Toyspeed.org.nz Message Board

by **nmcgowan** » Sun Sep 13, 2009 4:20 pm

Apologies for the lengthy description but hopefully it helps explain things fully.
I have a 20V silvertop in an AE82 Corolla GT thats caged and used for trackdays. Silvertop is totally stock standard running standard ECU. It has run without any problems for over 20,000 kms including numerous trackdays and has never missed a beat, all of a sudden driving home the other night it did a single solitary misfire as I was on the motorway offramp and I was like WTF was that?? by the time I'd gotten home some 2km's later it was missing like crazy, occasionally backfiring, had no power and was struggling to rev. At the time it was really low on fuel so I assumed it was running out of petrol. I took it out later that night to fill it up, more of the same misfire and now the car was really struggling to drive. I filled it up and discovered it wasnt as low on gas as I first thought (slightly unreliable fuel gauge) so it wasnt a low fuel issue.
I stopped on the side of the road and turned the car off, opened the bonnet and checked nothing obvious had come off, AFM connector, plug leads, vaccuum hoses etc and found nothing. I started the car and drove off and it revved just fine and had normal power like there was never a problem. About 500 meters later the misfire returned just like before and it really struggled to make it home.

At idle the car doesnt appear to have any misfire at all. If you bury the throttle wide open it bogs horribly and will miss and backfire and stall out unless you back right off. If you give it throttle slowly it will miss but revs will eventually climb to about 3500 and wont get any further, just more missing, bogging and backfiring.

I have done the following in the way of troubleshooting so far.
1) Checked the spark plugs - all appear ok
2) Checked the leads - appear ok
3) Pulled the plugs out and checked that they are sparking - they are but perhaps a little weakly, spark is a weak yellowy colour? Not sure what a normal spark looks like on a 4AGE thats running ok, I thought it should be a blueish colour?
4) Pulled out and cleaned AFM and checked plug and wiring.
5) Swapped distributor cap and rotor.
6) Checked engine codes and there are none except the O2 sensor, but thats fine as Its never had an O2 sensor since I've owned it.
7) Cleared engine codes, ran engine and re-checked, still no other codes.
8. Checked earths and wiring for any obvious issues.
9) Moved sensor wiring and vacuum hoses etc while attempting to rev engine to see if there was a dodgy connection anywhere, no change to misfire.
10) Pulled the injector plugs one at a time and there was a noticeable drop in idle for each one so I dont think its injectors.
11) Pulled the fuel line off the engine side of the fuel filter and there is plenty of flow and pressure and I can hear the fuel pump running.

After 10 or so minutes of blipping the throttle while wiggling the wires and pipes under the bonnet with no success I turned the car off to think some more about it. I had another look through the wiring and fuseboxes and gave everything a good wiggle to see if anything was loose, started the car and it ran fine again for another 10-15 seconds, revved freely, no misfire, no bogging down with WOT then the misfire returned just as before.

I've checked the wires to to the ignitor and coil and pulled the cables and connectors off and on to check they are secure. Is there any way to check the ignitor and coil are ok? I've heard theres not really much to the ignitors and that its just a big transistor so perhaps it's the coil?

There is also a slight smell of petrol that I havent noticed before so again this is leading me to believe it a spark/ignition issue.

The symptoms are very similar to what happened when I forgot to put a big vaccuum hose back on after doing the clutch once but I can't for the life of me see any pipes that have come off and I can't hear any leaks.

ANY help greatly appreciated, this is driving me nuts!!!

by **Crampy** » Sun Sep 13, 2009 4:33 pm

Where are you located?
Could just try swapping in another coil and ignitor and see how it goes (which is what the problem sounds like to me).

Could try the one off my Silvertop if your out West Auckland way.

by **nmcgowan** » Sun Sep 13, 2009 5:50 pm

One Tree Hill. Hey thanks for the offer but I might be able to save you the hassle as I have a mate (FXGT_race) that has exactly the same setup but with a full race prepped Blacktop. He might have a coil and ignitor I could borrow and he's about 5 minutes away. Hopefully he has some in his miscellaneous spares collection!

by **xsspeed** » Sun Sep 13, 2009 6:43 pm

May still have a spare 20v coil and ign. Just down the rd in mt eden, let me know if you get stuck finding one

by **Mr Revhead** » Sun Sep 13, 2009 11:21 pm

possibly the famous ecu or afm faults

by **nmcgowan** » Mon Sep 14, 2009 11:12 am

Thanks for the suggestion. I had another google/youtube session last night about how to check dodgy ignition and I couldn't seem to find any faults, I rechecked the spark in the garage with the light off and the spark seems to be blue, consistent and strong during cranking. The plugs themselves however are now covered in carbon where they werent before so its either over fuelling or ignition issue under load. Also did a vacuum leak check with some carb cleaner and didnt find anything.

So I guess Im left with swapping bits till I find the fault.

1) AFM
2) Coil/ignitor
3) ECU

Actually...When it ran ok for 10-15 seconds last time it was right after I'd just removed the ECU to check the cabling. Maybe I should pull it out and open the case to see if theres anything visibly wrong (swollen capacitor etc)

by **Crampy** » Mon Sep 14, 2009 3:54 pm

My offer still stands:
I have coil/ignitor, ECU and AFM you could try swapping in to check things.

Problem would be getting to car here though hehehe. Or I could travel, for some refreshing beverages.

by **YeMs** » Mon Sep 14, 2009 6:06 pm

check timing. sounds like the timing is way out, or 1 of the cams has skipped a tooth.

by **nmcgowan** » Sat Sep 19, 2009 9:23 pm

(sigh) Have now swapped out AFM, Coil/ignitor and ECU...nothing has helped. Im going to get under the dash tomorrow and check the earths. Also having said that...the ignitor I got today was totally stuffed, car wouldnt even fire till I swapped back to the old one.

YeMs, Thanks for the suggestion but if the timing was out or if it had skipped a cambelt tooth Im not sure how *very* intermittently it could run ok? All said and done I think the car is running worse and worse the more I test things, of course the plugs are pretty much f'd now so maybe its just that, I'll swap them out with some others I have tomorrow and see if it really is running worse.

Would a dodgy knock sensor cause it to run rich or misfire? I read in my Haynes manual today that knock sensor is integral to ignition along with the coil/ignitor.

...still no codes either from the ECU.

by **levinguy** » Sat Sep 19, 2009 10:57 pm

i would definantly check the computer for leaking caps.

i really did not think much of this until a few problems with my blacktop until, i pulled the computer out, what do you know, leaking caps on the computer.

by **Mr Revhead** » Sun Sep 20, 2009 11:57 am

knock sensor won't cause that

It could be the caps.... weird coincidence that it decides to fail just as you try to start it after having it all apart

by **MR2BOY23** » Sun Sep 20, 2009 12:05 pm

All this sounds so familiar

Same thing happend to mine, I kept driving it and the car cut out eventually and never started again

Changing the igniter and coil fixed everything there was a problem with the ecu as well

by **nmcgowan** » Mon Sep 21, 2009 3:00 pm

So another afternoon yesterday spent troubleshooting with the spares I bought on Saturday. I now have the ECU, coil, ignitor and AFM from another AE101 silvertop manual (Pickapart Takanini btw)

Through swapping the bits over and trying different combinations It doesnt look like any of the parts are faulty, unless the spares I bought are dodgy aswell!

Swap coil and or ignitor (ignitor wasnt working the other day as I didnt have it grounded properly.)...still misses. Swap AFM, still misses. Swap ECU same thing...but I did find that I can't run a code check on the 2nd ECU which is totally weird! The check engine light is just solid when you connect TE1 to E1, no flashing. If I put the old ECU back in I can get codes again (still the same old O2 sensor code). And I tried resetting the 2nd ECU of course. The 2nd ECU does start the car but its still misses. I opened both ECU's and they appear totally mint, no swollen or burst caps.

I also ran a two step check on my original ECU and it brought up the speed sensor error just as it should have as the car was stationary but it found no other errors.

I've tried swapping all the parts out and just about every combination between them incase its a fault with more than one item and still no joy.

I had the really weird thing again yesterday where once the car was hot I turned it off and was resetting the ECU, fired the car back up and it ran mint and revved freely for about 10 secs before missing again. I also noticed the idle changing as if something were trying to change the mixture. So I started looking at water temp sensor but it appears to be working just fine and the resistance is well within the norm of what the manuals say. I do have another temp sensor but I really dont think thats the issue.

I was asking about the knock sensor as this was the paragraph in the Haynes manual that had me thinking after YeMs mentioned about timing.
Granted this is an AE82 manual so maybe its not applicable to the 20V.
"Chapter 6 Page 9"
Electronic Spark Control
18 The ESC system has two major components, the ESC module, which is part of the ECU, and the ESC knock sensor.
19 The ESC knock sensor detects abnormal detonation in the engine. The sensor is mounted in the block near the cylinders. The ESC module receives the knock sensors information and sends a signal to the ECU. The ECU then adjusts the timing to reduce detonation. If a failure should occur a code 52 or 53 will be set.

Oh and just to clarify, I did the clutch about 1500kms ago and it had been running fine so its not a 'post surgery' non-starting issue.

Im on the verge of taking it down (thank god its mostly downhill form my house!) to a mechanic in Penrose as Im really stuck and pretty much out of ideas now. Im just worried that being a hybrid wiring loom will complicate matters and they'll spend days trying to work it out.

orrr...does anyone know of a reliable mobile mechanic in the One Tree Hill area who's knowledgeable about Toyotas? Id rather pay someone whos clued up on Toyotas than have them stare blankly at me when I tell them I've got an AE101 20V in an AE82.

by **Mr Revhead** » Mon Sep 21, 2009 3:04 pm

sorry, i thought i was replying to the guy who had just done his clutch and now it won't run right. too many dodgy 20vs! :lol:

did you look real hard at the caps? it can be bloody hard to spot

by **nmcgowan** » Mon Sep 21, 2009 3:06 pm

Haha no worries...I'll go and grab them out of the car again and have another look but what are the chances of getting two dodgy ECU's? (thinks about it for a second) ...Yeah I'll go check them again. =)

by **Mr Revhead** » Mon Sep 21, 2009 3:08 pm

while your there check the plug etc

by **Paulio** » Mon Sep 21, 2009 3:43 pm

Sux to be you dude.

Throwing ideas around, you sure its not fuel related, fuel leak, part line blockage, fuel pump failing? Seems strange that once the pump primes the line & builds up a little pressure, it will run fine for a few seconds, then once that prime is gone it will bog again.

Also make sure that the timing is set properly.

by **nmcgowan** » Mon Sep 21, 2009 10:12 pm

My original ECU is clean as a whistle inside, no leaking capacitors. The other ECU I got from Pickapart does have one leaky capacitor so maybe that explains the check engine light issue?

Plug has a teeny bit of damage on the plastic case in one corner of the largest plug but its superficial Other than that the wiring was all snugly cabled tied up under the dash.

Paulio, 99% of the time it has the misfire, it is only occasionally (like 3 times since it originally started doing it) that it will run fine on a subsequent restart. Also the plugs are sooty and black and have a strong smell of petrol which Is why Im thinking fuel is ok and spark is the issue.

Would a timing issue explain the symptoms? But then how does it explain the brief periods where it runs fine? The TPS and distributor arent loose..Ive checked the bolts on them and a jumped cambelt tooth would make the car run like pants all the time.

Does anyone have a crystal ball and/or magic wand?

by **Lloyd** » Mon Sep 21, 2009 11:41 pm

Have you actually tried new plugs in it yet?

by **MAGN1T** » Tue Sep 22, 2009 12:11 am

nmcgowan wrote:Does anyone have a crystal ball and/or magic wand?

You can't assume that the capacitors aren't leaking unless you remove them. That's because you can't always see the leaks as they're under the capacitor.
Once you've done that, you may as well put new ones into it.

How about a pic of the sparkplugs?

Steve

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Strange 20V Silvertop Misfire - FIXED!

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