Kain
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[BNE] Intermittent Poor start/Rough running - undriveable
Hi all, A few months ago I pulled the engine from my MR2 and a did a bunch of maintenance (timing belt, clutch and all that fun), and now after putting everything back together it won't run properly! My mechanic has been tracing the fault around and believes that it's the ECU, but he hasn't been able to find a known-good one to test the theory. Does anyone in Brisbane (preferably north side) have a spare ECU to suit a 3SGE in a 1991 SW20 that I could borrow to confirm the diagnosis? If it does prove to be the problem, I definitely wouldn't mind buying off you either :P Thanks!
post edited by Kain - 2016/09/07 11:11:12
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BEN77
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/06 21:57:57
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hi kain, the forum is a good place to start. contact me if your still stuck.
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Kain
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/07 10:11:09
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Thanks Ben, I've made progress but I'm still stuck! I'd posted up a bunch of details on the Brisbane MR2 facebook page, but only got fairly general advice so far. I'll copy-paste it here soon.
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Kain
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/07 10:35:59
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Okay, I managed to borrow an ECU off Monty, but it wasn't compatible with my car (the engine wouldn't even try to start). However, many of the strange symptoms that pointed in that direction originally have been sorted after finding the alternator not properly connected in the fuse box. I've still got a confusing set of symptoms: - The car will sometimes start okay and idle, particularly when it's been off for >1min
- Otherwise, the car will start poorly, idle for a few seconds while stumbling & missing then stall, most often if it's started right after it was shut down
- If it does manage to idle, giving it part throttle makes it stumble & miss, and the tacho bounces around randomly
- Giving full throttle brings the revs up okay with just the odd miss, but the missing and tacho bouncing comes back as the revs return to idle
- While idling, there is a CEL. The CEL goes away at >3000 rpm, but comes back <2000 rpm
- The ECU will occasionally store a 31 code - open or short circuit on MAP sensor input
At the moment I suspect either the MAP sensor or coil/ignitor. I can't see how the MAP sensor would cause bouncing tacho, as the tacho is driven directly from the ignitor, but the ignitor wouldn't be causing MAP sensor codes :( I've done as many BGB tests as I could: - ECU provides power & ground to the MAP sensor. I have no vacuum pump to do the signal tests, however.
- BGB says resistance of primary coil should be 0.4-0.5 Ω. Mine measures at 1.5 Ω.
- BGB says resistance of secondary coil should be 10-14 kΩ. Mine measures at 13 kΩ.
- BGB has no tests for ignitor, so nothing done there.
Anyone have any ideas, or has a known-good MAP sensor and/or ignitor & coils package they'd be willing to lend me? Thanks for any help you can give!
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Mrskylighter
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/07 11:02:36
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My suggestion is to try a different ecu with the correct part number in your car to see if there is any change. You could also take the cover off your ecu and check for blown capacitors.
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Eric
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/07 11:40:03
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Kain
Anyone have any ideas, or has a known-good MAP sensor and/or ignitor & coils package they'd be willing to lend me? Thanks for any help you can give!
Hi Kain, I believe that I have a map sensor, ignitor etc at home. I'll have a look for you tonight. You're welcome to borrow them and if they work you can swing me some cash for them, say $50? they are no use to me. I'm located on the south side
1990 SW20 Hardtop - Supercharged 2GR-FZE
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Kain
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/07 13:38:46
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Thanks Eric, swing me a PM when you've had a chance to take a look!
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Guest
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/07 15:00:21
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Had a similar issue with idle, fixed by removing the sensors from the coolant neck in the engine bay, wiped the end with smooth sandpaper to refresh the surface and reinstalled.
I also cleaned the throttle body (spray cleaner), as well as dialled up the air screw in the throttle body so when warmed it would sit on about 950rpm.
I think your issues are more involved.... possibly refreshing rotar and distro, sorting out your fault code, general service items (spark plugs, check timing / timing belt (that timing belt is firm and has not stretched or the pin not pushing to create correct tension)....
Good luck,
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5SGTE
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/07 17:07:42
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Pop the cover off your ecu n check the caps are good. Easy to do before replacing a heap of potentially unneeded parts.
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Kain
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/08 11:17:39
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Thanks Tony, all good ideas! Most of that I've checked - it's got a new dizzy (I rebuilt mine and the NE coil lost a connection somewhere  ), plugs have been checked, timing belt tension is good (was an issue before, brand new tensioner was DOA), cam timing has been checked. Just got to sort the fault code, all indications are that the sensor is faulty. 5SGTE, great idea, I never thought to actually look for a failure mode in the ECU. I've just pulled it out and checked it - I've never seen a 26yr old PCB so spotless! All components look perfect, and no flaws in the board or coating. Thanks for the ideas guys, keep them coming!
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Carmikey
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/08 12:31:29
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Kain,
Have you tried testing & seeing if you have or are getting fuel from pump?
An easy way to confirm, you can loop a wire from the FB to the B+ (same place when you loop to get fault codes) & then switch on ignition, as soon as switch on key to ign, you will hear the FB activate, (buzzing sound), if that works, proceed & crank it over & see how it runs.
Once it is running you should be able to disconnect the loop wire... then see what happens ;-)
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Kain
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/08 14:14:03
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My mechanic did with a dodgy test - he cracked the banjo bolt on top of the fuel filter, and when cranking there was enough pressure to have a decent jet of fuel spray out.
I like your method much better, to be honest :P
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James2
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/08 14:39:35
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That test only confirms operation of fuel pump... not whether it is creating enough pressure, or if the FPR is doing its job. Not really a fan of that test! Surely he had an adapter that would have allowed him to plumb a gauge to read the line pressure.
You can't always see the capacitors failing on an ecu. Unless you try a known working one of the same part# you haven't 100% eliminated it as a possible failure mode.
has ignition timing been checked?
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Reddtarga
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/08 15:20:27
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One thing I found that causes strange idling problems after a 3sge motor swap. If any of the small hoses from the end of the intake manifold to the ACIS, as well as the routing down on the side of the intake manifold that goes to the fuel regulator valve have been removed and not put back correctly. The 2 vacuum valves there should also be tested for correct operation. You would need the service manual diagram to check that out. This one-> http://www.mr2australia.com/mr2play/tm.aspx?m=87772Look on page EG 266 and EG 269 Even though the manual is for the gen3 motor it also applies to the gen2.
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Kain
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Re: [BNE] Borrow a 3SGE Rev2 ECU?
2016/09/09 09:05:56
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Thanks guys, I appreciate all the suggestions and input!
You're right James, but at that point the only question was 'do we have air, fuel & spark', in the initial stages of diagnosis. Fair point on the ECU as well, I haven't crossed it off the list but there are more likely suspects to pursue first - that MAP sensor code is the next on my hit list. By ignition timing I assume you mean static timing/adjustment of the dizzy - yeah that's been checked.
Reddtarga - None of those vac lines were removed, but I will check them out. I don't have much experience in telling the difference between the two, but my issue doesn't seem like a vac-leak though, more like ignition breakup/problems. Thanks for the engine manual too, I've got the gen2 version but more reference material is always good :D
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