Engine Backfiring and Unable to Diagnose.

Goeman · August 30, 2011, 00:07

Quote from: "ChrisGB"Defective rev counter, is it reading right or are you just running into the limiter and not knowing it?

Definitely not that one. s:shock: :shock: s:shock: Doesn't sound right and hasn't got the power to be hitting the limiter. Also new alternator was fitted before Christmas so that is unlikely to be at fault.

Could this be the greatest mystery the MR2roc has ever faced?

I'm not very good with electrics but I'm competent and I will try most of these things when I get home off of the rig.

What about specialist diagnosticians who are familiar with MR2 roadsters. Are there any? Any decent specialists at all worth going to? Anyone who's a bit bored want to have a crack at it?

Dyn-Evo · August 30, 2011, 23:12

If I was closer, I would defo have a pop at it.....! s:? :? s:?

Anonymous · August 31, 2011, 09:30

if it pops vry loud and sparks a flame, does that mean its running to rich?

Goeman · August 31, 2011, 09:37

Quote from: "blackskylinegtr"if it pops vry loud and sparks a flame, does that mean its running to rich?

That's a negative on that one. No flames and not very loud. Don't think it's a mixture problem.

Anonymous · August 31, 2011, 11:53

For what it's worth, I had very similar problems on my 200sx years ago.

I replaced the maf with a second hand one. The wiring wasn't quite right and it ran, ticked over and revved to a point. Then it popped farted and banged like the timing was out.

I'd swap your maf over, could have a short.

Or I could be completely wrong. Just trying to share a bit of experience.

Goeman · August 31, 2011, 11:55

Quote from: "Ron jeremy"I'd swap your maf over, could have a short.

I've tried a brand new MAF. Didn't change a thing.

Anonymous · August 31, 2011, 12:20

Quote from: "Ron jeremy"For what it's worth, I had very similar problems on my 200sx years ago.

I replaced the maf with a second hand one. The wiring wasn't quite right and it ran, ticked over and revved to a point. Then it popped farted and banged like the timing was out.

I'd swap your maf over, could have a short.

Or I could be completely wrong. Just trying to share a bit of experience.

u might be right, my mate told me it might been the timing from his past experience. cleaned it twice in 12k miles. i don't have a spare maf to test, but if anyone around essex harlow and doesn't mind helping, please let me know

dan_daran · August 31, 2011, 18:25

I know a little of a long shot but someone with an elise had a similar problem turned out to be one of the relays the" multi function relay" or somthing that controlled the fuel pump aswell as other things , also you may have a bad earth maybe check/run another grounding wire from the block to earth or batt(-)?
i guess its not possible for the timing chain to slip a cog causing timing to be wildly out ? maybe somthing is vibrating somwhere causing the knock sensor to pull timing ,are the all the spark plugs fouled or is there one which is v.bad? so far i think the valve spring idea fits as it happens load of no load but seems a long shot

Goeman · August 31, 2011, 18:40

The sparkplugs that I removed were all identical and in good condition. No physical sign of anything wrong with the mixture.

normanh · August 31, 2011, 18:56

Sticky injector, see that on another guys car here, I would have sworn it was plug/coilpack but was an injector.

norman

Anonymous · August 31, 2011, 20:03

try crank position with another owners to try i really think it might be that just a good gut feeling. ive even got a spare if your willing to pay postage just name the part you want to try.

Anonymous · August 31, 2011, 20:06

Quote from: "blackskylinegtr"
Quote from: "Ron jeremy"For what it's worth, I had very similar problems on my 200sx years ago.

I replaced the maf with a second hand one. The wiring wasn't quite right and it ran, ticked over and revved to a point. Then it popped farted and banged like the timing was out.

I'd swap your maf over, could have a short.

Or I could be completely wrong. Just trying to share a bit of experience.

u might be right, my mate told me it might been the timing from his past experience. cleaned it twice in 12k miles. i don't have a spare maf to test, but if anyone around essex harlow and doesn't mind helping, please let me know

if you come round mine 1 day you can try 1 of the mafs i have car not needing them at this point.

Anonymous · September 1, 2011, 12:29

Quote from: "rbuckingham"
Quote from: "blackskylinegtr"
Quote from: "Ron jeremy"For what it's worth, I had very similar problems on my 200sx years ago.

I replaced the maf with a second hand one. The wiring wasn't quite right and it ran, ticked over and revved to a point. Then it popped farted and banged like the timing was out.

I'd swap your maf over, could have a short.

Or I could be completely wrong. Just trying to share a bit of experience.

u might be right, my mate told me it might been the timing from his past experience. cleaned it twice in 12k miles. i don't have a spare maf to test, but if anyone around essex harlow and doesn't mind helping, please let me know

if you come round mine 1 day you can try 1 of the mafs i have car not needing them at this point.

you have PM

Goeman · December 11, 2011, 22:54

Right. I'll update this so that anyone else who has this problem in the future can at least search the forum and get an answer.

Everyone who said Crank Position Sensor can have a chuffty badge. The sensor itself wasn't faulty (hence no CEL) but it had a very poor earth. It looks like the water pump was weeping and coolant had crystallised around the crank sensor giving it a bad ground. There is also a secondary theory that at higher RPM my none OEM/Denso alternator was interfering with nearby wire for the sensor. I had already bought a new sensor so it was swapped out along with a 2nd hand OEM alternator (and water pump) and hay presto problem solved.

All credit to MattPerformance for solving this problem which was beyond me and Toyota

K T M Rider · December 11, 2011, 23:23

excellent news.

you must be well chuffed. s:bounce: :bounce: s:bounce:

Just in time for winter s:roll: :roll: s:roll:

Cap · December 11, 2011, 23:24

Thanks for the Information.. would have been Nice to have THE actual fix.. But your Problem is now gone.. and that is the Point..

The Crank Position Sensor does not get grounded .. So the Fuz, is not it.. But it still could have been a Bad Sensor..

This Chased you around for a While.. Glad yo got it Fixed.. Persistence and Bull-Headedness.. always pays off..

Cap

Goeman · December 12, 2011, 00:13

Quote from: "Cap"The Crank Position Sensor does not get grounded .. So the Fuz, is not it.. But it still could have been a Bad Sensor..

Then what's that wire attached to the bolt for if not to earth the sensor? It's clearly visible in the pictures. I think we can confidently say that it was related to the crank sensor and if anyone else encounters this difficult to track down problem then it's a good place to look. I'm sure Matt could tell you more than I can as he's now very familiar with it.

I'm very please that the car is fixed. I haven't driven the car yet as it's still with Matt getting lots of track orientated parts fitted and lots of underbody rust proofing done. I hope to collect the car by xmas/new years and then it's trackdays aplenty as I've got lots of lost time to catch up on.

Cap · December 13, 2011, 02:38

Quote from: "Goeman"Then what's that wire attached to the bolt for if not to earth the sensor? It's clearly visible in the pictures.

Good Question.. the Coils for the Sensor are Non-Grounded Inputs.. ( Double Ended for the Electronic Type )... So I hit the Wire Diagrams..

It's Likely a Shield for the Wire, to Prevent Interference.. BUT the Wire Diagram only shows the Shield Grounded Up in the Harness in one Place.. and it shares the Same Shield ground as the Cam Sensor..

So I'll have to dig Some More..

Still glad you got it..

Cap

ChrisGB · December 13, 2011, 09:17

Quote from: "Cap"
Quote from: "Goeman"Then what's that wire attached to the bolt for if not to earth the sensor? It's clearly visible in the pictures.

Good Question.. the Coils for the Sensor are Non-Grounded Inputs.. ( Double Ended for the Electronic Type )... So I hit the Wire Diagrams..

It's Likely a Shield for the Wire, to Prevent Interference.. BUT the Wire Diagram only shows the Shield Grounded Up in the Harness in one Place.. and it shares the Same Shield ground as the Cam Sensor..

So I'll have to dig Some More..

Still glad you got it..

Cap

If the shielding is not grounded correctly it becomes ineffective, so the signal in the cable will be subject to interference.

Chris

Goeman · December 13, 2011, 18:27

Quote from: "ChrisGB"If the shielding is not grounded correctly it becomes ineffective, so the signal in the cable will be subject to interference.

Chris

From the none OEM/Denso alternator which is sort of what we speculated. It was the last thing changed on the car before the misfire appeared although there was a 6-7 week gap. Rather than just do one thing at a time we decided it's just easier to change both. The same thing might still have occurred with an OEM alternator but we didn't want to chance it.

aaronjb · December 13, 2011, 19:10

Maybe it's something to do with your location, Russell .. I mean, the North Sea must be a pretty harsh environment for a car! s;)

s;)

At least you fixed it in the end - fingers crossed the fault stays away, now s:)

s:)

Goeman · December 13, 2011, 19:14

From the rust that has accumulated this year it looked like it'd been in the north sea.

At the moment it's harsh environment for a person out here. It's a case of 'Batten down the hatches!' tonight. I'm glad I work indoors.

aaronjb · December 13, 2011, 19:31

Quote from: "Goeman"From the rust that has accumulated this year it looked like it'd been in the north sea.

Mine too - and mine lives well inland! I'm sure Toyota took their cues from ex British Leyland engineers when they designed the rust proofing procedures for the chassis..

QuoteAt the moment it's harsh environment for a person out here. It's a case of 'Batten down the hatches!' tonight. I'm glad I work indoors.

Given how the weather was here last night, I don't envy you being in the middle of the sea in this!