RORERI: A JDM 1992 ST185H-BLMVZ

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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Sat May 07, 2022 4:59 pm

That sounds about right, you know. I'm undecided, and I'm for more diagnosis rather than firing the parts cannon at this matter. I gave a thought to that very procedure you mentioned, but it would have freaked out my passenger. So I did the less adventuresome thing.

There's no CEL at any point. According to the Lorelei's primitive little brain, all is well with the world.

So, as it stands:

1. Bad fuel? Maybe the JDM timing map doesn't like ethanol blended fuel?
2. Air Flow Meter? Maybe that old tech is just faulty and giving weird signal?
3. Fuel Pump? Maybe the fuel pump is giving out sporadically?
4. Knock Sensor? Could be indicating knock and engaging engine protection?

I'm curious about something...so...if I fill the tank to the click stop, and I park it on anything but dead level ground, it will leak. I used to think it was venting through the charcoal canister but I've given some thought to the possibility of one of the top gaskets being compromised. The leak always shows up on the right side (as you're looking at it from the back).

If that gasket is compromised, is there a fuel tank pressurization issue? Like leaving your gas cap unscrewed?

I ordered up some equipment that will allow me to set up a fuel pressure gauge where I can see it, and then move it back inside the engine compartment later if wanted.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Mon May 09, 2022 10:52 am

And Amayama just cancelled my order for a couple of front end structural parts, stating that the items were out of production.

Yeah. You think?

So no luck with MegaZip or Amayama for the front end parts I’m looking for. I’ll probably need to source them from an ST185 someone’s parting out. Eventually. Thankfully the need isn’t dire or urgent.

To be fair that’s probably what MegaZip would have been doing had I proceeded with sourcing the parts from Thailand. What car they’d be coming off of…who knows?
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby alltracman78 » Tue May 10, 2022 5:37 pm

Your issue might be either overboosting or timing.

Usually if you overboost (14.7 PSI?) you'll get a CEL though. And the timing retard won't go away until you recycle the key.
Are you running a boost gauge? Keep in mind there's a range of accuracy. With your gauge, the MAP sensor and the ECU....
You could try disconnecting the MAP hose (not the connector, that will give you a CEL) and see if that changes anything.

IIRC JDM ECUs are tuned for roughly (our) 94 octane. Seems like the cleaner (more pure) the fuel the better your car runs?
It's possible your knock sensor is a little on the sensitive side? Or the ECU is?
Have you checked your actual ignition timing? Maybe it's a tad advanced?
You could try water/methanol injection. See if that has any impact? Though the methanol makes you run slightly leaner? And as your JDM ECU has less leeway than a US spec one (they run much leaner) you may want to keep that in mind?

I think I asked this already, but I can't remember what you answered. Have you ran several cans of seafoam through the intake? To make sure there's no crud in the manifold ect?

The easiest ECU upgrade IMO is swapping in an ST205 ECU. Or a gen III MR2 one (you won't have to build a IC pump bypass circuit with this one). No tuning required. IIRC just need the ECU, MAP sensor, intake manifold temp sensor (goes in place of your CSI injector) and igniter. Because your car is pre revision you'll have to swap a few wires at the ECU. And you'll have to build that pump relay circuit if you use the 205 ECU.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Tue May 10, 2022 9:54 pm

I appreciate the input. Lots to think of here. I'll chunk it up.

Overboost

I'm not sure about overboost. No CEL.

I am running a boost gauge. It can make 1.1kg/cm2--so 15.6psi--on the high setting of the Blitz Twin Solenoid Boost Controller that's installed. It can make .8kg/cm2--11.6psi--on the low setting. With it turned off, it can make .6kg/cm2--8.5psi. All of these analog readings on an Omoni boost gauge.

I turned the boost controller off. Today on the drive home, no issues. But I wasn't driving hard.

Fuel

I am wondering about this. Like I said, on the trip back from the Blue Ridge Parkway I picked up some 93 octane out in the countryside where I saw no ethanol sticker on the pump. Then I drove home hundreds of miles no problem, and in to work and back Monday and in to work today. I got near E today and filled it up with 13 gallons of 93 octane on base. No problems on the return trip home. But like I said, I wasn't driving hard.

I agree that this could be a situation where the fuel is right on the line of being not enough octane for how this motor is set up. Depending on how it is, it could be inducing the issue.

Timing

I had a timing belt installed when I took delivery. It's possible that the timing is not set correctly. Per the decal under the hood, initial timing should be 10 degrees BDTC at 800rpm. I do not know what a good setting is for total timing for 93 octane E10. I do not have the equipment to check timing. I could get that, but then I'd be learning how to do it. Alternately, I do know a shop I could take it to and ask for what the settings are. I'd pay for the knowledge if I went that route.

Water/Methanol Injection

I knew nothing about this, except having heard of it. I read an article and watched a video. It's an interesting concept. I want to learn more.

Seafoam

I ran a can through it. I'll do another two tonight.

ECU Upgrade

I'm not there yet, but perhaps in the future. I'd go with a gen III MR2 ECU I think if I went that route.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby grip-addict » Tue May 10, 2022 10:37 pm

I'm showing my wife this thread so she believes me that I'm not the only one constantly working on the Celica.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Wed May 11, 2022 12:17 am

To grip-addict: Riiiiight?!

I got the daughter into the act tonight. I live in a cul de sac in a quiet neighborhood so rather than annoy them I took it over to the nearby strip mall parking lot where I would annoy nobody. I told her she could make $10 for a half hour of light work and she jumped on the opportunity. All she had to do was keep the revs at 2000 while I put two cans of SeaFoam through it. Her first time behind the wheel doing anything. She was looking around at all the gauges--turbo timer, temp gauges, AFM, boost gauge. Then she had to ride along with me after the warm soak.

Though I embarrass her on the daily by dropping her off at school on my way to work, she'd never been in it when I'd taken it hard into the onramp or into right hand turns at the speed limit. She was giggling pretty hard telling me that mom would be yelling at me. She had to agree that the Feal 441s had greatly improved the ride quality.

So, two (more) cans of SeaFoam through it, and I dumped two cans of SeaFoam motor treatment into a full tank of gas. We'll see whether it changes things up.

Carbon Microsystem is finishing up my carbon fiber hood. But, man... The shipping. 680 Euro. Brutal. International commerce is going through a very rough patch.

I also ordered a radiator grill. I was originally going to go with a carbon fiber one, but Carbon Microsystem wouldn't bundle the shipping and it would have been egregious--like, 280 Euro for the grill and they say 50 Euro for shipping but the way things are, I'd count on 100 Euro. So, an OEM radiator grill for a quarter of that price.

The restoration is nigh.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Thu May 12, 2022 12:58 am

Testing With Fuel Pressure Gauge

I got my hands on some AutoMeter equipment to set up an external fuel pressure gauge.

Fuel Pressure Gauge.JPG

I first thought I would try and run the line out the back of the hood and install the gauge on the hood cowling or use some double sided tape to stick it to the windscreen. That was obviously in error--the hood cowling situation is really very tight. And, like, there's no place to secure it to the windscreen with adhesive. I'd have needed to have gone with a much smaller gauge and gauge pod if I was going to try that. But the connections were holding and the gauge was working.

First Attempt.JPG

I tried again, running the line out through the right side hood vent, and lashing it down with double sided Gorilla tape. That worked.

Gauges.JPG

Having a big ole gauge out there on the hood like that is a little on the nose for my taste, but it served my purpose which was to check fuel pressure.

I took the Lorelei on a number of loops onto the expressway and off and back through the neighborhood, running on stock boost max 9psi. I gave it a number of full load onramp accelerations and some good load on the expressway. Did some video recording so I could analyze afterwards--too many gauges to look at all at once. My findings were as follows: 32psi at idle, 40psi at load, up to 45psi max.

This is lower that what grip-addict posted should be observed:

"At full vacuum, 30-32 something-ish psi fuel pressure
At 0 bar boost, 42-44ish fuel pressure (please review bgb for exactly numbers)
At 14.7 psi boost, 58ish psi fuel pressure.
1:1 is the law of the land."


Performance was generally good up through 9psi. Air-fuel ratio was properly rich under load. One time, I experienced dropout, while at full load--wasn't recording then so I don't know what exactly was going on, but I'm suspecting fuel starvation. I think I should be seeing above 50psi fuel pressure at 9psi boost.

So, I am leaning toward a new fuel pump, a Supra unit. One of these, which Tippo installed a while back:

https://www.rockauto.com/en/moreinfo.ph ... 56&jsn=877

I'm guessing I'll need a fuel strainer as well--one of these:

https://www.rockauto.com/en/moreinfo.ph ... 12&jsn=395

This weekend I have a 250 mile trip planned up into Pennsylvania. I'll leave the fuel pressure gauge installed out there during the trip, to use as a monitoring tool.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby underscore » Thu May 12, 2022 3:09 am

Where in the fuel system did you tap in for the gauge?
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Thu May 12, 2022 3:22 am

I took the pressure reading off the top of the fuel filter.

I used a banjo bolt with a 1/8" NPT female fitting, then added a 1/8"NPT to 4AN adapter and then connected a 4 foot braided steel line to a mechanical fuel pressure gauge.

Better to go off the fuel rail?
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Tippo » Thu May 12, 2022 1:08 pm

Roreri wrote:Testing With Fuel Pressure Gauge

I got my hands on some AutoMeter equipment to set up an external fuel pressure gauge.

Fuel Pressure Gauge.JPG

I first thought I would try and run the line out the back of the hood and install the gauge on the hood cowling or use some double sided tape to stick it to the windscreen. That was obviously in error--the hood cowling situation is really very tight. And, like, there's no place to secure it to the windscreen with adhesive. I'd have needed to have gone with a much smaller gauge and gauge pod if I was going to try that. But the connections were holding and the gauge was working.

First Attempt.JPG

I tried again, running the line out through the right side hood vent, and lashing it down with double sided Gorilla tape. That worked.

Gauges.JPG

Having a big ole gauge out there on the hood like that is a little on the nose for my taste, but it served my purpose which was to check fuel pressure.

I took the Lorelei on a number of loops onto the expressway and off and back through the neighborhood, running on stock boost max 9psi. I gave it a number of full load onramp accelerations and some good load on the expressway. Did some video recording so I could analyze afterwards--too many gauges to look at all at once. My findings were as follows: 32psi at idle, 40psi at load, up to 45psi max.

This is lower that what grip-addict posted should be observed:

"At full vacuum, 30-32 something-ish psi fuel pressure
At 0 bar boost, 42-44ish fuel pressure (please review bgb for exactly numbers)
At 14.7 psi boost, 58ish psi fuel pressure.
1:1 is the law of the land."


Performance was generally good up through 9psi. Air-fuel ratio was properly rich under load. One time, I experienced dropout, while at full load--wasn't recording then so I don't know what exactly was going on, but I'm suspecting fuel starvation. I think I should be seeing above 50psi fuel pressure at 9psi boost.

So, I am leaning toward a new fuel pump, a Supra unit. One of these, which Tippo installed a while back:

https://www.rockauto.com/en/moreinfo.ph ... 56&jsn=877

I'm guessing I'll need a fuel strainer as well--one of these:

https://www.rockauto.com/en/moreinfo.ph ... 12&jsn=395

This weekend I have a 250 mile trip planned up into Pennsylvania. I'll leave the fuel pressure gauge installed out there during the trip, to use as a monitoring tool.


If you ever happen to make your way a little further to the tri-state area, let me know. We can probably do a mini meet if we can get Tecker on board.

As for the fuel delivery, closest to the rail is probably best to get the most accurate reading but sounds like you are close to where it needs to be.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby underscore » Thu May 12, 2022 2:03 pm

I'm not sure where the best spot to tap in is, I'm just hunting for options to add an easy way to drain bad fuel without risking a fuel leak either.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Thu May 12, 2022 4:23 pm

Ah, understood. I picked the top of the fuel filter as one of two options suggested in a recent thread about installing a fuel pressure gauge.

If you were to get a passthru Banjo bolt then attach a male to male 1/8” NPT fitting and rubber hose to the top of it and run it down, you could probably do it that way. In my case that would not work as the fuel system does not pressurize when the key is turned to the ON position. Perhaps a JDM ECU peculiarity.

I am learning stuff every day, which is both great and a little overwhelming.

I observed that residual fuel pressure gradually drops to zero after shutting down. It immediately drops from 32-34 to 29psi, then to to 26psi in ten minutes, and after an hour, it had dropped to 12psi. Some time between an hour and three and a half hours, it drops to zero.

Is this pressure loss and rate of loss typical?

If not, or if the rate of loss is higher than normal, perhaps my fuel system is compromised in some way and the 45psi max I observe under full load is not the fault of the fuel pump but the fault of the fuel system being unable to sustain pressure.
Last edited by Roreri on Thu May 12, 2022 8:16 pm, edited 1 time in total.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby grip-addict » Thu May 12, 2022 5:50 pm

It's normal to expect the fuel pressure to drop when the pump's not active. We have a return-style system, where the pump in the tank pressurizes the line (And with modified pump circuits, the pump always runs flat out at max flow). The fuel goes through the lines, hits the fuel filter, then the rail/injectors, then the regulator before making the return trip to the tank. The return's always open and available, and all the regulator does is just compress a diaphragm/spring to increase pressure downstream of itself. As long as you're getting your sensor feed before the regulator, that should be a good reading. And it would make sense that pressure would dissipate after the pump is no longer pressurizing the line.

It would be nice if you were able to determine how your fuel pressure compares to other gen2 3s owners. Possibly someone on mr2oc has it logged if it's not recorded here. I also wonder what your base fuel pressure is; you can see what it is by unplugging the vacuum line to the FPR while the car is idling and see what the pressure is. Or just do the fp b+ bridge when it's off. I don't think you need to do it as a troubleshooting step at this point though, I'm just curious.
Actually, down this thought process, do you have an air compressor? You could manipulate the FPR by putting varying pressures on it and seeing how the fuel pressure reacts. Maybe your fuel pressure DOES get to the target but it takes a while to get there. A steady-state amount of air pressure would help you determine that.

And just to hit one of the last convo topics - water injection just gets you free octane boost basically. It's a really neat concept but it's expensive to install. The best setups in my opinion inject water directly into each intake manifold runner, which obviously would not be fun to do on our cars :\ I miiiiight kick it around as an idea whenever my motor gets pulled for service, but I'd have to find a place to mount the tank. That, or just steal water from the windshield washer res.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Fri May 13, 2022 2:16 am

That's good to know about the fuel pressure slackening over time. So, nothing to worry about.

Fuel System Flowchart (Check for Confirmation):

I think the fuel system is set up like this:

Tank-->Sender to Fuel Gauge
Pump
Fuel Line From Tank-->Charcoal Canister
Fuel Filter-->Fuel Pressure Gauge
Fuel Rail
Injectors-->Cylinders
Fuel Pressure Regulator
Return Line to Tank

2Gen 3S-GTE Fuel Pressure:

Various forum discussions I've found regarding the 2Gen 3S-GTE say stuff like:

Ignition to ON position, but engine off: 33-38psi--I do observe this range when starting the car.
FP and B+ jumped Ignition to ON, but engine off: 33-38psi
Idle: 27-31psi, or 28-30psi--I observe 34psi, which is a little high. Upgraded fuel pump? Something else?
"Stock Fuel Pressure" (while under load?): 40-42.5psi
"pump running full blast and the engine off (no vacuum on the regulator)": 40-43psi


I'll check the base fuel pressure with FP +B and ignition to ON tomorrow morning.

Fuel System Limitations:

This is a good old discussion about max boost and fuel system limitations:

viewtopic.php?f=10&t=3059

Especially ChrisD's reply which seems pretty full of useful detail, provided his facts are straight.

Here is his opinion on Fuel Pressure: "It is VERY important to calculate fuel pressure by using base FP + boost pressure. Both combined contribute to pressure in the fuel rail due to the 1:1 FPR."

So, in my case: If my max fuel pressure is 42.5psi, then base of 34psi + 8.5psi boost is my limit. So...thought here...I'm only seeing 42.5 because I'm only achieving that much boost. If I achieve more, I'll see more pressure up to the fuel pump limit and the injector duty cycle. That might be DUH to the wise, but I'm just now grokking these concepts with the aid of instrumentation.

This observation from ChrisD is particularly telling because it seems to speak directly to my observations: "I think most people can run 12-14psi safely on the stock turbo, as long as everything is in good condition and they *pay attention* to how their car responds to the boost. If there is anything like hesitation, loss of power like its being "held back", stumbling, etc., you might not be able to run as much power."

So, whatever the case, it seems evident that I'm outrunning my fuel pump or injectors when I try to go for the higher boost levels. The Blitz Twin SBC can boost beyond the setup's limitations. I observe plenty rich conditions. Low 11s under full load at up to 8.25psi stock boost (sometimes it will give me .64kg/cm2--9psi).

Here is a representative full load onramp run: https://youtu.be/Sr-txGnDAgE

Full rich (11.3:1) under stock 8.25psi boost at 5000rpm. 42.5psi fuel pressure. I think my base is 34psi. That's what it sits at on the gauge at idle. Which suggests something, because all the discussions seem to center around 30psi as the base for a 2Gen 3S-GTE. Upgraded fuel pump? Different FPR?

I could perhaps adjust the "high" boost setting (the Blitz Twin SBC has a dial knob for the "low band" and "high band") down to like 12psi and see how it does.

US 93 octane E10 fuel is almost certainly sucking for the JDM ECU which is probably always asking in its silent little digital Japanese voice: "Why you cheap out on gas, asshole?"

Fuel Pressure Regulator

I found this an interesting and informative article and video from Haltech discussing the Fuel Pressure Regulator:

https://www.dragzine.com/news/under-pre ... ith-boost/

Water/Meth Injection

Look...any time I think about being able to say "This car is on meth" with a straight face it makes me giggle. There's gotta be a bumper sticker. Plus, for whatever reason I'm not attracted to an FMIC. So, water/meth injection to achieve proper octane and correct IATs seems like a fine approach to mitigate U.S. gas octane deficiencies and get the most that I want out of this car: Stable 14psi boost, which is the limit of turbo efficiency and probably coming close to the advisable limit for stock 30 year old internals.

Though to be honest I have no idea about the engine build. Could be stock. Could be forged pistons and uprated injectors. Though why would anyone do that and keep the TMIC?

The stealing water from the windshield washer idea for a water/meth injection kit is of course classic. It is quality discourse like this that I come here for. Because most videos show people installing their tanks in the rear compartment and the pump in the spare tire well and running a line up through the cabin and through the firewall and yaddayaddayadda YAWWWWWNNN. Stealing from the windshield washer bottle you can use the blue 30/70 mix stuff too. If you have no ABS, there's some room there at the front right corner, too, that could fit a tank and pump.

I agree that a direct to manifold approach would be best, but God what a PITA. F that. From what I've read the best approach without going full manifold is to inject as far from the throttle body as possible on the engine side of the TMIC--so maybe actually on the intercooler outlet. Or...just skip the TMIC and let the water/meth do the charge cooling.

I wanted to know more. So I watched this: https://youtu.be/SgzDRaa4xLc

My takeaways: Water/Meth injection lowers charge temperatures and increases octane making higher boost possible. But it riches out the air:fuel ratio overmuch, sapping power. So, a tune might be necessary, to take fuel out to compensate for that. Might be possible to spray a little water/meth and get away with not having to do a tune, though. My goals are modest: Stable 14psi boost, elimination of possibility of detonation.
Last edited by Roreri on Fri May 13, 2022 3:15 am, edited 1 time in total.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby grip-addict » Fri May 13, 2022 2:58 am

Roreri wrote:Ignition to ON position, but engine off: 33-38psi--I do observe this range when starting the car.
FP and B+ jumped Ignition to ON, but engine off: 33-38psi
Idle: 27-31psi, or 28-30psi--I observe 34psi, which is a little high. Upgraded fuel pump? Something else?
"Stock Fuel Pressure" (while under load?): 40-42.5psi
"pump running full blast and the engine off (no vacuum on the regulator)": 40-43psi


I'll check the base fuel pressure with FP +B and ignition to ON tomorrow morning.

Are the running numbers with the vacuum hose still attached to the fpr? When at vacuum, the fuel should have less pressure than the "base" pressure. Base pressure is whatever the fuel pressure is when the pump is in high-voltage mode and when the FPR doesn't have any vacuum applied to it.

ChrisD wrote:Here is his opinion on Fuel Pressure: "It is VERY important to calculate fuel pressure by using base FP + boost pressure. Both combined contribute to pressure in the fuel rail due to the 1:1 FPR."


The idea is that after the intake manifold starts seeing positive pressure (something an NA car will never experience), there would start to be resistance pushing back on the injector. Adding 1psi of fuel pressure for 1 psi of boost solves that as the ratio of base pressure to manifold pressure should stay the same. It makes math calculations easy for the ECU and the injector doesn't have to stay open longer than it would normally need to (if fuel pressure didn't increase, that would be the requirement, and there is definitely a finite amount of time an injector can stay open, thus limiting power/safety/etc of an engine).
Modern ECU's that track fuel pressure can overcome deficiencies like this and keep the injector open longer than the map calls for if they see a lack of fuel pressure. Unfortunately, that wasn't a capability when our cars were manufactured.

Roreri wrote:Here is a representative full load onramp run: https://youtu.be/Sr-txGnDAgE


Video's private. Don't worry, I make this mistake too lol.

Roreri wrote:US 93 octane E10 fuel is almost certainly sucking for the JDM ECU which is probably always asking in its silent little digital Japanese voice: "Why you cheap out on gas, asshole?"


E10/93 Would be safer for the car to run than E0/93 since the ethanol keeps the burn a bit cooler. Don't beat yourself up that you're not putting in zero ethanol gas.

Edit - I watched the Haltech video. Scott does a much better job explaining fuel pressure differential than I did 8)
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