RORERI: A JDM 1992 ST185H-BLMVZ

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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Mon Aug 08, 2022 11:37 pm

That's excellent to hear--thank you for the reassurance.

As far as wetting the o-rings, I do not know where this advice comes, except perhaps to provide the slightest of protections against gasoline entering the rubber and causing damage?
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby alltracman78 » Tue Aug 09, 2022 2:42 pm

Best bet is to lube with gas. Oil residue will attract dirt. Gas will evaporate. And these seals are designed for gas. You lube so it slides in easy. Less chance of tearing/damage. SOP for any seal.

Roreri, FYI your car is a 92 for parts reference. I'm going off your ECU, which is a post revision ECU (has the second circuit board, which adds better diagnostic capabilities). Built between Sep and Dec 91. In Japan it was considered a late 91 model, which has some different parts than an early 91 model. In the US it would just be a 92 model. So if you need a replacement ECU you need a 92/93 one. Not a 91, which has different pinouts.
Same reason most (all?) of the ST185RC cars are 91 model years but actually have all the revisions for the 92 model year.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Tue Aug 09, 2022 11:27 pm

Good to know about the fuel injector o-ring wetting--gasoline it is!

Also thanks for the confirmation about the ECU. I've got to get the original GT-Four ECU (Toyota 89661-2B280) on the bench and see whether I can correct the solder job someday, once I'm more settled in.

I sent the injectors to Fuel Injector Specialists--I hope to have them back by the end of next week, and then I'll know whether I need to continue down the list.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Sat Aug 13, 2022 12:25 pm

As it seems likely that the Lorelei’s performance issue stems from clogged injectors, bad fuel pump, or bad fuel pressure regulator, would it be sound to change out the fuel pressure regulator while I’ve got the motor open and part way disassembled? Would give less satisfaction of knowing what the issue was for sure but greater chance of success.

Thoughts on OEM equivalent or upgrade part?
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby grip-addict » Sat Aug 13, 2022 1:36 pm

The hardest part of running an aftermarket fpr is running the fuel lines. It's not super difficult, but it's important to get to get to right, because, well, fuel.
You would also need a gauge so you could set the base pressure; and the goal is to set the pressure the same as factory unless you want to richen it up a bit (could help with the lean issues).

I would think the main goal would be to just make sure whatever for you run actually works and raises fuel pressure as boost increases.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Sat Aug 13, 2022 2:05 pm

I do have a fuel pressure gauge that I can hook into the top of the fuel pump or the fuel pressure regulator then snake out through a side vent and mount where I can see it. I can try that again—from after the fuel pressure regulator this time—and see.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby grip-addict » Sat Aug 13, 2022 3:18 pm

Ahh see I say you need a gauge because an adjustable fpr will need to be configured to provide the correct pressure. You can even use one of the simple on-fpr gauges for this activity.
Once it's set, you shouldn't need to mess with it again; but having a gauge to see what's actually happening is always nice.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Fri Aug 19, 2022 1:47 pm

I spoke to Chuck at Fuel Injector Specialists yesterday to just sort of check up on how things were going. He said he’d get to them maybe yesterday. He noted that sometimes these stick or have problems when they’ve been sitting for a long while. The Lorelei could have been sitting for a long while, indeed, before I bought it. It could be that over the last year of running it, stuff has come loose and got in the works. He related that the side feed Densos are an old style he doesn’t see too often. I know a lot of allTrac pilots convert to a top feed rail and more modern injectors.

We got to chatting a bit and I related that I was more or less just going down the list of possible causes because no CEL and pre-OBD2. I mentioned fuel injectors, fuel pressure regulator, and fuel pump and he replied his guess would be fuel pressure regulator.

So, given that I have the fuel rail out and the throttle body off, I’m going to just get a fuel pressure regulator. That will sort out the possibles on the motor side of the fuel/ignition system. I’ll get to searching today after work. If anyone has any advice I’d be grateful.

EDIT: Either an OEM Toyota 23280-74070 or aftermarket equivalent was elusive. I didn't find one I trusted enough to pay for.

I saw the Turbosmart Fuel Pressure Regulator. Any opinions on this unit?

https://www.summitracing.com/parts/tbs- ... ZkQAvD_BwE

Or, say, this DeatschWerks unit:

https://www.summitracing.com/parts/dwk- ... 5QQAvD_BwE
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Wed Aug 24, 2022 3:06 am

I got my injectors back from Fuel Injector Specialists in a pretty timely manner. The before and after pictures don't suggest that they were very clogged or dirty. They flow tested within 7% of each other--one of them is flowing a bit more than the others.

I got on reassembling everything tonight, and am proud to say that once it was all back together, it started! It took a bit of effort to get it started as I had to build up pressure in the system, but start it did. I put a fuel pressure gauge on, tapping from the fuel filter banjo bolt as before. No fuel leaks.

Didn't have time to do a road test tonight--that will have to wait until tomorrow after work. I suspect that some other factor is the cause of the Lorelei's performance issues, though. I did not install a new fuel pressure regulator.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Thu Aug 25, 2022 2:25 pm

Took the Lorelei out on a check ride this morning.

The fuel pressure gauge indicated 10psi residual fuel pressure remaining from the last time the fuel system was pressurized over a day ago, which I took as a good sign.

The motor started right up but idled low. I had removed the throttle position sensor to test it and perhaps didn’t remount it exactly where it should be. Fuel pressure at idle was just shy of 30psi.

I backed it out of the garage and observed some very rich conditions, like down to 10:1. I started the check ride and observed just shy of 30psi to 32psi (variable depending on throttle) and 15.5:1 afr as I eased out of the neighborhood.

As I pulled out onto a larger road I gave the motor a little gas and it hesitated, then kicked in, giving 6psi boost and 38psi of fuel pressure. At spec 32psi plus 6psi boost 38psi is exactly what I should see.

I settled into steady state “normal car” driving in traffic at 0psi boost and observed 29psi and 15.5:1 afr.

At the next stop light I accelerated under light boost (3psi) and sustained acceleration. I observed the fuel pressure drop gradually to 20psi. I thought this could be the fuel pressure regulator not doing its job or the fuel pump not keeping up with demand.

Under “normal car” driving conditions all is well. As long as I drive it like your normal gutless car all is well.

I was able to open it up on an expressway on ramp, and observed that though I can achieve boost, fuel pressure drops until fuel starvation occurs.

No smell of fuel in the engine compartment when I got back home, so I deem all of my fittings and connections are sound.

I’ll fiddle around with the throttle position sensor when I get home today after work to see whether I just screwed the pooch on that. And if that doesn’t (miraculously) fix the issue then it’s onward to fuel pressure regulator or fuel pump.

Onward and upward!
Last edited by Roreri on Thu Aug 25, 2022 4:01 pm, edited 1 time in total.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby simple » Thu Aug 25, 2022 2:42 pm

Cool!

TPS should have paint marks on factory setting. Not something you want to mess with. Taking the throttle plate off shouldn't have done much. Check your vacuum hoses.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Thu Aug 25, 2022 4:07 pm

There’s yellow paint on the screw but not on the throttle body so nothing to index to. I didn’t notice that ahead of time and didn’t index it, so…whoops. It will be trial and error, but I’ll figure it out. By the time I got home on the check ride the ECU had adjusted and the motor was idling right so it’s not egregiously off.

I’ll hit the motor with carb cleaner for vacuum leaks tonight too, thanks for the reminder. I’ve been checking and it’s not been that so far at any previous time.

On vacuum: I’ve noticed that at idle I only get 40cm Hg at 7200 feet elevation as opposed to 55cm Hg at sea level. Is that in line with what you observe here in Colorado?
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Gert » Fri Aug 26, 2022 5:36 am

I suppose you have the details how to adjust the TPS? If not, I have an BGB.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Fri Aug 26, 2022 10:05 pm

Thanks Gert! I have the BGB and know the "right way" which involves feeler gauges and checking impedance.

I didn't do that. I resorted to gross adjustments of the TPS, loosening the screws and rotating it first counterclockwise full which did not get a satisfactory result (excessive stalling), and then clockwise as much as possible which was fine.

But it didn't solve the problem. That doesn't mean that the Throttle Position Sensor isn't bad, though. I decided to just get a new Throttle Position Sensor. $22 was more cost and time effective than going and buying feeler gauges and uninstalling it, and testing, and so on.

Toyota 89452-12040 Throttle Position Sensor.JPG

In addition, I discovered that my work and moving things about caused a coolant leak. Nothing major, but also not one of the three lines going to the throttle body. And also imperative to correct. So, now I have to lock that down. So there's my Saturday morning after coffee project.
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Re: RORERI: A JDM 1992 ST185H-BLMVZ

Postby Roreri » Sat Aug 27, 2022 4:20 pm

As I know people will be curious, here is a report of the work that Chuck at Fuel Injector Specialists did for me. As pictures will tell the tale:

Before and After Servicing Fuel Injector Specialists.JPG

On the left is the before situation.

Spray Pattern: As can be seen, the spray pattern is pretty healthy. If anything, that #4 injector on the right has a little impingement that maybe that is reflected in a forked spray pattern right out of the injector but this resolves into a nice cloud of fuel immediately.

10 Second Static Flow Test at 42.5psi: 78cc of fuel remains across all injectors--performance is consistent.

30 Second 25/75 Duty Cycle Flow Test: Here, performance is variable, with the #1 injector trailing a bit, and #2, #3, and #4 performing pretty evenly (within 5.5% of each other).

On the right is the after situation.

Spray Pattern: Looking good.

10 Second Static Flow Test at 42.5psi: 75cc of fuel remains across all injectors--performance is consistent and 4% more flow compared to before servicing. 450cc/minute, 44.1 lbs/hr.

30 Second 25/75 Duty Cycle Flow Test: Performance is still variable, but the #1 injector is trailing a bit less. #2, #3, and #4 are more consistent (now within 2.8% of each other).

Inductance Testing:

Inductance.JPG

So, here's maybe why that #1 injector is trailing a bit in performance: It is slightly out of spec. These should--per the BGB--test out at 2-4, and that #1 is ever so slightly out of bounds. The others are right at the line but are giving proper service.

Did it stop me from putting them back in? No. I was curious to see whether I had cured the Lorelei's performance issues. But I could probably settle matters to my better satisfaction by sourcing and installing better and more modern parts--perhaps a top feed rail and higher throughput injectors.

As for why this is the case with injectors that have seen less than 50,000 miles? Your guess is as good as mine, but they are 30 years old, and saw some disuse over some years.

In any case, if you want your injectors serviced, Chuck at Fuel Injector Specialists will take care of you and give you the data to make an informed decision about how to proceed.
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