gear already.

I wouldn't mind trying the ignitor or another ecu either just to rule it out. So if anyone knows a friend or has one sitting around that wouldn't mine lending or selling for a test it would be greatly appreciated.

What's everyone's thoughts on the matter? It's got mechanics I know boggled :/

Did you ever get the problem sorted out?
I'm currently having the same problem with mine.
1jzgte vvti into a series 2 mx83 cressida.
3" turbo back, fmic