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Discussion Starter #1 (Edited)
Hello all,

Let me start by saying that I purchased my first MR2 about 2 months ago. I got an MK1 '88 Supercharged model. As far as I know the only after market things are HID lights, fuel pump & radio/speakers. Prior to this I owned a Toyota Camry & a Chevy Cavalier having a minimal amount of knowledge concerning cars and not really caring to have any more. Long story short, somebody crashed into me totaling my Cavalier, my roommate, being an MR2 enthusiast found one online and told me to get it. Needless to say, once I had it, I fell in love.

Now, my car being as stubborn as it is, decided to come with a few issues. Having minimal knowledge on cars, I am going to try my very best to explain in detail the issues I have been experiencing to give the most insight into my problems since my lack of knowledge hinders my ability to hone in on one individual cause.

Apart from needing a paint job, a new exhaust & a few electrical issues(lights); my main concern was an idle issue it was having. The issue was not consistent but was definitely persistent. Upon starting the car it would idle at 14.5V and after heating up the idle would begin to waver. It would fall begin to fall down to about 500 RPMs, the car would sound like it was about to die, it would catch itself & shoot back up to about 1500 RPMs and then continue in that cycle. Once in gear there were no issues with the RPMs & would run smoothly until back in neutral. My speed did not matter either. I could throw it into neutral while traveling 45 MPH and the problem could continue and my car would die on me.

As I said earlier my roommate is an MR2 enthusiast and owns one himself. He carries quite a bit of knowledge in the area of cars has been very helpful in fixing all of my issues since I've had the car. After doing a bit of research he came to the conclusion that he thinks my idle issue may be the result of my IC Regulator. We replaced my regulator using the regulator & directions suggested in this thread http://www.mr2oc.com/showthread.php?t=433856. However, when we did this my car began to run at only 12V & after driving for a while my battery died on me. I put the old regulator back on and after only a short time the "three lights of death" appeared on my dashboard & my car began running at 18V. I quit driving it at this point, put the Honda regulator back on it & it is back running at 12V again. However, the three lights of death went away.

I'm not too sure where to go from this point nor whether these two issues are even related. Either way, any amount of insight would be greatly appreciated.

Sidenote: The previous owner installed an after market fuel pump which is very loud & seems to wind up & down as the voltage is rising & falling with the RPMs. I am not sure if the before is causing the latter or visa versa.

Thank you all so very much.

Cliffs :
1. When in neutral car has the possibility of teetering between 500-1500RPMs and then dies on me
2. Tried replacing IC Regulator
3. Put on Honda VR 180 Regulator & car only ran at 12V then died on me
4. Put Toyota regulator back on & three lights of death appeared and began running at 18V
5. Put Honda regulator back on, car is running at 12V again, three lights of death are gone
6. Thanks:):)


Update 3/7/14:
Alternator was bad. I think I might have broken it in the process of replacing the IC Regulator. I got a new alternator & it is working again. I have it running with the Honda regulator & it is idling at 14.5V like it was originally before I replaced anything. So it seems that the Honda regulator is running just as efficiently as the original, but the voltage is still running high & the surging idle problem is still there.

Update 3//26/14
Fixed my exhaust. Surging idle problem has gone away.
 

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You need to change the wiring to use the Honda regulator. Did you do that? At any rate, it appears that neither regulator is working.
 

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Discussion Starter #3
Yes, I repinned it so that the wires matched up properly with the same letter they were wired to on the Toyota regulator.
 

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I suppose that there could be a problem with the wiring. If the alternator can make 18 volts, then it is unlikely that the problem is there. It sounds like your original regulator is bad and the Honda one is either bad, the wrong unit, or is somehow hooked up wrong. After inspecting the wiring again, I would get a new OE regulator and try to get the system back to original configuration.
 

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Dude,

There exist alternator/starter repair places. Hopefully there's one near you; you can take your alternator there and they can test it for you and tell you exactly what's going on.



- Chester
 

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Discussion Starter #6 (Edited)
Update :
Alternator was bad. I think I might have broken it in the process of replacing the IC Regulator. I got a new alternator & it is working again. I have it running with the Honda regulator & it is idling at 14.5V like it was originally before I replaced anything. So it seems that the Honda regulator is running just as efficiently as the original, but the voltage is still running high & the surging idle problem is still there.


Thanks
 

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Surging idle usually gets people screaming at you to bleed the cooling system and get all the air bubbles out.

So, have you bled the cooling system with the heater on so that the heater core gets bled too?

Surging idle can be caused by air bubbles in the coolant that get trapped by the temp sensor for the ECU. One second its at temp the next its not, then it is, then it isn't. That is what can cause the idle to go up and down. Drops too low and stalls the engine.

Also 14.5V is normal for an alternator to push out. your battery just sitting with the car off should have over 12V. Usually 12.4V or so. The alternator pumps out more voltage because it runs the electronics and charges the battery.
 

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Discussion Starter #8
Yes I have already bled the cooling system with the heater on. I will check again for possible vacuum leaks.
 

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The SC has tons of vacuum lines. You MUST check every single line and you must make sure every line is routed properly! Do a search and you will find a 'vacuum line diagram" for the SC. With any car that is having your problems you must first make sure you are having absolutely no vacuum leaks of any kind through out your engine bay. This is by far the most common problem with the issues you describe, the other being....air in the cooling system. The Haynes Manual (read the Troubling shooting section) and the BGB are the best friends you ever had. Start reading them. Good luck.
 

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If you're going to drive an antique car
having a minimal amount of knowledge concerning cars and not really caring to have any more
is going to be very expensive, very fast. They are incredibly reliable cars, but unless you are lucky enough to find a Toyota dealership with someone that has actually worked on one be ready to pay for their learning curve.
 

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Surging idle on my sc was a bad O2 sensor, not air in the coolant. Eventually thru a code but not initially. You didn't say what elect. problem with lights was, but a bad headlight switch is common, which is fixable.
 

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Discussion Starter #12 (Edited)
Surging idle on my sc was a bad O2 sensor, not air in the coolant. Eventually thru a code but not initially. You didn't say what elect. problem with lights was, but a bad headlight switch is common, which is fixable.
Interesting, thank you so much for pointing that out. I have a huge hole in my exhaust right next to the O2 sensor, so that definitely sounds like it may be contributing to the problem or be the entirety of it.

Also, as far as electrical, my tail light fuse keeps blowing as soon as I turn it on. Headlights still work. I lose my dash lights, running lights, tail lights & the flashers on the front sides.
 

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Discussion Starter #14
I have fixed my exhaust & the surging idle problem seems to have gone away. Car is running smoothly now. Car is still running at 14.5 V but no issues seem to be surfacing from this.
 

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Your car is supposed to be 14.5 volts. The battery is ~12, but it takes more juice to charge it. Glad you're up and running.
 

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Like you, I recently got through an alternator issue, which I thought was an issue with my wiring to my honda regulator, or the honda regulator itself.

This:
I put the old regulator back on and after only a short time the "three lights of death" appeared on my dashboard & my car began running at 18V. I quit driving it at this point, put the Honda regulator back on it & it is back running at 12V again. However, the three lights of death went away.
exactly happened to me too.

In fact, I had two spare Toyota regulators that I swapped in that was showing the same thing as yours. I re-wired my harness to allow going back from the Honda to the Toyota ICs, but was disappointed after seeing them go straight to 18Vdc and the 3 lights of death light up on the dash. I nearly threw them both in the dumpster.

I'm glad I didn't because, the auto electrician I had look over the car found an issue with faulty wiring inside the cabin, which was the true cause and unrelated to the honda regulator (or even my sub-standard cut 'n splice job at the connector harness) that I had been running.

To get to the point, the electrician determined that my two spare Toyota ICs were good. He figured out that I had only been plugging the connector to the regulator and did not mount it back to the chassis with the nut/bolt. He explains that if it was not mounted to the chassis, then the alternator will indeed go to 18vdc. To prove his point, he mounted it correctly then connected the connector and was reading 13.4 to 13/5v at the battery while the engine was idling and revving. This was also true of the second Toyota spare.

My honda regulator, on the other hand, had always been putting out a range of 14.5 - 14.7v, I guess depending on the state of charge of the battery (I've been watching the charge voltage closely since installing my lightweight car battery a little over a month ago.)

Cliff notes:
Toyota voltage regulator runs at 13.4 to 13.5v. (two spares putting out identical voltage)
Honda regulator runs at 14.5 to 14.7v (ran more than a month without issue until alt burned out due to oil leak from dizzy)
 

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Relative to the rear lights fuse failure a Tail Light Relay function test would be smart start.
There is a problematic, poorly enginnered junction box (#3) a bluish box located under the dash, look for the solid green wires at Junction Box #3 (#3E terminal 9-front)(#3C terminal 15-rear) and do continuity tests between these and the bulb holders and see about wire integrity. The ID of the #3 junction box is located on Page 16 of the Toyota Electrical Service Manual.

Your dash lights are all routed thru this POS #3 relay as well. Discounting a bad Rheostat (which is usual) the dash lights use #3I terminal 3 if you don't have 12v here it's a junction box problem.

Your front flashers use the "A" ground in the front trunk on the pass side fender. Check it for a good ground then check for 12V when flashers are activated.

Electrical trouble shooting is not easy, nor for the lazy. If you don't or can't understand the BGB electrical manual schematics man up and get a professional involved.

Most folks on this forum use the "crap against the wall method". And from the posts above you can understand the results they get.
 
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