ecu isnt clever enough to detect missfire caused by headgasket it only know when some thing is wrong on the electrical side of things
Technical failed mot emissions
- Thread starter seanhyde
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Technical failed mot emissions
cheers Dave
Update I cleared the codes .I removed and replaced HT connectors to coil packs and re fitted ( they were not over snug ). I removed and checked the other connections to coil packs and applied dialectic grease as described by Fingers. I think thats what he meant me to do. My daughter has taken the car for a 15 mile run .NO engine light has returned. I used my cheapo gunsons gas tester and (also put some cataclean stuff in before the long drive) CO readings now -1.8 ( it moves about a bit so hard to nail exact figure).
Even though my gas tester is probably crap and not accurate it does show a fall in CO levels is this good ?
Update I cleared the codes .I removed and replaced HT connectors to coil packs and re fitted ( they were not over snug ). I removed and checked the other connections to coil packs and applied dialectic grease as described by Fingers. I think thats what he meant me to do. My daughter has taken the car for a 15 mile run .NO engine light has returned. I used my cheapo gunsons gas tester and (also put some cataclean stuff in before the long drive) CO readings now -1.8 ( it moves about a bit so hard to nail exact figure).
Even though my gas tester is probably crap and not accurate it does show a fall in CO levels is this good ?
Interesting . I just found an old thread started by me from August 2013 entitled P0300. It seems the same codes as I'm getting now. this was after fitting new head gasket, coil packs,leads,spark plugs etc. This must be the same thing? I'm guessing dodgy connections .cos the code went away for a few months and they've gone now. One other thing when I pushed the car hard up long hill on duel carraigeway the engine light flashed at me. I eased off the throttle and it stopped flashing ? It's always done this.
i'd seal them exhaust leaks too, they can affect emission readings,
Yes the exhaust leaks? Not sure what to do here. Any one any experience of sealant or some stuff to use in /around the joints ? From reading I'm not sure how good the stuff is? I know there are lots of exhaust sealants in car spares shop. MOT man did not seem concerned ?
FAILED
So got up this morning started car engine light on again.Drove the car for 40 mins before test. MOT man stopped the test said he knew it was going to fail. 02 reading about 1.6. I asked if he could do some diagnostics to work out the problem. He seemed to think there was an air leak somewhere causing it to misfire slightly. He talked about fixing it up to some smoke machine to track down leaks. Does this sound plausable or is there anything I can do betweeen now and Monday to try and find the cause of the misfire.
Thanks
So got up this morning started car engine light on again.Drove the car for 40 mins before test. MOT man stopped the test said he knew it was going to fail. 02 reading about 1.6. I asked if he could do some diagnostics to work out the problem. He seemed to think there was an air leak somewhere causing it to misfire slightly. He talked about fixing it up to some smoke machine to track down leaks. Does this sound plausable or is there anything I can do betweeen now and Monday to try and find the cause of the misfire.
Thanks
Any leaks will effect what the MOT tester sees at the tailpipe.Leaks before cat is bad leaks after, not so bad. If it didn't fail on it I wouldn't worry about it. To paste it/seal it you need to pull it apart really
A leak in itself is not a failure point.
Yes, that is a common way of finding little leaks.
Thanks
I thought I'd also add the engine management light has always flashed when the car is driven hard at motorway speeds. I'm sure I read in the handbook that one should slow down until light stops flashing which is what we always do. I just add this as extra info. Over the 4 years of ownership random multiple misfire keeps popping up before and after the various Head gasket changes I've done.
Recap .Last August I re did the Head Gasket (3rd time). At the same time I replaced plugs, leads and coil packs.
I thought I'd also add the engine management light has always flashed when the car is driven hard at motorway speeds. I'm sure I read in the handbook that one should slow down until light stops flashing which is what we always do. I just add this as extra info. Over the 4 years of ownership random multiple misfire keeps popping up before and after the various Head gasket changes I've done.
Recap .Last August I re did the Head Gasket (3rd time). At the same time I replaced plugs, leads and coil packs.
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you know where exhaust leaks are as you have said you see the soot coming out, to check for air leaks around inlet system just spray carb cleaner around, if engine note changes you have found a leak
I don't understand why you've replaced the head gasket so often or why you're driving it with the EML flashing. A (very) occasional flash is one thing -- for it to keep happening is something else. This may be of some use.
Multiple random misfire should have nothing to do with the head gasket. And head gasket failures almost invariably have an underlying cause: as a well known thrasher and abuser of Centos, I've had one (suspect) HG failure in 10 years -- I didn't bother to check as I wanted to pop a better head on anyway!
When were the plugs and leads last replaced?
Ok
The head gasket went 3/4 years ago.Then I had a problem with noisy tappets . I fiddled with re shimming those and something was wrong ,so I bought Head from you a couple of years ago I think . The head gasket went on this in august.It was a clean break in the gasket between two of the cylinders. I only mention this as the back story. There is no evidence that there is something wrong with Head gasket now.
Car failing on 02 only/nothing else (reading 1.6) . Random multiple misfire is the theme since I've had the car. And the flashing engine light when driving over say 65/70 on motorway. As soon as this happens I back off a tiny bit and it stops.
When the head gasket went in August I replaced both coil packs ,HT leads and plugs.
ON theme of air leaks as suggested by MOT man ( who listened to the engine and said he could hear a slight misfire and feel it when he fran car at higher revs). I just lifted the air filter box to look at any hoses or pipes that could be leaking air. I found what I can only describe as oily deposits on the butterfly opening going into Throttle body ? (the bit that replaces a carb). I then wonderer whether the breather pipe on bottom of air box that goes to manifold and down to some other pipe was connected properly ? would this be a clue or a red Herring?
The head gasket went 3/4 years ago.Then I had a problem with noisy tappets . I fiddled with re shimming those and something was wrong ,so I bought Head from you a couple of years ago I think . The head gasket went on this in august.It was a clean break in the gasket between two of the cylinders. I only mention this as the back story. There is no evidence that there is something wrong with Head gasket now.
Car failing on 02 only/nothing else (reading 1.6) . Random multiple misfire is the theme since I've had the car. And the flashing engine light when driving over say 65/70 on motorway. As soon as this happens I back off a tiny bit and it stops.
When the head gasket went in August I replaced both coil packs ,HT leads and plugs.
ON theme of air leaks as suggested by MOT man ( who listened to the engine and said he could hear a slight misfire and feel it when he fran car at higher revs). I just lifted the air filter box to look at any hoses or pipes that could be leaking air. I found what I can only describe as oily deposits on the butterfly opening going into Throttle body ? (the bit that replaces a carb). I then wonderer whether the breather pipe on bottom of air box that goes to manifold and down to some other pipe was connected properly ? would this be a clue or a red Herring?
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Not uncommon to find some deposits on the TB (or even the inlet manifold). Unless it's actually fuming (pull off the oil filler cap with the engine up to temp and running) I'd not worry.
But the random misfire points to ECU, leads, plugs, coils, I'd think. I'd suspect the flashing of the EML is a lambda on its way out (or perhaps even reacting to the misfire).
May be worthwhile clearing the codes and driving until the EML comes on, then re-read. Or better yet, if the code reader will do live readings (many will) clear them and go for a drive.
But, as per before, you have an issue with one coil pack on the low tension side.
Thanks fingers
Have no access to code reader at moment . I've asked a seperate question on this .I've ordered myself a cheap one off ebay as mate can't find his and young lad with Torq pro on his phone is at work.Would Torque pro app give live data if I got the lad to come with me on a drive and see what info we get. If this possible what data am I looking for ?
" But, as per before, you have an issue with one coil pack on the low tension side." How do you know this and how do I sort it? Buy another coil pack? I just tried rmoving HT leads from coil pack one at a time. Each removal has an effect on the engine
Have no access to code reader at moment . I've asked a seperate question on this .I've ordered myself a cheap one off ebay as mate can't find his and young lad with Torq pro on his phone is at work.Would Torque pro app give live data if I got the lad to come with me on a drive and see what info we get. If this possible what data am I looking for ?
" But, as per before, you have an issue with one coil pack on the low tension side." How do you know this and how do I sort it? Buy another coil pack? I just tried rmoving HT leads from coil pack one at a time. Each removal has an effect on the engine
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Not sure -- worth a go, though! If it won't do live, chances are you can just keep it connected and it'll flag up the first fault.
Ill try when he gets back from work.
Found an old thread "P0300 seicento" I logged on as seanhyde12 as forgot password, you were helping me fingers. It seems we are continuing the same conversation as the fault was there then, the head gasket had gone ,but as part of diagnosing I changed HT leads coil packs ,plugs.
when I got car running the p0300 came up .
Found an old thread "P0300 seicento" I logged on as seanhyde12 as forgot password, you were helping me fingers. It seems we are continuing the same conversation as the fault was there then, the head gasket had gone ,but as part of diagnosing I changed HT leads coil packs ,plugs.
when I got car running the p0300 came up .
P0351 as discussed earlier. The fault is on the low tension side, not the HT side, so is likely to be the connector on top of one of the coil packs or the wiring to it. Changing the coil itself isn't likely to be the issue.
Fingers Thanks for your time once more .I thought I'd start at the beginning.so
1. checked all spark plugs. All look the same and good
2.Removed ht leads one at a time and checked spark. spark looked strong on all. but had a slight feeling middle two (2 and 3 ,left to right looking from front top of engine) were slightly weaker
3. removed the two pin connector from each coil pack one at a time to see what would happen. With rear coil pack only connected no start, with front coil pack connected engine starts and runs. I tried this twice with same result.
Does this mean one of my new coil packs is faulty ?
1. checked all spark plugs. All look the same and good
2.Removed ht leads one at a time and checked spark. spark looked strong on all. but had a slight feeling middle two (2 and 3 ,left to right looking from front top of engine) were slightly weaker
3. removed the two pin connector from each coil pack one at a time to see what would happen. With rear coil pack only connected no start, with front coil pack connected engine starts and runs. I tried this twice with same result.
Does this mean one of my new coil packs is faulty ?
