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Discussion Starter #1
Hi everyone, I’ve owned a MKIV non turbo car for a very long time now, about 5 years ago the car shut off while driving and after much troubleshooting, the ECU was the culprit. Ignore the W57 handwriting below. Car is a W58 5 speed car.

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Currently the car is running, driving on an AEM v2 stand-alone.

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I sent the original ECU off for repair to a company I found on eBay many years ago when this happened but that ECU even after repair will not crank the car. I need a name for a company that specializes in 2JZGE or GTE repair.

I also have not one, but two spare 2JZGE ECUs, both of which crank the car but it runs really bad as if no MAF sensor is connected.

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I’ve made posts here before about this but I’m trying to go into much detail this time.

The AEM has always given me problems if the car sets up for awhile on a battery tender. Yesterday the car wouldn’t crank on the AEM again. While it’s attempting to crank it feels or seems like timing is off. Normally what I do in this situation is hook up my laptop and re-upload my calibration and after turning the key off and on again, the car starts fine with the AEM. I tried to crank the car so many times but it would not fire.

Yesterday I instead yanked out the AEM and tested all the ECUs again. OEM ECU doesn’t crank it. I test my two spare GE ECUs and the crank the car immediately but it runs like shit and goes dead unless your giving it gas. Like the MAF is unplugged on a perfectly working car.

I put the AEM back in and the car after testing three different ECUs it now cranks and drives fine. I honestly didn’t even bother unhooking battery because I’m pretty fed up with the car and the AEM. I never grabbed a laptop or did anything other than swap ECUs.

I’ve contacted AEM they’ve told me the ECU shouldn’t lose its calibration. I believe they attempted to blame the battery tender but I’ve used several over the course of the last decade. If the battery goes completely dead the AEM will not crank the car useless I reupload the cal.

In addition to a trusted company that repairs factory ECU I’m interested in a company that does remote AEM tuning to check my setup.

I have been slowly building a stockpile of turbo parts and I have all the components at this point to turbo the car but I honestly trust my shit box MK3 more than I trust my immaculate 90k mile 2 owner MKIV.

1. repair factory ECU 2. AEM remote tuning.
 

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I would not worry about stock ECU’s, this is kind of a “well no duh” comment, but I would put all of my effort in the AEM. Far more worth your time.

Are you sure you don’t have some kind of weird grounding problem/something electrical that is causing all of these issues?
 

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This is just a side note, something to think/look at- i run Infinity 6, and recently i had issues of the engine cranking but stumbling and wont stay running, i was mystified, i checked everything , except one thing, and the reason and the way i found out, was , it kept giving ' no sync' under crank sensor/cam sensor, which are all brand new, while i was replacing my lower water neck , to clear the single turbo, i i noticed the crank sensor plugs one of the wires (2 of them only) was hanging on by one single wire strand, since the wiring harness is old, they become brittle and crack, i would have never found this if i did pay careful attention, to all connections , i re soldered it and shrink wrapped it and boom, it fired up

I'm hoping you don't have any hidden broken wires, or even the pigtail pins falling off, or coming out of its rubber seals
but i would check all main sensor plugs and wiring, even under the factory shrink tubes and insulation, the best way is to run a continuity test, not like me, where i spend weeks, feeling for broken connections buy pinching and touching the wiring, waste of time, i just got lucky this time. So , i would suggest, pay close attention to all signal wires, MAF plug, crank sensor, air temp, coils wire, distributor cover and rotor, if its got one, and so on.
 
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2 things high level.

Plugging, unplugging over and over the ECUs... you might be revealing a weak wire in your harness near the ECU. If the stock ECUs run, but badly, and then the AEM runs okay again, with no changes, it sounds to me like something is loose/grounding/broken/weak/rotted somewhere.

I use a battery tender on all my cars here without issue.

The AEM losing its config reminds me of a problem we had with our old SC400. The battery would always die about every 1.5 days. It got old jump starting it. What I finally figured out was the instrument panel light was being left in the ON position for the dome light , that little indent, but wasn't actually turning the dome light on. It WAS however draining the battery.

This leads me to think you might have some weirdness in the harness for the AEM that's making it reset or corrupt, or maybe even a bad ground.

And I like your shitbox MK3 :ROFLMAO:
 

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Discussion Starter #5
Electrical:

I’m running the powerhouse 150 amp alternator and I’ve replaced the leads from alternator to fuse box to battery with heavier gauge. I did all of that because of headlights dimming when subs hit.

Car has multiple amps and a cap on a separate circuit breaker that I have not turned on for many years to rule out stereo wiring. The circuit is disconnected to all that and I’ve checked it with multimeter, no voltage.

I’ve talked to AEM several times about the way it behaves and I’m pretty sure they tried to blame the battery tender each time.

I hear everything you guys are saying. You could eat off of the engine it’s so clean. None of my factory wiring is brittle.
 

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Discussion Starter #6
I sent the factory ECU to Relentless in TX for repair. I’m done with the car and want to unload it.
 

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^^ I am also chiming in to recommend Tanin Auto Electronix. They have their main office in Racine, Wisconsin and they have a relatively new satellite repair center located in San Diego. You can ship the ECU to either one.

They have done excellent work for me servicing three stock SC300 ECUs and one USDM 2JZ-GTE ECU. They're top notch and very professional and will go out of their way to help get your ECU in good shape again. And they use the correct type of capacitors these ECUs require (very important).

Driftmotion in Montclair, CA has also historically done ECU repair services but at the moment I think they are still on ECU repair hiatus status so go with Tanin.
 
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Another issue to keep in mind, even after the repair is complete which generally is replacing the capacitors and working around board damage, if any, there can be other portions of the ECU that are not just right.

Very few, if any, have the ability to test these ECU’s post repair to make sure each section of the ECU is functioning normally.

With that said, while improvement will be had, the chance is there that issues can still exist.
 

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Discussion Starter #11
Another issue to keep in mind, even after the repair is complete which generally is replacing the capacitors and working around board damage, if any, there can be other portions of the ECU that are not just right.

Very few, if any, have the ability to test these ECU’s post repair to make sure each section of the ECU is functioning normally.

With that said, while improvement will be had, the chance is there that issues can still exist.
I think you’ve probably hit on my problem right here. Two caps and two diodes were replaced I know but we’re the traces repaired, etc. I’m aware it may not be possible to have the OEM original ECU repaired. I’m always on the hunt for one and I’ve been watching some of relentless’s work they seem incredibly detail oriented. We’ll see, they received it today.

Ive ramen the car off the tender and I’ve been cranking every few days rn with the AEM no problems so far. When it stops firing and doesn’t throw CEL is usually when I bring out my laptop and recalibrate. I’ll keep the thread open.
 

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^^ I am also chiming in to recommend Tanin Auto Electronix. They have their main office in Racine, Wisconsin and they have a relatively new satellite repair center located in San Diego. You can ship the ECU to either one.

They have done excellent work for me servicing three stock SC300 ECUs and one USDM 2JZ-GTE ECU. They're top notch and very professional and will go out of their way to help get your ECU in good shape again. And they use the correct type of capacitors these ECUs require (very important).

Driftmotion in Montclair, CA has also historically done ECU repair services but at the moment I think they are still on ECU repair hiatus status so go with Tanin.
Just emailed driftmotion. Per arron he doesnt plan on continuing ecu repair service 😢
 

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Discussion Starter #13
Just emailed driftmotion. Per arron he doesnt plan on continuing ecu repair service 😢
that sucks but I can understand why. It’s not sales/revenue, it’s payroll and expertise and no way to test or expensive testing equipment. Makes sense repair shops are disappearing
 

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that sucks but I can understand why. It’s not sales/revenue, it’s payroll and expertise and no way to test or expensive testing equipment. Makes sense repair shops are disappearing
Yup Definitely a bummer. He said it was getting unhealthy because of the lead solder and too many people sending in unrepairable ecus.
 

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I'm currently on the hunt for an ECU repair shop as well. I have a 94 JDM non turbo 5 speed and my idle has been all over the place. Cold start it's at 2,000 rpms and when it warms up it stays between 1,700-2,100. After it warms up it'll start fluctuating 500rpms. The weird thing is that after I turn it off for about 10 minutes and start it back up, it goes to about 900 rpms consistently with no issues. It stays like that the rest of the day. Checked all vacuum lines and IACV and see no issues. Hesitant to fix the ecu but if it's going to cost 400+ I might as well just get a standalone...
 

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I'm currently on the hunt for an ECU repair shop as well. I have a 94 JDM non turbo 5 speed and my idle has been all over the place. Cold start it's at 2,000 rpms and when it warms up it stays between 1,700-2,100. After it warms up it'll start fluctuating 500rpms. The weird thing is that after I turn it off for about 10 minutes and start it back up, it goes to about 900 rpms consistently with no issues. It stays like that the rest of the day. Checked all vacuum lines and IACV and see no issues. Hesitant to fix the ecu but if it's going to cost 400+ I might as well just get a standalone...
THeres a slew of ecus on ebay if you wanna gamble. I believe the part number is 89661-14610. Im pretty sure being jdm your open to more cross compatibility(not sure on this). But theres a couple going for US398$. Hope this helped.
 

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I'm currently on the hunt for an ECU repair shop as well. I have a 94 JDM non turbo 5 speed and my idle has been all over the place. Cold start it's at 2,000 rpms and when it warms up it stays between 1,700-2,100. After it warms up it'll start fluctuating 500rpms. The weird thing is that after I turn it off for about 10 minutes and start it back up, it goes to about 900 rpms consistently with no issues. It stays like that the rest of the day. Checked all vacuum lines and IACV and see no issues. Hesitant to fix the ecu but if it's going to cost 400+ I might as well just get a standalone...
THeres a slew of ecus on ebay if you wanna gamble. I believe the part number is 89661-14610. Im pretty sure being jdm your open to more cross compatibility(not sure on this). But theres a couple going for US398$. Hope this helped.
And from what im reading seems like repair or capacitor replacement only works 30-40% of the time. So i bought two used ecus if those crap out im going stand alone. Good luck man!
 

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Discussion Starter #18
Relentless has had mine for a week or two but I haven’t received a quote yet. SIA Electronics on eBay “repaired” mine in August of 2018 but the original ECU hasn’t cranked the car before or after repair.

I chose Relentless based on Facebook feedback and following them for some time. They really do seem relentless in terms of repairing traces, etc. -14700 is the PN I’m looking for if anyone ever sees one.

I cranked the car the other day after NOT leaving it on the battery tender and revving the motor made all the lights in the car get brighter/dimmer based on RPM. I put the car back on the tender, haven’t cranked it again since. It’s the first time I’ve ever noticed that where the the dome and instrument lights getting brighter by revving the motor. I’ve checked the voltage coming from the alternator in the past 6 months and it was 14.7v IIRC but I haven’t checked it recently.

Ive suspected the PHR alternator for awhile because the ECU and airbag sensor have both burned up after installing that alternator but we’re talking a timespan of 5-7 years with the car just sitting up in storage.
 

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^^ Is the voltage regulator integrated into the alternator on our cars? Your bright/dim based on RPM sounds like a regulator. Also, in HS I had a 73 Dodge Charger that had the standalone voltage regulator go out. It went out gradually though. Some days it was fine, other days you'd be driving and the battery light would come on, and eventually it wouldn't crank.

Replacing the regulator fixed the problem. The alternator itself was fine.

Just a thought.
 

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Discussion Starter #20
^^ Is the voltage regulator integrated into the alternator on our cars? Your bright/dim based on RPM sounds like a regulator. Also, in HS I had a 73 Dodge Charger that had the standalone voltage regulator go out. It went out gradually though. Some days it was fine, other days you'd be driving and the battery light would come on, and eventually it wouldn't crank.

Replacing the regulator fixed the problem. The alternator itself was fine.

Just a thought.
Yeah the bright/dim thing is new I’ve never noticed that before. I’ll do some research and testing with a multimeter
 
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