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1MZ powered MR2
1991 MR2
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1,065 Posts
Discussion Starter #1 (Edited)
So, I've been having a problem getting my 1MZ swapped MR2 to pass CA smog on a loaded dynamometer smog test. It's failed the 15mph test twice, but all other test values are very, very good.

I should note that there are some differences between my M/T 1MZ and a "true" Camry/Solara M/T 1MZ:

1) A/T 255cc 4-hole injectors (versus 245cc 2-hole M/T or Federal injectors)
2) 2x Air-fuel ratio sensors (versus heated oxygen sensors)
3) 1999 CA spec A/T ECU - 89661-06641 (versus 1999 M/T ECU - 89661-06631)
3a) CA spec A/T ECU ground switched to M/T; requires use of AFR sensors
4) Injen CARB legal IS2030 intake
4a) Ported heads
5) Walbro 255LPH/HP fuel pump for future upgrades
6) Stock returnless fuel setup
7) All OBDII readiness monitors set; no codes
8) Brand new, CARB legal Magnaflow 46005 2.25" catalyst

I bolded the above 3 things because I have a feeling they're causing some issues.

Now, the smog test results:

Round 1:

15 mph:

CO2% - 14.6
O2% - 0.2
HC (PPM) - 102 (max: 54)
CO% - 0.07% (max: 0.50%)
NO (PPM) - 87 (max: 430)

Result: FAIL

25 mph:

CO2% - 14.7
O2% - 0.2
HC (PPM) - 37 (max: 37)
CO% - 0.06 (max: 0.47)
NO (PPM) - 125 (max: 717)

Result: PASS (barely)

Magnaflow 46005 CARB cat; Shell 91 octane. P0171 5 minutes after leaving; exhaust leak at rear bank manifold pipe mating. Fuel trims were +38% and +27% on the rear and front banks, respectively, but not during the test.


Round 2:

15 mph:

CO2% - 14.5
O2% - 0.2
HC (PPM) - 130 (max: 54)
CO% - 0.11% (max: 0.50%)
NO (PPM) - 172 (max: 430)

Result: FAIL

25 mph:

CO2% - 14.6
O2% - 0.2
HC (PPM) - 37 (max: 37)
CO% - 0.06 (max: 0.47)
NO (PPM) - 158 (max: 717)

Result: PASS (barely)

Chevron/Shell 91 octane (mixed). I lost my fuel trim readings when I was testing the ECU terminals, but I'll post them after finishing adjusting my valve clearance.

Now, keep in mind the CA emissions ECU is tuned for a 3-catalyst setup, while I am only running one main catalyst as required by the M/T setup.

I checked my spark plugs - they're excellent. No unburned fuel, no oil, and no carbon. I checked my coils - all within spec.

I will use some old fashioned tricks to pass if necessary, but I just thought I'd pick your brains and see what you guys think.

Also keep in mind, my engine has less than 1000 miles on it after being rebuilt.

So, post your thoughts.
 

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5,344 Posts
I have always thought that when doing a MT swap, you should definitely replace the ECU with one made for the new transmission. Regardless of whether or not you're getting codes, it still isn't made for the MT...it's made for the AT. I don't know if it really effects anything at all, but it certainly COULD.

That's my first thought.

Second thought is those injectors. Maybe you're just getting too much fuel since you have the AT injectors (same concept in my head as the ECU...you have a MT now so should theoretically need the MT injectors instead) Maybe it's the higher flow rate and you're wasting more gas causing more hydrocarbons?

I don't really know...just throwing some ideas out there. What I would try is to find someone with the ECU you need and ask if you can borrow it for a day, see if it makes a difference.

Also hit up a junkyard and get some injectors and see if you can pass with the MT injectors. I would use the injectors just for the inspection, then probably swap the old ones back in (who knows how bad the junkyard injectors are...)
 

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V8'sRGone
95 Cam
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1,956 Posts
Can you attempt to simulate those load conditions based on sound and RPM? In essence replicate what the dyno did during testing?

The goal here is to get the actual data from the trims ect.

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1) A/T 255cc 4-hole injectors (versus 245cc 2-hole M/T or Federal injectors)
2) 2x Air-fuel ratio sensors (versus heated oxygen sensors)
3) 1999 CA spec A/T ECU - 89661-06641 (versus 1999 M/T ECU - 89661-06631)
3a) CA spec A/T ECU ground switched to M/T; requires use of AFR sensors
4) Injen CARB legal IS2030 intake
4a) Ported heads
5) Walbro 255LPH/HP fuel pump for future upgrades
6) Stock returnless fuel setup
7) All OBDII readiness monitors set; no codes
8) Brand new, CARB legal Magnaflow 46005 2.25" catalyst
-------------------------------------
Honestly I don't see any of those changes causing a failure. That ECM supports A/F. The A/F does the mixing regardless of the injectors, pump, lines. . .

Leaks, leaks will hose things up bad. Honestly I don't know where the IAC transition is but looks like its the off idle loading thats killing you. So try to get the trims around there and check all the plumbing, IAC, T/B, and MAF for air leaks. The components are clearly capable, its the teacher telling them to do the wrong thing. So why is it doing that? Are your idle trims (-)?

Does your ECU support both sensors? (i'd guess not).

As for the heads and porting, was anything done to the actual combustion chamber shape? Its not like you added a quench area, which usually drive up the NO, but instead its the CO.
 

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1MZ powered MR2
1991 MR2
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1,065 Posts
Discussion Starter #4 (Edited)
Well for non-CA spec A/T 1MZs, the ECUs are the same between the M/T and A/T. Toyota only adds a ground terminal for the M/T to remove the A/T solenoid codes. That's why the ECU no longer says, "1MZ-FE M/T" or 1MZ-FE A/T" because they're dual purpose.

The 1999 Federal or M/T ECU is 89661-06630/31. Federal as in non-CA spec A/Ts.

The CA-spec ECU moves the 1MZ to air-fuel ratio sensors and the engine uses newer 4-hole injectors for better emissions. There's not much else different. It's true though, that the ECU could be enrichening the fuel trims at lower revs causing me to fail. It might be doing this because it expects 3 catalysts and it is trying to light off the warm-up catalysts closest to the manifolds.

The other thing is Injen's 2.75" intake pipe. The 1MZ MAFs don't like pipes any bigger than 2.5", so there's a little issue there. Some of the MR2 guys tried 3" pipes and that worked out even worse. I could try a restrictor around the MAF to get it down to 2.5".

Injen's intake wasn't specifically tested on the 1MZ, rather on a Focus, IS300, and Eclipse V6 where it was shown not to increase emissions. So, not sure what to think about that.

The only things I can think of, off the top of my head, are EVAP purge off-idle (it was a HOT day, both times). If I fill my tank up, it cuts off the purge valves, so that would eliminate one thing.

I'm also 3000 feet above sea level, so my fuel trims are almost always +. Usually around +5-15% depending.
 

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V8'sRGone
95 Cam
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1,956 Posts
OK - Anyway to pressurize the fuel rail and do a controlled leak test of the injectors? The nice way w/out removing them?

I could perhaps loan you a precision flow meter to detect flow vs pressure drop.

Still thinking out loud.
 

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1MZ powered MR2
1991 MR2
Joined
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1,065 Posts
Discussion Starter #6
OK - Anyway to pressurize the fuel rail and do a controlled leak test of the injectors? The nice way w/out removing them?

I could perhaps loan you a precision flow meter to detect flow vs pressure drop.

Still thinking out loud.
Well the great thing is RC Engineering already did that for me. None were leaking, but they were off balance. So cc/min went from 244cc to 255cc after cleaning and spray patterns returned to excellent. The injectors have 72k original miles on them from the donor car.
 

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V8'sRGone
95 Cam
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1,956 Posts
The other thing is Injen's 2.75" intake pipe. The 1MZ MAFs don't like pipes any bigger than 2.5", so there's a little issue there. Some of the MR2 guys tried 3" pipes and that worked out even worse. I could try a restrictor around the MAF to get it down to 2.5".

Injen's intake wasn't specifically tested on the 1MZ, rather on a Focus, IS300, and Eclipse V6 where it was shown not to increase emissions. So, not sure what to think about that.

The only things I can think of, off the top of my head, are EVAP purge off-idle (it was a HOT day, both times). If I fill my tank up, it cuts off the purge valves, so that would eliminate one thing.
Hot is almost always better than cold.
I'm thinking MAF, and/or MAF related. Ever ohm it? You have a spare? Any chance you have air leaks anywhere? It just seems like it should be able to get trims lower but??? WTF do I know?

Crazy, thinking on the purge, but we're talking very small amounts here to create this issue. That full tank thing could be worth a shot. Can you plug/pinch it and see what does to see if its worth a trip over there for that?
 

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V8'sRGone
95 Cam
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1,956 Posts
Well the great thing is RC Engineering already did that for me. None were leaking, but they were off balance. So cc/min went from 244cc to 255cc after cleaning and spray patterns returned to excellent. The injectors have 72k original miles on them from the donor car.

But that was when? Car sat for how long? Rust, chunks, assembly debris stirred up?
 

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1MZ powered MR2
1991 MR2
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1,065 Posts
Discussion Starter #9 (Edited)
But that was when? Car sat for how long? Rust, chunks, assembly debris stirred up?
:lol:

No rust, no chunks, and definitely no assembly debris. I kept the injectors sealed after cleaning. After that they were only exposed to the intake ports.

I also checked them when replacing my lower intake gasket a couple months ago. They spray great and don't leak.

Oh, I am running two fuel filters because the 1MZ rail has a quick connect fitting on the rail with a matching one on its fuel filter. I'm using a new MR2 filter and a new 1MZ filter connected to each other, then to the rail.

I will report back on the fuel trims once I get a new valve cover gasket for the front bank. Overall, the valve clearances weren't too bad, some were tight, some were just a tad loose (like 0.006mm) from spec. So, one or two exhaust valves had a clearance of 0.356mm when spec is 0.250mm-0.350mm. I did find one on cylinder 6 with a clearance of 0.432mm on the exhaust.



After about 800 miles. My 90 degree cylinder head bolt markings are still facing 90 degrees, so that's a good sign.

There, is, however a TSB on my ignition coils. The date stamp on them is 99/02, and they do fall under the TSB for engine misfires. My ECU hasn't detected a misfire yet, but I have heard one or two every now and then.
 

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V8'sRGone
95 Cam
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1,956 Posts
So we're all on the same page. is it fair to say its getting fuel beyond what the spec lists. This fuel is not being burned and leaves in a raw status as PPM?

Hotter plugs?
Although the igniter says it retains the same dwell angle throughout all RPMs (IIRC) I still find it hard to beleive the ign dwell is not higher at idle which would help this.

Your thoughts?
 

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V8'sRGone
95 Cam
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1,956 Posts
:lol:

No rust, no chunks, and definitely no assembly debris. I kept the injectors sealed after cleaning. After that they were only exposed to the intake ports.

I also checked them when replacing my lower intake gasket a couple months ago. They spray great and don't leak.

Oh, I am running two fuel filters because the 1MZ rail has a quick connect fitting on the rail with a matching one on its fuel filter. I'm using a new MR2 filter and a new 1MZ filter connected to each other, then to the rail.

I will report back on the fuel trims once I get a new valve cover gasket for the front bank. Overall, the valve clearances weren't too bad, some were tight, some were just a tad loose (like 0.006mm) from spec. So, one or two exhaust valves had a clearance of 0.356mm when spec is 0.250mm-0.350mm. I did find one on cylinder 6 with a clearance of 0.432mm on the exhaust.
Thinking of MR2 Fuel line - but youzzzz got filters! Good!
 

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1MZ powered MR2
1991 MR2
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1,065 Posts
Discussion Starter #12 (Edited)
So we're all on the same page. is it fair to say its getting fuel beyond what the spec lists. This fuel is not being burned and leaves in a raw status as PPM?

Hotter plugs?
Although the igniter says it retains the same dwell angle throughout all RPMs (IIRC) I still find it hard to beleive the ign dwell is not higher at idle which would help this.

Your thoughts?
You'd think the A/F ratio sensors would catch that unburned fuel and reduce the fuel trims. It's a possibility, for sure. When they were testing it on the dyno, it did smell a tad rich at 15mph, but at 25mph, it was clean.

I, too, am thinking of moving to a one-step hotter plug just for smog. The knock sensors might not be happy with it, but I won't be stressing the engine with those in. And perhaps a little alcohol to ensure a good result. ;)

Also, always recheck my posts. I make a lot of edits.
 

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V8'sRGone
95 Cam
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1,956 Posts
You'd think the A/F ratio sensors would catch that unburned fuel and reduce the fuel trims. It's a possibility, for sure. When they were testing it on the dyno, it did smell a tad rich at 15mph, but at 25mph, it was clean.

I, too, am thinking of moving to a one-step hotter plug just for smog. The knock sensors might not be happy with it, but I won't be stressing the engine with those in. And perhaps a little alcohol to ensure a good result. ;)

Also, always recheck my posts. I make a lot of edits.
Based on this thinking, it has more fuel than needed (you adding that you can smell it is the tell tale sign). In this case lower oct fuel might help you start and complete the burn sooner!

Hint leaving it that way post inspection could cost you a cat. . .
Back to the original issue - why is not burning the fuel? Ignition weak or the MAF is telling it theres more air than needed. Hence the plus trims. . . 3000ft, shouldn't be a big deal..

SAME - recheck. . . What about the EGR leaking at idle?

OK - thinking . . .
 

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1MZ powered MR2
1991 MR2
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1,065 Posts
Discussion Starter #14 (Edited)
The only other thing is the Injen intake pipe or quite a bit of built up fuel vapor purging. They didn't vent the cap prior to the test. They checked it after the loaded dyno test. The EVAP purge line always has a strong smell of fuel vapor and that can substantially increase HCs to the point of failing on a hot day/heat soak. The fuel tank naturally catches a bit of engine bay heat even with the heat shields in place, so fuel vapor will always be a factor for me in the MR2. Since it's returnless, the effect is greatly reduced though.

BTW, the EVAP VSV won't operate if the engine is started and just idles. They shut down and started my engine and let it sit. That doesn't initiate purge. Initial purge happens when you move above 0mph (like when they put it on the dyno), then it will purge while moving AND when it returns to idle. I've noted when the EVAP VSV operates by feeling it. When I come in from a drive and idle, it's operating and purging vapor. When I shut it down and restart it, it doesn't run even at operating temperature.

I've personally tested the EGR, and there is no leak.
 

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V8'sRGone
95 Cam
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1,956 Posts
Cuzzzz you're the sharpest guy on here about this stuff, I think you're screwwwwwweeeeddddd! :eek: :lol: :lol:

J/K, you running on trip permits?


Edit: feel free to call out anything I'm blatantly wrong on.

hehe - I didn't write this so feel free cut it up. . . lol
http://www.autoshop101.com/forms/h56.pdf

Ha - its actually a yoda doc about your MR2! How'd they do that so fast?
 

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1MZ powered MR2
1991 MR2
Joined
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1,065 Posts
Discussion Starter #16
Cuzzzz you're the sharpest guy on here about this stuff, I think you're screwwwwwweeeeddddd! :eek: :lol: :lol:

J/K, you running on trip permits?
:lol:

Yeah. I have temporary moving permits, but I'm about to get a 1-month smog exemption. They used to be free, but living in CA is expensive, and now they're $50, or nearly the amount I paid for my registration. :rolleyes:

I'm thinking it probably just needs some mileage. I am reusing my old Magnaflow muffler, which was used on my old 5SFE that had copious amounts of blow-by. There's a small chance there's still some old hydrocarbons in there that haven't been burnt off. :lol: That's a REAL long shot though.
 

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1MZ powered MR2
1991 MR2
Joined
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1,065 Posts
Discussion Starter #17
Cuzzzz you're the sharpest guy on here about this stuff, I think you're screwwwwwweeeeddddd! :eek: :lol: :lol:

J/K, you running on trip permits?


Edit: feel free to call out anything I'm blatantly wrong on.

hehe - I didn't write this so feel free cut it up. . . lol
http://www.autoshop101.com/forms/h56.pdf

Ha - its actually a yoda doc about your MR2! How'd they do that so fast?
Hmm, they do mention tight exhaust valve clearances. I do have some exhaust clearances that are a little tighter than spec. I felt it wouldn't matter too much. :ugh3:
 

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抵抗は無駄で&#
2002 Solara SLE V6
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9,085 Posts
just an idea.

are you sure that PVC on the rear bank is operating fine ?

HC's are controlled mostly by 2 things (per FSM) and they are PVC and the cat.
also there are evaporated HC's controlled by EVAP (VSV most likely as you noted).

i wouldn't bother with EGR much (unless it's about a vacuum leak), because EGR helps mostly NOx.

I'm also wondering how big of a difference the valve clearance out of adjustment caused on dyno ... it could cause some internal vacuum leak (exhaust valve loose you said). also maybe that exhaust manifold gasket leak played a role in bad results even though ECU has not adjusted yet for it during dyno test ?

I'm no expert by all means hehe, but you have (I think) too much oxygen in the exhaust stream.

also you saying that you have just one cat, but looking at your dyno numbers it looks like cat is operating fine as CO and NOx look good, only HC is too high...

just throwing some ideas.
 

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1MZ powered MR2
1991 MR2
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1,065 Posts
Discussion Starter #19
Ah, yeah, the PCV valve is new. I tested the old one just for kicks, and it was still good, but I replaced it with a new one. It, too, works. With manifold vacuum high (idle), the valve is nearly shut (it can't shut completely).
 

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V8'sRGone
95 Cam
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1,956 Posts
Hmm, they do mention tight exhaust valve clearances. I do have some exhaust clearances that are a little tighter than spec. I felt it wouldn't matter too much. :ugh3:

But its tight valve causing that. . . Valve opens before combustion is complete. Yours being loose is nbg.

What vacuum you hold at idle. Its fair indication of even valve timing.


EDIT: a tight intake can't help either - both result in holding the valve open when the engine gets real hot. I don't think you're are off enough to do this. But in the big picture, this means valves don't get the cooling from being shut on the head, they overheat and warp and then burn. Intakes are thinner cause they get cool charge to cool them. Exh not so much and why they are heavier and have more clearance. Again, yours seem fine. You're down to spillting hairs!

Near Zero clearance is an issue. You have spare shims lying around?
 
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